Double-blind randomized placebo-controlled trial to compare the effects of gabapentin, pregabalin and tramadol plus acetaminophen combination in improvement of pain in patients with painful diabetic neuropathy

Double-blind randomized placebo-controlled trial to compare the effects of gabapentin (900-3600 mg/per day)/pregabalin (150-600 mg per day) in improvement of pain in patients with painful diabetic neuropathy. All diabetic patients were subjected to detailed history and thorough clinical examination, and those with painful diabetic neuropathy were taken into account for study after informed consent. Total of 120 cases were examined and investigated (30 patients in each group, for a total of four groups). Each group was allotted one of the four drugs including placebo, methylcobalamin (1500 microgms) which was common to all groups, according to random number table for 6 weeks. Patients were followed at 0, 2, 4 and 6 weeks for relief of pain intensity and severity according to VAS and Likert scale, respectively. At 2, 4 and 6 weeks, means of both VAS and Likert scale comparison showed that difference was statistically significant (p<0.001) when all other groups are compared with C or placebo group. But it was statistically insignificant (p>0.05) when they are compared with each other. According to our study, all three drugs, i.e. pregabalin, gabapentin and tramadol-acetaminophen combinations, are equally effective in improvement of pain in patients with painful diabetic neuropathy, and also methylcobalamin alone is ineffective in improvement of pain in painful diabetic neuropathy (PDN) at 6 weeks. Researches done on drug treatment of PDN are limited, so large multicentric trials are needed to compare the effect of different drugs on pain in PDN.