Brand-name versus generic clozapine for the treatment of resistant schizophrenia: Bioequivalence and interchangeability issues [Clozapina «brand» e clozapina generica nel trattamento della schizofrenia farmacoresistente: Bioequivalenza ed intercambiabilità]

A generic formulation of clozapine became recently available in Italy, along with doubts on its use, stemming from conflicting American studies on its efficacy and bioequivalence. Aim of this study was to assess possible changes of clinical response and plasma level of clozapine and N-desmethylclozapine in a sample of chronic schizophrenic patients. 41 patients with resistant schizophrenia or intolerant to classical antipsychotic treatment were assessed in this open study before and after switching from the brand (Leponex®) to the generic formulation (Clozapina Chiesi). Before and after 4 weeks from abrupt formulation cross-over, psychopathology was assessed by means of the Brief Psychiatric Rating Scale. Clozapine and N-desmethylclozapine plasma levels were measured by reverse phase HPLC. We found no significant differences in clinical status and plasma levels across the two formulations, all patients maintained response and tolerability profile.