UPDATE 3-U.S. FDA releases list of potential drug risks

* FDA at early stage of safety reviews for the drugs

* Drugs for weight loss, sleep disorders on list

* List does not mean problems were caused by drug -- FDA (Adds Bristol-Myers comment)

By Lisa Richwine

WASHINGTON, June 4 (Reuters) - U.S. regulators on Thursday listed two dozen drugs, including weight-loss medicines and sleep disorder pills, that it is at an early stage of reviewing for potential safety problems.

Many of the issues have been previously disclosed, but remain under review by the Food and Drug Administration.

The FDA said it was checking Pfizer Inc's (PFE.N) smoking cessation drug Chantix for possible risk of accidental injury, vision impairment and other issues, and Cephalon Inc's (CEPH.O) sleep disorder drugs Nuvigil and Provigil for a potential of serious skin reactions.

Other drugs listed included orlistat, a weight-loss drug sold by Roche Inc (ROG.VX) as the prescription product Xenical and by GlaxoSmithKline Plc (GSK.L) as the over-the-counter drug Alli. The FDA said it was continuing to evaluate liver toxicity reports for orlistat.

The FDA also said Pfizer's overactive bladder drug Detrol was under investigation for reports of Stevens-Johnson syndrome, a serious skin reaction.