FDA adds warning to Cephalon's Provigil sleep drug

WASHINGTON, Oct 24 (Reuters) - A warning is being added to Cephalon Inc's (CEPH.O) drug Provigil for excessive sleepiness because of the risk of serious skin rash and psychiatric symptoms, the U.S. Food and Drug Administration said on Wednesday.

Provigil is used to treat adults with narcolepsy and obstructive sleep apnea who have difficulty staying awake. Provigil is one of Cephalon's biggest-selling products with global sales of $415 million in the first half of 2007.

The warning means patients should stop using Provigil and see their doctor if they develop a skin rash or other hypersensitivity reaction, the FDA and Cephalon said in a joint statement posted on the regulatory agency's Web site.

Physicians should also use caution when prescribing Provigil for patients with a history of depression or mania because of potential side effects such as hallucinations and suicidal thoughts, the agency said.

"Rare cases of serious or life-threatening rash" have been reported in some adults and children taking the drug, the FDA said. Some cases of angioedema, a swelling beneath the skin similar to hives, have also been reported.

A similar warning is already required for Cephalon's experimental new drug Nuvigil, which is also to treat excessive sleepiness. The company won FDA approval for that drug in June.