Hypokalemia potassium-sparing diuretics

Potassium Sparing Diuretics. Triamterene and amiloride, potassium sparing diuretics, by themselves produce only slight antihypertensive effects. The main use is to prevent or to treat the hypokalemia induced by thiazide-type and high ceiling loop diuretics, such as furosemide and bumetanide. 

No significant interactions have been reported when tiie expectorants are used as directed. The exception is iodine products. Lithium and other antithyroid drug may potentiate the hypotliyroid effects of these drug if used concurrently with iodine products. When potassium-containing medications and potassium-sparing diuretics are administered with iodine products, the patient may experience hypokalemia, cardiac arrhythmias, or cardiac arrest. Thyroid function tests may also be altered by iodine... 

Older adults are particularly prone to fluid volume deficit and electrolyte imbalances (see Display 46-1) while taking a diuretic. The older adult is carefully monitored for hypokalemia (when taking the loop or thiazide diuretic and hyperkalemia (with the potassium-sparing diuretics... 

The nurse must closely observe patients receiving a potassium-sparing diuretic for signs of hyperkalemia (see Display 46-1), a serious and potentially fatal electrolyte imbalance The patient is closely monitored for hypokalemia during loop or thiazide diuretic therapy. A supplemental potassium supplement may be prescribed to prevent hypokalemia. The primary health care provider may also encourage the patient to include... 

Potassium-sparing diuretics act on the late portion of the distal tubule and on the cortical collecting duct. As a result of their site of action, these diuretics also have a limited effect on diuresis compared to the loop diuretics (3% of the filtered Na+ ions may be excreted). However, the clinical advantage of these drugs is that the reabsorption of K+ ions is enhanced, reducing the risk of hypokalemia. 

Diuretics - Generally initiate therapy with a thiazide or other oral diuretic. Thiazide-type diuretics are drugs of choice hydrochlorothiazide or chlorthalidone are generally preferred. Reserve loop diuretics for selected patients. This therapy alone may control many cases of mild hypertension. Consider treating diuretic-induced hypokalemia (less than 3.5 mEq/L) with potassium supplementation or by adding a potassium-sparing diuretic to therapy. 

The potassium sparing diuretics are predominantly used in conjunction with thiazides or loop diuretics, with the aim to counteract the hypokalemia induced by the aforementioned types of diuretics. Enhanced natriuresis caused by thiazides or loop diuretics will lead to the following therapeutic benefits. 

Sodium removal is the next important step—by dietary salt restriction or a diuretic—especially if edema is present. In mild failure, it is reasonable to start with a thiazide diuretic, switching to more powerful agents as required. Sodium loss causes secondary loss of potassium, which is particularly hazardous if the patient is to be given digitalis. Hypokalemia can be treated with potassium supplementation or through the addition of a potassium-sparing diuretic such as spironolactone. As noted above, spironolactone should probably be considered in all patients with moderate or severe heart failure since it appears to reduce both morbidity and mortality. 

Hypokalemia eventually develops in many patients who are placed on loop diuretics or thiazides. This can often be managed with dietary NaCl restriction. When hypokalemia cannot be managed in this way, or with dietary KC1 supplements, the addition of a potassium-sparing diuretic can significantly lower potassium excretion. While this approach is generally safe, it should be avoided in patients with renal insufficiency in whom life-threatening hyperkalemia can develop in response to potassium-sparing diuretics. 

Alterations in the serum potassium level are hazardous because they may result in cardiac arrhythmias. Drugs that may cause hyperkalemia despite normal renal function include potassium itself, -blockers, digitalis glycosides, potassium-sparing diuretics, and fluoride. Drugs associated with hypokalemia include barium, B-agonists, caffeine, theophylline, and thiazide and loop diuretics. 

Hypokalemia should be treated in heart failure, because either hypokalemia or heart failure can predispose individuals to experience serious arrhythmias. Therefore, potassium-sparing diuretics are sometimes used in the treatment of congestive heart failure. 

In patients in whom hypokalemia needs to be prevented or corrected, potassium-sparing diuretics should be... 

Fixed combinations of thiazides and loop diuretics with potassium and of thiazides with beta-blockers serve little useful purpose and can in fact do harm. Combinations of thiazides and loop diuretics with potassium-sparing diuretics serve the needs of the small minority of patients who develop clinically significant hypokalemia when given diuretics alone, or in whom hypokalemia is particularly risky. In fact, these combinations are much too widely used, and since individual needs vary so much there is a spectrum of risk, ranging from hypokalemia to hyperkalemia (SEDA-10, 370) (SEDA-10, 371). 

Many drugs may cause hypokalemia by a variety of mechanisms. These mechanisms include intracellular potassium shifting and increased renal or stool losses (Table 50-1). Non-potassium-sparing diuretic administration is the most common cause of drug-induced hypokalemia. Loop and thiazide diuretics inhibit renal sodium reabsorption, which results in increased sodium delivery to the distal tubule. Consequently, hypokalemia develops because the distal... 

A potassium-sparing diuretic can be given along with a thiazide or a loop diuretic to prevent hypokalemia. Spironolactone can also be beneficial in some patients with severe CHF or cirrhosis associated with ascites. 

One of the major side effects of using a loop diuretic Is excessive excretion of electrolytes. Including potassium Ions. Loss of potassium can eventually lead to hypokalemia (low blood potassium), and hypokalemia alone can lead to the development of cardiac arrhythmias. Potassium loss, however, also potentiates the actions of digitalis (cardiac sodlum-potassium-adenosine triphosphatase Inhibition) and can lead to digitalis-induced cardiac arrhythmias as well. Hypokalemia can be treated/prevented by the use of potassium supplements or the use of a potassiumsparing diuretic (e.g., triamterene and amiloride). Because potassium-sparing diuretics are weakly basic drugs, they do not alter the active secretion of loop diuretics. 

Agents acting in the proximal tubule are seldom used to treat hypertension. Treatment is usually initiated with a thiazide-type diuretic. Chlorthalidone and indapamide are structurally different from thiazides but are functionally related. If renal function is severely impaired (i.e., serum creatinine above 2.5 mg/dl), a loop diuretic is needed. A potassium-sparing agent may be given with the diuretic to reduce the likelihood of hypokalemia. 

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