[Treatment of epidural morphine induced pruritus with butorphanol]

Epidural morphine has been used to provide postoperative analgesia. However, one of the most common side effects of epidural morphine is pruritus. The incidence may or may not be related to the dose of morphine administered. First, we examined whether epidural morphine induced a dose-related increase in pruritus or not. Secondly, the purpose of this study was to evaluate the relief of pruritus when a combination of epidural morphine (a mu-receptor agonist) and butorphanol (a mu-receptor antagonist and kappa-receptor agonist) was administered.

The incidence of pruritus, in 100 patients after abdominal surgery receiving continuous epidural analgesia with 0.2% ropivacaine + morphine, was retrospectively evaluated. Secondly, 60 adult patients undergoing abdominal surgery were randomly assigned to receive one of three epidural regimens; (1) continuous infusion of 0.2% ropivacaine with morphine 3.3 mg x day(-1) + butorphanol 2 mg x day(-1) (group MB), (2) morphine 3.3 mg x day(-1) alone (group M), or (3) butorphanol 2 mg x day(-1) alone (group B) at a rate of 4 ml x hr(-1), for 75 hours.

Continuous epidural morphine at more than 3 mg x day(-1) caused a dose-related increase in pruritus. Pruritus was 0% in group B and group MB, but 55% in group M.

Butorphanol 2 mg x day(-1) was effective in preventing pruritus associated with continuous epidural infusion of morphine 3.3 mg x day(-1).