WASHINGTON - Merck & Co.'s Singulair may be linked to suicide and changes in mood and behavior, US regulators said yesterday in disclosing a review of the company's top-selling asthma drug.
The Food and Drug Administration is working with Whitehouse Station, N.J.-based Merck to evaluate studies and patient reports, the agency said yesterday in a notice on its website.
The examination may take as long as nine months, the FDA said. The company declined to say how many deaths were reported.
Singulair is Merck's biggest product and the most-prescribed respiratory drug in the United States, with worldwide sales growing 19 percent to $4.27 billion last year. Merck revised the drug's prescribing information in the past year to include reports of tremors, depression, suicide, and anxiousness. The FDA told doctors and patients to continue to use Singulair until more information becomes available.
"This speaks more to a very cautious, safety-focused agency than it does to safety of Singulair," said Seamus Fernandez, an analyst who covers Merck for Leerink Swann, in an e-mail yesterday. "Since the FDA review will take roughly nine months, this is something that will come up again, but we expect it to be resolved in a benign way."
Merck gained 8 cents to $44.78 in New York Stock Exchange composite trading. The drug maker has lost 23 percent this year as studies questioning the benefits of the cholesterol drug Vytorin caused a drop in prescriptions for Merck and partner Schering-Plough Corp. Schering-Plough shares rose 60 cents to $19.30.
The FDA is also reviewing reports of suicide and behavioral changes in people who took AstraZeneca PLC's Accolate and Critical Therapeutics Inc.'s Zyflo and Zyflo CR, three asthma medicines that are similar to Singulair.
The agency said it will decide after the review if further investigation is warranted.
Drug-induced behavior changes and suicide risk have come under increased scrutiny by regulators, leading to warnings for a growing list of medications including antidepressants, and treatments for attention deficit hyperactivity disorder and epilepsy. Last month, the FDA warned that Pfizer Inc.'s antismoking drug Chantix may raise the risk of psychiatric disorders after 39 patients committed suicide while taking the medicine.
Last year, Sanofi-Aventis SA withdrew its application to market the weight loss pill Zimulti in the United States after regulators linked it to suicide.
"Suicide has been reported to us only in postmarketing experience in anecdotal reports that come to the company," not in clinical studies, said George Philip, head of Merck's Singulair development program, in a phone interview yesterday.
Singulair, which has been on the market for 10 years, is also used to treat allergies.
The company said the number of suicides is "very small" relative to the amount of people taking the drug. Merck plans to highlight the changes by talking with doctors and providing information leaflets for patients.