The effect of the combination of ketamine and tramadol in neuropathic pain induced rats

Treatment of chronic neuropathic pain is complex and the current drugs are often inadequate in the pain relief. The aim of this randomized experimental study was to investigate the possible antiallodynic effect of tramadol and ketamine when administered separately or in combination in neuropathic pain induced rats.60 male Wistar rats (190-240 g) were used in our study. Firstly, 24 healthy rats were divided into 6 groups (n=4) and the effects of ketamine and tramadol (alone or in combination) on the locomotor activity includig the stereotypic and ambulatory activity of healthy rats were investigated to search whether study drugs might cause dose-related sedation or not.Secondly, 36 rats with neuropathic pain were separated into 6 study groups (n=6) to determine the functional pain values. The neuropaty was produced by loosely tied ligatures of the common sciatic nerve under ether anaesthesia. The effects of intraperitoneal administration of ketamine (5mg/kg or 10 mg/kg), tramadol (10 mg/kg) and ketamine and tramadol combination (5 mg/kg +10 mg/kg or 10 mg/kg+10 mg/kg respectively) to the sciatic nerve ligation-induced neuropathic pain was tested by using a dynamic plantar test and the results were compared to the control group (SF). Variance analysis and Student?s t test were performed for statistical analysis and a value of p<0.05 was considered significant.No significant changes were observed in the stereotypic and ambulatory activity in the healthy rats given ketamin and/or tramadol between the groups. The antiallodynic effects of ketamine 10 mg/kg (60. and 90. min.), tramadol 10 mg/kg (30., 60. and 90. min.) and, combination of these drugs (30., 60. and 90. min) were significantly different when compared to control group. Contrary, no statistically significant difference was found between the combined and alone groups.In conclusion, it is observed that tramadol, ketamine and combination of these drugs have analgesic effect on neuropathic pain in rats. But, it is determined that the combined administration of these drugs don?t have favorable effect when compared with the administration of either of these drugs alone in neuropathic pain induced rats.Keywords: Tramadol, ketamine, pain, sciatic neurophaty, rat.