Pentazocine suppositories versus pethidine injections in 500 patients with post-operative pain.

Pentazocine (Fortral) suppositories (50 mg) were compared with pethidine (100 mg) by injection in 500 patients after general and gynaecological surgery. Pain was assessed by patients using a pain thermometer, (a modification of a visual analogue scale), and by observers using an adjectival scale. There was a good relationship between these methods. Good pain relief was obtained with both drugs and there was little difference between the treatments in moderate pain. Pethidine was faster and more effective, particularly in severe pain. There were fewer side-effects with pentazocine suppositories. They are a useful alternative to injections, especially in moderate pain.