Acura Pharmaceuticals Inc. said Thursday its first-quarter loss widened on higher costs as the company tries to gain approval for a potential abuse-resistant painkiller.

The company lost $4 million, or 9 cents per share, compared with a loss of $1.3 million, or 3 cents per share, a year prior. Revenue rose to $2 million from $1.4 million.

Acura's revenue came from its partnership with King Pharmaceuticals on the drug candidate Acurox. It is a potential abuse-resistant painkiller that combines oxycodone with the vitamin niacin. The vitamin is designed to cause nasal irritation as a way to prevent patients from taking excessive doses.

Operating expenses rose 70 percent to $6.1 million.

A panel of experts convened by the Food and Drug Administration is expected to make a recommendation Acurox Thursday. The FDA, in a review posted Tuesday, questioned whether niacin will work as an effective deterrent to abuse.

Trading for Acura stock was halted ahead of the panel recommendation.

A final FDA decision is expected by June 30 and the agency normally follows the advice of its panels, though it is not required.

King, which is based in Bristol, Tenn., has already launched the abuse-resistant painkiller Embeda. Another drug from the company called Remoxy is under FDA review.

Palatine, Ill.-based Acura develops technology to make drugs harder to tamper with. If approved, Acurox will be its first product to reach the market. Bristol, Tenn.-based King will manufacture and market the drug, paying royalties to Acura.