Pharmacokinetics of propylthiouracil in children and adolescents with Graves disease after a single oral dose.

Pharmacokinetics of propylthiouracil after a single oral dose were studied in six pediatric patients with Graves disease, with respect to influence of food intake. Propylthiouracil administration in the fasting state induced a rapid rise of plasma level reaching a peak of 30 to 60 min. Peak values ranged from 7.2 to 18 micrograms/ml with administered dose (100 to 280 mg/m2 BSA) and plasma half-life was 1.3 +/- 0.41 hr (mean +/- SD). Single compartment model with first order absorption showed excellent fit to the data obtained in the fasting state, but not in the fed state. Most individuals showed marked difference in the pattern of propylthiouracil concentration-time curves between the fasting and the fed state. Food intake prior to the drug ingestion was associated with lower and delayed peak and variable AUC values. These results indicate that propylthiouracil administration in the fasting state is more advisable for obtaining a consistent bioavailability.