Comparison of butorphanol and pentazocine as postoperative analgesics.

Sixty patients with moderate or severe postsurgical pain were randomly divided into three equal groups for a double-blind comparison of the analgesic effectiveness of intramuscular butorphanol (2 and 4 mg) and pentazocine (60 mg). The groups were demographically similar. Pain intensity and pain relief were scored at 10, 20, 30, 60, 120, 180, and 240 minutes after administration of the drug. All treatments provided significant analgesic activity (P less than .05) within ten minutes. However, both doses of butorphanol reached their peak effect at 30 minutes, in contrast to 60 minutes for pentazocine. The duration of effect appeared somewhat longer for butorphanol, though this did not achieve statistical significance. Butorphanol (4 mg) had a significantly greater (P less than .05) analgesic effect at ten minutes than pentazocine (60 mg), and both butorphanol treatments (2 and 4 mg) were significantly better than pentazocine, according to many parameters at 20 and 30 minutes. Side effects, chiefly sleepiness and dizziness, were seen in 15% of the patients, with no significant difference between the treatment groups.