Review of the efficacy and tolerability of the diclofenac epolamine topical patch 1.3% in patients with acute pain due to soft tissue injuries

The diclofenac epolamine topical patch 1.3% (DETP) was approved by the US Food and Drug Administration in January 2007 for the treatment of soft tissue injuries such as strains, sprains, and contusions, although it has been available for many years in >40 countries worldwide.The aim of this study was to review the efficacy and tolerability of the DETP in relieving acute pain caused by soft tissue injuries.The MEDLINE, Derwent Drug File, BIOSIS, and EMBASE databases were searched for literature published between 1984 and October 30, 2009, in any language, using the terms diclofenac epolamine patch, diclofenac hydroxyethylpyrrolidine patch, and FLECTOR Patch. Clinical studies of the efficacy and/or tolerability of the DETP in patients with acute pain due to soft tissue injuries or localized periarticular disorders were included. Efficacy studies that enrolled patients with other medical conditions were excluded, except for reports that focused on tolerability, which were included to supplement tolerability data. The bibliographies of included studies were reviewed manually for relevant articles based on inclusion and exclusion criteria, and the manufacturer was contacted for additional relevant postmarketing surveillance information and presentations from scientific meetings.The search identified 6 placebo-controlled clinical studies, 1 active-comparator-controlled clinical study, and 1 open-label comparator clinical study of the efficacy and tolerability of the DETP in patients with soft tissue injuries. Three studies reported on tolerability. Primary analyses among the 8 studies reported DETP-associated reductions in spontaneous pain from baseline, assessed using a visual analog scale, ranging from 26% to 88% on day 7 and 56% to 61% on day 14. The use of the DETP was associated with significantly greater reductions in pain scores compared with a placebo patch (2 studies) on day 7 (88% vs 74%; P = 0.001) and day 14 (56.5% vs 46.8%; P = 0.001) and compared with diclofenac diethylammonium topical gel (1 study) on day 14 (60.8% vs 40.8%; P < 0.001). With the use of the DETP, median time to pain resolution was 3 days less than with placebo (8.8 vs 12.4 days; P = 0.009). The prevalences of adverse events across the 11 studies were low (3.1%-14.0%) and not significantly different from those with placebo (5.8%-16.0%). The most commonly reported adverse events were cutaneous application-site reactions (pruritus, rash, and dermatitis) and gastrointestinal symptoms (nausea).Based on data from clinical studies and postmarketing experience, the DETP was associated with significant pain relief in patients with soft tissue injuries, with good tolerability.