The pain intensity at analgesic intake, and the efficacy of diflunisal in single doses and effervescent acetaminophen in single and repeated doses.

A double-blind, randomized analgesic trial was carried out in 150 patients undergoing surgical removal of their 2 impacted lower wisdom teeth. The analgesic efficacy of effervescent acetaminophen 500 or 1000 mg in a 2-dose regimen was compared with that of diflunisal 500 mg in a single dose. Each dose was taken when subjectively needed and the pain intensity was measured on a visual analog scale during the 10-hour period after first medication. The best pain reduction was achieved with diflunisal. The difference between diflunisal 500 mg and acetaminophen 1000 mg was significant, as was that between acetaminophen 1000 and 500 mg. The peak effect after the first dose occurred later but was greater with diflunisal than with acetaminophen. Patients needing analgesics at low pain intensities seemed to discriminate better between treatments, and the efficacy of acetaminophen was weakly dependent on the initial pain intensity. This intensity was difficult to predict, and only a poor correlation was found between the initial pain intensity and the patient's prior estimate of this.