To evaluate the efficacy of gabapentin at 20 mg/kg per day in the treatment of vincristine-related neuropathic pain.
Children aged 1-18 years who developed vincristine-induced neuropathy on a St Jude frontline acute lymphoblastic leukemia trial were prospectively enrolled on a randomized, double-blind, placebo-controlled, phase II trial with two treatment arms: gabapentin plus opioid versus placebo plus opioid. Daily evaluations of morphine dose (mg/kg per day) and pain scores were conducted for up to 21 days; the values of the two arms were compared to assess analgesic efficacy.
Of 51 study participants, 49 were eligible for analyses. Twenty-five participants were treated with gabapentin, with a mean (SD) dose of 17.97 (2.76) mg/kg per day (median 18.26, range 6.82-21.37). The mean (SD) opioid doses taken, expressed as morphine equivalent daily (mg/kg per day), were 0.26 (0.43) in the gabapentin group (25 patients, 432 days) and 0.15 (0.22) in the placebo group (24 patients, 411 days; P = .15). Only the risk classification of acute lymphoblastic leukemia was significantly associated with the daily morphine dosage (P = .0178): patients in the lower risk arm received higher daily morphine dosages. Multivariate analyses revealed a significant difference between the groups’ average daily scores for the previous 24 h and “right now.”
In this population of children with vincristine-related neuropathic pain, opioid consumption and pain scores were higher in the gabapentin group than in the placebo group. Future randomized, double-blind, placebo-controlled studies should test gabapentin given longer or at a higher dose.
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