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Evaluation of an Interchangeability Switch in Patients Treated With Clozapine: A Retrospective ReviewSilvia Alessi-Severini, Ph.D.; Patricia L. Honcharik, Pharm.D.; Karleen D. Simpson, B.Sc. (Pharm); Michael K. Eleff, M.D.; and David M. Collins, Ph.D.Objective: To report the findings of a switch from brand-name to generic clozapine in a Canadian outpatient population. Method: The medical records of 58 outpatients diagnosed with schizophrenia and other psychotic disorders and stabilized on brand-name clozapine therapy were reviewed retrospectively. Patients were switched from brand-name to generic clozapine on their next dispensing supply after September 29, 2003. Data regarding clozapine dose regimens, physicians' visits, hospitalizations, and adverse events were collected from the patients' charts for the 6 months preceding and the 6 months after the switch from brand-name to generic clozapine. Relevant measurement changes in those data associated with the switch are evaluated. Results: No significant changes in dose, number of physician's visits, or hospitalization rates were observed as a consequence of the switch from brand-name to generic clozapine. In addition, there were no reported increases in the frequency of the most common adverse events, including decreases in white blood cell counts. None of the patients received a "nonrechallengeable" status, and no discontinuation of clozapine therapy occurred for any reason (toxicity or treatment failure) in the 6 months after the formulation switch. Conclusion: In the current outpatient population, retrospective evaluation of the conversion from brand-name clozapine to the first generic alternative available on the Canadian market did not reveal any significant treatment changes. (J Clin Psychiatry 2006;67:1047-1054) Received Nov. 10, 2005; accepted Jan. 30, 2006. From the Faculty of Pharmacy (Drs. Alessi-Severini, Honcharik, and Collins and Ms. Simpson) and the Department of Psychiatry, Faculty of Medicine (Dr. Eleff), University of Manitoba; and the Department of Pharmaceutical Services-Psychiatry, Health Sciences Centre (Dr. Honcharik), Winnipeg, Manitoba, Canada. This study was funded through the University of Manitoba start-up grant to Dr. Alessi-Severini. Ms. Simpson received a Canadian Institutes of Health Research (CIHR) summer studentship award from the Faculty of Pharmacy, University of Manitoba. No additional funding was received in support of this study. Presented in part at the 2006 Canadian Agency for Drugs and Technologies in Health Invitational Symposium, held April 3-4, 2006, in Ottawa, Ontario, Canada. The authors report no other financial relationships or affiliations relevant to the subject of this article. Acknowledgments appear at the end of the article. Corresponding author and reprints: Dr. Silvia Alessi-Severini, Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada (e-mail: alessise@ms.umanitoba.ca). |