In a double-blind clinical trial, meptazinol (400-mg capsules) was shown to be significantly better than placebo in relieving postoperative pain in patients who had under gone total abdominal hysterectomy operations. Analgesic activity was assessed by patients rating their pain before and 1 hour after the administration of each treatment, by sequential analysis of patient and investigator preference for treatment, and by calculating the time interval between doses of the two treatments.