A new treatment for patients with moderate to severe acute pain following knee replacement surgery may be one step closer to market, according to the results of a phase II study reported by Redwood City, CAbased AcelRx Pharmaceuticals in December. The safety and efficacy of ARX-01 was evaluated. The product is a formulation of the opioid pain medication sufentanil and is based on the company’s proprietary NanoTab dosage form, which enables delivery by the noninvasive sublingual route.

Pain intensity was evaluated over a 12- hour period in 101 postsurgery patients who had undergone unilateral knee replacement surgery. Patients were randomized to receive either placebo or ARX-01 at one of three doses: 5 μg, 10 μg, or 15 μg. Doses were delivered as needed to treat pain with a 20-minute minimum redosing interval.

Results demonstrated that compared with placebo, patients receiving 15 mcg of ARX-01 experienced a statistically significant reduction in pain intensity over the study period (P = 0.015). No serious or unexpected adverse events were reported.

“We chose a very painful surgery in an elderly patient population to showcase the efficacy and safety of sublingual sufentanil NanoTabs in treating acute postoperative pain,” said Pamela Palmer, MD, PhD, chief medical officer of AcelRx Pharmaceuticals.