CLINICAL PHARMACOLOGY
The mechanism of the antihypertensive effect of thiazides is unknown. DIURIL does not usually affect normal blood pressure.
DIURIL affects the distal renal tubular mechanism of electrolyte reabsorption. At maximal therapeutic dosage all thiazides are approximately equal in their diuretic efficacy.
DIURIL increases excretion of sodium and chloride in approximately equivalent amounts. Natriuresis may be accompanied by some loss of potassium and bicarbonate.
After oral use diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to 12 hours.
Pharmacokinetics and Metabolism
DIURIL is not metabolized but is eliminated rapidly by the kidney. The plasma half-life of chlorothiazide is 45-120 minutes. After oral doses, 10-15 percent of the dose is excreted unchanged in the urine. Chlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk.
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