A double-blind comparison of parenteral dipyrone and pethidine in the treatment of post-operative pain.

A double-blind trial was carried out in 100 patients with moderate to severe post-operative pain to compare the analgesic effectiveness over a 6-hour period of single intramuscular injections of 2.5 g dipyrone and 100 mg pethidine. Maximum pain relief was seen 2 hours after drug administration in both groups and there was no statistically significant difference in responses. No side-effects were reported.