[Lidocaine pharmacokinetics when administered intramuscularly].

The pharmacokinetics of lidocain injected intramuscularly in doses of 300-600 mg was studied and compared to that on its intravenous administration in a dose of 80 mg in the same patients with acute myocardial infarction. When injected intramuscularly the drug rapidly and safely reached the systemic circulation. The relationship between the lidocain plasma concentration and time could be depicted adequately by an open one-compartmental model to determine the parameters of the model. The maximum concentration (2.34 micrograms/kg for a dose of 400 mg) was attained 44 min after the injection. The half-life was 101 min, and the total clearance 0.67 l/min. Analysis of the model curves concentration--time for the doses 400 and 600 mg showed that in the former case the effective concentration (2 micrograms/kg or more) was maintained for 1 h, whereas in the latter one for 2.3 h.