REGIONAL METABOLISM OF ARTICAINE IN 10 PATIENTS UNDERGOING INTRAVENOUS REGIONAL ANESTHESIA DURING DAY-CASE SURGERY

Aims To study the pharmacokinetics of articaine and its metabolite art icainic acid, in patients undergoing intravenous regional anaesthesia. Methods Ten patients (three male, seven female, ASA class 1-2), sched uled for surgery of the hand or forearm were included in the study. Ar ticaine (40 mi, 0.5% solution (200 mg) was injected over 30 s. In tota l fifteen arterial blood samples were taken; one before injection and then at 10 min intervals, starting 10 min after completion of injectio n, until the tourniquet was released; thereafter blood samples were dr awn at intervals of 1, 5, 10, 15, 20, 25, 30, 45, 60, 75 and 90 min. T he tourniquet was released 30 min after completing the injection. Resu lts During tourniquet application and regional analgesia of 30 min dur ation, 55% of articaine was hydrolysed by plasma (20%) and tissue (35% ) esterase activity to the metabolite articainic acid. After releasing the tourniquet, articaine and its metabolite appeared in the blood; a rticaine was rapidly eliminated with a t(1/2z) Of approximately 60 min . The plasma concentration of the metabolite articainic acid was the s um of the amount formed during IVRA (55%) and the amount formed after tourniquet release (45%). Conclusions Articaine is a safe agent for in travenous regional anaesthesia (IVRA) with rapid onset of good surgica l anaesthesia. During tourniquet application and regional analgesia, 5 5% of the administered dose is already hydrolysed, thus reducing the c hance of side effects after tourniquet release.