The new safety warnings are for the sleep drug zolpidem, which is sold as a generic and under the brand names Ambien, Ambien CR, Edluar and Zolpimist.
The new warnings came after clinical tests for a recently approved drug were coupled with tests involving driving simulators. The FDA will now require driving simulation tests be done as part of any new application for insomnia drugs.
IMS Health, a health care technology and information company, said about 60 million prescriptions were written for all sleeping pills in 2011, with about two thirds of those being some form of zolpidem.
Dr. Ellis Unger, a director in the FDA's Center for Drug Evaluation and Research, urged patients to discuss the situation with doctors before changing any medication regime.
"We hope less of the drug will be in the bloodstream in the morning driving hours," Unger said in a conference call with reporters.
Before it faced generic competition, IMS Health said, two versions of Ambien had nearly $2 billion in sales in 2007 for drug maker Sanofi-Aventis, which is based in Paris, but has big operations in New Jersey and a site in Malvern, Pa.
Teva Pharmaceuticals Ltd., which has big operations around Philadelphia, and Pittsburgh-based Mylan Pharmaceuticals, are the two largest generic drug makers and both list a generic version of zolpidem among their products.
Not all sleeping pills have zolpidem, but all FDA-approved drugs have label warnings about morning drowsiness. The agency said that extended release forms of zolpidem showed the highest risk for next-morning impairment and that women were more susceptible than men because the drug takes longer to flush from their system.
Usher said various reports of celebrities using Ambien around the time of car accidents did not influence the agency.
"The new information was not tied to any specific case," Usher said, without naming names. But he added in reference to reports of celebrity accidents, "We don't know the time of the accidents, we don't know the last dosage or whether there was alcohol or other drugs involved."
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