Safety of clozapine in patient with treatment resistant schizophrenia & asymptomatic constitutional macrothrombocytopenia (Harris syndrome)

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.

Haematological side effects associated with clozapine: A retrospective study from India

OBJECTIVE

To evaluate the incidence of clozapine induced haematological side effects among patients receiving clozapine.

METHODS

Data of 333 patients who were on clozapine for a mean duration of 52.96 (45.18) months were reviewed for haematological abnormalities.

RESULTS

Most of the patients (n = 320; 96.1 %) were diagnosed with psychotic disorders, mainly schizophrenia. These patients were receiving clozapine in the dose range of 12.5 mg-600 mg/day, with a mean dose of 212.08 (102.43) mg/day at the time of review of their records. About one-tenth (N = 33; 9.9 %) of patients developed eosinophilia (absolute eosinophil count >600), and 8.2 % (N = 27) experienced thrombocytopenia (platelet count <100,000 cmm³) and 7 patients developed anaemia (haemoglobin level <10 gm%). Only 2 (0.6%) patients developed neutropenia. Mean dose (mg/day) at which haematological side-effects occurred were as follows: 159.85 (87.65) mg/day for eosinophilia; 193.98 (148.93) mg/day for thrombocytopenia; 78.57 (22.49) mg/day for anaemia. In a small proportion of patients, clozapine was discontinued due to the haematological abnormalities and in other patients these abnormalities normalized on its own in subsequent follow-up.

CONCLUSION

Clozapine is associated eosinophilia and thrombocytopenia, which are often benign and in majority of the patients these normalize with time.