Flexion Therapeutics announced Oct. 6 the approval of Zilretta (triamcinolone acetonide extended-release injectable suspension) as the first and only extended-release, intra-articular injection for osteoarthritis knee pain.

Zilretta uses a proprietary microsphere-based formulation of triamcinolone acetonide to provide pain relief over 12 weeks by prolonging the release of triamcinolone acetonide inside the synovial fluid. The approval is based on data from a phase 3 clinical trial. The randomized, double-blind study enrolled 484 patients at 37 centers worldwide. The label also includes the results from a double-blind, randomized, parallel-group trial, which examined blood glucose concentrations in patients with type 2 diabetes to show how Zilretta can avoid blood glucose spikes observed with corticosteroid use.

“As OA progresses, many patients experience intractable joint pain, which can ultimately lead to the need for a total joint replacement,” John Richmond, MD, medical director for network development at New England Baptist Hospital, Boston, said in Flexion’s announcement . “As a result, health care providers are eager for new, nonopioid therapies that may help patients manage their OA pain for extended periods of time. Zilretta gives us an important new nonsurgical intervention.”

Zilretta is expected to be available in the United States by the end of October.