Randomized, Double-Blind, Double-Masked, Parallel Group Clinical Study to Compare the Effectiveness of Diclofenac Potassium 150 mg, LP OD, vs Diclofenac Potassium 50 mg, TID, Three Times a Day, in Knee Osteoarthritis

Background: Osteoarthritis is a chronic disease associated with pain, inflammation, stiffness and synovial effusion, with progressive functional limitation, compromising quality of life. It progressively leads to loss or decrease in joint function. Pharmacological and non-pharmacological therapy seeks symptomatic management, complicated by a lack of adherence. After acetaminophen, non-steroidal anti-inflammatory drugs such as diclofenac are the most widely used medications. Objectives: The primary objective compared the analgesic effect of diclofenac 150 mg once daily vs. 50 mg three times daily in patients with knee osteoarthritis. The secondary objective assessed changes in quality of life. Method: One group received diclofenac 150 mg OD with placebo TTD. Another group received placebo OD and 50 mg active diclofenac (reference) TTD, both for 30 days. The evaluation of pain was carried out by a visual analog scale (VAS), at the beginning, 2, 3, 4, 15 and 30 days, quality of life (the WOMAC scale) and adverse effects, at 15 and 30 days. Results: Pain decreased significantly on days 15 and 30, compared to day 0, in both groups, without differences between groups. The total results in the WOMAC scale showed a very marked improvement at 15 and 30 days, without differences between groups. The most frequent adverse effects were constipation 6% in the reference group, and gastric discomfort 30.3% in the reference group vs 28.1%, in the Test group. Conclusions: Prolonged-release diclofenac 150 mg OD is as effective as diclofenac 50 mg TID for the treatment of patients with knee osteoarthritis.