Therapeutic equivalence of antipsychotics and antidepressants - A systematic review

Abstract

The number of newly approved generic psychotropic drugs increases every year and, in many countries, their sales exceed the sales of brand-name counterparts. In order for any generic drug to receive an approval of regulatory authorities, its bioequivalence with the corresponding reference product must be demonstrated. Moreover, generic drugs must meet the same quality standards as reference drugs. However, many psychiatrists express concerns about use of generic drugs. We carried out a systematic analysis of the relevant literature indexed in PubMed and Cochrane databases. The MeSH term "generic" was combined with terms describing antipsychotic and antidepressive drugs, including their pharmaceutical names and relevant mental disorders. All 26 articles including either clinical studies or case reports have been qualified for a detailed analysis. No cases describing switches between two generics were found. Therapeutic equivalence studies evaluating antipsychotics included clozapine, olanzapine, and risperidone. The clinical status was judged to have worsened in 15.7% patients treated with clozapine. The number of relapses before and after the switch was not significantly different in patients treated with olanzapine. Two case reports showed clinical state deterioration after switch to generic risperidone. The clinical outcome after conversion to a generic antidepressant was evaluated only in one retrospective study. That study analyzed the outcomes of treatment with citalopram and revealed mental state deterioration in 11.6% of patients. Only single reports describe cases of impaired efficacy or adverse events after the switch to a generic antidepressant, including fluoxetine, mirtazapine, and venlafaxine. No cases of suicidal attempt after the switch were reported. Although the overall number of described cases is rather modest, health professionals should be aware of possible changes in the therapeutic effectiveness after changing to a generic medicine.

Keywords: Antidepressants; Antipsychotics; Bioequivalence; Generic drugs.