Antibe Therapeutics Inc. said its pain drug ATB-346 was shown to be safer for the gastrointestinal tract than naproxen in a phase 2b study.

Naproxen is a nonsteroidal anti-inflammatory drug that is widely used for treating pain but is associated with causing gastrointestinal ulceration and bleeding. ATB-346 is a hydrogen sulfide-releasing derivative of naproxen.

Secondary goal data from the phase 2b gastrointestinal safety study, which was conducted in 244 healthy volunteers, showed that no patients who were given ATB-346 had ulcers — or painful sores in the lining of gastrointestinal organs — of more than 5 millimeters in diameter. In comparison, 30 subjects given naproxen had ulcers of over 5 millimeters in diameter.

Additionally, four gastric ulcers and no duodenal ulcers were seen in the group who were given ATB-346, while a total of 203 gastric and duodenal ulcers was seen in the naproxen group.

The secondary data was consistent with the main goal data from the study, which showed that patients on ATB-346 showed an ulceration rate of 2.5%, while patients on naproxen had an ulceration rate of 42.1% after a 2-week treatment period.

Toronto-based Antibe plans to fully evaluate the effectiveness of ATB-346 in relieving pain in an upcoming phase 2 dose-ranging efficacy study.