FDA Approves Zilretta for Osteoarthritis Knee Pain

The US Food and Drug Administration (FDA) has approved triamcinolone acetonide extended-release injectable suspension, also known as FX006 (Zilretta, Flexion), a non-opioid, for the treatment of osteoarthritis (OA) knee pain.

It is currently the first and only extended-release, intra-articular injection available for OA. The treatment utilizes Flexion’s microsphere technology and has been shown to alleviate pain for more than 12 weeks.

“The approval of Zilretta marks a major advancement in the treatment landscape for managing OA knee pain," Michael Clayman, MD, the president and CEO of Flexion, said in a statement. “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.”

The decision to approve the medicine came based on data from a phase 3 randomized trial involving 484 patients around the world. The trial demonstrated highly significant, durable, and meaningful pain relief compared to placebo (p<0.0001).

The trial randomized patients to either a single intra-articular injection of 40 mg Zilretta or placebo. Patients reported an average of 50% reduction in pain from baseline across weeks 1 through 12. The therapy had previously received fast-track designation from the FDA as a result.

“Each time we get a new tool to use with patients, there are always many people who can benefit from that drug,” Angus Worthing, MD, the chair of the American College of Rheumatology’s Government Affairs Committee, told MD Magazine. “I think rheumatologists are aware of all of the safety concerns of the drugs we use, and if the drug is approved by the FDA, rheumatologists are able to bring up those concerns with their patients, and discuss the possibility of risks, and weigh those risks against the potential benefits of the drug.”

Data from an additional study examining blood glucose concentrations also appears on the drug’s label. According to Steven Russell, MD, PhD, an assistant professor of medicine at Massachusetts General Hospital Diabetes Research Center, the drug may help avoid spikes in blood glucose levels that are often seen in patients with type 2 diabetes and knee OA when using corticosteroids.

OA affects more than 30 million Americans yearly, and its prevalence is expected to continue rising in the future. Patient options are usually limited to immediate-release corticosteroid or hyaluronic acid intra-articular injection. The need for a non-opioid, non-surgical intervention for OA has been sought after for some time from physicians.

“We believe that Zilretta has the potential to be a transformative medicine for the more than five million patients who receive an intra-articular injection for OA knee pain each year,” Clayman added.

Flexion anticipates the availability of the drug by the end of October 2017.