Rapid Re-challenge with Clozapine Following Pronounced Myocarditis in a Treatment-Resistance Schizophrenia Patient

Can Slow Personalized Titration Using C-Reactive Protein Monitoring Decrease the High Rates and Mortality of Clozapine-Associated Myocarditis Seen in Some Countries? A Call for Research

PURPOSE/BACKGROUND

The hypothesis that slower personalized titration may prevent clozapine-associated myocarditis and decrease the disproportion incidence of 3% found in Australia was not described in a recent Australian article in this journal.

METHODS

Six countries in addition to Australia have published information suggesting a similar incidence of clozapine-associated myocarditis. On September 19, 2023, PubMed searches were updated for articles from the United States, Korea, Japan, Canada, New Zealand, and Turkey.

FINDINGS/RESULTS

An incidence of 3.5% (4/76) was found in a US hospital, but US experts were the first to propose that clozapine-associated myocarditis may be a hypersensitivity reaction associated with rapid titration and possibly preventable. Koreans and Japanese are of Asian ancestry and need lower minimum therapeutic doses for clozapine than patients of European ancestry. A 0.1% (2/1408) incidence of myocarditis during clozapine titration was found in a Korean hospital, but pneumonia incidence was 3.7% (52/1408). In 7 Japanese hospitals, 34% (37/110) of cases of clozapine-associated inflammation were found during faster titrations (based on the official Japanese titration) versus 13% (17/131) during slower titrations (based on the international titration guideline for average Asian patients). Recent limited studies from Canada, New Zealand, and Turkey suggest that slower personalized titration considering ancestry may help prevent clozapine-associated myocarditis.

IMPLICATIONS/CONCLUSIONS

Other countries have very limited published data on clozapine-associated myocarditis. Based on a recent Australian case series and these non-Australian studies, the author proposes that Australia (and other countries) should use slow personalized titration for clozapine based on ancestry and c-reactive protein monitoring.

Clozapine Rechallenge After Major Adverse Effects: Clinical Guidelines Based on 259 Cases

BACKGROUND

Clozapine is widely prescribed for treatment-refractory schizophrenia, but its use is limited by many potentially life-threatening adverse effects. The risk of rechallenge after these complications has never been comprehensively assessed in controlled studies. Thus, clinical guidelines must rely on the published case reports. The number of such reports is likely to increase over time, and updated analyses of larger samples are needed, as they may lead to changes in clinical guidelines.

STUDY QUESTIONS

How safe is the clozapine rechallenge after life-threatening adverse effects?

STUDY DESIGN

The published case reports of clozapine rechallenge were identified in a MEDLINE search. We added 121 cases reported from 2012 through 2017 to the 138 cases reported from 1972 through 2011 analyzed by us in a previous publication. The 95% confidence intervals (CIs) of the successful rechallenge rate were calculated for each adverse effect with at least 5 published case reports. The rechallenge was considered a valid clinical option when the lower end of the CI range was at least 50%.

RESULTS

A successful outcome was documented in 128/203 patients rechallenged after neutropenia (63.0%, CI, 56.0%-69.6%), 3/17 after agranulocytosis (17.7%, CI, 4.7%-44.2%), 11/17 after myocarditis (64.7%, CI, 38.6%-84.7%), and 7/7 after neuroleptic malignant syndrome (100%, CI, 56.1%-100%). Among the 15 patients with other clozapine-induced adverse effects, the rechallenge was successful in those with eosinophilia, cardiac complications other than myocarditis (QTc prolongation, pericarditis, cardiomyopathy, and atrial flutter), and gastrointestinal hypomotility. The rechallenge failed in patients who had developed pancreatitis or renal insufficiency.

CONCLUSION

Clozapine rechallenge is a reasonable clinical option after return to baseline for patients who had developed neutropenia and neuroleptic malignant syndrome, but not after agranulocytosis or myocarditis. Data are insufficient to formulate rechallenge guidelines for any other clozapine-related adverse effects.

Safety of antipsychotics for the treatment of schizophrenia: a focus on the adverse effects of clozapine

Clozapine, a dibenzodiazepine developed in 1961, is a multireceptorial atypical antipsychotic approved for the treatment of resistant schizophrenia. Since its introduction, it has remained the drug of choice in treatment-resistant schizophrenia, despite a wide range of adverse effects, as it is a very effective drug in everyday clinical practice. However, clozapine is not considered as a top-of-the-line treatment because it may often be difficult for some patients to tolerate as some adverse effects can be particularly bothersome (i.e. sedation, weight gain, sialorrhea etc.) and it has some other potentially dangerous and life-threatening side effects (i.e. myocarditis, seizures, agranulocytosis or granulocytopenia, gastrointestinal hypomotility etc.). As poor treatment adherence in patients with resistant schizophrenia may increase the risk of a psychotic relapse, which may further lead to impaired social and cognitive functioning, psychiatric hospitalizations and increased treatment costs, clozapine adverse effects are a common reason for discontinuing this medication. Therefore, every effort should be made to monitor and minimize these adverse effects in order to improve their early detection and management. The aim of this paper is to briefly summarize and provide an update on major clozapine adverse effects, especially focusing on those that are severe and potentially life threatening, even if most of the latter are relatively uncommon.

Systematic Review of Clozapine Cardiotoxicity

Clozapine is exceptionally effective in psychotic disorders and can reduce suicidal risk. Nevertheless, its use is limited due to potentially life-threatening adverse effects, including myocarditis and cardiomyopathy. Given their clinical importance, we systematically reviewed research on adverse cardiac effects of clozapine, aiming to improve estimates of their incidence, summarize features supporting their diagnosis, and evaluate proposed monitoring procedures. Incidence of early (≤2 months) myocarditis ranges from <0.1 to 1.0 % and later (3-12 months) cardiomyopathy about 10 times less. Diagnosis rests on relatively nonspecific symptoms, ECG changes, elevated indices of myocardial damage, cardiac MRI findings, and importantly, echocardiographic evidence of developing ventricular failure. Treatment involves stopping clozapine and empirical applications of steroids, diuretics, beta-blockers, and antiangiotensin agents. Mortality averages approximately 25 %. Safety of clozapine reuse remains uncertain. Systematic studies are needed to improve knowledge of the epidemiology, avoidance, early identification, and treatment of these adverse effects, with effective and practicable monitoring protocols.