Preoperative gabapentin prevents intrathecal morphine-induced pruritus after orthopedic surgery.

BACKGROUND: Pruritus is the most common side effect of intrathecal morphine. Gabapentin is an anticonvulsant and had been reported to be effective in some chronic pruritus conditions. Its effect in intrathecal morphine-induced pruritus has not yet undergone an evaluation.

METHODS: We randomly allocated 86 patients scheduled for lower limb surgery under spinal anesthesia into two equal groups that received either gabapentin 1200 mg or placebo 2 h before operation in a prospective, double-blind manner. All patients received an intrathecal injection of 15 mg of 0.5% isobaric bupivacaine and 0.2 mg preservative-free morphine. Pruritus was evaluated at 3, 6, 9, 12, and 24 h after intrathecal morphine administration.

RESULTS: The incidence of pruritus was significantly more frequent in the placebo group compared with the gabapentin group (77.5% vs 47.5%; P = 0.01). The onset time of pruritus in the gabapentin group (6.2 +/- 1.8 h) was significantly delayed compared with that in the placebo group (3.1 +/- 0.8 h) (P < 0.0001). The severity of pruritus was significantly more in the placebo group compared with the gabapentin group at 3 and 6 h after intrathecal morphine injection.

CONCLUSION: Preoperative gabapentin prevents pruritus induced by intrathecal morphine in patients undergoing lower limb surgery with spinal anesthesia.