General Information

Zilretta is an extended-release injectable suspension of triamcinolone acetonide, a short-acting corticosteroid.

Zilretta is specifically indicated for the management of osteoarthritis pain of the knee.

Zilretta is supplied as a suspension for intra-articular injection. Zilretta is supplied as a single use intra-articular extended-release injection, to deliver 32 mg (5 mL). Zilretta should not be administered by the following routes: epidural, intrathecal, intravenous, intraocular, intramuscular, intradermal, subcutaneous. 

Mechanism of Action

Zilretta is an extended-release injectable suspension of triamcinolone acetonide, a short-acting corticosteroid, with anti-inflammatory and immunomodulating properties. It binds to and activates the glucocorticoid receptor, leading to activation of anti-inflammatory transcription factors such as lipocortins and inhibition of inflammatory transduction pathways by blocking the release of arachidonic acid and preventing the synthesis of prostaglandins and leukotrienes.

Side Effects

Adverse effects associated with the use of Zilretta may include, but are not limited to, the following:

• sinusitis
• cough
• contusions

Clinical Trial Results

The FDA approval of Zilretta was based on a multi-center, international, randomized, double-blind, parallel-arm, placebo- and active-controlled study in subjects with osteoarthritis pain of the knee. A total of 484 patients were treated and followed for up to 24 weeks. A total of 470 patients (97%) completed follow-up to Week 12, the time point for primary efficacy determination, and 443 (91.5%) completed to Week 24. The primary efficacy endpoint comparing Zilretta to placebo was change from baseline at Week 12 in the weekly mean of the Average Daily Pain intensity scores (ADP) as assessed by a 0-10 Numeric Rating Scale (NRS). Zilretta demonstrated a statistically significant reduction in pain intensity at the primary endpoint versus placebo. Zilretta also demonstrated a reduction in pain intensity scores each week from Weeks 1 through 12.