Clinically Relevant Interactions between Atypical Antipsychotics and Anti-Infective Agents

Incidence and risk profiles for pneumonia in patients with schizophrenia receiving home-care case management intervention in Taiwan

BACKGROUND

Home-care case management is a type of community outreach service. However, research on the incidence of infectious diseases in patients receiving home-care case management is limited. This study investigated the incidence of various infectious diseases and risk factors for pneumonia in patients with schizophrenia receiving home-care case management.

METHODS

We used data from Taiwan's National Health Insurance Research Database between January 1, 2000, and December 31, 2019, to construct a schizophrenia cohort receiving home-care case management (n = 19,687). Pneumonia was the most common infectious disease at follow-up (n = 3966). To identify risk factors for pneumonia, a nested case-control study was conducted. Risk-set sampling was conducted to randomly select controls for each pneumonia case. Conditional logistic regression was employed for statistical analysis.

RESULTS

Among various infectious diseases, pneumonia had the highest standardized incidence ratio in our cohort. Of the 3966 patients with pneumonia identified, 56.9% were men. After pairing, 3961 case-control pairs were established. Psychiatric comorbidities, specifically dementia and depressive disorders, were associated with a higher risk of pneumonia (adjusted incidence rate ratios [aIRRs] = 2.73 and 1.34, respectively). In contrast to oral antipsychotics, long-acting injectables were not associated with an increased pneumonia risk, suggesting that long-acting injectables could be a safer treatment option for patients with schizophrenia.

CONCLUSION

Our results revealed a significantly elevated pneumonia risk in this patient population, especially in those with physical and psychiatric comorbidities. The findings advocate for comprehensive care strategies to reduce the risk of pneumonia in this population.

Letter to the FDA Proposing Major Changes in the US Clozapine Package Insert Supported by Clozapine Experts Worldwide. Part I: A Review of the Pharmacokinetic Literature and Proposed Changes

PURPOSE/BACKGROUND

Clozapine was approved in the United States (US) using 1989 regulations and knowledge. After 30 years, many sections of the US package insert (PI) are outdated.

METHODS

We comprehensively reviewed the literature to propose PI updates. We present the information in 2 articles. In Part I, we focus on basic pharmacology based on 407 relevant articles. Part II focuses on clinical aspects and pharmacovigilance.

FINDINGS/RESULTS

Based on more recent expectations of Food and Drug Administration regulations, we reviewed clozapine basic pharmacology including the following: 1) clearance, 2) pharmacokinetics and pharmacodynamics, and 3) monitoring tools. We identified 9 major problems in the basic pharmacological sections of the PI including the following: 1) in vivo studies indicate that clozapine is dependent on CYP1A2 for its metabolism, 2) the minor role of CYP2D6 in clozapine metabolism requires removing the PI recommendation to lower clozapine doses in CYP2D6 poor metabolizers, 3) in nontoxic concentrations CYP3A4 has a minor role in clozapine metabolism and potent CYP3A4 inhibitors lack clinically relevant effects, 4) several drug-drug interactions need to be updated based on recent literature, 5) systemic inflammation may decrease clozapine metabolism and increase the risk of clozapine intoxication, 6) obesity may decrease clozapine metabolism, 7) patients of Asian and Indigenous American ancestry need lower clozapine doses, 8) personalized titration and c-reactive protein monitoring should be considered until prospective studies are available, and 9) the half-life section needs to be modified to acknowledge that single dosing at night is frequent in the US.

IMPLICATIONS/CONCLUSIONS

An improvement in the US clozapine PI may lead to improvement in PIs worldwide.

Severe mental illness and infectious disease mortality: a systematic review and meta-analysis

Background

Evidence from meta-analyses suggest that people with severe mental illness (SMI) are at increased risk of death from infectious diseases compared to those without SMI. However, few reviews have focused on mortality risk from specific infection types, apart from COVID-19. The aim of this systematic review and meta-analysis was to comprehensively describe and quantify the risk of death from infections (excluding COVID-19) in people with SMI, exploring specific infection types where possible.

Methods

PubMed, Web of Science, PsycINFO, and EMBASE were searched for relevant studies up to 18th June 2024. Studies were included if they assessed the impact of SMI (bipolar disorder, schizophrenia and schizoaffective disorders, other psychoses) on risk of mortality from any infectious disease excluding COVID-19. Random-effects meta-analyses of the risk of death from 'infectious diseases', respiratory infections, sepsis, and 'other' infections in SMI were performed. The review protocol was registered in PROSPERO (CRD42023422151).

Findings

Twenty-nine articles were included in the review. All were observational cohort studies carried out in high income countries and 59% were judged to be of good quality. Narrative analysis indicated that having SMI was associated with increased risk of death from infectious disease (23/29 studies), with mixed results for sepsis. People with SMI were more than twice as likely to die from 'infectious diseases' than the general population (pooled relative risk (RR) = 2.71, 95% confidence interval (CI) = 2.33-3.16, N = 739,852) and more than three times more likely to die from respiratory infections (pooled RR = 3.27, 95% CI = 2.57-4.17, N = 1,353,905). Sources of heterogeneity across studies included SMI diagnosis, gender, type of control group, and infection type.

Interpretation

People with SMI are at an increased risk of death from infection, particularly from respiratory infections like influenza and pneumonia and should be prioritised for preventative strategies including influenza and pneumococcal vaccines. More work is needed to fully understand why infection mortality risk is increased in SMI.

Funding

MQ Mental Health Research Fellowship MQF22∖12.

Drug-Drug Interactions in Nosocomial Infections: An Updated Review for Clinicians

Prevention, assessment, and identification of drug-drug interactions (DDIs) represent a challenge for healthcare professionals, especially in nosocomial settings. This narrative review aims to provide a thorough assessment of the most clinically significant DDIs for antibiotics used in healthcare-associated infections. Complex poly-pharmaceutical regimens, targeting multiple pathogens or targeting one pathogen in the presence of another comorbidity, have an increased predisposition to result in life-threatening DDIs. Recognising, assessing, and limiting DDIs in nosocomial infections offers promising opportunities for improving health outcomes. The objective of this review is to provide clinicians with practical advice to prevent or mitigate DDIs, with the aim of increasing the safety and effectiveness of therapy. DDI management is of significant importance for individualising therapy according to the patient, disease status, and associated comorbidities.

Investigating in VigiBase over 6000 cases of pneumonia in clozapine-treated patients in the context of the literature: focus on high lethality and the association with aspiration pneumonia

BACKGROUND

The literature associates clozapine with pneumonia/aspiration pneumonia.

RESEARCH DESIGN AND METHODS

The international pharmacovigilance database (VigiBase™) uses the information component (IC) as statistical signal. VigiBase clozapine reports were analyzed for pneumonia/aspiration pneumonia from introduction to 10 May 2023.

RESULTS

There were 6392 cases of all types of pneumonia (5572 cases of pneumonia, 775 of aspiration pneumonia, and 45 combined). The IC was 3.52 for aspiration pneumonia, introduced as a VigiBase label in 2003, and 1.91 for pneumonia. Patients were reclassified as 3628 with no signs of aspiration and 1533 with signs. Signs of aspiration were strongly associated with some co-medications: olanzapine, odds ratio (OR) = 23.8, 95% confidence interval (CI), 14.9-38.0; risperidone OR = 18.6, CI, 11.4-30.4; valproic acid, OR = 5.5, CI, 4.5-6.6; and benzodiazepines OR = 5.5, CI, 4.5-6.6. In 2415 cases with completed data, fatal outcomes made up 45% (signs of aspiration made no difference), but there was wide variability from 0% (females <45 years of age; duration ≤30 days) to 76% (males >64 years of age; duration >1 year). During the first week, pneumonia was associated with 1) very high titration doses, 2) very small doses in Parkinson's disease, and 3) Japan vs other countries.

CONCLUSIONS

In clozapine-treated patients: 1) at least 30% of pneumonia cases may be aspiration pneumonia, 2) stopping some co-medications may decrease the risk of aspiration pneumonia, 3) average lethality in pneumonia was 45% but may be around 75% in geriatric patients with long-term treatment, and 4) safer titrations may sometimes require 5-mg tablets.

Exploring low clozapine C/D ratios, inverted clozapine-norclozapine ratios and undetectable concentrations as measures of non-adherence in clozapine patients: A literature review and a case series of 17 patients from 3 studies

BACKGROUND

Up to 1/2 of outpatients prescribed clozapine may be partially/fully non-adherent, based on therapeutic drug monitoring (TDM). Three indices for measuring partial/full non-adherence are proposed a: 1) clozapine concentration/dose (C/D) ratio which drops to half or more of what is expected in the patient; 2) clozapine/norclozapine ratio that becomes inverted; and 3) clozapine concentration that becomes non-detectable.

METHODS

These 3 proposed indices are based on a literature review and 17 cases of possible non-adherence from 3 samples: 1) an inpatient study in a Chinese hospital, 2) an inpatient randomized clinical trial in a United States hospital, and 3) and a Uruguayan outpatient study.

RESULTS

The first index of non-adherence is a clozapine C/D ratio which is less than half the ratio corresponding to the patient's specific ancestry group and sex-smoking subgroup. Knowing the minimum therapeutic dose of the patient based on repeated TDM makes it much easier to establish non-adherence. The second index is inverted clozapine/norclozapine ratios in the absence of alternative explanations. The third index is undetectable concentrations. By using half-lives, the chronology of the 3 indices of non-adherence was modeled in two patients: 1) the clozapine C/D ratio dropped to ≥1/2 of what is expected from the patient (around day 2); 2) the clozapine/norclozapine ratio became inverted (around day 3); and 3) the clozapine concentration became undetectable by the laboratory (around days 9-11).

CONCLUSION

Prospective studies should further explore these proposed clozapine indices in average patients, poor metabolizers (3 presented) and ultrarapid metabolizers (2 presented).

A Chinese medicine called Danggui Longhui may be a new clinically relevant clozapine inducer: Two case reports identified by therapeutic drug monitoring

BACKGROUND

Danggui Longhui is a traditional Chinese medicine made from the dried root of Angelica sinensis. It is used in psychiatric patients in China to reduce associated constipation. In a population pharmacokinetic model in olanzapine patients from Beijing Anding Hospital, we demonstrate that dangguilonghui tablets doubled olanzapine clearance, indicating the induction of olanzapine metabolism. Olanzapine metabolism is similar to clozapine metabolism.

METHODS

Two cases of possible clozapine induction using dangguilonghui tablets 4 g/day were identified in Beijing Anding Hospital. Dividing the minimum therapeutic concentration of 350 ng/mL by the concentration-to-dose (C/D) ratio provides the minimum therapeutic dose.

RESULTS

Case 1 was a female smoker on clozapine for 415 days. The mean of 6 clozapine C/D ratios associated with smoking provided a minimum therapeutic dose of 267 mg/day. There were 6 steady-state concentrations on the combination of valproic acid and dangguilonghui tablets, which provided a much higher minimum therapeutic dose of 833 mg/day. Four steady-state clozapine C/D ratios based on smoking and valproate after 4 months of carbamazepine 200 mg/day provided a minimum therapeutic dose of 603 mg/day. Case 2 was a female non-smoker on clozapine for 58 days. She had 3 clozapine C/D ratios on dangguilonghui tablets with a mean of 0.30 ng/mL providing a minimum therapeutic dose of 1167 mg/day.

CONCLUSION

Future clinical studies with repeated measures need to replicate the possibility that dangguilonghui tablets are a moderate-to-strong inducer of clozapine metabolism as suggested by these two limited cases.

Clozapine ultrarapid metabolism during weak induction probably exists but requires careful diagnosis. A literature review, five new cases and a proposed definition

During weak induction (from smoking and/or valproate co-prescription), clozapine ultrarapid metabolizers (UMs) need very high daily doses to reach the minimum therapeutic concentration of 350 ng/ml in plasma; clozapine UMs need clozapine doses higher than: 1) 900 mg/day in patients of European/African ancestry, or 2) 600 mg/day in those of Asian ancestry. Published clozapine UMs include 10 males of European/African ancestry, mainly assessed with single concentrations. Five new clozapine UMs (two of European and three of Asian ancestry) with repeated assessments are described. A US double-blind randomized trial included a 32-year-old male smoking two packages/day with a minimum therapeutic dose of 1,591 mg/day from a single TDM during open treatment of 900 mg/day. In a Turkish inpatient study, a 30-year-old male smoker was a possible clozapine UM needing a minimum therapeutic dose of 1,029 mg/day estimated from two trough steady-state concentrations on 600 mg/day. In a Chinese study, three possible clozapine UMs (all male smokers) were identified. The clozapine minimum therapeutic dose estimated with trough steady-state concentrations >150 ng/ml was: 1) 625 mg/day, based on a mean of 20 concentrations in Case 3; 2) 673 mg/day, based on a mean of 4 concentrations in Case 4; and 3) 648 mg/day, based on a mean of 11 concentrations in Case 5. Based on these limited studies, clozapine UMs during weak induction may account for 1-2% of clozapine-treated patients of European ancestry and <1% of those of Asian ancestry. A clozapine-to-norclozapine ratio <0.5 should not be used to identify clozapine UMs.

Exploring the impact of co-exposure timing on drug-drug interactions in signal detection through spontaneous reporting system databases: a scoping review

INTRODUCTION

Drug-drug interactions (DDIs) are defined as the pharmacological effects produced by the concomitant administration of two or more drugs. To minimize false positive signals and ensure their validity when analyzing Spontaneous Reporting System (SRS) databases, it has been suggested to incorporate key pharmacological principles, such as temporal plausibility.

AREAS COVERED

The scoping review of the literature was completed using MEDLINE from inception to March 2023. Included studies had to provide detailed methods for identifying DDIs in SRS databases. Any methodological approach and adverse event were accepted. Descriptive analyzes were excluded as we focused on automatic signal detection methods. The result is an overview of all the available methods for DDI signal detection in SRS databases, with a specific focus on the evaluation of the co-exposure time of the interacting drugs. It is worth noting that only a limited number of studies (n = 3) have attempted to address the issue of overlapping drug administration times.

EXPERT OPINION

Current guidelines for signal validation focus on factors like the number of reports and temporal association, but they lack guidance on addressing overlapping drug administration times, highlighting a need for further research and method development.

Therapeutic drug monitoring of clozapine in human serum by high-throughput paper spray mass spectrometry

Introduction

Monitoring the atypical antipsychotic drug clozapine is crucial to ensure patient safety. This article showcases a high-throughput analytical method for measuring clozapine and its primary metabolite norclozapine (N-desmethylclozapine) in serum using paper spray mass spectrometry (PS-MS).

Objectives

This study aimed to assess the viability of a PS-MS method for the rapid measurement of clozapine and norclozapine in human serum samples as an alternative to liquid chromatography mass spectrometry (LC-MS).

Methods

Serum samples were processed by protein precipitation followed by deposition of the supernatant containing labelled internal standards onto paper spray substrates mounted in cartridges. Analytes were then analyzed using a triple quadrupole mass spectrometer equipped with a commercial paper spray ionization source. The results obtained from the patient samples were compared to those from a validated LC-MS assay.

Results

PS-MS calibrations for clozapine and norclozapine were linear (R2 > 0.99) over five days. Between-run precision was below 8 %, and within-run precision did not exceed 10 %. When compared to a validated LC-MS method, the mean bias for 39 patient samples was -9% for clozapine and -1% for norclozapine, with no outliers. Mass spectrometry ion ratio comparisons indicated no interference for patient samples above the lower limit of quantification. There was less than 7 % change in the measured concentrations of both analytes over five days for samples dried on paper substrates. Notably, virtually no maintenance of the MS source was required during this study.

Conclusion

This study illustrates the potential of PS-MS for serum drug monitoring in the clinical laboratory.

Potentially inappropriate prescriptions of antibiotics in geriatric psychiatry-a retrospective cohort study

Introduction

Older patients are frequently affected by infectious diseases and adverse drug reactions (ADRs) of consecutively prescribed antibiotics. Particularly within geriatric psychiatry, high rates of potentially inappropriate prescriptions (PIPs) have been described, significantly complicating pharmacological treatment. Therefore, this study aimed to investigate the frequency and characteristics of antibiotic PIPs in geriatric psychiatry.

Methods

Medication charts of 139 patient cases (mean age 78.8 years; 69.8% female) receiving antibiotic treatment on a geriatric psychiatric ward were analyzed. Utilizing previously published definitions of antibiotic PIPs, adequacy of the antibiotic prescriptions was subsequently assessed.

Results

16.3% of all screened patient cases (139/851) received an antibiotic treatment during their inpatient stay. 59.5% of antibiotic prescriptions were due to urinary tract infections, followed by pulmonary (13.3%) and skin and soft tissue infections (11.3%). 46.7% of all antibiotic prescriptions fulfilled at least one PIP criterium, with the prescription of an antibiotic course for more than seven days as the most common PIP (15.3%).

Discussion

Antibiotic PIPs can be considered as a frequent phenomenon in geriatric psychiatry. Especially the use of fluoroquinolones and cephalosporins should be discussed critically due to their extensive side effect profiles. Due to the special characteristics of geriatric psychiatric patients, international guidelines on the use of antibiotics should consider frailty and psychotropic polypharmacy of this patient population more closely.

Drug-drug interactions between COVID-19 therapeutics and psychotropic medications

INTRODUCTION

The coronavirus (COVID-19) pandemic has led to as well as exacerbated mental health disorders, leading to increased use of psychotropic medications. Co-administration of COVID-19 and psychotropic medications may result in drug-drug interactions (DDIs), that may compromise both the safety and efficacy of both medications.

AREAS COVERED

This review provides an update of the current evidence on DDIs between COVID-19 and psychotropic medications. The interactions are categorized into pharmacokinetic, pharmacodynamic, and other relevant types. A thorough literature search was conducted using electronic databases to identify relevant studies, and extract data to highlight potential DDIs, clinical implications, and management strategies.

EXPERT OPINION

Understanding and managing potential DDIs between COVID-19 and psychotropic medications is paramount to ensuring safe and effective treatment of patients with COVID-19 and mental illness. Awareness of the diverse spectrum of DDIs, vigilant monitoring, and judicious dose modifications, while choosing pharmacotherapeutic options with low risk of interaction whenever possible, are necessary. Ongoing and future investigations should continue to review the dynamic landscape of COVID-19 therapeutic modalities and their interactions with psychotropic medications.

Gender Differences in Potentially Inappropriate Medication Use among Older Adults

BACKGROUND

Use of potentially inappropriate medication (PIMs) is a prominent concern that leads to significant medication-related issues among older adults. Notably, older women tend to utilize more medicines than men; older women frequently take more drugs. In addition, some evidence suggests that prescription PIMs vary by gender. This study examines the gender-based variation in prescribing PIM among older adults in Saudi Arabia.

METHODS

A cross-sectional retrospective analysis of electronic medical records from a large hospital in Saudi Arabia was carried out. Patients over the age of 65 who received ambulatory treatment were included in the study. The utilization of PIM was assessed based on Beers criteria. Descriptive statistics and logistic regression were employed to describe patterns of PIM utilization and identify factors associated with their use. All statistical analyses were performed using Version 9.4 of the Statistical Analysis Software (SAS^® 9.4).

RESULTS

The study comprised 4062 older people (age 65) who visited ambulatory care clinics; the average age was (72.6 ± 6.2) years. The majority of the study sample was women (56.8%). Among older adults, 44.7% of older men and 58.3% of older women reported having PIMs that should be avoided, indicating a higher prevalence of PIMs among women compared to men. In terms of the PIM categories used, women had a much higher utilization rate of cardiovascular and gastrointestinal drugs than men. In men, the use of PIMs was frequently associated with hypertension, ischemic heart disease, asthma, osteoarthritis, and cancer, while in women PIM use was associated with age, dyslipidemia, chronic kidney disease, and osteoporosis.

CONCLUSIONS

This study revealed sex differences in PIM prescribing among older adults; PIM use is more common among women. Sex differences exist in clinical and socioeconomic characteristics and factors related to using potentially inappropriate medications. This study revealed essential areas that could be targeted by further interventions to improve drug-prescribing practices among older adults at risk of PIM.

Escaping the Long Shadow Cast by Agranulocytosis: Reflections on Clozapine Pharmacovigilance Focused on the United Kingdom

PURPOSE/BACKGROUND

A recent article in this journal presented a US perspective regarding the modernization of clozapine prescription and proposed an escape from the long shadow cast by agranulocytosis.

METHODS

Here, an international group of collaborators discusses a point of view complementary to the US view by focusing on worldwide outcomes of clozapine usage that may be uneven in terms of frequency of clozapine adverse drug reactions.

FINDINGS/RESULTS

Studies from the Scandinavian national registries (Finland and Denmark) did not find increased mortality in clozapine patients or any clear evidence of the alleged toxicity of clozapine. Data on clozapine-associated fatal outcomes were obtained from 2 recently published pharmacovigilance studies and from the UK pharmacovigilance database. A pharmacovigilance study focused on physician reports to assess worldwide lethality of drugs from 2010 to 2019 found 968 clozapine-associated fatal outcomes in the United Kingdom. Moreover, the United Kingdom accounted for 55% (968 of 1761) of worldwide and 90% (968 of 1073) of European fatal clozapine-associated outcomes. In a pharmacovigilance study from the UK database (from 2008 to 2017), clozapine was associated with 383 fatal outcomes/year including all reports from physicians and nonphysicians. From 2018 to 2021, UK clozapine-associated fatal outcomes increased to 440/year.

IMPLICATIONS/CONCLUSIONS

The interpretation of fatal outcomes in each country using pharmacovigilance databases is limited and only allows gross comparisons; even with those limitations, the UK data seem concerning. Pneumonia and myocarditis may be more important than agranulocytosis in explaining the uneven distribution of fatal outcomes in clozapine patients across countries.

An Atypical Case of Neuroleptic Malignant Syndrome Associated With Ciprofloxacin and Quetiapine

A 29-year-old male presented to the emergency department with complaints of shortness of breath and numbness in bilateral upper and lower extremities that started a few hours prior to arrival. On physical examination, the patient was afebrile, disoriented, tachypneic, tachycardic, and hypertensive with generalized muscle rigidity. Further investigation revealed that the patient had recently been prescribed ciprofloxacin and restarted on quetiapine. The initial differential diagnosis was acute dystonia, and subsequently, the patient was placed on fluids, lorazepam, diazepam, and later benztropine. The patient's symptoms began to resolve, and psychiatry was consulted. Given the patient's autonomic instability, altered mental status, muscle rigidity, and leukocytosis, psychiatric consultation revealed an atypical case of neuroleptic malignant syndrome (NMS). It was postulated that the patient's NMS was caused by a drug-drug interaction (DDI) between ciprofloxacin, a moderate cytochrome P450 (CYP) 3A4 inhibitor, and quetiapine, which is primarily metabolized by CYP3A4. The patient was then taken off quetiapine, admitted overnight, and discharged the next morning with complete resolution of his symptoms along with a prescription for diazepam. This case highlights the variable presentation of NMS and the need for clinicians to consider DDI when managing psychiatric patients.

Comorbidities and the right dose: antipsychotics

INTRODUCTION

The effects of antipsychotic drugs are dose-dependent, which is particularly true for their efficacy, each antipsychotic having a specific dose-response curve. This may justify individualizing doses for these agents.

AREAS COVERED

We review the pharmacokinetic profiles of seven oral antipsychotics: haloperidol, risperidone, olanzapine, clozapine, quetiapine, ziprasidone, and aripiprazole. Their main indications are psychotic and affective disorders. They are prescribed in a very large population which may have comorbidities. Hence, we analyze the impact of the latter on the pharmacokinetic profiles of these antipsychotics, focusing on renal and hepatic impairment. Reviews and clinical trials were discussed based on a systematic literature search (PubMed) ranging from 1995 to 2022.

EXPERT OPINION

Factors liable to impact antipsychotic dosage are numerous and their subsequent effects often hard to predict, due to multi-level interactions and compensatory phenomena. In clinical practice, physicians must be aware of these potential effects, but base their decisions on monitoring antipsychotic plasma levels.

Ascorbic Acid Ameliorates Cardiac and Hepatic Toxicity Induced by Azithromycin-Etoricoxib Drug Interaction

The complexity of prescribing safe and effective drug therapy is still challenging. Due to the increased number of medications taken by patients, the potential for drug-drug interactions has clinically important consequences. This study focuses on the potential drug-drug interaction between azithromycin and etoricoxib and the possibility of counteracting this adverse reaction by giving ascorbic acid intraperitoneally to male albino rats. Sixty adult male albino rats weighing 150–180 g were used. The rats were allocated into six equal groups. One group was a control, and the others were given azithromycin, etoricoxib, either alone or combination, with one group treated with ascorbic acid and the last group treated with the drug combination and ascorbic acid. Blood samples were collected for measuring AST, ALT, LDH, CK-MB, and troponin alongside antioxidant enzymes and histopathological examination for both liver and heart tissue. The results showed both hepatic and cardiac damage in azithromycin and etoricoxib groups represented by increasing levels of heaptoc enzymes (ALT, AST, LDH, CK-MB, and troponin) with declining antioxidant enzymes and elevation of malondialdehyde and the appearance of hepatic and cardiac toxicities. Upon administration, ascorbic acid ameliorated all the mentioned biochemical parameters. In conclusion, ascorbic acid has great antioxidant capacities and hepatic and cardiac ameliorative effects and can alleviate drug interaction toxicity.

Precision psychiatry: The complexity of personalizing antipsychotic dosing

Recently, Salagre and Vieta commented on the complexity of implementing precision medicine in psychiatry. For 25 years, this author has focused on a circumscribed type of precision medicine: personalized dosing using pharmacokinetic mechanisms to stratified patients. This short communication focuses on personalized dosing of three oral antipsychotics (clozapine, risperidone and paliperidone) and presents their maintenance dosing in a table which provides dose-correction factors generated by pharmacokinetic studies. Inhibitors need dose-correction factors < 1 and inducers need correction factors >1. Clozapine maintenance dosing is based on the dose needed to reach 350 ng/ml (the minimum plasma therapeutic concentration in treatment-resistant schizophrenia). Clozapine maintenance dosing is influenced by 3 levels of complexity: 1) ancestry groups (Asians/Native Americans; Europeans and Blacks), 2) sex-smoking subgroups (lowest dose in female non-smokers and highest in male smokers) and 3) presence/absence of poor metabolizer status (due to genetic and non-genetic causes including co-prescription of inhibitors, obesity or inflammation). Risperidone and paliperidone maintenance dosing are based on the dose needed to reach plasma concentrations of 20-60 ng/ml. Risperidone PMs need approximately half the dose, which can be explained by genetics (CYP2D6 PMs) or co-prescription of CYP2D6 inhibitors. Fluoxetine co-prescription may require one fourth the risperidone maintenance dose. Carbamazepine co-prescription may require twice the risperidone maintenance dose. Although not well studied, two groups may need higher doses of oral paliperidone: Koreans may need 1.5 times higher doses while those taking carbamazepine may need 3 times higher paliperidone maintenance doses. Precision dosing in psychiatry requires using blood levels of individuals.

Correction: An International Adult Guideline for Making Clozapine Titration Safer by Using Six Ancestry-Based Personalized Dosing Titrations, CRP, and Clozapine Levels

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.

Pharmacokinetic drug interactions with oral haloperidol in adults: dose correction factors from a combined weighted analysis

INTRODUCTION

Pharmacokinetic (PK) drug-drug interactions (DDIs) of oral haloperidol, a first-generation antipsychotic, are systematically reviewed.

AREAS COVERED

After exclusions, the search for DDIs with oral haloperidol provided 47 articles as victim and 7 as perpetrator. Changes in mean haloperidol concentration-to-dose (C/D) ratios after weighting each study's size were used to calculate the effects of other drugs (inhibitors/inducers) on haloperidol. These changes of haloperidol C/D ratio were used to estimate dose-correction factors (<1 for inhibitors and >1 for inducers).

EXPERT OPINION

A box summarizes our recommendations for clinicians regarding our current knowledge of haloperidol PK DDIs, which will need to be updated as new information becomes available. Moderate to strong inducers (carbamazepine, phenobarbital, phenytoin, or rifampin) should be avoided since they required dose-correction factors of 2-5. Smoking appeared to be a weak inducer (dose-correction factor 1.2). Fluvoxamine, promethazine, and combinations of CYP3A4 and CYP2D6 inhibitors should be avoided. There are no long-term studies on fluoxetine to provide a dose correction factor. Limited information suggests that valproate may be an inhibitor (dose-correction factor 0.6). In most patients, haloperidol may not have clinically relevant effects as a perpetrator, but in vitro and clinical studies suggest it is a weak CYP2D6 inhibitor.

Identification of clinical phenotypes in schizophrenia: the role of lurasidone

The treatment of schizophrenia includes the control of symptoms, the prevention of relapses, and amelioration of adaptive skills for patient re-integration into society. Antipsychotic drugs are the agents of choice for the treatment of schizophrenia, as they reduce the positive symptoms of psychosis. Lurasidone is a second-generation antipsychotic drug representing a novel and useful clinical tool for the management of schizophrenia. A board consisting of a panel of Italian expert psychiatrists was organized with the following aims: (a) defining the current modalities of use of lurasidone, highlighted through 17 specific questions; (b) defining and agreeing the main features of the drug and the principal reasons to suggest its administration. We established that lurasidone is suggested at any age, with no gender difference, at all stages of the disease. The switch from previous treatments is done primarily because of lack of efficacy as well as poor adherence/tolerability. Lurasidone is among the best-tolerated antipsychotics, and its use is indicated in the presence of different comorbidities. A wide range of dosages is available, allowing safe titration in particular cases, with the highest dose (148 mg) generally used for the treatment of the acute phase. The discontinuation rate due to poor tolerability, low compliance, and interactions with other drugs is very low. Akathisia is the most reported adverse event, but it may be controlled by dose reduction. Lurasidone does not possess a marked sedative action but, in agitated patients, can be associated with sedative drugs, such as benzodiazepines. The most frequent reason for switching to other therapies is the need for long-acting formulations, as in patients at risk of very low adherence or suicide. Lurasidone does not strongly impact metabolism or the cardiovascular system (QT interval), and does not influence the metabolism of other drugs, showing good efficacy and tolerability.