A chronic pain drug from BioDelivery Sciences International (NASDAQ:BDSI) is demonstrating efficacy, according to initial late-stage clinical trial results released Friday.

Raleigh-based BDSI and drug partner Endo Pharmaceuticals (NASDAQ:ENDP) said that the drug candidate BEMA buprenorphine successfully met the primary clinical trial goal of significant chronic pain relief compared to a placebo. The companies said that secondary study targets also support BEMA buprenorphine’s case for efficacy when compared against a placebo.

In addition to the top-line phase III trial results, BDSI’s CEO Mark Sirgo said that trial data from patients who have not been previously treated with opioids is now ready for analysis, a milestone that triggers a $10 million payment to BDSI. BDSI could also see more payments.

“We will receive a similar milestone payment related to the completion of the opioid experienced study and if successful, the potential for an NDA (new drug application) submission by late this year,” Sirgo said in a statement.

BDSI has developed a proprietary drug delivery technology that administers a drug through a small piece of dissolvable film placed on the inside of a patient’s cheek. BEMA buprenorphine uses this transmucosal technology to administer the pain drug buprenorphine. BEMA buprenorphine was developed to treat moderate to severe chronic pain in patients that require round-the-clock opioid therapy for an extended period of time. The treatment was developed for patients who have never been treated with opioids before, or are opioid naïve, as well as those who have and are opioid experienced.

In the top-line phase III clinical trial results released Friday, the companies said the most commonly reported adverse events in patients treated with buprenorphine compared to placebo were nausea (10 percent vs. 8 percent), vomiting (4 percent vs. 2 percent and constipation (4 percent vs. 2 percent).

“We are encouraged by today’s announced study results, which we believe are meaningful for patients suffering from moderate to severe chronic pain,” Dr. Ivan Gergel, Endo’s executive vice president of research and development said in a statement. “And we look forward to providing additional updates in mid-2014 regarding the BEMA buprenorphine chronic pain program.”

Pennsylvania-based Endo licensed BEMA buprenorphine from BDSI in 2012, a deal that could pay BDSI up to $180 million if the chronic pain treatment is successfully commercialized.