Pharmacokinetics and pharmacodynamics of lidocaine carbonate in patients during brachial plexus block

AIM To investigate pharmacokinetics and pharmacodynamics of lidocaine carbonate in the patients duringbrachial plexus block. METHODS 20 patients undergoing brachial plexus block were randomly and equally allocated into two groups. The patients were given lidocaine carbonate and lidocaine hydrochloride (6 mg·kg -1 ) respectively. Serum levels of lidocaine were measured using FPIA. Pharmacodynaimcs was evaluated by subjective observation of an anesthetist. The results of pharmacokinetics and pharmacodynamics of lidocaine carbonate were compared with those of lidocaine hydrochloride. RESULTS The peak time, the maximal concentrations and AUC of the lidocaine carbonate group and lidocaine hydrochloride group were (17.2±8.9) vs (25.6±9.7) min, (4.2±1.6) vs (3.3±1.2) mg·L -1 , (11.8± 1.8 ) vs (8.7±1.6) mg·h·L -1 , respectively. The onset time, finishing time and persistent time of blockade of the lidocaine carbonate group and lidocaine hydrochloride group were (4.9±1.8) vs (9.1±2.1) min; (8.9±4.6) vs (13.7±5.2) min; (211.3±47.4) vs (152.6±31.4) min, respectively. CONCLUSION The results showed constant of the absorption rate and AUC of lidocaine carbonate were singificantly greater than those of lidocaine hydrochloride. The peak time was shorter than that of lidocaine hydrocloride too. The onset time and finishing time of blockade of lidocaine carbonate were shorter than those of lidocaine hydrochloride. The study suggested that onset of blockade of lidocaine carbonate was faster, but elimination of lidocaine in human body was almost the same as that of lidocaine hydrochloride during brachial plexus block.