Hypertension Blog

Diuretics promote renal excretion of water and electrolytes by increasing the glomerular filtration rate. They can also decrease sodium reabsorption and increase the rate of sodium excretion .

Diuretics are divided into several classes: loop, potassium sparing, thiazide, and thiazide-like. Each of these classes has a single mechanism of action. Combination diuretics contain two different classes of diuretic .

Potassium Sparing Diuretics

Potassium sparing diuretics have weaker diuretic and antihypertensive effects than loop diuretics. However, by acting on the distal tubule to inhibit the reabsorption of sodium and water, these drugs increase potassium retention. The potassium sparing diuretics include amiloride, spironolactone, and triamterene.

Indications and Contraindications

Physicians prescribe potassium sparing diuretics to treat patients with hypertension or with edema from heart failure. These drugs are also used in combination with other classes of diuretics to maintain a patient’s serum potassium levels.

Potassium sparing diuretics shouldn’t be used to treat patients with anuria, hyperkalemia, or impaired renal function. Amiloride should be used cautiously in those with dehydration, diabetes, or acidosis. And spironolactone should be given cautiously to patients with hepatic disease. Use triamterene cautiously in patients with heart failure, renal disease, and cirrhosis. When administering any potassium sparing diuretics, monitor your patient’s serum chemistry levels for early indications of electrolyte imbalance and increasing renal or hepatic failure.

Diuretics Side Effects

These drugs produce fewer side effects than other diuretics. However, a patient taking a potassium sparing diuretic has a greater risk of hyperkalemia, especially if he’s also taking potassium supplements.

Dose-related adverse effects include megaloblastic anemia, arrhythmias, headache, dizziness, and orthostatic hypotension. Spironolactone may cause amenorrhea, a deeper voice, gynecomastia, hirsutism, irregular menses, and postmenopausal bleeding. Triamterene may cause a bluish discoloration of the urine.

Your patient may experience hyperkalemia if he takes one of these drugs with another potassium sparing diuretic, an ACE inhibitor, or a salt substitute. If given with lithium, a potassium sparing diuretic may provoke lithium toxicity. Nephrotoxicity may increase if a patient takes triamterene with indomethacin. Also, aspirin decreases the effects of spironolactone.