Influence of food on the bioavailability of a sustained‐release verapamil preparation

The effects of food on the bioavailability of a sustained‐release (SR) formulation of verapamil (SR‐verapamil; Isoptin SR) were determined in an open, three‐way single‐dose study involving 12 volunteers receiving (in randomized order) the SR preparation (1 × 240 mg) either fasting or with food and a conventional formulation of verapamil (3 × 80 mg) fasting. Compared with the conventional formulation, SR‐verapamil had a reduced C_max, prolonged t_max, and unchanged t_1/2, consistent with its SR formulation. The AUC was 80% of the conventional preparation. Concomitant food administration significantly prolonged the t_max of SR‐verapamil from 7.3 ± 3.4 to 11.7 ± 6.3 h, but had little effect on C_max, t_1/2, or AUC. Similar results were obtained with the metabolite, norverapamil. Food administration also had little effect on the blood pressure and ECG effects of SR‐verapamil. Cautions regarding taking this preparation with food therefore appear to be unnecessary.