Another Possible Side Effect for Atypical Antipsychotic Class of Drugs
On June 17, 2005 The Wall Street Journal reported that Risperdal, one of the so-called atypical antipsychotic drugs, has been associated with benign tumors in the pituitary gland. FDA researchers reviewing the MedWatch database of adverse drug reactions found a higher incidence of benign tumors in the pituitary gland among patients taking Johnson & Johnson's antipsychotic Risperdal than for similar drugs.
It is important to keep in mind that this finding is preliminary, and the observed association between Risperdal and the pituitary tumors does not prove whether these tumors were caused by the use of Risperdal or other factors. Moreover, "Patients should not stop taking their medications before talking to their doctor about all the risks and benefits," said P. Murali Doraiswamy, a psychiatrist at Duke University and co-author on the study.
The atypical antipsychotics are used primarily to treat schizophrenia and bipolar disorder. Risperdal is one of the most widely prescribed antipsychotics, and it was Johnson & Johnson's second-biggest-selling drug last year, with world-wide sales of $3.1 billion. A Johnson & Johnson spokesman said the drug company would be analyzing the FDA researchers' study to determine if further study is warranted.
Risperdal competes for market share with several other major drugs in the so-called atypical antipsychotic class, including Eli Lilly & Co.'s Zyprexa, AstraZeneca PLC's Seroquel, and Bristol-Myers Squibb Co.'s Abilify. Side-effect issues have a big impact on sales in the highly competitive atypical antipsychotic class. For example, Zyprexa's market share has slipped six percentage points over the past year over concerns about weight gain and diabetes. Notably, the FDA in 2003 required all the atypical antipsychotic drugs to carry warnings about weight gain and diabetes.
The FDA researchers' study has not been published, yet. It was presented June 18, 2005 at a University of Pittsburgh conference. The Wall Street Journal published on June 17, however, the following information about the methodology and findings of this FDA researchers' study:
The researchers analyzed 2.5 million adverse events reported by doctors, patients, and individuals since 1968. Of the 307 reports of pituitary tumors, 64, or 21%, occurred in patients taking antipsychotics. Forty-eight reports of pituitary tumors were reported in patients taking Risperdal, six in patients taking Zyprexa, four associated with Pfizer Inc.'s Geodon, and one with Seroquel. Novartis AG's Clozaril, which is also available as a generic clozapine, had three reports, while haloperidol, an older generic antipsychotic, had eight reports. Abilify had zero cases, but hasn't been on the market for as long as the other drugs.
Significantly, Ana Szarfman, a FDA medical officer and lead author of the study, said this kind of study cannot reveal how common the pituitary tumor side effect may be for users of Risperdal and the other atypical antipsychotics because, unfortunately, it is well-known that doctors do not report all suspected adverse drug reactions to the FDA's MedWatch program.
(Posted by: Tom Lamb)