Effectiveness and safety of diclofenac epolamine topical patch 1.3% for the treatment of acute pain due to back strain: an open-label, uncontrolled study.

The diclofenac epolamine topical patch 1.3% (DETP) is indicated for topical treatment of acute pain due to minor strains, sprains, and contusions. This exploratory, multicenter, open-label study evaluated effectiveness and safety of DETP in patients with acute pain due to back strain. Patients aged ≥ 18 years with acute pain due to nonradicular back strain with an average pain intensity of ≥ 4 (0 = no pain, 10 = pain as bad as you can imagine) entered a 3-day observation/washout period and completed daily diary modified Brief Pain Inventory assessments. At baseline, patients with an average pain intensity of ≥ 4 started DETP treatment (q12h). Patients were treated for 7 or 14 days, depending on investigator and patient assessment of pain resolution. Primary endpoint was mean change from baseline to end of treatment in average pain intensity. Key secondary endpoints included changes from baseline in least, worst, and current pain scores and Beck Depression Inventory(®) II scores. Patients and investigators assessed patch satisfaction and global pain relief. In 123 enrolled patients, baseline mean ± standard deviation average pain score was 6.5 ± 1.3, which decreased to 2.5 ± 2.4 (P < 0.0001) at end of treatment. Similarly, least, worst, and current pain scores were also reduced (P < 0.0001). Sixty-three percent of patients achieved ≥ 50% pain reduction from baseline. At the end of treatment, most patients (88%) were satisfied or very satisfied with DETP. For 85% of patients, investigators also reported being satisfied or very satisfied with DETP. Most patients (87%) and investigators (88%, rating the patient's response) rated global pain relief as moderate to complete. Fifteen patients experienced a total of 19 adverse events (AEs), 17 of which were mild to moderate, and 2 of which were severe. Three AEs were treatment related (application site rash, nausea, and tachycardia); 1 patient had a serious AE (noncardiac chest pain) considered unrelated to DETP. In this exploratory study, patients experienced well-tolerated relief for acute pain due to back strain, with ≥ 85% of patients and their investigators expressing satisfaction with DETP treatment.