FDA OKs First Extended-Release Corticosteroid Shot for Knee OA

Megan Brooks

October 06, 2017

The US Food and Drug Administration (FDA) has approved triamcinolone acetonide extended-release injectable suspension (Zilretta, Flexion Therapeutics, Inc), the first and only extended-release, intra-articular injection for osteoarthritis (OA) knee pain.

"Zilretta is a non-opioid medicine that employs Flexion's proprietary microsphere technology to provide proven pain relief over 12 weeks," the company said in a news release.  They expect Zilretta to be available in the US by the end of this month.

"The approval of Zilretta marks a major advancement in the treatment landscape for managing OA knee pain. It comes at a time when our society is in urgent need of non-addictive therapies to help the millions of Americans who suffer from this condition," Michael Clayman, MD, president and chief executive officer of Flexion, said in the release.

The FDA approved approved Zilretta based on data from a phase 3 randomized, double-blind clinical trial involving 484 patients with OA knee pain at 37 centers worldwide.

Clinical trial data for Zilretta also suggest that the drug "may avoid the disruptive blood glucose spikes that can be seen with corticosteroid use in patients coping with both knee OA and type 2 diabetes," Steven Russell, MD, PhD, from Massachusetts General Hospital Diabetes Research Center, in Boston, said in the release. 

"As OA progresses, many patients experience intractable joint pain, which can ultimately lead to the need for a total joint replacement," said John Richmond, MD, medical director for Network Development, New England Baptist Hospital, Dedham, Massachusetts. "As a result, healthcare providers are eager for new, non-opioid therapies that may help patients manage their OA pain for extended periods of time. Zilretta gives us an important new non-surgical intervention."

Zilretta is not intended for repeat administration, as the efficacy and safety of repeat administration of Zilretta have not been evaluated, the company said. It is contraindicated in patients who are hypersensitive to triamcinolone acetonide, corticosteroids, or any components of the product.

The most commonly reported adverse reactions (incidence ≥1%) in clinical studies included sinusitis, cough, and contusions.

Zilretta is only for intra-articular injection. It has not been evaluated and should not be administered by epidural, intrathecal, intravenous, intraocular, intramuscular, intradermal, or subcutaneous routes, the company cautions. Serious events have been reported with epidural and intrathecal administration of corticosteroids, and none are approved for this use. Full prescribing information is available online.

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