DOES EPIDURAL ADMINISTRATION OF BUTORPHANOL OFFER ANY CLINICAL ADVANTAGE OVER THE INTRAVENOUS ROUTE - A DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL

The differential effects of intravenous versus epidural administration of short-acting, lipid-soluble opioids is controversial. This study was undertaken to compare these two routes of administration using the mixed agonist-antagonist opioid, butorphanol. Forty-five women undergoing elective cesarean delivery at term under epidural lidocaine anesthesia were randomized to receive a single bolus of either epidural or intravenous butorphanol 2 mg or saline control for postoperative analgesia. At precisely 60 min after the last dose of epidural local anesthetic, all patients received a simultaneous epidural and intravenous injection in a randomized, double-blinded fashion. The intravenous group received butorphanol intravenous and saline epidurally; the epidural group received saline intravenous and butorphanol epidurally; and a control group received saline via both routes. When additional analgesia was requested, all patients received patient-controlled analgesia (PCA) with intravenous morphine 2-mg demand dose, 7-min lockout interval). Analgesia was quantitated using a visual analogue scale and subsequent PCA morphine requirements. The interval from study drug injection until first request for PCA use was equivalent for the intravenous and epidural groups (89 +/- 9 and 83 +/- 8 min, respectively) and significantly longer than in control group (39 +/- 4 min, P < 0.001, intravenous and epidural vs. control). Analgesia was equivalent in the intravenous and epidural groups at all observation points, and pain scores were significantly lower than control for the first 120 min after study drug injection. Both intravenous and epidural groups had similar patterns of morphine usage. Both butorphanol groups used significantly less morphine during the first 2 h of the study period than did the control group; thereafter, morphine usage was similar in all three groups. After initiation of PCA therapy, pruritus was noted in 60% (9 of 15) of control patients, 13% (2 of 15) in the epidural group, and none in the intravenous group (P < 0.005, intravenous and epidural vs. control). Nausea occurred in 53% (8 of 15) in the control group and 13% (2 of 15) in both intravenous and epidural groups (P < 0.05, intravenous, epidural vs. control). Somnolence occurred in 66% (10 of 15) in the intravenous group, 13% (2 of 15) in the epidural group, and 7%, (1 of 15) in the control group (P < 0.005, intravenous vs. control and epidural). In summary, 2 mg of either intravenous or epidural butorphanol produced similar analgesic profiles, and both were equally effective in decreasing pruritus and nausea during subsequent PCA morphine usage. We conclude that under the conditions of this study, epidural administration of butorphanol offers few, if any, clinical advantages over the intravenous route.