spironolactone brands

Molecular formula: C24H32O4S

Aldosterone is a key hormone in the renin-angiotensin-aldosterone system. By binding to the mineralocorticoid receptor at the distal tubules and collecting duct, it causes sodium reabsorption and potassium secretion, increases vascular stiffness and remodelling, and activates pro-inflammatory pathways. Spironolactone and its active metabolites are aldosterone antagonists that produce a potassium-sparing diuretic effect. They competitively bind to 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 that act more proximally in the renal tubule. Spironolactone can exert antiandrogenic effects by several mechanisms: it can destroy testicular CYP and decrease 17alpha-hydroxylase activity, resulting in decreased testosterone synthesis; and it can inhibit 5alpha-dihydrotestosterone binding to cytosolic androgen receptor in the prostate. Spironolactone exhibits antiandrogenic effects in males and females. The mechanism of antiandrogenic activity of spironolactone is complex and appears to involve several effects of the drug. Spironolactone decreases testosterone biosynthesis by inhibiting steroid 17alpha-monooxygenase (17alpha-hydroxylase) activity, possibly secondary to destruction of microsomal cytochrome P-450 in tissues with high steroid 17alpha-monooxygenase activity (e.g., testes, adrenals). The drug also appears to competitively inhibit binding of dihydrotestosterone to its cytoplasmic receptor protein, thus decreasing androgenic actions at target tissues. Spironolactone-induced increases in serum estradiol concentration also may contribute to its antiandrogenic activity, although such increases may not occur consistently; such increases appear to result from increased conversion of testosterone to estradiol. Spironolactone may have variable effects on serum 17-hydroxyprogesterone concentrations, possibly decreasing its production by inhibiting steroid 17alpha-monooxygenase activity or decreasing its conversion (with resultant accumulation) to androstenedione by inhibiting cytochrome P450-dependent 17alpha-hydroxyprogesterone aldolase (17,20-desmolase) activity. Serum progesterone concentrations may increase with the drug secondary to decreased hydroxylation (via steroid 17alpha-monooxygenase) to 17-hydroxyprogesterone. In children, compensatory increases in lutropin (luteinizing hormone, LH) and follicle-stimulating hormone (FSH) secretion can occur, probably secondary to the drug's antiandrogenic effects (i.e., a feedback response to decreasing serum testosterone concentrations and/or peripheral androgenic activity). MEDICATION (VET): Spironolactone is used most frequently and is a competitive antagonist of aldosterone. Aldosterone is elevated in animals with congestive heart failure in which the renin-angiotensin system is activated in response to hyponatremia, hyperkalemia, and reductions in blood pressure or cardiac output. Aldosterone is responsible for increasing sodium and chloride reabsorption and potassium and calcium excretion from renal tubules. Spironolactone competes with aldosterone at its receptor site, causing a mild diuresis and potassium retention. High concentrations of spironolactone have been reported to interfere with steroid biosynthesis by inhibiting 11 beta- and 18-, 21-, and 17 alpha-hydroxylase.

Source: PubChem (NCBI) · compound 5833