Research

BACKGROUND: There is a need for newer therapies for chronic painful diabetic neuropathy as the existing drugs have their own limitations. Clinical trials on low-dose naltrexone (1-5 mg/day) showed efficacy and safety in certain chronic painful conditions, but not in painful diabetic neuropathy. Hence the present study was planned.

METHODS: Sixty-seven participants with painful diabetic neuropathy were randomized to receive either 2 mg naltrexone or 10 mg amitriptyline daily following a 2-week run-in period. The participants were followed up every two weeks for total 6 weeks. Up-titration was done (to 4 mg naltrexone or 25 /50 mg amitriptyline) if the pain reduction was less than 20% on visual analogue scale (VAS) score during the next follow-up visit. Efficacy was assessed using the change in VAS score at the end of 6 weeks from baseline. Safety was evaluated at each follow-up visit. After 2 weeks of wash-out period, the participants were crossed over to receive the comparator drug for another six weeks with similar evaluations

RESULTS: The difference (confidence interval) in the change in VAS between groups from baseline was 1.64 (-0.92 to 4.20) in per-protocol analysis and 1.5 (-1.11 to 4.13) in intention to treat analysis. Eight and 52 adverse events were reported in the naltrexone and amitriptyline groups, respectively (P < 0.001). The most common adverse events were mild diarrhea with naltrexone and somnolence with amitriptyline.

CONCLUSIONS: Low-dose naltrexone exhibited similar efficacy and superior safety profile compared to amitriptyline in painful diabetic neuropathy.