The feasibility of giving a supplementary starting dose of the antiarrhythmic drug lorcainide, in order to minimalize the impact of the extensive, but saturable first-pass metabolism, was evaluated. Twenty-five adult patients were given 100 mg lorcainide tablets according to one of 3 different dosage schedules: Eight patients took one tablet at 0, 12 and 24 h, 8 took 1 tablet at 0, 1, 12 and 24 h and 9 took 1 tablet at 0, 2, 12 and 24 h. Levels of lorcainide and its metabolite, nor-lorcainide, during treatment were determined by gas-liquid chromatography. The results show that giving a second tablet 1 or 2 h after the first may produce faster saturation of the pre-systemic metabolism of lorcainide in the liver.