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Krejčí V, Murínová I, Slanař O, Šíma M. Evidence for Therapeutic Drug Monitoring of Atypical Antipsychotics. Prague Med Rep 2024; 125:101-129. [PMID: 38761044 DOI: 10.14712/23362936.2024.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2024] Open
Abstract
Second-generation antipsychotics (SGAs), also known as atypical antipsychotics, are a newer class of antipsychotic drugs used to treat schizophrenia, bipolar disorder, and related psychiatric conditions. The plasma concentration of antipsychotic drugs is a valid measure of the drug at its primary target structure in the brain, and therefore determines the efficacy and safety of these drugs. However, despite the well-known high variability in pharmacokinetics of these substances, psychiatric medication is usually administered in uniform dosage schedules. Therapeutic drug monitoring (TDM), as the specific method that can help personalised medicine in dose adjustment according to the characteristics of the individual patient, minimizing the risk of toxicity, monitoring adherence, and increasing cost-effectiveness in the treatment, thus seems to be an elegant tool to solve this problem. Non-response to therapeutic doses, uncertain adherence to medication, suboptimal tolerability, or pharmacokinetic drug-drug interactions are typical indications for TDM of SGAs. This review aims to summarize an overview of the current knowledge and evidence of the possibilities to tailor the dosage of selected SGAs using TDM, including the necessary pharmacokinetic parameters for personalised pharmacotherapy.
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Affiliation(s)
- Veronika Krejčí
- Department of Clinical Pharmacy, Military University Hospital Prague, Prague, Czech Republic.
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.
| | - Irena Murínová
- Department of Applied Pharmacy, Faculty of Pharmacy, Masaryk University, Brno, Czech Republic
- Department of Clinical Pharmacy, Military University Hospital Prague, Prague, Czech Republic
| | - Ondřej Slanař
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Martin Šíma
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
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Tsukahara M, So R, Yoshimura Y, Yamashita R, Yada Y, Kodama M, Nakajima S, Kishi Y, Takeda T, Yamada N, Takeuchi H. Effect of smoking habits and concomitant valproic acid use on relapse in patients with treatment-resistant schizophrenia receiving clozapine: A 1-year retrospective cohort study. Acta Psychiatr Scand 2023; 148:437-446. [PMID: 37681448 DOI: 10.1111/acps.13612] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/09/2023]
Abstract
INTRODUCTION No study has investigated the impact of smoking habits and concomitant valproic acid (VPA) use on clinical outcomes in maintenance treatment with clozapine. Thus, we aimed to examine the effect of smoking habits and concomitant VPA use on relapse during the first year after discharge in patients with treatment-resistant schizophrenia (TRS) receiving clozapine. METHODS This retrospective cohort study included patients with TRS who were initiated on clozapine during hospitalization and discharged between April 2012 and January 2021 in two tertiary psychiatric hospitals in Japan. Relapse was defined as rehospitalization due to psychiatric exacerbation during the first year after discharge. A multivariable Cox proportional hazards regression analysis was performed to analyze the effect of smoking habits and concomitant VPA use on relapse. Subgroup analyses were also conducted to examine potential interactions between smoking habits and concomitant VPA use. RESULTS Among the included 192 patients, 69 (35.9%) met the criteria of relapse. While smoking habits (adjusted hazard ratio [aHR], 2.27; 95% confidence interval [CI], 1.28-4.01; p < 0.01) independently increased the risk of relapse, a significant interaction for relapse risk was found between smoking habits and concomitant VPA use (p-interaction = 0.015). Concomitant VPA use may be an effective modifier of the increased relapse risk associated with smoking habits. Among patients who smoked, those using VPA concomitantly exhibited a higher risk of relapse (aHR, 5.32; 95% CI, 1.68-16.9; p < 0.01) than those not using VPA (aHR, 1.41; 95% CI, 0.73-2.70; p = 0.30). CONCLUSION The findings suggest that the combination of smoking habits and concomitant VPA use may increase the risk of relapse after discharge. Future studies are required to elucidate the mechanisms underlying these findings, such as a decrease in clozapine blood levels.
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Affiliation(s)
- Masaru Tsukahara
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | - Ryuhei So
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | | | | | - Yuji Yada
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | - Masafumi Kodama
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | - Shinichiro Nakajima
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Yoshiki Kishi
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | | | - Norihito Yamada
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | - Hiroyoshi Takeuchi
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
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Besag FMC, Berry D, Vasey MJ, Patsalos PN. Drug-drug interactions between antiseizure medications and antipsychotic medications: a narrative review and expert opinion. Expert Opin Drug Metab Toxicol 2023; 19:829-847. [PMID: 37925741 DOI: 10.1080/17425255.2023.2278676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
INTRODUCTION Antiseizure medications (ASMs) and antipsychotic drugs are frequently coadministered with the potential for drug-drug interactions. Interactions may either be pharmacokinetic or pharmacodynamic, resulting in a decrease or increase in efficacy and/or an increase or decrease in adverse effects. AREAS COVERED The clinical evidence for pharmacokinetic and pharmacodynamic interactions between ASMs and antipsychotics is reviewed based on the results of a literature search in MEDLINE conducted in April 2023. EXPERT OPINION There is now extensive published evidence for the clinical importance of interactions between ASMs and antipsychotics. Enzyme-inducing ASMs can decrease blood concentrations of many of the antipsychotics. There is also evidence that enzyme-inhibiting ASMs can increase antipsychotic blood concentrations. Similarly, there is limited evidence showing that antipsychotic drugs may affect the blood concentrations of ASMs through pharmacokinetic interactions. There is less available evidence for pharmacodynamic interactions, but these can also be important, as can displacement from protein binding. The lack of published evidence for an interaction should not be interpreted as meaning that the given interaction does not occur; the evidence is building continually. There is no substitute for careful patient monitoring and sound clinical judgment.
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Affiliation(s)
- Frank M C Besag
- Child and Adolescent Mental Health Services (CAMHS), East London NHS Foundation Trust, Bedford, UK
- School of Pharmacy, University College London, London, UK
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Dave Berry
- Toxicology Unit, Kings College Hospital, London, UK
| | - Michael J Vasey
- Child and Adolescent Mental Health Services (CAMHS), East London NHS Foundation Trust, Bedford, UK
| | - Philip N Patsalos
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK
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Tralongo F, Konecki C, Feliu C, Kaladjian A, Djerada Z. Association Between Clozapine Plasma Concentrations and Treatment Response: A Systematic Review, Meta-analysis and Individual Participant Data Meta-analysis. Clin Pharmacokinet 2023; 62:807-818. [PMID: 37145296 DOI: 10.1007/s40262-023-01247-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2023] [Indexed: 05/06/2023]
Abstract
BACKGROUND AND OBJECTIVES Although therapeutic drug monitoring of clozapine is recommended, its optimisation is often adjusted only on the basis of dosage. The aim of this study was to assess the link between clozapine plasma concentrations and clinical response by a meta-analysis of published studies and by an individual participant data meta-analysis. METHODS We conducted a computerised search of bibliographic databases (EMBASE, PubMed, Clinical Trials, and Web of Science) to identify studies that assessed the relationship between clozapine serum or plasma concentrations and clinical efficacy. Using pooled data, we investigated the association between improvement of clinical outcome and clozapine or norclozapine plasma concentrations, the sum of clozapine and norclozapine plasma concentrations, and the coefficient of variation of clozapine plasma concentrations. Using available individual data, we assessed the relationship between clozapine plasma concentrations and clinical response (changes in the Brief Psychiatric Rating Scale score) and identified a threshold level for a favourable clinical response. RESULTS Fifteen studies satisfied inclusion criteria. Our meta-analysis showed that responders had clozapine plasma concentrations that were, on average, 117 ng/mL higher than non-responders. The patients with plasma clozapine concentrations above the thresholds identified in each study had a higher likelihood of responding (odds ratio = 2.94, p < 0.001). Norclozapine plasma concentrations were not associated with a clinical response. The meta-analysis of individual data supported this result and confirmed the link between clozapine concentrations and a change in the Brief Psychiatric Rating Scale score and/or the probability of clinical response. Finally, with the analysis of the coefficient of variation of clozapine plasma concentrations, we found that a greater inter-individual fluctuation in plasma concentrations was associated with a loss of clinical response. CONCLUSIONS Our work confirmed that, in contrast to clozapine doses, clozapine plasma concentrations were related to a favourable clinical response, with a mean difference between responders and non-responders of 117 ng/mL. A threshold for a treatment response of 407 ng/mL was determined, with a high discriminatory capacity, and a sensitivity and specificity of 71% and 89.1%, respectively.
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Affiliation(s)
- Federica Tralongo
- Department of Pharmacology, University of Reims Champagne-Ardenne, HERVI EA 3801, Reims University Hospital, Reims, France
- Department of Psychiatry, Marne Public Mental Health Institution, Reims University Hospital, Reims, France
| | - Céline Konecki
- Department of Pharmacology, University of Reims Champagne-Ardenne, HERVI EA 3801, Reims University Hospital, Reims, France
| | - Catherine Feliu
- Department of Pharmacology, University of Reims Champagne-Ardenne, HERVI EA 3801, Reims University Hospital, Reims, France
| | - Arthur Kaladjian
- Department of Psychiatry, Marne Public Mental Health Institution, Reims University Hospital, Reims, France
| | - Zoubir Djerada
- Department of Pharmacology, University of Reims Champagne-Ardenne, HERVI EA 3801, Reims University Hospital, Reims, France.
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Masumo Y, Kanahara N, Kogure M, Yamasaki F, Nakata Y, Iyo M. Dopamine supersensitivity psychosis and delay of clozapine treatment in patients with treatment-resistant schizophrenia. Int Clin Psychopharmacol 2023; 38:102-109. [PMID: 36719338 DOI: 10.1097/yic.0000000000000442] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Both the underutilization of clozapine and treatment resistance of patients to clozapine are serious problems worldwide. Identifying clinical markers predicting response to clozapine would help clinicians more effectively utilize clozapine treatment. The present study retrospectively assessed dopamine supersensitivity psychosis (DSP) in addition to other measures such as age at disease onset and delay of clozapine introduction for a total of 47 treatment-resistant schizophrenia (TRS) patients. The response to clozapine was judged with CGI-C at 1 and 2 years from clozapine introduction. Results revealed that the DSP group tended to have a longer delay between designation of TRS and introduction of clozapine and continued to have slightly more severe psychopathology after treatment with clozapine, showing only slight improvement. The logistic regression analysis showed that the age at disease onset was the only significant indicator, predicting responsiveness to clozapine: patients with an onset age <20 years had a significantly better response to clozapine than patients with an onset age ≥20 years. The present study suggests that DSP might be related to a longer delay in clozapine introduction and the persistence of refractory symptoms despite clozapine treatment, whereas early age of disease onset might be related to a better response to clozapine.
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Affiliation(s)
- Yuto Masumo
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba
- Department of Psychiatry, Naoki-kai Isogaya Hospital, Ichihara
| | - Nobuhisa Kanahara
- Division of Medical Treatment and Rehabilitation, Center for Forensic Mental Health, Chiba University, Chiba
- Shirayuri-kai Ichihara Tsuruoka Hospital, Ichihara, Japan
| | - Masanobu Kogure
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba
| | - Fumiaki Yamasaki
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba
| | - Yusuke Nakata
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba
| | - Masaomi Iyo
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba
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Feasibility and Effect of Increasing Clozapine Plasma Levels in Long-Stay Patients With Treatment-Resistant Schizophrenia. J Clin Psychopharmacol 2023; 43:97-105. [PMID: 36825865 DOI: 10.1097/jcp.0000000000001657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
BACKGROUND It is unknown whether increasing the clozapine plasma level to 400, 750, or even 1000 ng/mL is a feasible and effective strategy in patients with treatment-resistant schizophrenia (TRS). We investigated this in long-stay patients with TRS. METHODS In long-stay TRS patients, doses of clozapine were increased gradually to reach target plasma levels of 400, 750, or 1000 ng/mL, depending on the clinical response and tolerability. After an effective or tolerated level was reached, positive and negative syndrome scale scores were evaluated after 3 months and 1 year. RESULTS Twenty-eight patients were included. Overall, 54% of the patients, and especially patients 60 years and older, could not achieve one of the clozapine target levels because of adverse effects. Three physically vulnerable patients died, probably not directly related to clozapine use. Although only 21% of patients achieved a more than 20% reduction in total symptoms at the 1-year follow-up, the mean severity of positive symptoms decreased from 18.18 to 15.10 ( P < 0.01). The largest decrease in positive symptoms was seen in TRS patients who achieved a plasma level of 750 ng/mL of clozapine. CONCLUSIONS Most TRS patients older than 60 years could not tolerate high clozapine levels and so this should not be attempted in older or otherwise physically vulnerable patients. Increasing clozapine levels to approximately 750 ng/mL in middle-aged patients with longstanding TRS may modestly reduce the severity of positive symptoms and improve the response rate.
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Sangüesa E, Cirujeda C, Concha J, Padilla PP, García CB, Ribate MP. Pharmacokinetic interactions between clozapine and valproic acid in patients with treatment-resistant schizophrenia: Does UGT polymorphism affect these drug interactions? Chem Biol Interact 2022; 364:110042. [PMID: 35853541 DOI: 10.1016/j.cbi.2022.110042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/13/2022] [Indexed: 11/29/2022]
Abstract
The combination of valproic acid (VPA) and clozapine (CLZ) is regularly prescribed for augmentation therapy in treatment resistant schizophrenia. The VPA has been shown to reduce norclozapine (NCLZ) plasma levels, but the mechanism of this interaction remains unknown. The aim of this study is to examine the differences between patients treated with CLZ and patients treated with CLZ plus VPA. For it, various factors have been evaluated. The study was based on plasma samples from CLZ and CLZ plus VPA treated patients (n = 61) subjected to routine therapeutic drug monitoring considering clinical data, smoking status, daily dose of CLZ and VPA, concomitant medications, albumin, and renal and hepatic function. Genotyping of polymorphisms of CYP1A2, CYP3A4/5, CYP2C19, ABCB1, UGT2B10 and CYP2C19 were performed by real time PCR. CYP2D6 were genotyped using competitive allele-specific PCR and by a long PCR based method. Plasma CLZ and NCLZ concentrations were measured by Liquid Chromatography-Tandem masses (LC-MS/MS) and plasma VPA by Ultraviolet-Visible (UV-vis) spectrophotometric immunoassay. The patients presented adequate CLZ levels in relation to the dose. However, NCLZ levels were excessively low and the CLZ/NCLZ ratio very high. Patients with UGT2B10 GT (rs61750900) genotype showed lower NCLZ plasma levels and C/D NCLZ, and higher CLZ/NCLZ ratio versus patients with UGT2B10 GG genotype. VPA, smoking, the presence of UGT2B10 GT genotype and having low albumin levels indicate that the CLZ/NCLZ ratio is affected, mostly coinciding with decreased NCLZ levels and possibly with an increased risk of neutropenia.
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Affiliation(s)
- Estela Sangüesa
- Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego- Zaragoza, Spain
| | - Christine Cirujeda
- Centro Neuropsiquiátrico Nuestra Señora del Carmen, Hermanas Hospitalarias, Zaragoza, Spain
| | - Julia Concha
- Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego- Zaragoza, Spain
| | - Pedro Pablo Padilla
- Centro Neuropsiquiátrico Nuestra Señora del Carmen, Hermanas Hospitalarias, Zaragoza, Spain
| | - Cristina Belén García
- Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego- Zaragoza, Spain.
| | - María Pilar Ribate
- Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego- Zaragoza, Spain
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Adverse Drug Reactions in Relation to Clozapine Plasma Levels: A Systematic Review. Pharmaceuticals (Basel) 2022; 15:ph15070817. [PMID: 35890117 PMCID: PMC9317288 DOI: 10.3390/ph15070817] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
Clozapine is the gold standard for treatment-resistant schizophrenia. Serious and even life-threatening adverse effects, mostly granulocytopenia, myocarditis, and constipation, are of great clinical concern and constitute a barrier to prescribing clozapine, thus depriving many eligible patients of a lifesaving treatment option. Interestingly, clozapine presents variable pharmacokinetics affected by numerous parameters, leading to significant inter- and intra-individual variation. Therefore, therapeutic drug monitoring of plasma clozapine levels confers a significant benefit in everyday clinical practice by increasing the confidence of the prescribing doctor to the drug and the adherence of the patient to the treatment, mainly by ensuring effective treatment and limited dose-related side effects. In the present systematic review, we aimed at identifying how a full range of adverse effects relates to plasma clozapine levels, using the Jadad grading system for assessing the quality of the available clinical evidence. Our findings indicate that EEG slowing, obsessive-compulsive symptoms, heart rate variability, hyperinsulinemia, metabolic syndrome, and constipation correlate to plasma clozapine levels, whereas QTc, myocarditis, sudden death, leucopenia, neutropenia, sialorrhea, are rather unrelated. Rapid dose escalation at the initiation of treatment might contribute to the emergence of myocarditis, or leucopenia. Strategies for managing adverse effects are different in these conditions and are discussed accordingly.
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Vickers M, Ramineni V, Malacova E, Eriksson L, McMahon K, Moudgil V, Scott J, Siskind D. Risk factors for clozapine-induced myocarditis and cardiomyopathy: A systematic review and meta-analysis. Acta Psychiatr Scand 2022; 145:442-455. [PMID: 35067911 DOI: 10.1111/acps.13398] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/25/2021] [Accepted: 12/18/2021] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Clozapine is the most effective medication for treatment-refractory schizophrenia, but it is associated with severe cardiac adverse events including myocarditis and cardiomyopathy. To aid treatment decision-making for clinicians, patients and their carers, we conducted a systematic review and meta-analysis to identify potential risk factors for clozapine-induced myocarditis and cardiomyopathy. METHODS A systematic search was conducted of PubMed, Embase, CINAHL, Web of Science, Cochrane and PsycInfo for studies reporting myocarditis and cardiomyopathy among people on clozapine and potential risk factors. We calculated pooled effect sizes on risk factors using a random-effects meta-analytic model. Risk of publication bias was assessed using the Newcastle-Ottawa scale. RESULTS Seven studies met the inclusion criteria, of which six studies had quantitative data included in the meta-analysis. The odds of clozapine-induced myocarditis increased with concurrent sodium valproate use (k = 6, n = 903, pooled OR 3.58, 95% CI 1.81-7.06), but were not significantly greater with the use of quetiapine, lithium or selective serotonin reuptake inhibitors. Our qualitative review identified conflicting results reported for increasing age and higher clozapine dose as risk factors for myocarditis. No other factors, including genetic risk, sex, ethnicity, smoking, alcohol, substance abuse or cardiometabolic disease, were associated with greater odds of myocarditis. No risk factors for cardiomyopathy were identified in the literature. CONCLUSION Concurrent use of sodium valproate increases the odds of clozapine-induced myocarditis. Thus, clinicians should consider the temporary cessation of sodium valproate during the initial titration phase of clozapine.
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Affiliation(s)
- Mark Vickers
- Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.,Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.,Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Vinay Ramineni
- Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.,Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Eva Malacova
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Lars Eriksson
- Herston Health Sciences Library, University of Queensland, Brisbane, Queensland, Australia
| | - Kirsten McMahon
- Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.,Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Vikas Moudgil
- Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.,Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - James Scott
- Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.,QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Dan Siskind
- Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.,Queensland Centre for Mental Health Research, Brisbane, Queensland, Australia.,Metro South Addiction and Mental Health Service, Brisbane, Queensland, Australia
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Hassab Errasoul A, Alarabi MA. Factors predicting serum clozapine levels in Middle Eastern patients: an observational study. BMC Psychiatry 2022; 22:269. [PMID: 35428222 PMCID: PMC9011948 DOI: 10.1186/s12888-022-03910-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 04/01/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Despite its superiority over other drugs for psychosis, clozapine remains underused and is associated with many clinical challenges, including difficulties in predicting therapeutic serum levels (350-600 ng/mL). We found no large or recent study that investigated the determinants of serum clozapine levels in Middle Eastern patients. Therefore, we investigated the association between clozapine dose and serum level, and the clinical predictors of the clozapine serum level, in Middle Eastern patients. METHODS This cross-sectional study included 94 patients of Middle Eastern ethnicity who attended the Clozapine Clinic in King Saud University Medical City in Riyadh, Saudi Arabia. We used a single measure of the serum clozapine level, which was collected 12 h after the last oral dose of clozapine under steady-state conditions. RESULTS The average clozapine dose and serum level were 400 mg/daily and 705 ng/mL, respectively. The majority of patients (59.8%) had serum levels higher than 600 ng/mL. Clozapine dose and serum level were positively correlated (rs [94] = 0.32, p = 0.002). We generated a predictive model of the serum clozapine level, which revealed that the daily dose, smoking status, use of fluvoxamine or lamotrigine, and body mass index (BMI) predicted 43.6% of the variance in the serum level (p < 0.001). Using this model, we calculated that patients with a BMI of 25 kg/m2 would require a clozapine dose between 50 to 275 mg/daily if they were non-smokers, and a dose of 200 to 450 mg/daily if they were smokers, in order to reach a serum clozapine level between 350 to 600 ng/mL. Patients with higher BMI and those receiving fluvoxamine would require lower doses. CONCLUSIONS This was a naturalistic study of the clozapine dose-level relationship and the clinical predictors of the serum clozapine level in a sample of Middle Eastern patients. The ratios of clozapine level to dose in our patients more closely resembled those reported in Asian samples than in European samples. These findings do not reduce the value of individualised therapeutic drug monitoring, but may assist clinicians when prescribing clozapine to Middle Eastern patients. Further psychopharmacological studies are needed on this demographic population.
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Affiliation(s)
- Ahmed Hassab Errasoul
- grid.56302.320000 0004 1773 5396Department of Psychiatry, College of Medicine, King Saud University, PO Box 7805, Riyadh, 11472 Kingdom of Saudi Arabia
| | - Mohammed A. Alarabi
- grid.56302.320000 0004 1773 5396Department of Psychiatry, College of Medicine, King Saud University, PO Box 7805, Riyadh, 11472 Kingdom of Saudi Arabia
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de Leon J, Schoretsanitis G, Smith RL, Molden E, Solismaa A, Seppälä N, Kopeček M, Švancer P, Olmos I, Ricciardi C, Iglesias-Garcia C, Iglesias-Alonso A, Spina E, Ruan CJ, Wang CY, Wang G, Tang YL, Lin SK, Lane HY, Kim YS, Kim SH, Rajkumar AP, González-Esquivel DF, Jung-Cook H, Baptista T, Rohde C, Nielsen J, Verdoux H, Quiles C, Sanz EJ, Las Cuevas CD, Cohen D, Schulte PFJ, Ertuğrul A, Yağcıoğlu AEA, Chopra N, McCollum B, Shelton C, Cotes RO, Kaithi AR, Kane JM, Farooq S, Ng CH, Bilbily J, Hiemke C, López-Jaramillo C, McGrane I, Lana F, Eap CB, Arrojo-Romero M, Rădulescu FŞ, Seifritz E, Every-Palmer S, Bousman CA, Bebawi E, Bhattacharya R, Kelly DL, Otsuka Y, Lazary J, Torres R, Yecora A, Motuca M, Chan SKW, Zolezzi M, Ouanes S, Berardis DD, Grover S, Procyshyn RM, Adebayo RA, Kirilochev OO, Soloviev A, Fountoulakis KN, Wilkowska A, Cubała WJ, Ayub M, Silva A, Bonelli RM, Villagrán-Moreno JM, Crespo-Facorro B, Temmingh H, Decloedt E, Pedro MR, Takeuchi H, Tsukahara M, Gründer G, Sagud M, Celofiga A, Ristic DI, Ortiz BB, Elkis H, Pacheco Palha AJ, LLerena A, Fernandez-Egea E, Siskind D, Weizman A, Masmoudi R, Saffian SM, Leung JG, Buckley PF, Marder SR, Citrome L, Freudenreich O, Correll CU, Müller DJ. An International Adult Guideline for Making Clozapine Titration Safer by Using Six Ancestry-Based Personalized Dosing Titrations, CRP, and Clozapine Levels. PHARMACOPSYCHIATRY 2021; 55:73-86. [PMID: 34911124 DOI: 10.1055/a-1625-6388] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This international guideline proposes improving clozapine package inserts worldwide by using ancestry-based dosing and titration. Adverse drug reaction (ADR) databases suggest that clozapine is the third most toxic drug in the United States (US), and it produces four times higher worldwide pneumonia mortality than that by agranulocytosis or myocarditis. For trough steady-state clozapine serum concentrations, the therapeutic reference range is narrow, from 350 to 600 ng/mL with the potential for toxicity and ADRs as concentrations increase. Clozapine is mainly metabolized by CYP1A2 (female non-smokers, the lowest dose; male smokers, the highest dose). Poor metabolizer status through phenotypic conversion is associated with co-prescription of inhibitors (including oral contraceptives and valproate), obesity, or inflammation with C-reactive protein (CRP) elevations. The Asian population (Pakistan to Japan) or the Americas' original inhabitants have lower CYP1A2 activity and require lower clozapine doses to reach concentrations of 350 ng/mL. In the US, daily doses of 300-600 mg/day are recommended. Slow personalized titration may prevent early ADRs (including syncope, myocarditis, and pneumonia). This guideline defines six personalized titration schedules for inpatients: 1) ancestry from Asia or the original people from the Americas with lower metabolism (obesity or valproate) needing minimum therapeutic dosages of 75-150 mg/day, 2) ancestry from Asia or the original people from the Americas with average metabolism needing 175-300 mg/day, 3) European/Western Asian ancestry with lower metabolism (obesity or valproate) needing 100-200 mg/day, 4) European/Western Asian ancestry with average metabolism needing 250-400 mg/day, 5) in the US with ancestries other than from Asia or the original people from the Americas with lower clozapine metabolism (obesity or valproate) needing 150-300 mg/day, and 6) in the US with ancestries other than from Asia or the original people from the Americas with average clozapine metabolism needing 300-600 mg/day. Baseline and weekly CRP monitoring for at least four weeks is required to identify any inflammation, including inflammation secondary to clozapine rapid titration.
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Affiliation(s)
- Jose de Leon
- Mental Health Research Center, Eastern State Hospital, Lexington, KY, USA.,Department of Psychiatry, University of Kentucky, Lexington, KY, USA.,Psychiatry and Neurosciences Research Group (CTS-549), Institute of Neurosciences, University of Granada, Granada, Spain.,Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apostol Hospital, University of the Basque Country, Vitoria, Spain
| | - Georgios Schoretsanitis
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zürich, Zürich, Switzerland.,The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, New York, USA
| | - Robert L Smith
- Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway
| | - Espen Molden
- Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway.,Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Anssi Solismaa
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Department of Psychiatry, Tampere University Hospital, Tampere, Finland
| | | | - Miloslav Kopeček
- National Institute of Mental Health, Klecany, Czech Republic.,Department of Psychiatry, Charles University, Third Faculty of Medicine, Prague, Czech Republic
| | - Patrik Švancer
- National Institute of Mental Health, Klecany, Czech Republic.,Department of Psychiatry, Charles University, Third Faculty of Medicine, Prague, Czech Republic
| | - Ismael Olmos
- Clinical Pharmacology Unit and Pharmacy Department, Vilardebó Hospital, Administración de Servicios de Salud, Montevideo, Uruguay
| | - Carina Ricciardi
- Clinical Pharmacology Unit and Outpatient Clinic, Vilardebó Hospital, Administración de Servicios de Salud, Montevideo, Uruguay
| | - Celso Iglesias-Garcia
- Universidad de Oviedo. CIBERSAM. INEUROPA. ISPA-FIMBA, Oviedo, Spain.,Hospital Valle del Nalón, Langreo, Spain
| | | | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Can-Jun Ruan
- Laboratory of Clinical Psychopharmacology, Beijing Anding Hospital, Capital Medical University, Beijing, China.,The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | - Chuan-Yue Wang
- The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China.,Department of Psychiatry, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | - Gang Wang
- The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | - Yi-Lang Tang
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia, USA.,Substance Abuse Treatment Program, Atlanta VA Medical Center, Decatur, Georgia, USA
| | - Shih-Ku Lin
- Department of Psychiatry, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.,Department of Psychiatry, School of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Hsien-Yuan Lane
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.,Department of Psychiatry and Brain Disease Research Center, China Medical University Hospital, Taichung, Taiwan.,Department of Psychology, College of Medical and Health Sciences, Asia University, Taichung, Taiwan
| | - Yong Sik Kim
- Department of Neuropsychiatry, Nowon Eulji Medical Center, Eulji University, School of Medicine, Seoul, Korea
| | - Se Hyun Kim
- Department of Psychiatry, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Anto P Rajkumar
- Department of Psychiatry, Christian Medical College, Vellore, India.,Institute of Mental Health, Jubilee Campus, University of Nottingham, Triumph Road, Nottingham, United Kingdom
| | | | - Helgi Jung-Cook
- Instituto Nacional de Neurología y Neurocirugía, México City, México.,Facultad de Química, Universidad Nacional Autónoma de México (UNAM), México City, México
| | - Trino Baptista
- Department of Physiology, Los Andes University Medical School, Mérida, Venezuela
| | - Christopher Rohde
- Department of Affective Disorders, Aarhus University Hospital - Psychiatry, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Jimmi Nielsen
- Mental Health Centre Glostrup, Copenhagen University Hospital, Copenhagen, Denmark
| | - Hélène Verdoux
- Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, Team Pharmacoepidemiology, UMR 1219, F-33000 Bordeaux, France
| | - Clelia Quiles
- Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, Team Pharmacoepidemiology, UMR 1219, F-33000 Bordeaux, France
| | - Emilio J Sanz
- Department of Physical Medicine and Pharmacology, School of Medicine, Universidad de La Laguna, Canary Islands, Spain.,Hospital Universitario de Canarias, Tenerife, Spain
| | - Carlos De Las Cuevas
- Department of Internal Medicine, Dermatology and Psychiatry, School of Medicine, and Instituto Universitario de Neurociencia (IUNE), University of La Laguna, Canary Islands, Spain
| | - Dan Cohen
- Dutch Clozapine Collaboration Group, Castricum, The Netherlands.,FACT-team in Heerhugowaard, Department of Severe Mental Illness, Mental Health Services North-Holland North, The Netherlands
| | - Peter F J Schulte
- Dutch Clozapine Collaboration Group, Castricum, The Netherlands.,Mental Health Team Alkmaar, Mental Health Services Noord-Holland-Noord, Alkmaar, The Netherlands
| | - Aygün Ertuğrul
- Department of Psychiatry, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | | | - Nitin Chopra
- Addictions Division, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | | | - Charles Shelton
- Department of Psychiatry, University of Kentucky, Lexington, KY, USA.,Eastern State Hospital, Lexington, Kentucky, USA
| | - Robert O Cotes
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - John M Kane
- The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, New York, USA.,Department of Psychiatry and Molecular Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell Hempstead, New York, USA
| | - Saeed Farooq
- School of Medicine, Keele University, Staffordshire, and Midlands Partnership NHS Foundation Trust, Staffordshire, United Kingdom
| | - Chee H Ng
- Department of Psychiatry, The University of Melbourne, Melbourne, Victoria, Australia
| | - John Bilbily
- Department of Psychiatry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Christoph Hiemke
- Department of Psychiatry and Psychotherapy, University Medical Center of Mainz, Germany
| | - Carlos López-Jaramillo
- Grupo de Investigación en Psiquiatría GIPSI, Departamento de Psiquiatría, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia.,Programa Trastornos del Ánimo, Hospital Universitario San Vicente Fundación, Medellín, Colombia
| | - Ian McGrane
- Department of Pharmacy Practice, University of Montana, Missoula, USA
| | - Fernando Lana
- Institute of Neuropsychiatry and Addictions (INAD), Parc de Salut Mar, Barcelona, Spain.,Department of Psychiatry, Autonomous University of Barcelona, Spain
| | - Chin B Eap
- Unit of Pharmacogenetics and Clinical Psychopharmacology, Center for Psychiatric Neurosciences, Lausanne University Hospital and University of Lausanne, Switzerland.,Center for Research and Innovation in Clinical Pharmaceutical Sciences, Lausanne University Hospital and University of Lausanne, Switzerland.,School of Pharmaceutical Sciences, University of Geneva, Switzerland.,Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, University of Lausanne, Switzerland
| | - Manuel Arrojo-Romero
- Department of Psychiatry, Complejo Hospitalario Universitario de Santiago, Santiago de Compostela, Spain
| | - Flavian Ş Rădulescu
- Center for Drug Sciences, Faculty of Pharmacy, University of Medicine and Pharmacy Carol Davila, Bucharest, Romania
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zürich, Zürich, Switzerland
| | - Susanna Every-Palmer
- Te Korowai Whāriki Central Regional Forensic Service, Capital and Coast District Health Board, Wellington, New Zealand.,Department of Psychological Medicine, University of Otago, Wellington, New Zealand
| | - Chad A Bousman
- Departments of Medical Genetics, Psychiatry, Physiology & Pharmacology, and Community Health Sciences University of Calgary, Alberta, Canada
| | - Emmanuel Bebawi
- Faculty of Medicine, University of Montreal, Montreal, Canada.,Department of Pharmacy, Hôpital du Sacré-Cœur de Montréal, Montreal, Canada
| | - Rahul Bhattacharya
- East London NHS Foundation Trust, London, United Kingdom.,Honorary Clinical Senior Lecturer, Barts and the London School of Medicine, Queen Mary University of London, United Kingdom
| | - Deanna L Kelly
- Department of Psychiatry, School of Medicine, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yuji Otsuka
- Department of Psychiatry, Asahi General Hospital, Chiba, Japan
| | - Judit Lazary
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
| | - Rafael Torres
- Department of Psychiatry, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Agustin Yecora
- Secretaría de Salud Mental y Adicciones, Ministerio de Salud de la Provincia de Jujuy, San Salvador de Jujuy, Argentina
| | - Mariano Motuca
- Instituto Vilapriño, Center for Studies, Assistance and Research in Neurosciences, Mendoza, Argentina
| | - Sherry K W Chan
- Department of Psychiatry, LSK Faculty of Medicine, The University of Hong Kong, Hong Kong SAR.,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR
| | - Monica Zolezzi
- College of Pharmacy, QU Health, Qatar University, Doha, Qatar
| | - Sami Ouanes
- Department of Psychiatry, Hamad Medical Corporation, Doha, Qatar
| | | | - Sandeep Grover
- Department of Psychiatry, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Ric M Procyshyn
- British Columbia Mental Health and Substance Use Research Institute, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | | | - Oleg O Kirilochev
- Department of Clinical Pharmacology, Astrakhan State Medical University, Astrakhan, Russian Federation
| | - Andrey Soloviev
- Department of Psychiatry and Clinical Psychology, Northern State Medical University, Arkhangelsk, Russia
| | - Konstantinos N Fountoulakis
- 3rd Department of Psychiatry, Division of Neurosciences, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece
| | - Alina Wilkowska
- Department of Psychiatry, Medical University of Gdańsk, Gdańsk, Poland
| | - Wiesław J Cubała
- Department of Psychiatry, Medical University of Gdańsk, Gdańsk, Poland
| | - Muhammad Ayub
- Department of Psychiatry, Queens University, Kingston, Canada
| | - Alzira Silva
- Psychiatry Department, Centro Hospitalar Universitário de S. João, Porto, Portugal., Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | | | - José M Villagrán-Moreno
- Department of Neurosciences, Jerez University Hospital, Andalusian Health Service, University of Cadiz, Jerez, Spain
| | - Benedicto Crespo-Facorro
- Department of Psychiatry, School of Medicine, University Hospital Virgen del Rocio-IBIS, Sevilla, Spain., Spanish Network for Research in Mental Health (CIBERSAM), Sevilla, Spain
| | - Henk Temmingh
- Department of Psychiatry and Mental Health, University of Cape Town, Valkenberg Hospital, Western Cape, Cape Town, South Africa
| | - Eric Decloedt
- Division of Clinical Pharmacology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | | | - Hiroyoshi Takeuchi
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Masaru Tsukahara
- Department of Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan
| | - Gerhard Gründer
- Central Institute of Mental Health, Department of Molecular Neuroimaging, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Marina Sagud
- Department of Psychiatry, School of Medicine, University of Zagreb, Zagreb, Croatia.,Department for Psychiatry and Psychological Medicine, University Hospital Center Zagreb, Croatia
| | - Andreja Celofiga
- Department of Psychiatry, University Medical Centre Maribor, Maribor, Slovenia
| | | | - Bruno B Ortiz
- Group of Resistant Schizophrenia (GER), Schizophrenia Program (Proesq), Federal University of Sao Paulo, SP, Brazil
| | - Helio Elkis
- Department and Institute of Psychiatry, University of São Paulo Medical School (FMUSP), Sao Paulo, Brazil
| | - António J Pacheco Palha
- Department and Institute of Psychiatry and Mental Health, Oporto Faculty of Medicine, Oporto, Portugal.,Casa de Salidedo Som Jesus (Psychiatric Hospital), Oporto, Portugal
| | - Adrián LLerena
- INUBE Biosanitary Research Institute of Extremadura. Extremadura University Hospital and Medical School, Badajoz, Spain.,Spanish Network for Research in Mental Health (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain
| | - Emilio Fernandez-Egea
- Cambridge Psychosis Centre, Cambrigeshire and Peterborough NHS Foundation Trust & Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
| | - Dan Siskind
- Metro South Addiction and Mental Health Service, Brisbane, Australia.,Queensland Centre for Mental Health Research and School of Clinical Medicine, University of Queensland, Brisbane, Australia
| | - Abraham Weizman
- Research Unit, Geha Mental Health Center and Molecular Psychiatry Laboratory, Felsenstein Medical Research Center, Tel Aviv, Israel.,Department of Psychiatry Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Rim Masmoudi
- Psychiatry "A" Department, Hedi Chaker University Hospital, Sfax, Tunisia.,Faculty of Medicine, University of Sfax, Sfax, Tunisia
| | - Shamin Mohd Saffian
- Centre for Quality Management of Medicines, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | | | - Peter F Buckley
- School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Stephen R Marder
- Semel Institute for Neuroscience at UCLA, Los Angeles, CA, USA.,VA Desert Pacific Mental Illness Research, Education, and Clinical Center, Los Angeles, CA, USA
| | - Leslie Citrome
- New York Medical College, Department of Psychiatry and Behavioral Sciences, Valhalla, NY, USA
| | - Oliver Freudenreich
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Christoph U Correll
- The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, New York, USA.,Department of Psychiatry and Molecular Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell Hempstead, New York, USA.,Charité Universitätsmedizin Berlin, Department of Child and Adolescent Psychiatry, Berlin, Germany
| | - Daniel J Müller
- Addictions Division, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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12
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Siskind D, Sharma M, Pawar M, Pearson E, Wagner E, Warren N, Kisely S. Clozapine levels as a predictor for therapeutic response: A systematic review and meta-analysis. Acta Psychiatr Scand 2021; 144:422-432. [PMID: 34374073 DOI: 10.1111/acps.13361] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Clozapine levels may be a more useful predictor of therapeutic response than the dose, given the variability in clozapine metabolism between individuals. We therefore systematically reviewed and meta-analysed the impact of clozapine levels on response and/or relapse to provide guidance on optimal clozapine levels. METHODS We systematically searched PubMed, PsycInfo and Embase for studies exploring clozapine levels and response and/or relapse. Our primary meta-analysis was rates of response above and below clozapine level thresholds of 350 ng/ml and 600 ng/ml. Secondary analyses were undertaken of mean clozapine levels, dose and concentration/dose (C/D) ratio and response and/or relapse. A meta-regression by study duration was conducted. RESULTS Twenty studies met inclusion criteria. Clozapine levels above 350 ng/ml were associated with statistically significantly higher rates of response (OR 2.27 95% CI 1.40-3.67, p < 0.001), but not above 600 ng/ml (OR 1.40 95% CI 0.85-2.31, p = 0.19). Higher mean clozapine levels were associated with better rates of response (SMD 0.24, 95% CI 0.00-0.49, p = 0.05), and lower rates of relapse (SMD -0.72, 95% CI -1.26 to -0.19, p = 0.008). By contrast, neither clozapine dose nor C/D ratio was associated with differing rates of response. Similarly, study duration did not affect outcome. CONCLUSIONS Our findings are in keeping with current guidelines that recommend targeting clozapine levels above 350 ng/ml before augmentation is considered. As some clozapine associated ADRs are dose dependent, levels above 600 ng/ml may have an unfavourable risk-benefit ratio.
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Affiliation(s)
- Dan Siskind
- Metro South Addiction and Mental Health Service, Brisbane, QLD, Australia.,School of Clinical Medicine, University of Queensland, Brisbane, QLD, Australia.,Physical and Mental Health Stream, Queensland Centre for Mental Health Research, Brisbane, QLD, Australia
| | - Meghna Sharma
- School of Clinical Medicine, University of Queensland, Brisbane, QLD, Australia.,Cairns Base Hospital, Cairns, QLD, Australia
| | - Mrinal Pawar
- School of Clinical Medicine, University of Queensland, Brisbane, QLD, Australia.,Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
| | - Ella Pearson
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Elias Wagner
- Department of Psychiatry and Psychotherapy, University Hospital, LMU Munich, Munich, Germany
| | - Nicola Warren
- Metro South Addiction and Mental Health Service, Brisbane, QLD, Australia.,School of Clinical Medicine, University of Queensland, Brisbane, QLD, Australia.,Physical and Mental Health Stream, Queensland Centre for Mental Health Research, Brisbane, QLD, Australia
| | - Steve Kisely
- Metro South Addiction and Mental Health Service, Brisbane, QLD, Australia.,School of Clinical Medicine, University of Queensland, Brisbane, QLD, Australia.,Physical and Mental Health Stream, Queensland Centre for Mental Health Research, Brisbane, QLD, Australia.,Departments of Psychiatry, Community Health and Epidemiology, Dalhousie University, Halifax, NS, Canada
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13
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Lee J, Kim MG, Jeong HC, Shin KH. Physiologically-based pharmacokinetic model for clozapine in Korean patients with schizophrenia. Transl Clin Pharmacol 2021; 29:33-44. [PMID: 33854999 PMCID: PMC8020364 DOI: 10.12793/tcp.2021.29.e3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 12/18/2022] Open
Abstract
Clozapine has been used as a treatment of schizophrenia. Despite its large interindividual variability, few reports addressed the physiologically-based pharmacokinetic modeling and simulation (PBPK M&S) of clozapine in patients. This study aimed to develop a PBPK M&S of clozapine in Korean patients with schizophrenia. PBPK modeling for clozapine was constructed using a population-based PBPK platform, the SimCYP® Simulator (V19; Certara, Sheffield, UK). The PBPK model was developed by optimizing the physiological parameters of the built-in population and compound libraries in the SimCYP® Simulator. The model verification was performed with the predicted/observed ratio for pharmacokinetic parameters and visual predictive checks (VPCs) plot. Simulations were performed to predict toxicities according to dosing regimens. From published data, 230 virtual trials were simulated for each dosing regimen. The predicted/observed ratio for the area under the curve and peak plasma concentration was calculated to be from 0.78 to 1.34. The observation profiles were within the 5th and 95th percentile range with no serious model misspecification through the VPC plot. A significant impact on age and gender was found for clozapine clearance. The simulation results suggested that 150 mg twice a day and 150 mg three times a day of clozapine have toxicity concerns. In conclusion, a PBPK model was developed and reasonable parameters were made from the data of Korean patients with schizophrenia. The provided model might be used to predict the pharmacokinetics of clozapine and assist dose adjustment in clinical settings.
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Affiliation(s)
- Joomi Lee
- College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 41566, Korea
| | - Min-Gul Kim
- Center for Clinical Pharmacology and Biomedical Research Institute, Jeonbuk National University Hospital, Jeonju 54907, Korea.,Department of Pharmacology, School of Medicine, Jeonbuk National University, Jeonju 54907, Korea
| | - Hyeon-Cheol Jeong
- College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 41566, Korea
| | - Kwang-Hee Shin
- College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 41566, Korea
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14
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A systematic review and meta-analysis of the association between clozapine and norclozapine serum levels and peripheral adverse drug reactions. Psychopharmacology (Berl) 2021; 238:615-637. [PMID: 33410989 DOI: 10.1007/s00213-020-05746-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/01/2020] [Indexed: 12/13/2022]
Abstract
RATIONALE Clozapine is the most effective antipsychotic for treatment-refractory schizophrenia for reducing positive psychotic symptoms. It is associated with a reduction in hospitalisation and overall mortality. In spite of this, clozapine remains underutilised due to its complex adverse drug reaction (ADR) profile. OBJECTIVE This systematic review aims to investigate the association of clozapine and norclozapine serum levels, and peripheral ADRs. METHODS Studies were searched from four electronic databases (PubMed, EMBASE, PsycINFO and CINAHL) from inception to 12 June 2020. Studies were included if they had adult patients, provided data on steady-state trough clozapine or norclozapine levels and reported on clozapine-associated ADRs. Pregnant women, case reports and series were excluded. RESULTS A statistically significant correlation was found for clozapine serum levels and triglycerides (n = 70; r = 0.303, 95% CI 0.0119-0.546, p = 0.042), heart rate (n = 137; r = 0.269, 95% CI 0.0918-0.486, p = 0.035), and overall combined ADRs (n = 160; r = 0.264, 95% CI 0.110-0.405, p = 0.001), but not for absolute neutrophil count (n = 223; r = - 0.164, 95% CI - 0.529-0.253, p = 0.444) or total white cell count (n = 18; r = 0.0176, 95% CI - 0.203-0.237, p = 0.878). Interestingly, norclozapine serum levels were found to be statistically correlated to triglycerides (n = 120; r = 0.211, 95% CI 0.0305-0.378, p = 0.022), total cholesterol (n = 120; r = 0.272, 95% CI 0.0948-0.432, p = 0.003) and weight gain (n = 118; r = 0.208, 95% CI 0.0261-0.377, p = 0.025). CONCLUSIONS Heart rate, triglycerides and combined ADRs are significantly correlated with clozapine levels, and triglycerides, total cholesterol and weight gain with norclozapine levels. Future prospective, randomised controlled studies are needed to identify the cause-effect relationship between clozapine levels and peripheral ADRs.
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15
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Griffiths K, Millgate E, Egerton A, MacCabe JH. Demographic and clinical variables associated with response to clozapine in schizophrenia: a systematic review and meta-analysis. Psychol Med 2021; 51:376-386. [PMID: 33602358 DOI: 10.1017/s0033291721000246] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Clozapine is the only licensed pharmacotherapy for treatment-resistant schizophrenia. However, response to clozapine is variable. Understanding the demographic and clinical features associated with response to clozapine may be useful for patient stratification for clinical trials or for identifying patients for earlier initiation of clozapine. We systematically reviewed the literature to investigate clinical and demographic factors associated with variation in clozapine response in treatment-resistant patients with schizophrenia spectrum disorders. Subsequently, we performed a random-effects meta-analysis to evaluate differences in duration of illness, age at clozapine initiation, age of illness onset, body weight and years of education between clozapine responders and non-responders. Thirty-one articles were eligible for qualitative review and 17 of these were quantitatively reviewed. Shorter duration of illness, later illness onset, younger age at clozapine initiation, fewer hospitalisations and fewer antipsychotic trials prior to clozapine initiation showed a trend to be significantly associated with a better response to clozapine. Meta-analysis of seven studies, totalling 313 subjects, found that clozapine responders had a significantly shorter duration of illness compared to clozapine non-responders [g = 0.31; 95% confidence interval (CI) 0.06-0.56; p = 0.01]. The results imply that a delay in clozapine treatment may result in a poorer response and that a focus on prompt treatment with clozapine is warranted.
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Affiliation(s)
- Kira Griffiths
- Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Edward Millgate
- Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Alice Egerton
- Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - James H MacCabe
- Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
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Krivoy A, Whiskey E, Webb-Wilson H, Joyce D, Tracy DK, Gaughran F, MacCabe JH, Shergill SS. Outcomes in treatment-resistant schizophrenia: symptoms, function and clozapine plasma concentrations. Ther Adv Psychopharmacol 2021; 11:20451253211037179. [PMID: 34676067 PMCID: PMC8524694 DOI: 10.1177/20451253211037179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 07/16/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Clozapine is the only medication licenced for treating patients with treatment-refractory schizophrenia. However, there are no evidence-based guidelines as to the optimal plasma level of clozapine to aim for, and their association with clinical and functional outcome. OBJECTIVE We assessed the relationship between clinical and functional outcome measures and blood concentrations of clozapine among patients with treatment-refractory psychosis. METHODS Data were reviewed in 82 patients with treatment-refractory psychosis admitted to a specialised tertiary-level service and treated with clozapine. Analysis focussed on the relationship between clozapine and norclozapine plasma concentrations and the patient's clinical symptoms and functional status. RESULTS Clinical symptom improvement was positively correlated with norclozapine plasma concentrations and inversely correlated with clozapine to norclozapine plasma concentrations ratio. Clozapine concentrations showed a bimodal association with clinical improvement (peaks around 350 and 660 ng/ml). Clinical symptom improvement correlated with functional outcomes, although there was no significant correlation between the latter and clozapine or norclozapine plasma concentrations. CONCLUSION Clozapine treatment was associated with optimal clinical improvement at two different peak plasma concentrations around 350 and 650 ng/ml. Clinical improvement was associated with functional outcome; however, functionality was not directly associated with clozapine concentrations. A subset of patients may require higher clozapine plasma concentrations to achieve clinical improvement.
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Affiliation(s)
- Amir Krivoy
- Geha Mental Health Center, Petach-Tikva, Israel
| | - Eromona Whiskey
- National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK
| | - Henrietta Webb-Wilson
- National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK
| | - Dan Joyce
- National Institute of Health Research Oxford Health Biomedical Research Center and Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, UK
| | - Derek K Tracy
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Fiona Gaughran
- National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK
| | - James H MacCabe
- National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK
| | - Sukhwinder S Shergill
- National Psychosis Service, South London and Maudsley NHS Foundation Trust, London, UK
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de Leon J, Schoretsanitis G, Kane JM, Ruan CJ. Using therapeutic drug monitoring to personalize clozapine dosing in Asians. Asia Pac Psychiatry 2020; 12:e12384. [PMID: 32119764 DOI: 10.1111/appy.12384] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/19/2020] [Accepted: 02/10/2020] [Indexed: 12/27/2022]
Abstract
This narrative review on clozapine blood levels or therapeutic drug monitoring (TDM) includes sections focused on drug clearance and TDM, personalized dosing with TDM, clinical applications of TDM in Asians, and areas needing further study. Asian patients need half the clozapine dose (D) used in the United States to get the same blood concentrations (C). The concentration-to-dose (C/D) ratio measures drug clearance. In the United States, the average clozapine patient usually needs from 300 to 600 mg/day to reach 350 ng/mL. US male smokers reach this therapeutic C with a D of 600 mg/day (C/D ratio of 0.60 = 600/350), whereas US female nonsmokers usually need a D of 300 mg/day (C/D ratio of 1.17 = 300/350). While in the United States, average CLO C/D ratios typically are 0.6-1.2 ng/mL per mg/day, in Asian populations they range from 1.20 in male smokers to 2.40 in female smokers, requiring Ds of 300 to 150 mg/day to obtain 350 ng/mL. Asian patients can become clozapine poor metabolizers (PMs), needing very low Ds (50-150 mg/day) to get therapeutic Cs, by taking inhibitors (fluvoxamine, oral contraceptives and valproic acid), due to obesity, or during inflammations with systemic effects. In 573 Asian patients from five samples, around 1% were PMs due to taking inhibitors, 1% due to inflammation, 1% due to obesity, and 7% were potential genetic PMs. The potential genetic PMs ranged between 3% and 13%, but this prevalence will have to be better established in future studies including genetic testing for possible CYP1A2 mutations, which may explain PM status.
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Affiliation(s)
- Jose de Leon
- Mental Health Research Center, Eastern State Hospital, Lexington, Kentucky.,Psychiatry and Neurosciences Research Group (CTS-549), Institute of Neurosciences, University of Granada, Granada, Spain.,Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apóstol Hospital, University of the Basque Country, Vitoria, Spain
| | - Georgios Schoretsanitis
- Department of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, Glen Oaks, New York
| | - John M Kane
- Department of Psychiatry Research, Zucker Hillside Hospital, Northwell Health, Glen Oaks, New York.,Department of Psychiatry and Molecular Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, New York
| | - Can-Jun Ruan
- Laboratory of Clinical Psychopharmacology & The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
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Schoretsanitis G, Kane JM, Ruan CJ, Spina E, Hiemke C, de Leon J. A comprehensive review of the clinical utility of and a combined analysis of the clozapine/norclozapine ratio in therapeutic drug monitoring for adult patients. Expert Rev Clin Pharmacol 2019; 12:603-621. [DOI: 10.1080/17512433.2019.1617695] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Georgios Schoretsanitis
- Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY, USA
- Hofstra Northwell School of Medicine, Hempstead, NY, USA
- Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - John M. Kane
- Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY, USA
- Hofstra Northwell School of Medicine, Hempstead, NY, USA
- Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - Can-Jun Ruan
- Laboratory of Clinical Psychopharmacology & The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Christoph Hiemke
- Department of Psychiatry and Psychotherapy, University Medical Center of Mainz, Mainz, Germany
| | - Jose de Leon
- University of Kentucky Mental Health Research Center at Eastern State Hospital, Lexington, KY, USA
- Psychiatry and Neurosciences Research Group (CTS-549), Institute of Neurosciences, University of Granada, Granada, Spain
- Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apostol Hospital, University of the Basque Country, Vitoria, Spain
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Association between electroencephalogram changes and plasma clozapine levels in clozapine-treated patients. Int Clin Psychopharmacol 2019; 34:131-137. [PMID: 30855515 DOI: 10.1097/yic.0000000000000255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This retrospective observational study was performed to investigate electroencephalogram abnormalities in clozapine-treated patients with refractory schizophrenia or bipolar disorder. The electroencephalogram and plasma clozapine and norclozapine levels in 71 patients were measured on the same day. Fifty-nine patients (85.9%) had a diagnosis of schizophrenia, and 12 patients (14.1%) had a diagnosis of bipolar disorder. The mean daily clozapine dose was 242.9 ± 105.5 mg (range 25-500 mg), and the mean plasma clozapine and norclozapine levels were 429.4 ± 264.1 and 197.8 ± 132.6 ng/ml, respectively. Twenty-five patients (35.2%) were taking valproate in combination with clozapine. electroencephalogram abnormalities were found in 51 (71.8%) patients. No patient reported clinical seizures. Plasma clozapine level was significantly associated with electroencephalogram abnormalities and was identified as a significant predictor of electroencephalogram abnormalities in a logistic regression analysis. The plasma norclozapine levels of patients taking both clozapine and valproic acid were significantly lower than those of patients treated with clozapine alone. These results demonstrate that electroencephalogram abnormalities are closely correlated with plasma clozapine levels. Valproate reduced plasma norclozapine levels. Simultaneous monitoring of electroencephalogram and plasma clozapine levels was useful for adjusting clozapine doses, improving clinical efficacy, and preventing the side effects of clozapine treatment.
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Clozapine Metabolism in East Asians and Caucasians: A Pilot Exploration of the Prevalence of Poor Metabolizers and a Systematic Review. J Clin Psychopharmacol 2019; 39:135-144. [PMID: 30811372 DOI: 10.1097/jcp.0000000000001018] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE/BACKGROUND In clozapine therapeutic drug monitoring (TDM) studies, Chinese reached the same concentrations using half the dosage Caucasians use. Defining clozapine poor metabolizers (PMs) requires stratification by ethnicity, smoking, and sex. METHODS/PROCEDURES After sex and smoking stratification in 129 Chinese inpatients (mean, 8.8 TDM samples per patient), we explored the association between the total concentration-dose (C/D) ratio and CYP1A2 (*1C, *1F, and *7) and CYP2C19 alleles (*2 and *3). A systematic literature review identified 22 clozapine TDM prior studies (13 in Caucasians and 7 in East Asians). FINDINGS/RESULTS In our Chinese sample, the mean total clozapine C/D ratio (ng/mL per mg/d) was 1.96 for 22 male smokers, 2.07 for 5 female smokers, 2.47 for 36 male nonsmokers, and 2.95 for 66 female nonsmokers. CYP1A2 *1C had no significant effects, and CYP1A2 *1F had small effects. Five clozapine PMs (4%) needed low clozapine doses of 75 to 115 mg/d to get therapeutic concentrations. Using the same methodology in a published Italian sample, we found 5 PMs (3.3% of 152). In the systematic review, the clozapine C/D ratio (ng/mL per mg/d) was higher when comparing: (1) weighted mean values of 1.57 in 876 East Asians versus 1.07 in 1147 Caucasians and (2) ranks of 8 East Asians versus 13 Caucasian samples (P < 0.001). IMPLICATIONS/CONCLUSIONS Future TDM studies need to further explore the frequency of clozapine PMs after sex and smoking stratification in East Asian and Caucasian patients. Compared with Caucasians, East Asians appear to have a clinically relevant decrease in clozapine clearance.
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Population Pharmacokinetics of Clozapine and Norclozapine and Switchability Assessment between Brands in Uruguayan Patients with Schizophrenia. BIOMED RESEARCH INTERNATIONAL 2019; 2019:3163502. [PMID: 30956977 PMCID: PMC6431368 DOI: 10.1155/2019/3163502] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/14/2019] [Indexed: 01/01/2023]
Abstract
Clozapine (CZP) is an atypical antipsychotic agent commonly used in the treatment of schizophrenia. It is metabolized primarily by CYP1A2 enzyme, yielding a pharmacologically active metabolite, norclozapine (NCZP). Significant intra- and interindividual pharmacokinetic (PK) variability for CZP and NCZP has been observed in routine therapeutic drug monitoring. So the goal of this study was to evaluate the magnitude and variability of concentration exposure to CZP and its active metabolite NCZP on pharmacokinetic parameters in Uruguayan patients with schizophrenia with a focus on covariates such as cigarette smoking, age, sex, caffeine consumption, brands available of CZP, and comedication using population PK (PPK) modeling methodologies. Patients with a diagnosis of schizophrenia treated with brand-name CZP (Leponex®) for more than a year were included in the study. Then these patients were switched to the similar brand of CZP (Luverina®). Morning predose blood samples for determination of CZP and NCZP using a HPLC system equipped with a UV detector were withdrawn on both occasions at steady state and under the same comedication. Ninety-eight patients, 22 women and 76 men, took part in the study. Mean ± standard deviation for CZP and NCZP concentration was 421 ± 262 ng/mL and 275 ± 180 ng/mL, respectively. After covariate evaluation, only smoking status remained significant in CZP apparent clearance, inducing a mean increment of 32% but with no clinical impact. The results obtained with the two brands of CZP should ensure comparable efficacy and tolerability with the clinical use of either product. Smoking was significantly associated with a lower exposure to CZP due to higher clearance. The results obtained with the two brands commercialized in our country hint a bioequivalence scenario in the clinical setting.
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Effect of Valproate and Antidepressant Drugs on Clozapine Metabolism in Patients With Psychotic Mood Disorders. Ther Drug Monit 2018; 40:443-451. [DOI: 10.1097/ftd.0000000000000513] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
OBJECTIVES Valproic acid and clozapine are drugs commonly used in the treatment of schizophrenic and schizoaffective disorders. Pharmacokinetic interactions of valproic acid with several drugs are well known, yet results concerning the interaction with clozapine are inconsistent. METHODS Steady-state dose-corrected serum concentrations of clozapine and its main metabolite norclozapine were retrospectively analyzed in 45 patients receiving both clozapine and valproic acid. Controls were matched for sex, age, smoking, comedication, and inflammatory response. RESULTS The group receiving comedication with valproic acid showed significantly lower median dose-corrected serum concentrations of norclozapine (0.44 [0.27-0.58] (ng/mL)/(mg/d) vs 0.78 [0.60-1.07] (ng/mL)/(mg/d)) as well as metabolite to parent compound ratios (0.40 [0.36-0.47] vs 0.71 [0.58-0.84]) by approximately 44%. Dose-corrected serum concentrations of clozapine were not significantly lower. The effect of valproic acid was independent of sex and smoking. CONCLUSIONS Comedication with valproic acid accelerated metabolism of clozapine with predominant effects on the degradation of norclozapine. Therapeutic drug monitoring should be applied to guide individual patient responses upon initiation of comedication.
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Response after Infection-Associated Rise in Clozapine Levels in Treatment-Resistant Schizoaffective Disorder. Case Rep Psychiatry 2018; 2018:3174368. [PMID: 29623228 PMCID: PMC5829329 DOI: 10.1155/2018/3174368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 01/11/2018] [Accepted: 01/16/2018] [Indexed: 11/17/2022] Open
Abstract
The clinical management of patients with treatment-resistant psychotic disorders is still challenging despite years of extensive research. If first-line antipsychotic treatment proves ineffective, clozapine is considered golden standard. Herein, we report on a patient with schizoaffective disorder that initially showed no response to treatment with clozapine and ECT and therefore reached a therapeutic dead end. After an unintentional exposure to supratherapeutic clozapine levels, related to a pneumonia, a significant and persistent reduction of psychotic symptoms occurred. The report suggests a careful reevaluation of the clozapine dose in cases of treatment-resistant psychotic disorders with failed trials of clozapine. Further increase of dose may prove efficacious, although side effects should be closely monitored. Research to determine the upper threshold of clozapine for antipsychotic efficacy is warranted.
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Wang ST, Li Y. Development of a UPLC-MS/MS method for routine therapeutic drug monitoring of aripiprazole, amisulpride, olanzapine, paliperidone and ziprasidone with a discussion of their therapeutic reference ranges for Chinese patients. Biomed Chromatogr 2017; 31. [PMID: 28054367 DOI: 10.1002/bmc.3928] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/04/2016] [Accepted: 01/02/2017] [Indexed: 01/04/2023]
Affiliation(s)
- Shao-Ting Wang
- Department of Clinical Laboratory; Renmin Hospital of Wuhan University; Wuhan China
| | - Yan Li
- Department of Clinical Laboratory; Renmin Hospital of Wuhan University; Wuhan China
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Spina E, Pisani F, de Leon J. Clinically significant pharmacokinetic drug interactions of antiepileptic drugs with new antidepressants and new antipsychotics. Pharmacol Res 2016; 106:72-86. [DOI: 10.1016/j.phrs.2016.02.014] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/08/2016] [Accepted: 02/11/2016] [Indexed: 12/14/2022]
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Potanin SS, Burminskiy DS, Morozova MA, Platova AI, Baymeeva NV, Miroshnichenko II. [Plasma levels of antipsychotics and the severity of side-effects in the treatment of schizophrenia exacerbation]. Zh Nevrol Psikhiatr Im S S Korsakova 2015; 115:40-46. [PMID: 26978050 DOI: 10.17116/jnevro201511511140-46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To study a relationship between plasma levels of antipsychotics (AP) and severity of side-effects (SE) during the treatment of inpatients with exacerbation of schizophrenia. MATERIAL AND METHODS The study included 39 patients treated with risperidone, haloperidol, zuclopenthixol, clozapine, aripiprazole or olanzapine as monotherapy or in combination of two AP. Blood sampling to measure the AP plasma level was performed twice (at 7-10 and 26-30 day from start of treatment), the levels of prolactin and glucose were determined once (at 26-30 day from start of treatment). Patients were assessed by psychometric scales PANSS and NSA and the side-effects scale UKU. RESULTS The increased concentration of AP was noted in 33% of the patients. The high concentration of AP was significantly associated with akathisia and hyperkinesia (by UKU scale), NSA retardation factor and hyperprolactinemia. Patients with severe hyperprolactinemia were twice as likely to have a clinically significant depression. Increased blood glucose levels were observed in 18% of the patients, there was no significant association with AP plasma levels. Mental SE were most prominent, with a drift towards the neurological SE in the group with higher AP plasma levels. Chlorpromazine equivalent didn't significantly differ in the groups with normal, high and low AP concentrations. CONCLUSION Elevated AP plasma levels, which were associated with some clinically significant SE and some negative symptoms, were found in most patients. In this regard, therapeutic drug monitoring is a promising method for the individualization of schizophrenia exacerbation treatment in routine clinical practice.
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Affiliation(s)
- S S Potanin
- Mental Health Research Centre, Moscow, Russia
| | | | | | - A I Platova
- Mental Health Research Centre, Moscow, Russia
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Diaz FJ, Eap CB, Ansermot N, Crettol S, Spina E, de Leon J. Can valproic acid be an inducer of clozapine metabolism? PHARMACOPSYCHIATRY 2014; 47:89-96. [PMID: 24764199 DOI: 10.1055/s-0034-1371866] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Prior clozapine studies indicated no effects, mild inhibition or induction of valproic acid (VPA) on clozapine metabolism. The hypotheses that (i) VPA is a net inducer of clozapine metabolism, and (ii) smoking modifies this inductive effect were tested in a therapeutic drug monitoring study. METHODS After excluding strong inhibitors and inducers, 353 steady-state total clozapine (clozapine plus norclozapine) concentrations provided by 151 patients were analyzed using a random intercept linear model. RESULTS VPA appeared to be an inducer of clozapine metabolism since total plasma clozapine concentrations in subjects taking VPA were significantly lower (27% lower; 95% confidence interval, 14-39%) after controlling for confounding variables including smoking (35% lower, 28-56%). DISCUSSION Prospective studies are needed to definitively establish that VPA may (i) be an inducer of clozapine metabolism when induction prevails over competitive inhibition, and (ii) be an inducer even in smokers who are under the influence of smoking inductive effects on clozapine metabolism.
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Affiliation(s)
- F J Diaz
- Department of Biostatistics, The University of Kansas Medical Center, -Kansas City, KS, USA
| | - C B Eap
- Unit of Pharmacogenetics and Clinical Psychopharmacology, Centre for Psychiatric Neurosciences, Department of Psychiatry, Lausanne University, Hospital of Cery, Prilly-Lausanne, Switzerland
| | - N Ansermot
- Unit of Pharmacogenetics and Clinical Psychopharmacology, Centre for Psychiatric Neurosciences, Department of Psychiatry, Lausanne University, Hospital of Cery, Prilly-Lausanne, Switzerland
| | - S Crettol
- Unit of Pharmacogenetics and Clinical Psychopharmacology, Centre for Psychiatric Neurosciences, Department of Psychiatry, Lausanne University, Hospital of Cery, Prilly-Lausanne, Switzerland
| | - E Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - J de Leon
- Mental Health Research Center at Eastern State Hospital, Lexington, KY, USA
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Couchman L, Bowskill SVJ, Handley S, Patel MX, Flanagan RJ. Plasma clozapine and norclozapine in relation to prescribed dose and other factors in patients aged <18 years: data from a therapeutic drug monitoring service, 1994-2010. Early Interv Psychiatry 2013; 7:122-30. [PMID: 22747759 DOI: 10.1111/j.1751-7893.2012.00374.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 04/07/2012] [Indexed: 11/26/2022]
Abstract
AIM Clozapine is used in children and adolescents to treat early onset schizophrenia, but data on efficacy and on the plasma clozapine concentrations attained are limited. METHODS We studied data from a clozapine therapeutic drug monitoring (TDM) service, patients in the UK and Eire aged <18 years, 1994-2010. Multiple linear regression analysis was performed to investigate the relationship between plasma clozapine concentration and dose, age, sex, body weight, plasma clozapine:norclozapine ratio (clozapine metabolic ratio (MR)) and smoking habit. RESULTS There were 1408 samples from 454 patients, 267 (59%) males aged at time of first sample (median = 17; range = 8-17 years) and 187 (41%) females aged 16 (10-17) years. The plasma clozapine concentration was <0.35 mg L(-1) in 36%, and ≥0.60 mg L(-1) in 31% of samples (6.4% samples ≥1.0 mg L(-1) ). Although plasma clozapine was broadly related to prescribed dose, there was much variation: 10% of samples had plasma clozapine >0.60 mg L(-1) at prescribed clozapine doses of 50-150 mg d(-1) (66% <0.35 mg L(-1) ), while 12% of samples had plasma clozapine <0.35 mg L(-1) at doses ≥650 mg d(-1) (62% >0.6 mg L(-1) ). The covariates studied in the 16-17-year-olds had proportionately similar influences to those observed in adults. Together they explained 48% of the variance observed in plasma clozapine, with dose, smoking habit, MR and sex being major influences. In the younger patients, there were very few smokers, and the influence of sex did not reach statistical significance. CONCLUSIONS As in adults, clozapine TDM may help in assessing adherence and in dose adjustment, for example if smoking habit changes.
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Affiliation(s)
- Lewis Couchman
- Toxicology Unit, Department of Clinical Biochemistry, King's College Hospital NHS Foundation Trust
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Abstract
RATIONALE Clozapine levels are advocated in the monitoring of patients on this drug and have now been used for a number of years. A safety-related threshold has also been proposed, as well as therapeutic lower and upper thresholds. While there has been reasonable consensus regarding a lower therapeutic threshold, this is not the case for the upper thresholds. OBJECTIVES Our aim was to review available evidence related to upper thresholds. METHODS We carried out an electronic search of different databases and a manual search of articles between 1960 and 2011, cross-referencing the following terms with clozapine-interactions, monitoring, pharmacokinetics, plasma levels, serum levels, and toxicity. RESULTS Sixty-nine articles met our search criteria and these could be divided into reviews (11), studies (24), and case reports (35). Study quality was evaluated, and none met criteria for a prospective, randomized controlled trial specifically addressing higher plasma levels, e.g., >500 ng/ml. Case reports emphasize in particular the impact of interactions, e.g., antidepressants and smoking. There is clear evidence indicating a dose-related increased risk of seizures, at least to 500-600 mg/day, but a lack of data to suggest such a relationship between plasma levels, dose, and side effects linked to safety, e.g., seizures, myocarditis, and agranulocytosis. The very limited evidence addressing an upper threshold related to clinical response suggests a "ceiling effect" in the range of 600-838 ng/ml. CONCLUSIONS It appears that the current safety-related threshold is not supported by evidence. There may be an upper threshold for clinical response, beyond which chance of response falls off, although further studies are warranted.
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Stark A, Scott J. A review of the use of clozapine levels to guide treatment and determine cause of death. Aust N Z J Psychiatry 2012; 46:816-25. [PMID: 22327098 DOI: 10.1177/0004867412438871] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE To review the literature to examine the use of clozapine levels to (i) guide therapy and prevent toxicity in clinical care and (ii) determine cause of death in post-mortem examination of patients who were treated with clozapine. METHODS MEDLINE was searched in December 2010 using the following keywords: 'clozapine levels', 'clozapine and toxicity', 'clozapine and death', 'clozapine and mortality' and 'post-mortem redistribution'. Data was also collected from the 2010 MIMS Annual. RESULTS The literature reported significant variation in clozapine levels attained with any given dose, and considerable variability in the clinical response achieved at any given clozapine level. The lowest effective clozapine levels ranged from 250 to 550 µg/L, while the recommended upper limit to prevent toxicity varied from 600 to 2000 µg/L. There was minimal correlation between clozapine levels and side effects, with the exception of sedation, hypotension and seizure activity. The risk of seizures increased with plasma clozapine levels greater than 600 µg/L or rapid upward titration. In addition to prescribed dose, there are many factors that influence plasma clozapine levels. After death, the process of post-mortem drug redistribution resulted in 3.00 to 4.89 times increases in clozapine levels in central blood vessels and 1.5 fold increases in peripheral vessels compared to ante-mortem levels. CONCLUSIONS The exact range of clozapine levels that corresponds to toxicity remains unclear. However, levels between 350 µg/L and 1000 µg/L achieved with gradual upward titration are more likely to be effective and less likely to cause toxicity. Ongoing clozapine level monitoring is indicated, especially when (i) prescribing higher doses (> 600 mg/day) of clozapine, (ii) there has been a change in a patient's concomitant pharmacotherapy or cigarette use and (iii) there has been a suboptimal response to treatment. The use of post-mortem clozapine levels to determine clozapine toxicity as a cause of death is unreliable.
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Affiliation(s)
- Anne Stark
- Metro North Mental Health, Royal Brisbane and Women's Hospital, Herston, Australia
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de Leon J, Santoro V, D'Arrigo C, Spina E. Interactions between antiepileptics and second-generation antipsychotics. Expert Opin Drug Metab Toxicol 2012; 8:311-34. [PMID: 22332980 DOI: 10.1517/17425255.2012.660918] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Pharmacokinetic and pharmacodynamic drug interactions (DIs) can occur between antiepileptics (AEDs) and second-generation antipsychotics (SGAPs). Some AED and SGAP pharmacodynamic mechanisms are poorly understood. AED-SGAP combinations are used for treating comorbid illnesses or increasing efficacy, particularly in bipolar disorder. AREAS COVERED This article provides a comprehensive review of the interactions between antiepileptics and second-generation antipsychotics. The authors cover pharmacokinetic AED-SGAP DI studies, the newest drug pharmacokinetics in addition to the limited pharmacodynamic DI studies. EXPERT OPINION Dosing correction factors and measuring SGAP levels can help to compensate for the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone. Further studies are needed to establish the clinical relevance of combining: i) AED strong inducers with amisulpride, asenapine, iloperidone, lurasidone and paliperidone; ii) valproate with aripiprazole, asenapine, clozapine and olanzapine; iii) high doses of oxcarbazepine (≥ 1500 mg/day) or topiramate (≥ 400 mg/day) with aripiprazole, lurasidone, quetiapine, risperidone, asenapine and olanzapine. Two pharmacodynamic DIs are beneficial: i) valproate-SGAP combinations may have additive effects in bipolar disorder, ii) combining topiramate or zonisamide with SGAPs may decrease weight gain. Three pharmacodynamic DIs contributing to decreased safety are common: sedation, weight gain and swallowing disturbances. A few AED-SGAP combinations may increase risk for osteoporosis or nausea. Three potentially lethal but rare pharmacodynamic DIs include pancreatitis, agranulocytosis/leukopenia and heat stroke. The authors believe that collaboration is needed from drug agencies and pharmaceutical companies, the clinicians using these combinations, researchers with expertise in meta-analyses, grant agencies, pharmacoepidemiologists and DI pharmacologists for future progression in this field.
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Affiliation(s)
- Jose de Leon
- University of Kentucky Mental Health Research Center at Eastern State Hospital, 627 West Fourth St., Lexington, KY 40508, USA.
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Taieb A, B’chir F, Molinié R, Nava-Saucedo JE, Nakhli J, Fliniaux MA, Ben Hadj Ali B, Saguem S. Relationships between clozapine and norclozapine plasma concentrations, clozapine dose, and clinical response in Tunisian patients with schizophrenia-treatment resistance. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/ojpsych.2012.24036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Plasma clozapine, norclozapine, and the clozapine:norclozapine ratio in relation to prescribed dose and other factors: data from a therapeutic drug monitoring service, 1993-2007. Ther Drug Monit 2010; 32:438-47. [PMID: 20463634 DOI: 10.1097/ftd.0b013e3181dad1fb] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Therapeutic drug monitoring of plasma clozapine and of its principal plasma metabolite N-desmethylclozapine (norclozapine) (predose or "trough" sample) can help in monitoring adherence, in dose adjustment, and in minimizing the risk of toxicity. To obtain data to assist in the interpretation of analytical results, the results from a clozapine therapeutic drug monitoring service, 1993-2007, have been audited. There were 104,127 samples from 26,796 patients [18,750 (70%) men aged at time of first sample (median, range) 34 (10-89) years, and 7763 (30%) female aged 38 (12-90) years]. Clozapine was not detected (plasma concentration <0.01 mg/L) in 1.5% of samples (prescribed clozapine dose up to 900 mg/d). Plasma clozapine was either below 0.35 mg/L or greater than 0.60 mg/L in 42.5% and 28.4% of samples, respectively; in 0.4% samples plasma clozapine was 2.0 mg/L or more. Although plasma clozapine was broadly related to prescribed dose, there was much variation: 1.2% of samples had plasma clozapine >1.0 mg/L at prescribed clozapine doses up to 150 mg/d (76.2% < 0.35 mg/L), whereas 23.3% of samples had plasma clozapine < 0.35 mg/L at doses of 850 mg/d and over (18.0% > 1.0 mg/L). The highest plasma clozapine and norclozapine concentrations encountered were 4.95 and 2.45 mg/L, respectively. Although the median plasma clozapine:norclozapine ratio was 1.25 at plasma clozapine concentrations < 0.35 mg/L, the median ratio was 2.08 at plasma clozapine concentrations > 1.0 mg/L. Data (median, 10th-90th percentile) for both clozapine and norclozapine by prescribed clozapine dose band are useful in assessing partial adherence. Analysis of the plasma clozapine:norclozapine ratio by clozapine concentration provides clear evidence that clozapine N-demethylation becomes saturated at higher plasma clozapine concentrations and adds urgency to the requirement for dose adjustment should smoking habit change. A clozapine:norclozapine ratio greater then 2 suggests either a nontrough sample, or that clozapine N-demethylation has become saturated.
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Atypical antipsychotics as noncompetitive inhibitors of alpha4beta2 and alpha7 neuronal nicotinic receptors. Neuropharmacology 2009; 57:183-91. [PMID: 19481556 DOI: 10.1016/j.neuropharm.2009.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 05/08/2009] [Accepted: 05/16/2009] [Indexed: 01/30/2023]
Abstract
It has been suggested that the interaction of antipsychotic medications with neuronal nicotinic receptors may increase the cognitive dysfunction associated with schizophrenia and may explain why current therapies only partially address this core feature of the illness. In the present studies we compared the effects of the atypical antipsychotics quetiapine, clozapine and N-desmethylclozapine to those of the typical antipsychotics haloperidol and chlorpromazine on the alpha4beta2 and alpha7 nicotinic receptor subtypes. The binding of [(3)H]-nicotine to rat cortical alpha4beta2 receptors and [(3)H]-methyllycaconitine to rat hippocampal alpha7 receptors was not affected by any of the compounds tested. However, Rb(+) efflux evoked either by nicotine or the selective alpha4beta2 agonist TC-1827 from alpha4beta2 receptors expressed in SH-EP1 cells and nicotine-evoked [(3)H]-dopamine release from rat striatal synaptosomes were non-competitively inhibited by all of the antipsychotics. Similarly, alpha-bungarotoxin-sensitive epibatidine-evoked [(3)H]-norepinephrine release from rat hippocampal slices and acetylcholine-activated currents of alpha7 nicotinic receptors expressed in oocytes were inhibited by haloperidol, chlorpromazine, clozapine and N-desmethylclozapine. The inhibitory effects on nicotinic receptor function produced by the antipsychotics tested occurred at concentrations similar to plasma levels achieved in schizophrenia patients, suggesting that they may lead to clinically relevant effects on cognition.
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Inefficacité de la clozapine en rapport avec un métabolisme augmenté et intérêt de la fluvoxamine : à propos de quatre cas. Encephale 2007; 33:811-8. [DOI: 10.1016/j.encep.2007.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Semiz UB, Cetin M, Basoglu C, Ebrinc S, Uzun O, Herken H, Balibey H, Algul A, Ates A. Clinical predictors of therapeutic response to clozapine in a sample of Turkish patients with treatment-resistant schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:1330-6. [PMID: 17618026 DOI: 10.1016/j.pnpbp.2007.06.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 06/04/2007] [Accepted: 06/04/2007] [Indexed: 12/01/2022]
Abstract
BACKGROUND Several lines of evidence suggest that clozapine is more effective than both first- and second-generation antipsychotic drugs in treatment-resistant schizophrenia (TRS). However, clinicians appear to be hesitant to prescribe this drug. It would therefore be extremely valuable if predictors of response to clozapine could be identified. The aim of this study was to evaluate the predictive factors of clinical responses to clozapine in a group of Turkish patients with TRS. METHODS This was a 16-week uncontrolled open study carried out among 97 TRS patients (80 males and 17 females; DSM-IV diagnosis). All patients fulfilled the criteria for refractory schizophrenia according to the UK guidelines for the National Institute of Clinical Excellence (NICE). After all previous antipsychotic medications had run their course, the patients were started on clozapine according to a standardized titration and dosage schedule. Psychopathology was evaluated before the initiation of clozapine therapy and once every 4 weeks using the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment for Positive Symptoms, and the Scale for the Assessment of Negative Symptoms. RESULTS Of the TRS patients on clozapine, 55.7% achieved a clinical response, defined as at least a 20% decrease in BPRS. We observed a favorable effect of clozapine on both positive and negative symptoms. Logistic regression analysis showed that a good clozapine response was more likely when schizophrenia began at a later age, when negative symptoms were severe, and when patients had an early response at 4 weeks. CONCLUSION A combination of demographic, baseline clinical, and acute treatment response variables may accurately predict response to clozapine in TRS. Priority should be given to initiating clozapine at the earliest phase of TRS, especially for patients with evident negative symptoms.
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Affiliation(s)
- Umit B Semiz
- GATA Haydarpasa Veteran Hospital, Department of Psychiatry, Istanbul, Turkey.
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