New Antipsychotic Invega Offers Few Advantages, Poses Cardiac Risks, According to Company Studies

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The latest antipsychotic to be approved by the FDA, Janssen's Invega, offers few advantages over existing agents, and poses significant cardiac risks, according to a new analysis by The Carlat Psychiatry Report.

According to an analysis conducted by The Carlat Psychiatry Report, the newest antipsychotic to be approved by the FDA--Janssen's Invega (paliperidone)--offers few advantages over existing antipsychotic drugs and poses significant cardiovascular hazards when dosed adequately.

Antipsychotic medications represent a $10 billion market for the pharmaceutical industry, and several companies compete for industry dominance. Janssen's original antipsychotic, Risperdal, will lose patent protection in June of 2008, and Invega is the company's best hope to maintain its presence in this hugely profitable sector.

Daniel J. Carlat, M.D., editor-in-chief of The Carlat Psychiatry Report, analyzed available data on Invega, including both published and unpublished research findings, in addition to prescribing information provided by Janssen Pharmaceutica.

The newsletter notes that while Invega is marketed by Janssen as a "new treatment for schizophrenia," the drug is actually a liver by-product of risperidone (called "paliperidone") isolated in a laboratory and packaged in an extended-release form. Thus, patients who ingest the original medication, risperidone, produce therapeutic quantities of paliperidone through normal liver metabolism.

In company promotional material obtained by the newsletter, Invega is advertised as having no more side effects than a placebo sugar pill when the 6 mg dose is prescribed. However, according to unpublicized company data, this dose was less effective for psychotic symptoms than a competing antipsychotic medication, Zyprexa (manufactured by Eli Lilly). This study did not enroll enough patients to assess the statistical significance of this difference.

Also unemphasized in company statements is the fact that Invega caused a potentially dangerous change in some patients' heart rhythms. This change, referred to as "QT interval prolongation," has been associated with fatalities due to other medications with this side effect. In addition, Invega caused rapid heart beat in over 12% of patients taking the compound.

The only clear advantage of Invega documented by the company is that it is not metabolized by the liver and so can be given safely to patients with liver disease. Otherwise, according to the newsletter, Invega has no advantages over soon-to-be-generic risperidone, and poses side effect disadvantages.

About the newsletter: The Carlat Psychiatry Report is a monthly print and web-based newsletter which provides continuing medical education to psychiatrists both within the United States and internationally. It does not accept pharmaceutical funding.

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