Diclofenac Sodium Topical Solution 1.5% w/w with Dimethyl Sulfoxide Compared with Placebo for the Treatment of Osteoarthritis: Pooled Safety Results

Abstract

Oral nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2-selective inhibitors are frequently recommended for management of osteoarthritis (OA). However, serious gastrointestinal and cardiovascular systemic adverse events (AEs) are associated with oral NSAIDs and can be treatment limiting. The efficacy of diclofenac sodium topical solution 1.5% w/w with dimethyl sulfoxide (TDiclo) has been established as superior to placebo and comparable with oral NSAIDs in the management of OA. This study characterizes the safety and tolerability profile of TDiclo compared with placebo through a pooled analysis of data from 1252 patients in 7 randomized controlled trials across 61 centers in the United States and 97 centers in Canada. Patients received TDiclo (n = 911) or placebo (n = 341) for 4 to 12 weeks for management of OA of the hand or knee. The most frequently reported AE was dry skin, occurring in 33.0% of patients receiving TDiclo and 5.0% of patients receiving placebo (P < 0.001). Dyspepsia was the most common gastrointestinal reaction, reported by 7.7% of patients receiving TDiclo and 2.9% of patients receiving placebo (P = 0.002). Changes in vital signs and laboratory assessments of hepatic and renal function were similar between the 2 groups; TDiclo did not increase mean blood pressure, nor was it associated with hypertension. The rate of serious AEs favored placebo in both groups (0.9% for TDiclo vs 1.5% for placebo; P = 0.358), as did the rate of severe AEs (4.4% vs 7.6%; P = 0.023). The most common reason for study discontinuation was dry skin (2.5% vs 0.3%). Results from this analysis suggest that TDiclo is well tolerated in a large population and may offer an alternative to oral NSAID therapy for OA of the knee or hand, particularly for patients at increased risk for serious systemic AEs. Larger head-to-head, long-term, multicenter trials would be beneficial to further evaluate safety data comparing both topical and oral NSAIDs.