Does levobupivacaine have a benefit over bupivacaine in our practice?

Abstract

Background The well-known toxic effects of bupivacaine on central nervous system and cardiovascular system were a base for the development of new long-acting local anesthetics. Levobupivacaine is the pure S(-)-enantiomer of racemic bupivacaine. This study compares the efficacy of levobupivacaine as against bupivacaine by epidural clinical study and by different routes in animal study. Materials and methods Evaluation of the analgesic activities by the hot plate method was carried out in nine groups of mice. Each four groups were injected intraperitoneally with either levobupivacaine or bupivacaine. The control group received saline. The hemodynamic effects of levobupivacaine and bupivacaine were carried out on the isolated rabbit's heart and anesthetized cats for carotid blood pressure and ECG. Thirty patients undergoing limb surgery were randomized to receive 15 ml of 0.5% levobupivacaine or bupivacaine through epidural needle. Intraoperative blood pressure and heart rate were recorded. Onset time of sensory and motor block, time to T 10 sensory block, complete motor block, quality of analgesia, and times for two segment regressions were detected. Results Experimentally, the intensity and duration of analgesia produced by levobupivacaine was more than that of bupivacaine. Both drugs induced significant dose-dependent negative inotropic effect, but it was lesser in levobupivacaine than in bupivacaine. An amount of 2 mg/kg levobupivacaine produced a significant rise in blood pressure and 4 mg/kg significantly decreased it, whereas 1 and 2 mg/kg bupivacaine produced a significant decrease in blood pressure. The ECG pattern of levobupivacaine showed no abnormalities, but bupivacaine at a dose of 2 mg/kg produced significant bradycardia and ECG changes. Cardiac arrest and death of cats occurred when 4 mg/kg of bupivacaine was injected. Clinically, the onset time of sensory block, time to T 10 sensory block and time to complete motor block are lower with bupivacaine than with levobupivacaine. Conclusion We found, based on the current pharmacodynamics evidence from this experimental and clinical study, that levobupivacaine has good analgesic activity and less cardiodepressant effect, and it offers advantages over bupivacaine.