UPDATE 1-US FDA to warn public over Cephalon drug risks

(Adds context, company comments)

WASHINGTON, Sept 26 (Reuters) - U.S. drug regulators on Wednesday will issue a public health advisory about the potential risks of a pain drug made by Cephalon Inc (CEPH.O: Quote, Profile, Research, Stock Buzz), an agency official said.

The U.S. Food and Drug Administration's warning comes after Cephalon earlier this month warned doctors about several patient deaths related to inappropriate prescribing of the drug, called Fentora.

Fentora is approved to treat cancer patients whose severe pain cannot be sufficiently controlled by conventional painkillers like morphine or other powerful drugs.

Cephalon said it is working with the FDA to finalize a new label to reflect new safety messages about the drug, which comes in pill form.

In its letter to health professionals dated Sept. 10, the company said patient deaths were due to improper patient selection, dosing and/or product substitution. It also warned that Fentora should not be used as a replacement for a similar painkiller sold by Cephalon called Actiq.

Fentora is made from fentanyl, which in raw form is 80 times stronger than morphine. Cephalon officials said once it is processed, the difference is much less.

The company is seeking expanded use of the drug beyond cancer patients.