REGIONAL DISTRIBUTION OF C-11 LABELED LIDOCAINE, BUPIVACAINE, AND ROPIVACAINE IN THE HEART, LUNGS, AND SKELETAL-MUSCLE OF PIGS STUDIED WITHPOSITRON EMISSION TOMOGRAPHY

The regional myocardial uptake and kinetics of C-11-lidocaine, C-11-bu pivacaine, and C-11-ropivacaine were examined in the pig, utilizing po sitron emission tomography to determine whether disproportionate distr ibution exists among these agents. The three drugs were rapidly distri buted to the myocardium and lung with mean peak radioactivities occurr ing between 0.35 and 0.48 min post-injection in myocardium and 0.35 an d 0.65 min in lung. Radioactivities peaked later in skeletal muscle th an in the myocardium and lung, occurring between 1.1 and 2.7 min post- end injection. Blood radioactivities for bupivacaine and ropivacaine w ere significantly higher than those of lidocaine, whereas myocardial, lung, and muscle uptakes for the three agents were not significantly d ifferent. Myocardium-blood partition coefficients were similar for bup ivacaine and ropivacaine (0.55 and 0.49 respectively), while it was th ree times higher for lidocaine (1.4). A similar relationship existed f or skeletal muscle- and lung-blood partition coefficients. Bupivacaine and ropivacaine t(1/2z) in skeletal muscle were significantly longer than those of lidocaine. The results of this study indicate that the i ncreased cardiotoxicity associated with bupivacaine does not appear to be related to disproportionate distribution in the myocardium when co mpared to lidocaine and ropivacaine. (C) 1997 by John Wiley & Sons, Lt d.