The objective of this study was to compare the efficacy and tolerability of
gabapentin and
amitriptyline monotherapy in
painful diabetic neuropathy. This was a 12-week, open-label, prospective, randomized trial. Twenty-five type-II diabetic patients with
pain attributed to
diabetic neuropathy and a minimum score of 2 on a
pain intensity scale ranging from 0 (no
pain) to 4 (excruciating
pain) were randomized to receive either
gabapentin, titrated from 1,200 mg/day to a maximum of 2,400 mg/day, or
amitriptyline, titrated from 30 mg/day to a maximum of 90 mg/day. Both drugs were titrated over a 4-week period and maintained at the maximum tolerated dose for 8 weeks. The main outcome measures were weekly
pain intensity and
paresthesia intensity, measured on two categorical scales. Thirteen patients received
gabapentin and 12 received
amitriptyline. All 25 patients completed the trial.
Gabapentin produced greater
pain reductions than
amitriptyline (mean final scores were 1.9 vs. 1.3 points below baseline scores; P = 0.026). Decreases in
paresthesia scores also were in favor of
gabapentin (1.8 vs. 0.9 points; P = 0. 004). Adverse events were more frequent in the
amitriptyline group than in the
gabapentin group: they were reported by 11/12 (92%) and 4/13 (31%) of patients, respectively (P = 0.003). Side effects were the main limiting factor preventing dose escalation.
Gabapentin produced greater improvements than
amitriptyline in
pain and
paresthesia associated with
diabetic neuropathy. Additionally,
gabapentin was better tolerated than
amitriptyline. Further controlled trials are needed to confirm these preliminary results.