The finding from this case-series of 20 patients attending an anxiety clinic should alert clinicians to the fact that generic and brand name drugs may not always have the same efficacy, reported Michael Van Ameringen, MD, FRCPC, associate professor of psychiatry, McMaster University, Hamilton, Ontario, Canada.

Generic medications are cheaper than brand name ones, and can reduce health care costs. However, manufacturers of generic drugs are not required to test these agents in large clinical trials of safety and efficacy, as do those of brand name drugs. While generics do need to have pharmacological equivalence, this may not translate into clinical equivalence, Dr. Van Ameringen said. This is especially true for psychotropic drugs, the investigators noted in their paper.

The 20 patients in the case series were examined after complaining that their symptoms had inexplicably worsened since their last clinic appointment. Some patients also reported an increase in physical adverse effects, such as gastrointestinal problems and headaches.

In these patients, the most common primary diagnosis was obsessive-compulsive disorder (n=11), followed by panic disorder with agoraphobia (n=5), social phobia (n=3), and posttraumatic stress disorder (n=1).

All patients had been well controlled on Celexa, and their symptoms had been stable for a mean of 114.7 ± 109.39 weeks (range 6 – 472 weeks) prior to the switch to generic citalopram.

The investigators obtained patients' consent to contact their pharmacies to determine whether and when generic citalopram was dispensed. "In Canada, pharmacies are not required to inform patients of a change to generic, and most private drug plans mandate the use of generics when available," Dr. Van Ameringen explained.

Examination of the pharmacy records revealed that the mean dose of Celexa at the time of the switch to generic was 45.2 ± 20.6 mg and that half of the patients were taking other medications when they were switched.

Adverse symptoms began to reappear after as few as 4 days of switching. However, once patients were switched back to Celexa, the mean time for response was 3.8 ± 2.6 weeks (range 0.7 – 12 weeks).

"Clinicians should be aware of the potential risks of loss of treatment effect or symptom re-emergence posed by a switch to a generic agent," Dr. Van Ameringen noted. "Prospective, randomized, double blind, controlled investigations would likely provide useful information on this issue."


[Presentation title: Symptom Relapse Following Switch From Celexa to Generic Citalopram: A Clinical Case Series in an Anxiety Disorders Sample. Abstract 408]

Copyright © 2009 P\S\L Consulting Group Inc. All rights reserved. Republication or redistribution of P\S\L content is expressly prohibited without the prior written consent of P\S\L. P\S\L shall not be liable for any errors, omissions or delays in this content or any other content on its sites, newsletters or other publications, nor for any decisions or actions taken in reliance on such content.