Effects of two doses of tramadol on pain and some biochemical parameters in rabbits post-gastrotomy

Abstract

This study was conducted to evaluate the effect of two doses of tramadol on pain and some biochemical parameters in rabbits post-gastrotomy. Fifteen 6-month-old male rabbits were used for the study. The animals were randomly assigned into three groups of five rabbits each. Physiological (heart rate [HR], respiratory rate [RR], body weight [bw], temperature, blood glucose and serum cortisol) and biochemical (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [ALP], blood urea nitrogen [BUN] and creatinine) parameters of all the animals were determined and recorded as the baseline values. Thirty minutes before gastrotomy, groups 1 and 2 were injected subcutaneously with 10 and 20 mg/kg body weight tramadol, respectively, while group 3 was similarly injected with sterile normal saline and served as the control. Anaesthesia was induced in the three groups by intravenous injection of diazepam and ketamine at the doses of 1 and 30 mg/kg, respectively. Gastrotomy was performed by a standard method. The HR, RR, rectal temperature, blood glucose and serum cortisol levels were re-assessed at 0.5, 2, 3, 4 and 5 h post-gastrotomy (hpg). The body weight was re-measured for 14 days post-surgery (dps). Tramadol was re-administered to groups 1 and 2 using the same doses and route as above, twice daily for 3 dpg. Penicillin and streptomycin at the doses of 0.5 and 1 mg/kg bw was given intramuscularly to all the groups, once daily for 5 dpg. Wound swabs were collected at 2 and 5 dpg. The swabs were cultured for isolation and identification of wound-contaminating bacteria following standard methods. The activities of ALT, AST and ALP and the levels of BUN and creatinine were re-assayed at 3 and 6 dpg. The mean blood glucose and serum cortisol levels of the groups increased above their baseline values from 0.5 to 5 hpg. Blood glucose level of groups 1 and 2 significantly (p < 0.05) increased when compared with the control from 0.5 to 5 hpg. Serum cortisol level decreased significantly (p < 0.05) when groups 1 and 2 were compared with the control from 0.5 to 5 hpg. The mean RR of the groups was more than their baseline values from 0.5 to 5 hpg. RR of group 2 increased significantly (p < 0.05) when compared with group 1 and the control at 0.5, 3 and 4 hpg. At 5 hpg, RR of groups 1 and 2 significantly increased (p < 0.05) when compared with the control. The mean rectal temperature of groups 1 and 2 were slightly below the baseline values throughout the experiment. No significant (p > 0.05) difference occurred when the mean rectal temperature of the groups were compared. At 6 dpg, the activities of ALT, AST and ALP significantly decreased (p < 0.05) when groups 1 and 2 were compared with the control. No significant (p > 0.05) difference existed when the mean BUN and creatinine of the groups were compared. This study has shown that pre-surgical subcutaneous administration of tramadol at doses of 10 and 20 mg/kg bw can provide adequate analgesia in post-surgical period and has no adverse effect on some biochemical parameters in rabbits.