Blood lidocaine levels and kinetics following high-dose intramuscular administration.

a high dose (6 mg/kg) of lidocaine, and blood lidocaine levels were measured over a 4-hour study period. Intradeltoid injection produced higher blood lidocaine levels and more rapid development of peak blood levels than did intragluteal injection. Administration of high-dose lidocaine (average dose 450 mg) into the deltoid muscle produced the ideal combination of rapid peak blood levels (6.5 gg/ml 2.1 SEM at 5 min) and persistence of therapeutic levels (>1.5 ,ug/ml) for over 2 hours. Although drowsiness, paresthesias, slurred speech, and tinnitus occurred in seven of the 12 patients in the high-dose group, no major neurotoxicity, such as grand mal seizures, were observed, nor was there evidence of hypotension or increase in atrioventricular block. Prophylactic administration of high-dose 10% lidocaine into the deltoid muscle appears to have potential for reducing the early mortality following acute myocardial infarction.