Painful neuropathy: comparative observational analysis of safety profile of pregabalin and amitriptyline

Background: Chronic neuropathic pain, caused by a lesion or disease of the somatosensory nervous system is a common debilitating condition in clinical practice. Pregabalin and Amitriptyline are most commonly used drugs for its management. The aim of the study was to study the safety of Pregabalin and Amitriptyline in chronic neuropathic pain.Methods: Prospective observational study at Department of Medicine and Orthopaedics at All India Institute of Medical Sciences, Rishikesh. Newly diagnosed patients of neuropathic pain who were prescribed either Pregabalin or Amitriptyline were included in the study. Patients were followed up telephonically or during routine visits for a period of 3 months after initiation of any of these drugs. Appropriate measures of central tendency were used to describe demographic and clinical parameters and Correlation test was used between different variables and occurrence of adverse drug reactions.Results: 317 patients were prescribed these drugs. A total of 276 ADRs were observed (128 with Pregabalin and 148 with Amitriptyline). Central nervous system symptoms like sedation and dizziness were most commonly present in both the groups. Diabetes mellitus (47.1%) was most common etiology for neuropathic pain. Causality assessment showed probable association with Amitriptyline (n=140) and Pregabalin (n=118). Majority of ADRs with Amitriptyline group (49.32%) were moderate in severity whereas it was mild with Pregabalin (59.7%). A weak positive correlation (R=0.273) was seen with number of ADRs occurrence and total drug exposure in patients taking Pregabalin whereas a weak negative correlation (R=-0.623) was seen in Amitriptyline treated group.Conclusions: Safety profile of Pregabalin was better than Amitriptyline in the present study. The study findings must be replicated in larger patient population and for a prolonged duration for better understanding of the pattern of adverse drug reactions.