Shenfu injection reduces toxicity of bupivacaine in rats.

OBJECTIVE: To investigate the effects of injecting Shenfu, an extract of traditional Chinese herbal medicines, on the central nervous system (CNS) and the cardiac toxicity of bupivacaine in rats.

METHODS: Sixteen male Sprague-Dawley rats, weighing form 280 to 320 g, were randomly assigned to two groups (n = 8 in each group). Animals in the control group received a saline injection 10 ml/kg while animals in the Shenfu group received an injection of Shenfu 10 ml/kg intraperitoneally 30 minutes before intravenous infusion of bupivacaine. Lead II of an electrocardiogram (EEG) was continuously monitored after 3 needles were inserted into the skin of both forelimbs and the left hind-leg of each rat. The femoral artery was cannulated for measurement of arterial blood pressure and blood sampling. The femoral vein was cannulated for the infusion of bupivacaine. After baseline measurement (arterial blood pressure, heart rate and arterial blood gas), 0.5% bupivacaine was infused intravenously at a rate of 2 mg.kg(-1).min(-1) to all animals until asystole occurred. The time of bupivacaine-induced convulsions, arrhythmia and asystole were determined. The dose of bupivacaine was then calculated at the corresponding time point.

RESULTS: The doses of bupivacaine that induced convulsions, arrhythmia and cardiac arrest were remarkably larger in Shenfu injection-treated animals than in saline-treated rats [convulsions, (10.5 +/- 1.9) mg/kg vs (7.2 +/- 1.5) mg/kg; arrhythmia (10.5 +/- 2.0) mg/kg vs (7.2 +/- 1.9) mg/kg; asystole, (32.8 +/- 8.5) mg/kg vs (25.0 +/- 5.0) mg/kg; P = 0.006, 0.009 and 0.044, respectively].

CONCLUSION: The Shenfu injection is able to reduce the toxicity of bupivacaine to CNS and cardiac system in rats.