Evaluation of analgesic and anti-inflammatory activity of a combination of tramadol-pregabalin in animal models of pain and inflammation

Background: A major goal of pain management is to provide pain relief that is clinically meaningful, sustained, and associated with minimum and reversible adverse effects. Since single analgesic drug is not effective in all patients, there is a need either to develop new and more effective drugs or to identify favourable combinations of drugs that are already available. The aim of the present was to evaluate the analgesic and anti-inflammatory activity of tramadol and pregabalin when used alone or in combination in animal models of pain and inflammation.Methods: The animals (rats and mice) were divided into eight groups with six animals in each group. Analgesia was assessed by acetic acid induced writhing and tail flick methods in mice and hot plate method in rats. Paw oedema model in rats after induction with 0.1 ml of 1% carrageenan was used to assess the anti‑inflammatory activity. The percentage inhibition of writhes and prolongation of reaction time were used for assessing analgesic activity and reduction in paw volume was used for assessing anti-inflammatory activity. The results obtained were analysed by ANOVA and Tukey HSD Post-hoc Test.Results: Treatment with tramadol pregabalin alone or in combination reduced writhing episodes significantly in acetic acid induced writhing in mice as compared to control indicating its analgesic effect and the highest percentage inhibition of pain was seen with high dose tramadol plus pregabalin. Treatment in Hot plate and Tail flick methods significantly prolonged the reaction time at all time points.Conclusions: Tramadol when combined with pregabalin may enhance its anti-nociceptive effects. If confirmed in additional models of acute and/or chronic pain this combination might be useful in the clinical management of pain not associated with inflammation.