Using Time-Released Corticosteroids to Treat Pain in Osteoarthritic Knees
Depending on the severity of OA, treatments can range from physical therapy or weight loss recommendations to intra-articular injections or surgery. For many, OA is debilitating. Pain can limit mobility and the range of life experiences that are accessible. More invasive treatments are indicated depending on the severity of the disease and symptoms.
Zilretta (triamcinolone acetonide release injectable suspension) is the first time-released corticosteroid. It has been on the market for just over two years and has now been successfully administered to over 100,000 patients.
While typical steroids dissipate quickly after injection and thus require significant doses, Zilretta dissipates slowly over 60 to 90 days, allowing a smaller dose to have longer pain-relief effects.
Zilretta is manufactured by Burlington, Massachusetts-based Flexion Therapeutics, “a biopharmaceutical company focused on the development and commercialization of novel, local therapies for the treatment of patients with musculoskeletal conditions, beginning with osteoarthritis (OA), a type of degenerative arthritis.”
Zilretta consists of a suspension of microspheres With “small crystals of TA are embedded in a poly lactic-co-glycolic acid (PLGA) co-polymer matrix.” Flexion reports that, “In vitro, release of TA from the microsphere nano-channels, limit both egress of TA from the microsphere’s interior and internal hydration of the polymer,” prolonging drug release.
John Richmond, M.D. on How to Use Time Release Corticosteroids
John C. Richmond, M.D., the former chairman of orthopedic surgery at New England Baptist Hospital, Boston Sports and Shoulder Center, spoke about the unique benefits of Zilretta. Dr. Richmond is a spokesperson and consultant for Zilretta, a medical provider who administers Zilretta, and a patient who has received injection himself. He said that Zilretta “truly does what we want a corticosteroid to do.”
Richmond explained that the treatment is injected into the synovial space and “stays there with measurable quantities within the joint.” He explained, “The extended release corticosteroid Zilretta is designed specifically to stay within the joint space so when it’s injected intra-articularly. You want to keep it within the synovial space so there’s a huge concentration of corticosteroid intra-articularly.”
As a side benefit, Richmond noted, “at the same time it actually has a secondary benefit… it keeps it out of the plasma which is one of the potential issues with corticosteroid injections.” Richmond pointed out that this is particularly significant for type 2 diabetes patients suffering from OA, as standard corticosteroid injections can increase blood glucose levels past amounts recommended by the American Diabetes Association.
Richmond explained that pain relief reports by patients have been significant. In a clinical research trial including only patients with moderate to severe pain, 15% had no to mild pain 7 days after the injection and 70% still reported no to mild pain 12 weeks after injection.
According to Richmond, research has not indicated any significant adverse reactions. Contraindications are common to other corticosteroids and include injection into infected sites, repeated use with risk of endocrine disruption, and injection into sites other than intra-articular space. Zilretta literature indicates that its common side effects “include sinus infections (sinusitis), cough bruising, and joint swelling.”
Zilretta is not yet intended for repeat use. FDA approval requires additional research for more than a single injection. A phase 3 study completed and has been submitted to FDA.
