Pharmacokinetics of lorcainide, a new antiarrhythmic drug, in patients with cardiac rhythm disorders.

Lorcainide, a new class I antiarrhythmic drug, was administered intravenously to 10 patients with a documented history of ventricular arrhythmias. Three patients had arrhythmias resistant to all conventional antiarrhythmic drugs; in all other patients except one, previous antiarrhythmic drug therapy had to be discontinued because of poor efficacy or unacceptable adverse effects. Lorcainide was injected in incremental doses of 25 mg every 15 minutes and a dose of 182.4 +/- 26.5 mg (mean +/- standard deviation) of the drug was given. Lorcainide reduced the frequency of premature ventricular complexes in a dose-dependent manner. Plasma samples were analyzed for the drug concentrations which ranged from 0.31 to 1.14 mg/liter during the loading phase. Distribution and elimination of lorcainide follow a biexponential pattern and a fourfold intersubject variability in the pharmacokinetics of the drug was observed in these patients. The plasma half-life ranged from 6.2 to 23.1 hours (mean 13.1 +/- 5.0). Three patients are currently being treated orally with lorcainide. These data suggest that lorcainide is an effective antiarrhythmic drug with desirable pharmacokinetic properties, and long-term definitive studies are recommended.