Tramadol/acetaminophen combination tablets and codeine/acetaminophen combination capsules for the management of chronic pain: A comparative trial

Background: Opioid/acetaminophen (APAP) combination analgesics are widely prescribed for the relief of moderate pain. Tramadol is a synthetic analgesic that has been shown to be effective both alone and in combination with APAP. Objective: The purpose of this study was to compare the efficacy and tolerability of tramadol/APAP tablets with codeine/APAP capsules. Methods: This 4-week, randomized, double-blind, parallel-group, active-control, double-dummy, multicenter trial compared tramadol/APAP (37.5 mg/325 mg) with codeine/APAP (30 mg/300 mg) for the management of chronic nonmalignant low back pain, osteoarthritis (OA) pain, or both in adults. Pain relief (scale, 0 = none to 4 = complete) and pain intensity (scale, 0 = none to 3 = severe) were measured 30 minutes and then hourly for 6 hours after the first daily dose each week. Patients and investigators assessed the efficacy (scale, 1 = poor to 5 = excellent) of each medication, and patients recorded daily doses of study and rescue medications. Results: A total of 462 patients (mean age, 57.6 years) were randomly assigned to treatment, with 112 (24%) reporting chronic low back pain, 162 (35%) reporting OA pain, and 188 (41%) reporting both low back and OA pain; 309 patients (67%) received tramadol/APAP and 153 (33%) received codeine/APAP. Pain relief and changes in pain intensity were comparable from day 1, as early as 30 minutes after the first dose, and lasted for at least 6 hours. Total pain relief scores (11.9 for tramadol/APAP; 11.4 for codeine/APAP) and sum of pain intensity differences (3.8 for tramadol/APAP; 3.3 for codeine/APAP) were also comparable throughout. Overall assessments of efficacy by patients (mean score 2.9 in each treatment group) and investigators (mean score 3.0 for tramadol/APAP, 2.9 for codeine/APAP) were similar for the 2 treatment groups. Equivalent mean doses (3.5 tablets or capsules daily) and maximum daily doses (5.5 tablets or 5.7 capsules) were used in the 2 treatment groups. The overall incidence of adverse events was comparable, with a significantly higher proportion of patients in the codeine/APAP group reporting somnolence (24% [37/153] vs 17% [54/309], P=0.05) or constipation (21% [32/153] vs 11% [35/309], P<0.01) and a larger proportion of patients in the tramadol/APAP group reporting headache (11% [34/309] vs 7% [11/153], P=0.08). Conclusion: The results of this study suggest that tramadol/APAP tablets (37.5 mg/325 mg) are as effective as codeine/APAP capsules (30 mg/300 mg) in the treatment of chronic nonmalignant low back pain and OA pain and are better tolerated.