The Food and Drug Administration (FDA), in its “complete response” letter to Cephalon Inc regarding the company´s application to market painkiller Fentora – approved for only certain cancer patients - for conditions such as chronic low back pain and neuropathic pain, has requested the company for improvements on this drug´s risk management program.

Fentora is an opioid painkiller, a class of drugs highly subject to abuse.

"The FDA request for revisions to the Fentora risk management program was expected and over the last four months we have been working diligently to prepare for implementation of the program as soon as possible," said Dr. Lesley Russell, Cephalon's chief medical officer.

Stating the FDA did not ask for any additional safety or efficacy studies, Cephalon said it plans to implement a first-of-its-kind initiative designed to minimize the potential risk of overdose from an opioid through appropriate patient selection.

Fentora (generically fentanyl) had sales for $ 75 million dollars in the first half of this year. The biotechnology company´s other painkiller is Actiq, and its top-selling product is insomnia treatment Provigil.