(Reuters) - KemPharm Inc said on Friday the U.S. Food and Drug Administration approved its opioid painkiller Apadaz for the short-term management of acute pain, sending the shares of the drugmaker up as much as 36 percent in late afternoon trading.

The company resubmitted the drug’s marketing application for review in September after appealing against a rejection by the drug regulator in 2016 on concerns of opioid abuse.

KemPharm said Apadaz is likely to be scheduled as a C-II product - a drug with a high potential for abuse.

The company, prior to rejection by the regulator in 2016, had tried for an abuse-deterrent label for the drug but an advisory committee to the FDA voted against the move.

“It’s a product that has differentiation, but not the traditional abuse-deterrent claims,” KemPharm’s Chief Executive Officer Travis Mickle told Reuters.

Mickle said the company would try new ways to sell the drug without an abuse-deterrent label.

The company, which expects to produce close to 5 billion tablets a year, said it would try to establish either a non-traditional pact with a pharmacy benefit manager or a tie-up with a generic pharmaceutical company.

“We are in active discussions on both approaches,” Chief Operating Officer Gordon Johnson said on a conference call.

KemPharm is planning to price Apadaz close to low-cost generic products as many drugmakers such as Egalet Corp and Collegium Pharmaceuticals have opioid-based branded drugs with an abuse-deterrent label.

“The generics are cheap and people are going to continue using them over some sort of branded molecule that’s going to cost a lot more,” Oppenheimer analyst Derek Archila told Reuters.

The company shares touched a more than 18-month high at $7.15 and were trading up about 15 percent at $6.