Generic Substitution for Psychotropic Drugs

Abstract

Most antidepressants and other psychotropics in clinical use are available as generic formulations (Table). The availability of lower-priced, generic drugs can benefit patients and third-party payers, but it should not be assumed that all generic drugs are equally beneficial. There are numerous reports in the literature of unexpected and untoward consequences that occur when a generic drug is substituted for the original brand-name drug. A previously stable clinical response may suddenly deteriorate, or the patient may experience new or more severe adverse events (AEs). The United States Food and Drug Administration requires that manufacturers of generic drugs demonstrate that their formulation has pharmacokinetic properties similar (or bioequivalent) to the brand-name drug. Bioequivalency studies are conducted in healthy volunteers, not in patients who would be treated with that drug. Moreover, bioequivalency studies are conducted on a current lot of the branded drug and do not account for variability between lots of the generic formulation. The manufacturer is only required to submit bioequivalency data that support the Abbreviated New Drug Application (ANDA); the FDA does not require disclosure of failed bioequivalence studies. Unlike brand-name drugs, lengthy and costly clinical studies are not required to show that the generic drug is effective and safe.Although the FDA has taken the position that bioequivalence and therapeutic equivalence are equal, many questions related to the use of generic drugs remain unanswered. The following question-and-answer session is an excerpt of an interview with Pierre Blier, MD, PhD, conducted by Diane Sloan, PharmD, which addresses the issue of generic substitution of psychotropic drugs.