Effectiveness of clozapine: A study from North India

Clozapine research from India: A systematic review

BACKGROUND

Although clozapine is much researched in western literature, a review on Indian research on clozapine published in 2010 reported limited data and need for further research in this area.

AIM

We aimed to conduct a systematic review of research on clozapine from India from 2010 to mid-2022 and also compare the same with research output before 2010.

METHODOLOGY

A systematic various search engines, i.e., PUBMED, Medknow, Hinari and Google Scholar was done using the key words clozapine and India. Published articles with clozapine in the title and having an author from India, published during 2010 to July 2022 were included.

RESULTS

Initial Internet and hand searches yielded 280 articles, out of which 126 articles were excluded due to various reasons and 154 articles, were included for the review. This included 84 case reports, 49 original articles, 11 review articles and 10 letters to the editor as comments. We found an increase in the number of publications during the period of 2010-2022 compared to 1997-2009 in all types of publications. Over the years a significant proportion of the articles focused on various side effects of clozapine, factors associated with response and non-response to clozapine and evaluation of outcomes other than efficacy/effectiveness. However, all the studies were limited to a single centre with no multicentric studies on clozapine.

CONCLUSION

Over the last 12 years or so, there is increase in the number of publications on clozapine. However, there is lack of multicentric studies.

Pharmacometabolomics-guided clozapine therapy in treatment resistant schizophrenia: Preliminary exploration of future too near

AIM

To study the association of clozapine pharmacometabolomics and clozapine response in Asian patients with treatment-resistant schizophrenia (TRS).

METHOD

A cross-sectional study was performed on 50 consecutive TRS patients following up in psychiatry department of the tertiary care hospital. Demographic details, response assessment, were collected on the case record form. A blood sample was also collected for trough concentration assessment of drug and its metabolites. Clozapine (CLZ) the parent drug and its two major metabolites - Clozapine N oxide (CNO) and N-Desmethyl clozapine (N-DSMC) levels were assessed using a high-performance liquid chromatography method. Clozapine responders and nonresponders patients were classified based upon Andreasen criteria.

RESULTS

The average trough concentration of CNO, N-DSMC, and CLZ were 123 ± 76.04, 171.93 ± 93.24, 229.27 ± 124.25 ng/ml, respectively. The two patient subgroups did not differ for CLZ, CNO, and N-DSMC concentrations statistically. However, clozapine nonresponse was associated with a higher CLZ/N-DSMC ratio (p = 0.03) and clozapine dose (p = 0.01). The receiver operator characteristic curve showed that the cut-off CLZ/N-DSMC ratio of 1.54 with a sensitivity of 85% and a positive predictive value of 84% for identifying nonresponders.

CONCLUSION

CLZ/N-DSMC ratio and clozapine dose were identified as significant variables for future dose optimization algorithms. Pharmacometabolomics-guided clozapine therapy has the potential to revolutionize TRS management.

Socio demographic, clinical, and side effect profile of patients on clozapine in Kashmir, North India

Background

Clozapine is an atypical second-generation antipsychotic belonging to the family of dibenzodiazepines. There is lack of literature on clozapine from this part of the world. So, our aim was to study the socio demographic, clinical and side effect profile of patients on clozapine in Kashmir.

Results

The mean age of the study group was 32.6 ± 8.9 years with majority being males (78.4%), unmarried (78.4%), unemployed (77.2%), and belonging to nuclear families (77.2%). Almost half of them resided in urban localities (51.1%) and studied upto middle school (55.7%). Around three- fourth (75%) of the patients had diagnosis of treatment-resistant schizophrenia. The mean dose of clozapine was 338.92 ± 158.11 mgs. Sedation (76.1%), hypersalivation (69.5%), constipation (46.6%), and weight gain (34.1%) were most common side effects noted in patients. 4.5% cases developed seizures while on clozapine. 2.3% patients developed agranulocytosis while 4.5% patients developed neutropenia on clozapine. The neutropenia was more pronounced in patients of schizophrenia with suicidal tendencies with doses of more than 400 mg.

Conclusions

We have used clozapine in a wide range of indications. Our patients seem to tolerate and respond to higher doses of clozapine and the prevalence of blood dyscrasias in our study sample was much higher than the rest of India.

Prevalence and Predictors of Clozapine-Associated Constipation: A Systematic Review and Meta-Analysis

Constipation is a frequently overlooked side effect of clozapine treatment that can prove fatal. We conducted a systematic review and meta-analysis to estimate the prevalence and risk factors for clozapine-associated constipation. Two authors performed a systematic search of major electronic databases from January 1990 to March 2016 for articles reporting the prevalence of constipation in adults treated with clozapine. A random effects meta-analysis was conducted. A total of 32 studies were meta-analyzed, establishing a pooled prevalence of clozapine-associated constipation of 31.2% (95% CI: 25.6-37.4) (n = 2013). People taking clozapine were significantly more likely to be constipated versus other antipsychotics (OR 3.02 (CI: 1.91-4.77), p < 0.001, n = 11 studies). Meta-regression identified two significant study-level factors associated with constipation prevalence: significantly higher (p = 0.02) rates of constipation were observed for those treated in inpatient versus outpatient or mixed settings and for those studies in which constipation was a primary or secondary outcome measure (36.9%) compared to studies in which constipation was not a specified outcome measure (24.8%, p = 0.048). Clozapine-associated constipation is common and approximately three times more likely than with other antipsychotics. Screening and preventative strategies should be established and appropriate symptomatic treatment applied when required.

Indian research: Focus on clozapine

Clozapine has been used in the treatment of schizophrenia for about two decades and extensive data have been accumulated with regard to its use in various parts of the world. However, in contrast to Western countries, there are few studies which have evaluated the usefulness of clozapine in Indian patients. This article attempts to review the available data on clozapine originating from India. This review reflects the fact that there are few studies from the Indian subcontinent and most of these are case reports. In view of the same, there is a need for further research to evaluate the effectiveness of clozapine in India.

Research on antipsychotics in India

Antipsychotic as a class of medications became available for treatment of various psychiatric disorders in the early 1950's. Over the last 60 years many antipsychotics have become available. In line with the west, Indian researchers have evaluated the efficacy of antipsychotics in various conditions. Additionally, researchers have also evaluated the important safety and tolerability issues. Here, we review data originating from India in the form of drug trials, effectiveness, usefulness, safety and tolerability of antipsychotics. Additionally, data with respect to other important treatment related issues is discussed.