Letter to the editor

Generic substitution for psychotropic drugs

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.

Patients' attitudes towards generic substitution of oral atypical antipsychotics: a questionnaire-based survey in a hypothetical pharmacy setting

BACKGROUND

Generic atypical antipsychotics in tablet form differ in name, appearance and packaging from the innovator brand antipsychotics. These differences might cause anxiety, confusion and misperceptions in some ambulant patients with psychoses/schizophrenia, especially if the brand atypical antipsychotic is substituted in the pharmacy without the acknowledgement of the patient and treating psychiatrist. Furthermore, generic substitution of branded oral atypical antipsychotics in the pharmacy might cause nonadherence and potentially lead to suboptimal treatment outcomes if patients perceive the medicines to be clinically different.

OBJECTIVE

To determine the attitudes of patients with psychoses/schizophrenia towards generic substitution of oral atypical antipsychotics in a pharmacy setting.

METHODS

A total of 106 ambulant patients with psychoses/schizophrenia currently taking an oral atypical antipsychotic (risperidone [Risperdal], olanzapine [Zyprexa], quetiapine [Seroquel] or aripiprazole [Abilify]) were confronted with generic substitution in a hypothetical pharmacy setting.Two conditions were used: one granting patients a short explanation about the substitution, and one without explanation. Patients' attitudes towards the generic substitution were assessed using a combined quantitative and qualitative design.

RESULTS

Of the respondents, 73% stated that they would be unlikely to take a generic antipsychotic if their pharmacist were to substitute it. Providing patients with a short explanation had a significantly positive effect on their intention to take a generic version; however, overall, the patients' intention to take the generic antipsychotic lay well below a neutral midpoint.

CONCLUSION

Patients with psychoses/schizophrenia using atypical antipsychotics in tablet form perceive generic versions of their antipsychotics as being significantly different. This perceived difference lowers their intention of continuing to take the medication, thus possibly jeopardizing treatment outcome. Caution with the generic substitution of atypical antipsychotics in the pharmacy is therefore recommended. Generic substitution should take place only with the knowledge and agreement of the psychiatrist and the patient.