Abstract

Convulsant doses of lidocaine (11.0-16.5 mg/kg) and bupivacaine (3.4-5.1 mg/kg) were administered intravenously at 48-hour intervals in a randomized crossover design to seven awake dogs. Five dogs survived both drug injections, which were given on different occasions. Two dogs developed ventricular fibrillation and died following the IV administration of bupivacaine. No difference in control cardiovascular parameters, arterial pH, pO₂ and pCO₂, electrolytes, PR, QRS, or QT intervals, or drug concentrations were observed in these two animals compared with five dogs that survived a convulsive dose of bupivacaine. In the survivors, no arrhythmias were seen following Iidocaine, but one bupivacaine-treated dog developed transient ventricular tachycardia. In surviving dogs, mean peak arterial blood concentrations of Iidocaine and bupivacaine were 70.9 ± 14.8 μg/ml and 29.4 ± 3.2 μg/ml, respectively (mean ± SEM). In surviving animals tested with Iidocaine, mean maximum increases in HR, MABP, and MPAP were 108 ± 37%, 52 ± 6%, and 190 ± 73%, respectively (mean ± SEM). Foilowing bupivacaine, these increases in HR, MABP, and MPAP were 141 ± 38%, 46 ± 12%, and 284 ± 64%, respectively, and were not significantly different from the Iidocaine-treated dogs.