Coadministration of Novel Analgesic Isovaline with Tramadol Reduces Inflammatory Pain Response in Rats

Abstract

Aim: Isovaline is a new and promising analgesic with an antinociceptive effect and, unlike µ-opioid agonists, interacts with aminobutyric acid receptors without causing sedation or respiratory depression. In this study, we compare the effect on thermal hyperalgesia and mechanical allodynia coadministration of subcutaneous isovaline and tramadol with individual administrations in a carrageenan-induced hind paw inflammatory pain model in rats. Methods: In this study, isovaline, tramadol, and the combination of isovaline and tramadol were subcutaneously administered to rats with carrageenan-induced inflammation of the hind paws. Hyperalgesia in response to thermal stimuli and allodynia in response to mechanic stimuli were assessed by using a thermal plantar test and a dynamic plantar aesthesiometer, respectively. Results: The administration of subcutaneous isovaline 400mg/kg and tramadol 4mg/ kg combination effect was higher than the other groups on latencies and thresholds (P