COMPARATIVE-EVALUATION OF THE ANALGESIC EFFICACY OF IBUPROFEN, DEXTROPROPOXYPHENE, AND THEIR COMBINATION IN HEALTHY-VOLUNTEERS

Nine healthy male volunteers received ibuprofen 400 mg + dextropropoxyphene 65 mg, ibuprofen 400 mg alone, and dextropropoxyphene 65 mg alone in a three-way crossover study, using a Latin-square, complete-block multiple group design. Pain threshold was measured by using the ischemic pain and radiant heat tolerance tests. The volunteers underwent both tests before drug therapy and periodically for up to 5 hours after drug administration. The ischemic pain tolerance test was administered at baseline, at drug dosing, and at 30, 60, 90, 120, 150, 180, 210, 240, 300, 330, 360 minutes after drug therapy. The radiant heat tolerance test was performed at baseline, at drug dosing, and at 45, 75, 105, 135, 165, 195, 225, 285, 315, 345, 375 minutes after drug therapy. In both tests, the fixed-dose combination of ibuprofen 400 mg + dextropropoxyphene 65 mg showed a significantly (P < 0.05) larger area under the curve than either ibuprofen 400 mg or dextropropoxyphene 65 mg alone. These results suggest that the two drugs have a synergistic effect and confirm that the combination of ibuprofen 400 mg + dextropropoxyphene 65 mg is superior to the individual drugs used alone.