| Spironolactone: Pharmacology
Spironolactone is a synthetic steroid with an aldosterone-like structure; it acts as a competitive antagonist at aldosterone receptors. The most important of these receptors are situated in the distal portion of the renal tubules. Spironolactone thus inhibits sodium and water reabsorption while sparing the potassium and magnesium metabolism. The optimal effect is dependent on a sufficient sodium supply in the distal portion of the renal tubules, as it can be observed in thiazide treatments. Immediate inhibitory effect on aldosterone synthesis is of secondary importance. Spironolactone is also an anti-androgen.