Pharmacokinetics of hydrochlorothiazide in patients with congestive heart failure.

1. Hydrochlorothiazide (HCT, 50-75 mg) was administered orally to seven patients with cardiac failure. 2. Plasma levels and urinary concentration of HCT were determined by GLC. 3. The gastrointestinal uptake of the diuretic in three patients was reduced to approximately half that seen in healthy controls. 4. Plasma halflife of HCT was correlated with endogenous creatinine clearance. 5. Pharmacokinetics of HCT are considerably changed in cardiac failure.