Comparative evaluation of ciramadol (WY-15.705), morphine and placebo for treatment of postoperative pain.

The efficacy and safety of intramuscular ciramadol to alleviate postoperative pain was compared to morphine in a double-blind placebo controlled study of 100 patients. Postoperative analgesia was assessed using a visual analog scale and two categorical measurements. Two dose levels of ciramadol (30 and 60 mg) were compared to morphine (5 and 10 mg). A valid dose-response curve was obtained for both drugs with no significant deviation from parallelism. Compared to morphine 10 mg, ciramadol 60 mg induced a faster onset of analgesia and showed a longer lasting effect as deduced from the pain intensity difference and pain analog intensity difference time-effect curves (P less than 0.01). All active therapy groups provided better analgesia than the placebo group. The estimated relative analgesic potency of ciramadol to morphine was 0.3 to 1. Some increase in sedation level was seen following therapy in each group with the largest increase in the ciramadol 60 mg group. There was no statistically meaningful among group differences in the adverse experience incidence rates. Postoperative respiratory function showed a significant decrease from the baseline respiration rate in the ciramadol 60 mg group, although respiration rate was notably reduced in each active therapy group more than in the placebo group. Blood pressure was not impaired following ciramadol whereas morphine 10 mg induced a significant decrease in diastolic blood pressure.