An Open-Label, Long-Term Safety and Tolerability Trial of Diclofenac Sodium 1% Gel in Patients with Knee Osteoarthritis

Abstract

Objective: To evaluate the long-term safety and tolerability of topical diclofenac sodium 1% gel (DSG) in the treatment of knee osteoarthritis (OA) for up to 12 months. Methods: This was a multicenter open-label, extension of two 3-month, randomized, double-blind studies of DSG in patients with knee OA (NCT ID: NCT00171691, “Safety of Diclofenac Sodium Gel in Knee Osteoarthritis”). To ensure adequate enrollment, some DSG-naïve patients with OA who had not participated in the double-blind studies were also enrolled. Patients applied 4 g DSG to 1 or both knees 4 times daily for 9 to 12 months. Safety was evaluated through adverse event (AE) reporting, physical examination, and laboratory investigations. Patients completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and physical function scales every 3 months to assess long-term effectiveness. Results: The extension study enrolled 583 patients; 294 patients completed the study. Use of DSG was documented for 578 patients (safety population). The mean age was 62.3 years, and 63.7% of patients were women. Overall, 112 (19.4%) patients reported ≥ 1 treatment-related AE, and the only treatment-related AE occurring in ≥ 1% of patients was application-site dermatitis. Treatment-related gastrointestinal, renal-function, hepatic-function, and cardiovascular AEs were reported by 3, 1, 2, and 0 patients, respectively. There were no serious AEs or deaths. At 1 year, improvements from baseline for WOMAC pain, stiffness, and physical function scale scores were 39.8%, 33.4%, and 36.9%, respectively. Conclusion: The long-term safety profile of DSG was consistent with previous 12-week studies, and DSG remained effective for a 1-year period.