Effect of Adrenaline on Venous Plasma Concentrations of Bupivacaine after Interpleural Administration

Kelvin Chan, University of Wolverhampton, United Kingdom

Abstract

Bupivacaine 2.5 mg kg-1 (0.5 ml kg-1 of 0.5% solution), with or without adrenaline 5 µg ml-1, was administered by interpleural injection to 12 patients after elective cholecystectomy. Non-compartmental analysis indicated that the addition of adrenaline had no effect on total body clearance, apparent volume of distribution at steady state or elimination half-life of bupivacaine. However, peak plasma concentrations were lower in the adrenaline group (mean (SD) [range] : 2.57 (0.61) [1.52-3.11] vs 3.22 (0.27) [2.84-3.53] µg ml-1, P < 0.05) and the time to maximum concentration was delayed (median [range] : 25 [15-30] vs 15 [10-20] min, P < 0.05). Analgesia was variable and no differences were detected between the two groups. The addition of adrenaline appears prudent to minimize possible bupivacaine toxicity.