Adults treated with gabapentin enacarbil for painful bouts of diabetic peripheral neuropathy demonstrate a lower incidence of peripheral oedema and weight gain than those treated with pregabalin or placebo, according to a randomised, phase 2 safety study presented at the 66th Annual Meeting of the American Academy of Neurology (AAN).
The 20-week trial included 420 patients who had experienced weight gain while undergoing treatment for diabetic peripheral neuropathy with gabapentin enacarbil (1200 mg/day, 2400 mg/day, or 3600 mg/day), pregabalin (300 mg/day), or placebo, explained lead author Anne M. Calkins, MD, Saint Joseph’s Hospital Health Center, Syracuse, New York, speaking here on April 29.
Incidences of peripheral oedema varied by dosage amount, with the following results: gabapentin enacarbil, 3% (1200 mg), 0% (2400 mg), and 9% (3600 mg); pregabalin, 17%; and placebo, 4%.
Weight gain also was related to dosage amount: gabapentin enacarbil, 0% (1200 mg), 4% (2400 mg), and 4% (3600 mg); pregabalin, 8%; and placebo, 1%. The proportion of patients who experienced a greater-than-7% weight gain were as follows: gabapentin enacarbil, 5% (1200 mg), 7% (2400 mg), and 10% (3600 mg); pregabalin, 15%; placebo, 3%.
At the end of the 12-week maintenance phase, the mean (± 2 standard error) changes in weight gain from baseline were 1.22 kg (± 0.95), 1.71 kg (±0.84), and 1.85 kg (±0.77) for gabapentin enacarbil 1200, 2400, and 3600 mg, respectively; 2.65 kg (±0.92) for pregabalin; and -0.55 kg (±0.72) for placebo.
Gabapentin enacarbil was well tolerated across the dosage amounts.
The primary efficacy endpoint in this trial — change from baseline in the mean 24-hour average pain intensity score — found that neither gabapentin enacarbil nor pregabalin differed from placebo in terms of reducing pain in this population. The researchers hypothesised that this may be a consequence of the unexpectedly high placebo response rate observed in the study, and concluded that the data require further evaluation.
Funding for this study was provided by Xenoport, Inc., Santa Clara, California.