[On the bioavailability of hydrochlorothiazide and triamterene from commercial drugs (author's transl)].

In a study on the bioavailability of triamterene and hydrochlorothiazide from 3 diuretics, preparation A (25 mg hydrochlorothiazide), preparation B (50 mg triamterene) and preparation C (combination of hydrochlorothiazide and triamterene), the data for tmax, Cmax, AUC and the cumulative urine excretion were determined in 7 healthy volunteers. The different formulations of the diuretics influenced the kinetics of the agents. The in vivo data agreed well with those obtained in vitro. Plasma levels of triamterene and its active metabolite from preparation C were reached more rapidly than from preparation B. However, the bioavailability of the agents was not significant different in the two diuretics when given immediately after breakfast. The AUC-data of hydrochlorothiazide determined after administration of preparation A or C do not differ significantly, only the comulative excretion of hydrochlorothiazide in urine is greater after application of preparation A than after application of preparation C.