Clinical efficacy and tolerability of Gabapentinoids with current prescription patterns in patients with Neuropathic pain

Objective: To investigate the current dosing regimens of gabapentinoids in Pakistani patients with neuropathic pain and to compare their clinical efficacy and tolerability in terms of pain relief and adverse effects using difference in pain score as a treatment outcome.

Methods: This observational, prospective study was conducted in 320 patients with neuropathic pain from August 2016 to March 2018 at Basic Medical Sciences Institute (BMSI), Karachi in collaboration with Shifa International Hospital and Benazir Bhutto Hospital, Islamabad. Demographic data, treatment-related adverse effects and pain intensity was documented at recruitment and follow up visits at two, four and eight weeks. Discontinuation due to adverse effects and lack of efficacy were also recorded. Data was entered and analyzed using SPSS version 22.

Results: Mean age of patients was 52.57±12.47 and the most common ethnicity were Punjabi speaking population (66%). Diabetic neuropathy (51%) was the most common etiology followed by radicular pain (25%). Mean dosages of pregabalin and gabapentin were 114mg and 470mg respectively. Mean pain score was significantly reduced by gabapentinoids (<0.001). Dizziness, drowsiness and somnolence were frequent adverse effects. Common dosages for pregabalin and gabapentin were 75 mg/day and 300 mg/day respectively.

Conclusion: Current dosing regimens of gabapentinoids in Pakistani patients with neuropathic pain were found to be efficacious at low dosages in comparison to international recommended dosages. Gabapentin and pregabalin were both similar in terms of reducing pain score but onset of pain relief was relatively faster with pregabalin. Dizziness, drowsiness and somnolence were frequently reported with both gabapentinoids; however, visual blurring, ataxia and weight gain were observed only with the use of pregabalin. Adverse effects are frequently observed with gabapentinoids which necessitates reverting back to low dosages or switching to other drugs for pain relief.