Case reports of the reemergence of psychotic symptoms after conversion from brand-name clozapine to a generic formulation

Abstract

Background: The use of generic drugs has resulted in considerable cost savings; however, whether all generics are truly bioequivalent to their brand-name counterparts is questionable. Although the efficacy of clozapine in the management of treatment-resistant schizophrenia has been well established, reports of relapse after conversion to a generic formulation are becoming more common.

Objective: This article presents 7 case studies of patients in a long-term residential care facility who experienced a relapse of psychotic symptoms when the pharmacy inadvertently switched their therapy from brand-name clozapine to a generic formulation. Neither patients, physicians, nor staff of the facility were aware of this switch. Possible reasons for the apparent increased risk of relapse in some patients switched to the generic formulation of clozapine are explored, with reference to US Food and Drug Administration bioequivalence standards and reports.

Results: All 7 patients, whose condition had been well stabilized with brand-name clozapine, experienced a rapid and profound deterioration after the switch to the generic formulation. Five patients required hospitalization. All patients responded well when brand-name clozapine was reinstated.

Conclusion: The findings suggest that brand-name clozapine and the generic formulation may display important clinical differences, and a comparable therapeutic response may not be achievable despite adequate monitoring. Large, controlled, prospective trials are needed to clarify the potential for treatment failure with the use of generic clozapine.