Cephalon

(CEPH)

said it has provided regulators with new information that might allay their concerns about Sparlon, its experimental drug for attention deficit hyperactivity disorder.

The company said in a filing with the

Securities and Exchange Commission

Tuesday that a skin ailment found on a participant in one of its clinical trials doesn't appear to be Stevens-Johnson syndrome, a potentially deadly condition that can be caused by adverse drug reactions.

Last month, a Food and Drug Administration advisory committee voted not to recommend approval for Sparlon and said Cephalon should collect additional data to verify the safety of the drug. The decision was based on the fear surrounding a suspected case of Stevens-Johnson in a child taking part in a late-stage study.

The FDA isn't required to follow its advisers' recommendations, but it usually does. Cephalon is seeking FDA approval for Sparlon to treat ADHD in children ages 6 to 17.

Since the meeting, the company has been gathering data about the case and has had discussions with the treating physicians and dermatology experts, along with informal talks with the FDA. Last week, Cephalon said, it "formally submitted this new information to the FDA in support of the position that this case is not, in fact, SJS."

The full FDA is scheduled to decide whether to approve Sparlon by May 22. The company said it could "provide no assurance that it can convince the FDA that this case was not SJS" or that the agency will allow Sparlon on the market.

Sparlon contains modafinil, the same ingredient in Provigil, a sleep-disorders drug that's Cephalon's best-selling product. Sparlon has a higher dose of modafinil than Provigil does.

Cephalon's shares rose $4.59, or 7.6%, to $64.92 in regular trading. After hours, the stock gained another 88 cents to $65.80.