Comparative Analysis of Efficacy and Safety of Gabapentin Vs Amitriptyline in Patients of Peripheral Neuropathic Pain in Case of Diabetes Mellitus

Introduction: Diabetes mellitus frequently leads to development of peripheral neuropathies in almost 30-50% of patients and the most common type of neuropathy associated with this condition is Distal Symmetric Sensorimotor Polyneuropathy (DSPN). Gabapentin and Amitriptyline are two drugs frequently used for the treatment of neuropathic pain associated with type 2 diabetes. Aim of the study: The aim of this study was to compare efficacy and safety of Gabapentin and Amitriptyline in subjects of Type 2 diabetes mellitus with peripheral neuropathic pain. Material and Methods: A prospective, open, randomized, parallel group, comparative study was conducted in 60 patients coming to Department of Medicine, Rajindra Hospital attached to Government Medical College Patiala, to evaluate the efficacy and safety of Gabapentin and Amitriptyline in patients with diabetic peripheral neuropathic pain. The patients fulfilling the inclusion criteria were included in the study after taking written informed consent. The patients were divided into two groups of 30 cases each by simple randomization. Group I patients received Gabapentin 300 mg HS by oral route. Group II patients received Amitriptyline 25 mg HS by oral route. Therapeutic efficacy of both drugs, by using Michigan Neuropathy Screening Instrument (MNSI) was compared at the baseline and at the end of 4 months. Any adverse drug reactions of the respective drug observed in patient were also noted. All the observations thus made were statistically analysed using appropriate tests. Results: Baseline characteristics of the patients in two groups such as age, sex, duration of diabetes were similar (p>0.05). The mean age in group I and group II were 53.40±8.41 years and 57.17±8.55 years, respectively. There was statistically significant reduction in mean MNSI scores in questionnaire part and physical examination part in both the groups. Also, there was statistically significant difference between the two drugs in reducing mean MNSI score. Mean difference between two drugs in reducing MNSI score in history part (0.77±0.16, p<0.01) and physical examination part (0.75±0.19, p<0.01) favoured Gabapentin. No. of adverse drug reactions reported were significantly higher in Amitriptyline group, p value (<0.05) for the difference in ADRs between two drugs was statistically significant. Conclusion: In this study, we concluded that both drugs lead to improvement in signs and symptoms of diabetic neuropathy. Gabapentin was proved to be more efficacious than Amitriptyline. Gabapentin treated patient’s mean MNSI score at the study end point was significantly lower as compared to the Amitriptyline treated patient’s end-point score. Adverse drug reactions reported in our study were mild in both the groups and a significantly higher number of adverse effects were reported in the amitriptyline group. Dizziness and somnolence were two most commonly reported adverse drug reactions.