Effects of bupivacaine and ropivacaine on hemodynamic parameters in rabbits

In the present study the toxic effects of ropivacaine and bupivacaine on the cardiovascular and respiratory systems of rabbits were studied. Both drugs were administered intravenously at doses of 0.5, 1, 2.5, 5 and 10 mumol/kg. The effects of the two drugs on blood pressure, ECG and respiration rate were evaluated by considering the changes occurring 30 sec after intravenous bolus injection. High doses (5 and 10 mumol/kg) of bupivacaine and ropivacaine significantly reduced the heart rate and systolic pressure (p < 0.05). Five and 10 mumol/kg of bupivacaine significantly reduced diastolic pressure (p < 0.05), but only the 10 mumol/kg dose of ropivacaine had the same effect. Low doses of bupivacaine and high doses of ropivacaine significantly increased the PR interval, QRS duration and QT interval (p < 0.05). The 5 mumol/kg dose of bupivacaine caused ventricular tachycardia in 3 of 6 rabbits, whereas ropivacaine caused tachycardia in 1 of 5 rabbits. Neither drug had a significant effect on respiration rate or blood gas values (p > 0.05). The results indicate that ropivacaine is less cardiodepressive and arrhythmogenic than bupivacaine.