Spironolactone:
Is a diuretic and is used as an antiandrogen which is a renal competitive aldosterone antagonist in a class of pharmaceuticals called potassium-sparing diuretics, used primarily to treat heart failure, ascites in patients with liver disease, low-renin hypertension, hypokalemia, and Conn's syndrome as well as high blood pressure.
On its own, spironolactone is only a weak diuretic, but it can be combined with other diuretics. About one person in one hundred with hypertension has elevated levels of aldosterone; in these persons the antihypertensive effect of spironolactone may exceed that of complex combined regimens of other antihypertensives.
Mechanism of action:
Spironolactone inhibits the effect of aldosterone by competing for intracellular aldosterone receptor in the distal tubule cells (it actually works on Aldosterone receptors in the collecting duct). This increases the secretion of water and sodium, while decreasing the excretion of potassium.
Spironolactone has a fairly slow onset of action, taking several days to develop and similarly the effect diminishes slowly.
Adverse effects:
- Increased risk of bleeding from the stomach and duodenum
- It can cause gynecomastia
- Menstrual irregularities
- Testicular atrophy
- Ataxia
- Erectile dysfunction
- Drowsiness
- Rashes
Amiloride:
Is a potassium-sparing diuretic, used in the management of hypertension and congestive heart failure.
Mode of action:
Amiloride works by directly blocking the epithelial sodium channel (ENaC) thereby inhibiting sodium reabsorption in the distal convoluted tubules and collecting ducts in the kidneys. This promotes the loss of sodium and water from the body, but without depleting potassium. The drug is often used in conjunction with thiazide. Due to its potassium-sparing capacities, hyperkalemia (high blood potassium levels) are occasionally observed in patients taking amiloride. The risk is high in concurrent use of ACE inhibitors or spironolactone. Patients are also advised not to use potassium-containing salt replacements.
Sources:
Wikipedia the free encyclopedia
