Shares of BioDelivery Sciences jumped 31 percent before the opening bell Friday after the drug developer said its experimental pain treatment outperformed a placebo in late-stage testing.

The Raleigh, N.C., company also said after markets closed Thursday that the research on BEMA buprenorphine triggered a $10 million milestone payment from Endo Health Solutions Inc., in accordance with a licensing agreement between the companies.

BioDelivery Sciences is developing BEMA buprenorphine as a possible treatment for moderate-to-severe chronic pain in patients who need opioid therapy around the clock. It said early results from a late-stage study showed that the treatment delivered significantly improved chronic pain relief compared to a placebo.

The company expects to announce results from a second late-stage study later this year. Late-stage research is the last and most expensive testing phase to which a drug is submitted before being sent to federal regulators for approval.

Janney Capital Markets analyst Jim Molloy said in a Friday morning research note that the results represent a big win for BioDelivery Sciences. He noted that Endo owes BioDelivery Sciences up to $80 million in milestone payments if both trials succeed and regulators approve the drug.

Endo may eventually even want to buy the drug developer, Molloy said.

Shares of BioDelivery Sciences International Inc. rose 31 percent to $8.20 Friday, more than two hours before markets opened.