A controlled comparative evaluation of acetaminophen and aspirin in the treatment of postoperative pain.

The analgesic effects of acetaminophen (1 gm), aspirin (650 mg), and placebo were evaluated in a double-blind, randomized parallel study. The subjects were 162 outpatients who had experienced moderate or severe pain as a result of dental surgery involving bone removal. Patients evaluated the intensity of their pain and the extent of their relief from pain at 30 minutes, at one hour, and at each subsequent hour for six hours after the administration of the study medication. During the six-hour period, 135 of the 162 patients were remedicated. At the end of the six-hour period each patient assessed overall treatment. Two measures of analgesia were derived from patients' evaluations of the intensity of pain, and three other measures were derived from evaluations of relief from pain. On all six measures used, the groups receiving acetaminophen and aspirin reported analgesic effects significantly superior (P less than 0.05) to those of placebo. Acetaminophen was significantly better than aspirin with respect to the maximum difference in the intensity of pain (P less than 0.05) and the maximum pain relief achieved (P less than 0.03) and according to the global evaluation (P less than 0.02). These differences were most striking in patients with severe initial pain.