October 12, 2005

Antipsychotic polypharmacy widespread, but limited evidence

A study published in the Brown University Psychopharmacology Update (October 1, 2005) suggests that antipsychotic polypharmacy (the taking of many antipsychotic drugs at the same time) continues to be widespread; but the evidence for effectiveness is limited. As a counterpoint - the study was carried out by Eli Lilly - (makers of Zyprexa, the leading drug on the market) - so the results may be biased. It seems that the issue of polypharmacy is something that the NIMH should, if it hasn't already, take up in one of their studies (so that doctors and patients can get an unbiased view of the issue).

The study summary notes:

* Results show prolonged antipsychotic polypharmacy is common during treatment of patients with schizophrenia in usual care settings

..." analysis of prescribing patterns showed that most of the patients had been treated with antipsychotic polypharmacy for prolonged periods. This is despite consensus guidelines recommending monotherapy for standard treatment of schizophrenia, with polypharmacy as a last resort."

The study was carried out by Douglas Faries of Eli Lilly and company, and colleagues. Christoph U. Correll, M.D., a coauthor of the study, told The Update: "This prospective naturalistic study adds to the existing, mostly shorter-term data, reconfirming the high prevalence of antipsychotic polypharmacy in the treatment of schizophrenia." Correll is a research psychiatrist at the Zucker Hillside Hospital, Glen Oaks, New York.

Monotherapy is recognized as a preferred method of treatment, according to Faries and colleagues, in part because it facilitates the clinician's ability to accurately evaluate a patient's response to new treatment. It allows documentation of a patient's response to "an adequate trial of each medication, helping to reduce the complexity of the medication regimen, reducing the risk of adverse events, and making it easier to assess and manage future symptom exacerbations."

The researchers indicate that "the body of evidence supporting the benefits of antipsychotic polypharmacy is limited and is in contrast to the extensive and compelling body of evidence supporting monotherapy with atypical antipsychotics." Only one consensus guideline, (2) they say, presents guidance on duration of antipsychotic polypharmacy, and that recommends it be used during cross-titration of drugs for 60 days or less.

Source: Brown University Psychopharmacology Update


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