Oral triamterene disposition.

Earlier studies of triamterene (T) disposition in man have reported hydroxytriamterene (T-OH) and hydroxytriamterene sulfate (T-O-SO3H) conjugate to be the major metabolites. We describe T kinetics through use of an HPLC method and confirm that after hydroxylation, T is rapidly converted to T-O-SO3H. The intermediate T-OH metabolite could not be detected in urine or plasma. Plasma concentrations of T-O-SO3H exceeded those of T by sevenfold to 26-fold, whereas concentrations of that metabolite in the urine were fourfold to thirteenfold higher than those of the parent. Renal clearance of T was 314.5 +/- 121.6 ml/min, exceeding that of the metabolite, which was 206.1 +/- 93.6 ml/min. Coadministration of hydrochlorothiazide increased urine flow and urinary pH, but it did not affect renal clearance of the parent drug or the metabolite. T bioavailability from capsules was poorer and more variable than that from a suspension. Hydrochlorothiazide did not influence the bioavailability of T.