Tramadol/acetaminophen combination tablets for the treatment of osteoarthritis flare pain: a multicenter, outpatient, randomized, double-blind, placebo-controlled, parallel-group, add-on study

Abstract

Background: In a flare of osteoarthritis (OA) pain, increasing the dose of standard anti-inflammatory or routine analgesic drugs may not be practical because of an increased incidence of side effects. In patients achieving inadequate pain relief from traditional nonsteroidal anti-inflammatory drugs (NSAIDs) or cyclooxygenase (COX)-2—selective inhibitors, it may be appropriate to add an analgesic agent with a different mechanism of action, thereby targeting multiple components of the pain pathway. Objective: The addition of tramadol/acetaminophen tablets to existing therapy was compared with the addition of placebo in the treatment of OA flare pain. Methods: This was a multicenter, outpatient, randomized, double-blind, placebo-controlled, parallel-group, add-on study. Patients received 1 or 2 tramadol/acetaminophen (37.5 mg/325 mg) tablets QID or matching placebo for 10 days in addition to ongoing NSAID or COX-2—selective inhibitor therapy. The primary outcome measures were average daily pain intensity and average daily pain relief scores from days 1 through 5. Results: Three hundred eight patients were randomized to tramadol/acetaminophen (n = 197) or placebo (n = 111) and were followed for up to 10 days. Patients had a mean (±SD) age of 60.1 ± 9.87 years, and were predominantly female (71.8%) and white (87.7%). Their mean (±SD) pain visual analog score at baseline was 73.2 ± 11.8 mm, and their mean pain intensity score was 2.4 ± 0.5 (on a scale from 0 = none to 3 = severe). Average daily pain intensity and pain relief scores were significantly improved with tramadol/acetaminophen compared with placebo on the primary assessment of efficacy from days 1 through 5 (both, P < 0.001) and on the assessment of efficacy from days 1 through 10 (both, P < 0.001). Tramadol/acetaminophen was significantly superior to placebo on the patients' and physicians' overall assessments of medication (both, P < 0.001) and on 3 of 4 subscales (pain [ P = 0.004], physical function [ P = 0.013], and overall [ P = 0.008]) of the Western Ontario and McMaster Universities Osteoarthritis Index Questionnaire. The most common treatment-emergent adverse events with tramadol/acetaminophen were nausea, vomiting, and dizziness. No serious adverse events were reported in the tramadol/acetaminophen group. Conclusion: In this study, addition of tramadol/acetaminophen to NSAID or COX-2—selective inhibitor therapy was well tolerated and effective in the treatment of OA flare pain.