Recro Pharma Inc said an intravenous version of its lead painkiller was successful in the first of two pivotal late-stage trials, sending the company's shares surging 50 percent in trading after the bell.

The drug, Meloxicam, was being evaluated to treat acute pain in patients after a bunionectomy surgery, which involves removing or realigning soft tissue and bones in the joint of the big toe.

Meloxicam is a non-opioid drug, a class of drugs that do not have the side effects associated with commonly prescribed opioid drugs. These effects include addiction, constipation and respiratory distress.

Meloxicam met its primary goal of a statistically significant difference in the intensity of pain, over the first 48 hours, between patients given the drug and those given a placebo, the company said.

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The drug also achieved 15 of the 19 secondary endpoints and was well tolerated, with no serious adverse or bleeding events, the company said.

Recro Pharma said it was on track to report data from the second ongoing late-stage trial by the end of the fourth quarter, and that it expects to seek marketing approval for the drug in mid-summer 2017.

The company bought the rights to make an intravenous and injectable version of Meloxicam from Alkermes Plc in March last year.

The company's shares were trading at $11.50 in extended trade after closing at $7.68 in the regular session on Tuesday on the Nasdaq.