Single dose of gabapentin for prophylaxis intrathecal morphine-induced pruritus in orthopedic surgery: a randomized controlled trial.

Gabapentin has an antipruritus effect, which its efficacy in reducing pruritus induced by intrathecal morphine has not been well documented. The purpose of the present study was to know if a single smaller dose of gabapentin could decrease the intrathecal morphine-induced pruritus.One hundred sixty eight patients from the 180 recruited patients fulfilled the trial requirement and were scheduled for orthopedic surgery under spinal anesthesia using 0.5% isobaric bupivacaine and 0.2 mg preservative-free morphine. The patients were divided into two groups, each of 84 subjects and received either gabapentin 600 mg or a placebo, two hours preoperatively, in a prospective, randomized, double-blind, placebo-controlled trial. The pruritus was evaluated at 1, 2, 3, 4, 6, 9, 12 and 24 hours after intrathecal morphine administration. Adverse events were noted.The overall incidence of pruritus was not significantly different between the two groups while the incidence and severity of pruritus was significantly decreased in the gabapentin group at four hours after intrathecal morphine injection (18 of 84 subjects, 21.4% vs. 35 of 84 subjects, 41.7%; p = 0.008 and 0.045 respectively). The urinary retention was significantly higher in the study group compared to the placebo group (50.0% (42 of 84 subjects) vs. 33.3% (28 of 84 subjects) p = 0.042).Preoperative gabapentin 600 mg did not significantly reduce the postoperative intrathecal morphine-induced pruritus.