FRAZER, Pa. (Bloomberg) — Cephalon Inc. failed to win U.S. approval to expand marketing of its painkiller Fentora to patients who don't have cancer because of concerns that the drug may be misused.

The Food and Drug Administration issued a so-called complete-response letter asking Cephalon to start its proposed new risk-management strategies and prove that they work for cancer patients before wider use would be approved, the company based in Frazer, Pa., said Monday in an e-mailed statement. The fast-acting tablet contains the narcotic fentanyl.

An FDA advisory panel voted 17-3 in May to recommend against widening Fentora uses, saying Cephalon didn't show it could keep the drug from patients already taking other morphine-like painkillers.