[Clinical evaluation of buprenorphine suppositories in postoperative patients--plasma concentrations and effects on the respiratory and circulatory system].

The plasma concentrations of buprenorphine were measured and blood gas analysis was done after administration of buprenorphine suppositories (0.2 and 0.4 mg) or its intramuscular injection (0.2mg) in postoperative patients. The C max for 0.4mg suppositories was comparable to that for 0.2mg injection, whereas the T max for suppositories was as large as about 2 hrs in contrast to 1.5 hrs for 0.2mg injection. The size of AUC was in the following order: 0.4mg suppositories greater than 0.2mg injection greater than 0.2mg suppositories. Neither notable increase in PaCO2 nor decrease in respiration rate was observed after administration of the suppositories, indicating that the formulation will not cause clinically significant respiratory depression. No significant changes were observed in blood pressure or pulse rate. Buprenorphine suppositories are considered to be safe for use in postoperative patients. Percent pain relief in the suppository group was smaller than that in the injection group. This appears to be due to a slower rate of increase in the plasma levels of buprenorphine after administration of suppositories than that after intramuscular injection. Therefore, it seems practical to give this drug to postoperative patients before the start of pain.