Anaesthetic potency and physiological effects of refrigerated solution of thiopentone sodium in rabbits

Several in vitro studies have justified the use of thiopentone solutions beyond the period recommended by the manufacturer. We conducted this in vivo study to investigate the anaesthetic potency and physiological effect of refrigerated thiopentone solution. Rabbits in four groups designated A, B, C and D were anaesthetized using 25 mg/kg thiopentone solution stored for 0 (fresh solution), 3, 7 and 14 days in the refrigerator. Anaesthetic potency of the thiopentone solution was determined by monitoring the durations of anaesthesia and recovery time while its physiological effect was assessed by evaluating the changes in the heart and respiratory rates, packed cell volume and blood glucose post injections. The durations of anaesthesia and recovery time in group A were significantly (P < 0.05) longer than those obtained in groups B, C, and D. At 20 min during anaesthesia, heart rates of rabbits in group A and B were significantly (P < 0.05) lower than heart rates of rabbits in group C. Respiratory rates decreased significantly (P<0.05) in the four groups post induction of anaesthesia. Packed cell volumes (PCV) in all groups decreased significantly (P<0.05) by 10 min post induction while PCV of the groups increased at 30 and 60 min. In the four groups, no significant increase (P>0.05) in blood glucose occurred at 10 min post induction while blood glucose decreased significantly (P<0.05) at 60 min post induction. Our findings showed that the potency of thiopentone solution decreased with refrigeration. Also significant drop in blood glucose of rabbits occurred post thiopentone injection. Based on these findings, we discourage the use of refrigerated solutions of thiopentoneKeywords: Glucose, Rabbits, Refrigeration, Respiratory rate, Thiopentone sodium