title: Bioavailability of hydrochlorothiazide from tablets and suspensions.
abstract: The bioavailability of hydrochlorothiazide was determined following single oral 25-, 50-, 100-, and 200-mg tablet and suspension doses in 12 healthy male volunteers. Plasma and urine levels of hydrochlorothiazide were determined by HPLC. Plasma levels of hydrochlorothiazide were satisfactorily described by a triexponential function. Mean peak plasma levels, Cmax (127-135, 270-280, and 437-490 ng/mL from the 25-, 50-, and 100-mg doses, respectively) were dose proportional, as were areas under plasma profiles, AUC0----36. Mean percentage recovery of unchanged hydrochlorothiazide in 48-h urine samples accounted for 50-59, 54-55, 60-63, and 54-57% of the 25-, 50-, 100-, and 200-mg doses, respectively. There were no significant differences among these values. Correlation coefficients between 48-h urinary recovery of hydrochlorothiazide and the plasma values (Cmax and AUC0----36) for the 25-, 50-, and 100-mg doses were 0.73 and 0.84. There were no differences in the net increases in electrolyte excretion among the treatments during the 0-12-h postdose period. The systematic availability of hydrochlorothiazide, unlike that of chlorothiazide, is dose proportional in the therapeutic range.
mesh_terms: D000328:Adult; D001682:Biological Availability; D004573:Electrolytes / Q000652:urine; D006801:Humans; D006852:Hydrochlorothiazide / Q000008:administration & dosage* / Q000378:metabolism; D007408:Intestinal Absorption; D008297:Male; D013535:Suspensions; D013607:Tablets; D013997:Time Factors
chemical_list: D004573:Electrolytes; D013535:Suspensions; D013607:Tablets; D006852:Hydrochlorothiazide