Use of very-high-dose olanzapine in treatment-resistant schizophrenia

High-dose olanzapine in treatment-resistant schizophrenia: a systematic review

Background

Treatment-resistant schizophrenia (TRS) affects approximately 30% of people with schizophrenia. Clozapine is the gold standard treatment for TRS but is not always suitable, with a proportion of individuals intolerant of side effects or unable to engage in necessary blood monitoring. Given the profound impact TRS can have on those affected, alternative pharmacological approaches to care are needed.

Objectives

To review the literature on the efficacy and tolerability of high-dose olanzapine (>20 mg daily) in adults with TRS.

Design

This is a systematic review.

Data Sources and Methods

We searched for eligible trials published prior to April 2022 in PubMed/MEDLINE, Scopus and Google Scholar. Ten studies met the inclusion criteria [five randomised controlled trials (RCTs), one randomised crossover trial and four open label studies]. Data were extracted for predefined primary outcomes (efficacy, tolerability).

Results

Compared with standard treatment, high-dose olanzapine was non-inferior in four RCTs, three of which used clozapine as the comparator. Clozapine was superior to high-dose olanzapine in a double-blind crossover trial. Open-label studies demonstrated tentative evidence in support of high-dose olanzapine use. It was better tolerated than clozapine and chlorpromazine in two respective RCTs, and was generally well tolerated in open-label studies.

Conclusion

This evidence suggests high-dose olanzapine is superior for TRS when compared with other commonly used first- and second-generation antipsychotics, including haloperidol and risperidone. In comparison with clozapine, the data are encouraging for the use of high-dose olanzapine where clozapine use is problematic, but larger, better designed trials are needed to assess the comparative efficacy of both treatments. There is insufficient evidence to consider high-dose olanzapine equivalent to clozapine when clozapine is not contraindicated. Overall, high-dose olanzapine was well tolerated, with no serious side effects.

Registration

This systematic review was preregistered with PROSPERO [CRD42022312817].

Association between olanzapine concentration and metabolic dysfunction in drug-naive and chronic patients: similarities and differences

Second-generation antipsychotics are widely used to treat schizophrenia but their use could induce metabolic dysfunction. To balance efficacy and side effects, various guidelines recommend the use of therapeutic drug monitoring. Given the controversial relationship between olanzapine serum concentration and metabolic dysfunction, its use in clinical practice is still debated. To address this issue, we conducted a prospective cohort study to explore the associations in patients with schizophrenia. Specifically, first-episode drug-naive patients and patients with chronic schizophrenia were recruited. All participants received olanzapine monotherapy for 8 weeks. Anthropometric parameters and metabolic indices were tested at baseline and at week 8, and olanzapine serum concentration was tested at week 4. After 8 weeks of observation, body weight and BMI increased significantly in drug-naive patients. Moreover, triglycerides and LDL increased significantly in both drug-naive and chronic patients. Among chronic patients, those who have never used olanzapine/clozapine before had a significantly higher increase in weight and BMI than those who have previously used olanzapine/clozapine. Furthermore, olanzapine concentration was associated with changes in weight, BMI, and LDL levels in the drug-naive group and glucose, triglyceride and LDL levels in chronic patients who have not used olanzapine/clozapine previously. In conclusion, the metabolic dysfunction induced by olanzapine is more severe and dose-dependent in drug-naive patients but independent in patients with chronic schizophrenia. Future studies with a longer period of observation and a larger sample are warranted.

miR143-3p-Mediated NRG-1-Dependent Mitochondrial Dysfunction Contributes to Olanzapine Resistance in Refractory Schizophrenia

BACKGROUND

Olanzapine is an effective antipsychotic medication for treatment-resistant schizophrenia (TRS); however, the therapeutic effectiveness of olanzapine has been found to vary in individual patients. It is imperative to unravel its resistance mechanisms and find reliable targets to develop novel precise therapeutic strategies.

METHODS

Unbiased RNA sequencing analysis was performed using homogeneous populations of neural stem cells derived from induced pluripotent stem cells in 3 olanzapine responder (reduction of Positive and Negative Syndrome Scale score ≥25%) and 4 nonresponder (reduction of Positive and Negative Syndrome Scale score <25%) inpatients with TRS. We also used a genotyping study from patients with TRS to assess the candidate genes associated with the olanzapine response. CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9-mediated genome editing, neurologic behavioral tests, RNA silencing, and microRNA sequencing were used to investigate the phenotypic mechanisms of an olanzapine resistance gene in patients with TRS.

RESULTS

Neuregulin-1 (NRG-1) deficiency-induced mitochondrial dysfunction is associated with olanzapine treatment outcomes in TRS. NRG-1 knockout mice showed schizophrenia-relevant behavioral deficits and yielded olanzapine resistance. Notably, miR143-3p is a critical NRG-1 target related to mitochondrial dysfunction, and miR143-3p levels in neural stem cells associate with severity to olanzapine resistance in TRS. Meanwhile, olanzapine resistance in NRG-1 knockout mice could be rescued by treatment with miR143-3p agomir via intracerebral injection.

CONCLUSIONS

Our findings provide direct evidence of olanzapine resistance resulting from NRG-1 deficiency-induced mitochondrial dysfunction, and they link olanzapine resistance and NRG-1 deficiency-induced mitochondrial dysfunction to an NRG-1/miR143-3p axis, which constitutes a novel biomarker and target for TRS.

Therapeutic Drug Monitoring of Olanzapine and Cytochrome P450 Genotyping in Nonsmoking Subjects

BACKGROUND

The relationship between a daily dose of olanzapine, its serum concentration, and the genotype of young nonsmoking men treated for schizophrenia or schizophreniform disorder was investigated in day-to-day clinical practice. Pharmacogenetics was also examined for the selected patients.

METHODS

A total of 49 participants were recruited as in-patients at the Mental Health Research Center (Moscow, Russia). Inclusion criteria were patients who had been diagnosed with schizophrenia or schizoaffective disorder (following DSM-IV guidelines) and were being treated with OLZ. A prospective, observational, open-study design was implemented. In line with the literature, patients were only included if they attained steady-state OLZ concentrations lasting for at least 8 days. A liquid chromatographic-tandem mass spectrometric method was developed for analyzing OLZ in human serum. The single cytochrome P450 polymorphisms were genotyped using an amplifier real-time polymerase chain reaction system following standard protocols.

RESULTS

Evidence indicating that CYP2D6 polymorphism has a significant (P = 0.046) effect on the pharmacokinetics of olanzapine was obtained, confirming the beneficial effects of therapeutic drug monitoring (TDM) for olanzapine.

CONCLUSIONS

TDM should therefore be used as a standard care during olanzapine therapy. TDM is also useful in assessing adherence and may have a role in limiting olanzapine dosage geared at minimizing the risk of long-term toxicity.

A randomized-controlled trial of blonanserin and olanzapine as adjunct to antipsychotics in the treatment of patients with schizophrenia and dopamine supersensitivity psychosis: The ROADS study

Dopamine supersensitivity psychosis (DSP) is a key factor contributing to the development of antipsychotic treatment-resistant schizophrenia. We examined the efficacy and safety of blonanserin (BNS) and olanzapine (OLZ) as adjuncts to prior antipsychotic treatment in patients with schizophrenia and DSP in a 24-week, multicenter (17 sites), randomized, rater-blinded study with two parallel groups (BNS and OLZ add-on treatments) in patients with schizophrenia and DSP: the ROADS Study. The primary outcome was the change in the Positive and Negative Syndrome Scale (PANSS) total score from baseline to week 24. Secondary outcomes were changes in the PANSS subscale scores, Clinical Global Impressions, and Extrapyramidal Symptom Rating Scale (ESRS), and changes in antipsychotic doses. The 61 assessed patients were allocated into a BNS group (n = 26) and an OLZ group (n = 29). The PANSS total scores were reduced in both groups (mean ± SD: -14.8 ± 24.0, p = 0.0042; -10.5 ± 12.9, p = 0.0003; respectively) with no significant between-group difference (mean, -4.3, 95 %CI 15.1-6.4, p = 0.42). The BNS group showed significant reductions from week 4; the OLZ group showed significant reductions from week 8. The ESRS scores were reduced in the BNS group and the others were reduced in both groups. The antipsychotic monotherapy rates at the endpoint were 26.3 % (n = 6) for BNS and 23.8 % (n = 5) for OLZ. The concomitant antipsychotic doses were reduced in both groups with good tolerability. Our results suggest that augmentations with BNS and OLZ are antipsychotic treatment options for DSP patients, and BNS may be favorable for DSP based on the relatively quick responses to BNS observed herein.

Striatal Volume Increase After Six Weeks of Selective Dopamine D2/3 Receptor Blockade in First-Episode, Antipsychotic-Naïve Schizophrenia Patients

Patients with chronic schizophrenia often display enlarged striatal volumes, and antipsychotic drugs may contribute via the dopamine D_2/3 receptor (D_2/3R) blockade. Separating the effects of disease from medication is challenging due to the lack of a proper placebo-group. To address this, we conducted a longitudinal study of antipsychotic-naïve, first-episode schizophrenia patients to test the hypothesis that selective blockade of D_2/3R would induce a dose-dependent striatal volume increase. Twenty-one patients underwent structural magnetic resonance imaging (sMRI), single-photon emission computed tomography (SPECT), and symptom severity ratings before and after six weeks of amisulpride treatment. Twenty-three matched healthy controls underwent sMRI and baseline SPECT. Data were analyzed using repeated measures and multiple regression analyses. Correlations between symptom severity decrease, volume changes, dose and receptor occupancy were explored. Striatal volumes did not differ between patients and controls at baseline or follow-up, but a significant group-by-time interaction was found (p = 0.01). This interaction was explained by a significant striatal volume increase of 2.1% in patients (Cohens d = 0.45). Striatal increase was predicted by amisulpride dose, but not by either D_2/3R occupancy or baseline symptom severity. A significant reduction in symptom severity was observed at a mean dose of 233.3 (SD = 109.9) mg, corresponding to D_2/3R occupancy of 44.65%. Reduction in positive symptoms correlated significantly with striatal volume increase, driven by reductions in hallucinations. Our data demonstrate a clear link between antipsychotic treatment and striatal volume increase in antipsychotic-naïve schizophrenia patients. Moreover, the treatment-induced striatal volume increase appears clinically relevant by correlating to reductions in core symptoms of schizophrenia.

Cigarette smoking and heavy coffee consumption affecting response to olanzapine: The role of genetic polymorphism

Objectives: To evaluate the effect of cigarette smoking and heavy coffee consumption on efficacy and safety of olanzapine treatment in schizophrenia patients, in relation to genetic polymorphism.Methods: The study involved 120 patients with schizophrenia, treated with olanzapine for 30 days. Therapy efficacy was determined using three different psychiatric scales, and safety by assessing metabolic adverse effects and extrapyramidal symptoms. Genotyping included CYP1A2*1C, CYP1A2*1F and CYP1A1/1A2 intergenic polymorphism, as well as CYP2D6*3, CYP2D6*4 and CYP2D6*6.Results: Cigarette smoking and heavy coffee consumption decreased the efficacy and increased the safety of olanzapine treatment (P < 0.001). Although the effect was detected only in carriers of CYP1A2*1F allele, covariate analysis revealed that it is independent of CYP1A2 genotype. Olanzapine dose was inversely correlated with the drug efficacy (P ≤ 0.002) and LDL level (P = 0.004). Women and older subjects responded better to therapy (P < 0.026), but had more certain adverse effects (P ≤ 0.049). When controlling for other relevant factors, CYP2D6 metabolizer status affects olanzapine efficacy (P = 0.032).Conclusions: We confirm the effect of cigarette smoking and heavy coffee consumption on olanzapine efficacy and safety. The relevance of CYP1A2 genotype for the described effect needs further investigation. Olanzapine treatment outcome is also affected by dose, sex, age and CYP2D6 metabolizer status.

High Doses of Drugs Extensively Metabolized by CYP3A4 Were Needed to Reach Therapeutic Concentrations in Two Patients Taking Inducers

INTRODUCTION

In the last 20 years of clinical practice, the senior author has identified these 2 rare cases in which the patients needed extremely high doses of drugs metabolized by CYP3A4 to reach and maintain serum therapeutic concentrations.

METHODS

The high metabolic ability of these 2 patients was demonstrated by the low concentration-to-dose ratios (C/D ratios) of several drugs metabolized by CYP3A4.

RESULTS

Case 1 was characterized by a history of high carbamazepine doses (up to 2,000mg/day) and needed 170 mg/day of diazepam in 2 days to cooperate with dental cleaning. The high activity of the CYP3A4 isoenzyme was manifested by fast metabolism for quetiapine and diazepam, which took more than 1 year to normalize after the inducer, phenytoin, was stopped. Case 2 was also very sensitive to CYP3A4 inducers as indicated by very low C/D ratios for carbamazepine, risperidone and paliperidone. The carbamazepine (2,800 mg/day) and risperidone (20 mg/day) dosages for this second patient are the highest doses ever seen for these drugs by the senior author. Risperidone induction appeared to last for many months and metabolism was definitively normal 3 years after stopping carbamazepine. On the other hand, olanzapine C/D ratios were normal for induction.

CONCLUSIONS

The literature has never described similar cases of very high doses of drugs metabolized by CYP3A4. We speculate that these 2 patients may have unusual genetic profiles at the nuclear receptor levels; these receptors regulate induction of drugs.

Application of plasma levels of olanzapine and N-desmethyl-olanzapine to monitor metabolic parameters in patients with schizophrenia

Metabolic disturbance is a common side effect of olanzapine (OLZ); however, the relationships between plasma OLZ concentration (C_OLZ) and metabolic disturbance remain unclear. Our previous study revealed that C_OLZ≧22.77ng/mL was a positive predictor of therapeutic efficacy in patients with schizophrenia. This study aimed to investigate the roles of OLZ or N-desmethyl-olanzapine (DMO) in metabolic outcomes among OLZ-treated patients with schizophrenia. The metabolic syndrome (MS) was diagnosed based on the modified the National Cholesterol Education Program Adult Treatment Panel III criteria for Asians. HPLC-ECD analytical system was applied to determine the C_OLZ and DMO concentration (C_DMO). The absolute drug levels and concentration-to-dose ratios (C/D ratios) were tested for their correlations to metabolic parameters. Total 151 fasting blood samples from patients with schizophrenia were collected. DMO C/D ratio negatively correlated with weight, body mass index, waist circumference, and C-peptide level. The receiver operator characteristic analysis determined a threshold C_DMO>5.63ng/mL and DMO C/D ratio>0.35ng/mL/mg were negative predictors of MS. The C_OLZ/C_DMO ratio>6.03 was identified as positive predictor of MS. Combined with previous study result, we proposed that the optimal OLZ treatment should maintain C_OLZ/C_DMO ratio between 3 and 6 to maximize the clinical efficacy and minimize the metabolic side effects. Our findings suggested that therapeutic drug monitoring on OLZ and DMO is a valuable tool to monitor metabolic side effects in OLZ-treated patients with schizophrenia.

Brain stem as a target site for the metabolic side effects of olanzapine

Olanzapine, an atypical antipsychotic, is widely prescribed for the treatment of schizophrenia and bipolar disorder despite causing undesirable metabolic side effects. A variety of mechanisms and brain sites have been proposed as contributors to the side effects; however, the role of the dorsal motor nucleus of the vagus nerve (DMV), which plays a crucial role in the regulation of subdiaphragmatic organs and thus governs energy and glucose homeostasis, is largely unknown. Identifying the effect of olanzapine on the excitability of DMV neurons in both sexes is thus crucial to understanding possible underlying mechanisms. Whole cell patch-clamp electrophysiological recordings were conducted in stomach- and liver-related DMV neurons identified with retrograde viral tracers and in random DMV neurons. The effect of olanzapine on the neuronal excitability of DMV neurons both in male and female mice was established. Our data demonstrate that olanzapine hyperpolarizes the DMV neurons in both sexes and this effect is reversible. The hyperpolarization is associated with decreased firing rate and input resistance. Olanzapine also decreases the excitability of a subset of stomach- and liver-related DMV neurons. Our study demonstrates that olanzapine has a powerful effect on DMV neurons in both sexes, indicating its ability to reduce vagal output to the subdiaphragmatic organs, which likely contributes to the metabolic side effects observed in both humans and experimental models. These findings suggest that the metabolic side effects of olanzapine may partially originate in the DMV.