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Abstract Introduction In clinical trials for knee osteoarthritis (OAK), rescue medication is commonly provided to manage uncontrolled index-knee pain. The impact of treatment on rescue medication utilization provides important information on the robustness of analgesic effect. In randomized controlled OAK trials (NCT01487161, NCT02116972, NCT02357459), intra-articular (IA) triamcinolone acetonide extended-release (TA-ER) demonstrated substantial, prolonged analgesia versus saline-placebo and TA crystalline solution (TAcs) as assessed by patient-reported pain scales. This pooled analysis assessed the impact of TA-ER on rescue medication use. Methods Patients (N = 798) with OAK (American College of Rheumatology criteria; Kellgren–Lawrence grade 2/3) and baseline average daily pain intensity score ≥ 5 to ≤ 9 (0–10 numeric rating scale) received a single IA injection of TA-ER (N = 324), saline-placebo (N = 262), or TAcs (N = 212). Acetaminophen/paracetamol tablets were provided to treat uncontrolled pain (knee or otherwise). Rescue medication consumption was monitored through a daily diary; pill counts were confirmed at the clinical site. Differences in rescue medication use were measured by least-squares mean (LSM) differences, number of rescue medication tablets used per day, and in area under the effect (AUE) curves of rescue medication tablets used per week. Results The overall number of rescue medication tablets used per day through week 24 was significantly less (p ≤ 0.05) for TA-ER versus saline-placebo (LSM difference, − 0.43) and TAcs (− 0.24). Rescue medication use was significantly (p ≤ 0.05) lower following TA-ER versus saline-placebo across weeks 1–12 (AUEweeks1–12; LSM difference, − 24.5) and weeks 1–24 (AUEweeks1–24; − 51.6) and versus TAcs across weeks 1–12 (AUEweeks1–12; − 21.1). Conclusions In patients with painful OAK, reduced rescue medication use may be a potential benefit of TA-ER and further supports its analgesic efficacy. Additional research is needed to assess whether TA-ER impacts the use of other common oral analgesics (nonsteroidal anti-inflammatory drugs, opioids) for patients with OAK. Funding Flexion Therapeutics, Inc., Burlington, MA, USA. Plain Language Summary Plain language summary available for this article.

Abstract Introduction The aim of this work is to assess the safety and efficacy of repeat administration of triamcinolone acetonide extended-release (TA–ER) in patients with symptomatic knee osteoarthritis (OA), including those with advanced radiographic severity. Methods In this phase 3b, single-arm, open-label study, patients aged ≥ 40 years received the first intra-articular TA-ER injection on day 1. Patients received the second injection timed to the response to the first injection (at either week 12, 16, 20, or 24). Patients who received two injections were evaluated every 4 weeks for 52 weeks. Safety was evaluated via treatment-emergent adverse events and any change at 52 weeks in index-knee radiographs (chondrolysis, osteonecrosis, insufficiency fractures, subchondral bone changes). Exploratory efficacy endpoints included Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)-A (pain), -B (stiffness), -C (function), and Knee Injury and Osteoarthritis Outcome Score-Quality of Life (KOOS-QoL) after each injection. Initiative in Methods, Measurements and Pain Assessment in Clinical Trials (IMMPACT) criteria were used to determine moderate and substantial treatment response. Results A total of 208 patients were enrolled and received the first injection of TA-ER; 179 (86.1%) received the second injection (median time to second injection: 16.6 weeks). Both injections were well tolerated, with no unexpected adverse events or significant radiographic changes at week 52. The magnitude and duration of clinical benefit after the first and second injections were similar, and most patients reported a substantial (≥ 50%) analgesic response after both doses. Conclusions Repeat administration of TA–ER using a flexible dosing schedule timed to patient response was well tolerated, with no radiographic evidence of cartilage impact. Both injections resulted in similar improvements in OA symptoms across a broad spectrum of disease severity reflective of that seen in clinical practice. Trial Registration Information ClinicalTrials.gov identifier: NCT03046446. Funding Flexion Therapeutics, Inc. Plain Language Summary Plain language summary available for this article.

Background: Intra-articular corticosteroids are commonly used for pain relief in patients with knee osteoarthritis. Simultaneous intra-articular corticosteroid (CS) knee injections may be beneficial for the ~80–90% of patients who present with, or develop, bilateral knee osteoarthritis, but concurrent injections may increase systemic CS exposure and data on safety/tolerability are lacking. Triamcinolone acetonide extended release (TA-ER) has shown decreased systemic triamcinolone acetonide exposure compared with traditional triamcinolone acetonide crystalline suspension (TAcs) after a single knee injection in patients with knee osteoarthritis. This phase IIa study was designed to assess the safety and systemic triamcinolone acetonide exposure following injections of TA-ER or TAcs into each knee of patients with bilateral knee osteoarthritis. Methods: Patients (⩾40 years) meeting American College of Rheumatology criteria for knee osteoarthritis in both knees received concurrent single intra-articular injections of TA-ER 32 mg or TAcs 40 mg into each knee (total: 64 mg and 80 mg, respectively) and were followed for 6 weeks. Safety was evaluated based on treatment-emergent adverse events (TEAEs). Blood samples for pharmacokinetic analysis were collected pre-injection, and at the following postinjection time points: 1, 2, 3, 4, 5, 6, 8, 10, 12, and 24 h, and days 8, 15, 29, and 43. Results: Baseline characteristics were balanced between patients randomly assigned to TA-ER ( n = 12) or TAcs ( n = 12). Both treatments were well tolerated with comparable TEAE profiles. Peak plasma triamcinolone acetonide concentrations (C max ) were lower following bilateral TA-ER injections [geometric mean, 2277.7 pg/ml (95% CI, 1602.13–3238.04)] compared with bilateral TAcs injections [7394.7 pg/ml (2201.06–24,843.43)], with median times to C max (T max ) of 4.5 and 6.5 h, respectively. Conclusions: In patients with bilateral knee osteoarthritis, intra-articular injection of TA-ER into both knees was well tolerated. Consistent with pharmacokinetic profiles observed after a single knee injection, plasma triamcinolone acetonide concentrations were lower after bilateral TA-ER injections compared with the higher and more variable concentrations observed after bilateral TAcs injections. ClinicalTrials.gov identifier: NCT03378076