Pharmacokinetics of bendroflumethiazide after low oral doses

The pharmacokinetics of bendroflumethiazide after oral administration of 1.25, 2.5, and 5.0 mg were studied in nine healthy male volunteers. Bendroflumethiazide was analyzed by GLC after extractive alkylation. After the lowest dose, the plasma concentration, could be followed to 14 hr, and the data were adequately fitted by a one-compartment model; the half-life was 3.1 hr. After the 2.5 and 5.0 mg doses, the plasma concentration was followed for 24 hr, and the data were fitted by a two-compartment model with half-lives of 8.9 hr. The urinary sodium concentration was doubled after bendroflumethiazide intake, but the urinary potassium concentration remained almost constant. The renal clearance of bendroflumethiazide was around 30 ml . min-1.