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Spironolactone
- indication:Used primarily to treat low-renin hypertension, hypokalemia, and Conn's syndrome.
- pharmacologypharmacology:
- mechanism: Spironolactone is a specific pharmacologic antagonist of aldosterone, acting primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule. Spironolactone causes increased amounts of sodium and water to be excreted, while potassium is retained. Spironolactone acts both as a diuretic and as an antihypertensive drug by this mechanism. It may be given alone or with other diuretic agents which act more proximally in the renal tubule.
- toxicity: The oral LD<sub>50</sub> of spironolactone is greater than 1,000 mg/kg in mice, rats, and rabbits. Acute overdosage of spironolactone may be manifested by drowsiness, mental confusion, maculopapular or erythematous rash, nausea, vomiting, dizziness, or diarrhea. Spironolactone has been shown to be a tumorigen in chronic toxicity studies in rats.
- absorprion: Fairly rapidly absorbed from the gastrointestinal tract. Food increases the bioavailability of unmetabolized spironolactone by almost 100%.
- halflife: 10 minutes
- roouteelimination: The metabolites are excreted primarily in the urine and secondarily in bile.
- volumedistribution:
- clearance: