Pooled safety analysis of diclofenac sodium topical solution 1.5% (w/w) in the treatment of osteoarthritis in patients aged 75 years or older

BACKGROUND: This study aimed to determine the safety of diclofenac sodium topical solution 1.5% (w/w) in 45.5% dimethyl sulfoxide (TDiclo) for the treatment of knee or hand osteoarthritis in persons aged 75 years or older. METHODS: A pooled analysis of safety data from seven multicenter, randomized, blinded, Phase III clinical trials (4–12 weeks’ duration) of TDiclo was conducted. The analysis focused on a subset of patients (n = 280) aged 75 years or older with a primary diagnosis of osteoarthritis of the knee (six trials) or hand (one trial). Patients received one of three topical treatments: TDiclo (n = 138); placebo (2.33% or 4.55% dimethyl sulfoxide, n = 39); or control (45.5% dimethyl sulfoxide, n = 103). Treatment groups were compared using Chi-square analysis, Fisher’s Exact test, or analysis of variance. RESULTS: The most common adverse events involved the skin or subcutaneous tissue, primarily at the application site. The incidence of dry skin was higher in the TDiclo (36.2%; P < 0.0001) and dimethyl sulfoxide control (18.4%; P = 0.0142) groups than in the placebo group (2.6%); the incidence of other skin or subcutaneous tissue adverse events was similar between the groups. Relatively few patients (<18%) experienced gastrointestinal adverse events, and group differences were not detected. In the TDiclo group, constipation (3.6%), diarrhea (3.6%), and nausea (3.6%) were the most common gastrointestinal adverse events. Cardiovascular and renal/ urinary adverse events were rare, and group differences were not detected. There was one case (0.7%) each of hypertension, spider veins, and vasodilation in the TDiclo group. Changes from baseline to the final visit in blood pressure and hepatic/renal enzyme levels were also similar between the groups. CONCLUSION: TDiclo appears to be well tolerated for the treatment of osteoarthritis in persons aged 75 years or older.