Pharmacokinetics
Spironolactone has a half-life of about 1–2 hours. Due to its relatively short half-life, it is thought that spironolactone may behave mainly as a prodrug to an array of active metabolites with much longer half-lives (e.g., 12–20 hours in the case of canrenone) including canrenone, 7α-methylthiospironolactone, and 6β-hydroxy-7α-methylthiospironolactone, among many others. The drug is highly plasma protein bound. It is metabolized by the liver, and is eliminated mostly renally, with only minimal biliary excretion.
The bioavailability of spironolactone improves significantly when it is taken with food.
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