Clozapine rechallenge after clozapine-induced myocarditis: A case report to validate a previously published protocol

Clozapine is an effective antipsychotic indicated for treatment-resistant schizophrenia (TRS). Its use is limited by its extensive adverse effect profile featuring rare but serious consequences like clozapine-induced myocarditis (CIM). In the event of CIM, clozapine is discontinued; however, there is often no effective alternative for TRS. In this case, a rechallenge of clozapine may be considered. However, there is no standardized protocol to guide clinicians in this process.

This report describes the case of a 28-year-old male with a history of CIM who successfully underwent a clozapine rechallenge using a cautious titration protocol described in the literature and reached a daily dose of 150 mg without recurrence of CIM.

This case differed from the previously published research protocol in some respects, including the concurrent use of zuclopenthixol for antiaggression and no significant eosinophil-related concerns during monitoring. Despite confounding factors, including concurrent cellulitis affecting inflammatory markers, the patient was successfully rechallenged with clozapine. Limitations of the case include unknown postdischarge outcomes and lack of measurement-based care, such as the use of rating scales, to assess treatment response objectively.

This case report validates the previously published protocol and contributes to the literature on CIM rechallenge, helping clinicians weigh the risks and benefits of rechallenging clozapine in select patients.