Influence of food intake on the bioavailability of urapidil in healthy volunteers.

The influence of food intake on the pharmacokinetics of a single dose (30 mg) of urapidil in a tablet and a sustained-release capsule form were examined in 12 healthy volunteers in a double crossover trial. Drug administration under fasting conditions requires that a standardized breakfast be eaten, 4 h after drug intake. Drug application with breakfast requires drug intake with the standardized breakfast. Blood was sampled and blood pressure measured before and at 0.25, 0.5, 1, 2, 3, 4, 6, 8, 12, 15, 18, 21, 28 and 32 h after drug administration. Urapidil was determined by HPLC. AUC, Cmax, tmax and t1/2 were calculated. Food intake did not influence the bioavailability of urapidil in tablet form. After the administration of the sustained-release capsule Cmax and tmax were increased while t1/2 was decreased by food intake. Despite these differences, the AUC was not influenced by concomitant food intake with the sustained-release capsule. In the fasting state, the AUC of the sustained-release capsule was 28% lower than that of the tablet. Food intake together with the sustained-release capsule abolished this difference. Since blood pressure decreases in hypertensive patients treated with urapidil are most pronounced in the inclining part of the urapidil-serum concentration curve, maximizing this part of the curve, as is the case with the administration of the sustained-release capsule together with breakfast, should be advantageous. Therefore, the suggestion that the sustained-release capsule be taken with breakfast is of therapeutic significance.