Abstract
Twenty-five patients receiving Mexiletine post cardiopulmonary bypass were involved in the study and determined for optimum dosage of the drug and its effective plasma concentrations. In an effort to determine the appropriate dosage of the drug, the patients were administered with the drug by continuous intravenous infusion at 0.01, 0.015, 0.02, 0.025 and 0.03mg/kg/min and then measured for plasma levels of the drug at 30, 60, 90, and 120min. after the initiation of infusion. Plasma levels of the drug bhus found were 0.49±0.16μg/ml (mean±SD) at 30min., 0.68±0.18 at 60min., 0.85±0.29 at 90min. and 0.92±0.26 at 120min. In order to obtain effective plasma levels more quickly a 125mg dose was administered as a bolus injection. This yielded a therapeutically effective plasma level of 0.78±0.11, 30min. after dosing. Significantly higher plasma levels of the drug were attained at 30min. after administration with bolus injection of 125mg than continuous intravenous infusion at a rate of 0.03mg/kg/min. (p<0.05).
