Heart failure potassium-sparing

Medications can increase the risk of hyperkalemia in patients with CKD, including angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, used for the treatment of proteinuria and hypertension. Potassium-sparing diuretics, used for the treatment of edema and chronic heart failure, can also exacerbate the development of hyperkalemia, and should be used with caution in patients with stage 3 CKD or higher. 

Potassium-sparing diuretics, such as amiloride and triamterene. These agents reduce at the tubular level the reabsorption of sodium and water, whereas the excretion of potassium is diminished. Their primary effects are independent of aldosterone. They are slow-acting and weak diuretics, which are unsuitable as monotherapy of hypertension or heart failure. For this reason, they are always combined with thiazide or loop diuretics. Several combined preparations are commercially available. 

Potassium-sparing diuretics are useful both to avoid excessive potassium depletion and to enhance the natriuretic effects of other diuretics. Aldosterone receptor antagonists in particular also have a favorable effect on cardiac function in people with heart failure. 

See Table 15-6. Potassium-sparing diuretics are most useful in states of mineralocorticoid excess or hyperaldosteronism (also called aldosteronism), due either to primary hypersecretion (Conn s syndrome, ectopic adrenocorticotropic hormone production) or secondary hyperaldosteronism (evoked by heart failure, hepatic cirrhosis, nephrotic syndrome, or other conditions associated with diminished effective intravascular volume). Use of diuretics such as thiazides or loop agents can cause or exacerbate volume contraction and may cause secondary hyperaldosteronism. In the setting of enhanced mineralocorticoid secretion and excessive delivery of Na+ to distal nephron sites, renal K+ wasting occurs. Potassium-sparing diuretics of either type may be used in this setting to blunt the K+ secretory response. 

Potassium-sparing diuretics include amiloride (Midamor) and triamterene (Dyrenium). They are used in the treatment of cirrhosis and congestive heart failure. They may be used in conjunction with thiazide diuretics to offset the potassium loss associated with those medications. 

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 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. 

Thiazide diuretics are ineffective once the GFR becomes less than 25 mL/min, and loop diuretics are often used at high doses (e.g. furosemide 500 mg to 1 g daily) to gain an effect. Metolazone is effective when combined with a loop diuretic. Potassium-sparing diuretics such as amiloride are not recommended. Spironolactone is not generally used, but is beneficial in low dose for the treatment of heart failure even in patients on dialysis. Beta-blockers and calcium channel blockers are generally well tolerated. Any ankle swelling with calcium channel blockers must not be confused with fluid overload. 

POTASSIUM-SPARING DIURETICS ANTI HYPERTENSIVES AND HEART FAILURE DRUGS -ACE INHIBITORS, ANGIOTENSIN II RECEPTOR ANTAGONISTS t risk of hyperkalaemia Additive retention of potassium Monitor serum potassium every week until stable, then eveiy 3-6 months... 

PROGESTOGENS 1. ANALGESICS -NSAIDs 2. ANTI HYPERTENSIVES AND HEART FAILURE DRUGS - ACE inhibitors, angiotensin II receptor antagonists 3. DIURETICS — potassium-sparing t risk of hyperkalaemia Drospirenone (component of the Yasmin brand of combined contraceptive pill) is a progestogen derived from spironolactone that can cause potassium retention Monitor serum potassium weekly until stable and then every 6 months... 

USE OF DIURETICS IN CLINICAL PRACTICE The majority of patients with heart failure will require chronic administration of a loop diuretic to maintain euvolemia. In patients with clinically evident fluid retention, furosemide typically is started at a dose of 40 mg once or twice/day and increased until an adequate diuresis is achieved. A larger initial dose may be required in patients with more advanced heart failure or with concurrent azotemia. Serum electrolytes and renal function should be monitored frequently in patients with preexisting renal insufficiency or those in whom a rapid diuresis is desirable. Once fluid retention has resolved, the diuretic dose should be reduced to the minimal level necessary to maintain euvolemia. Electrolyte abnormalities and/or worsening azotemia may supervene before euvolemia is achieved. Hypokalemia may be corrected by potassium supplementation or addition of a K-sparing diuretic. 

Consequently, diuretics have a variety of uses. Thiazide diuretics may be used either alone or in combination with other pharmacotherapy for the treatment of hypertension. Loop diuretics can provide immediate diuresis and are used for heart failure and in lieu of thiazides in patients with compromised renal function. In addition to more traditional uses, certain potassium-sparing diuretics provide added benefit to other pharmacotherapy in patients with primary hyperaldosteronism, heart failure, or post-acute myocardial infarction. Carbonic anhydrase inhibitors have limited use for diuresis however, they may be used to reduce intraocular pressure and treat acute mountain sickness. 

Diuretics are also prescribed to treat heart failure. Diuretics, which will be discussed in detail later in this chapter, are the first line of treatment for reducing fluid volume and are frequently prescribed with digoxin. Spironalactone (Aldactone) is a potassium-sparing diuretic and is effective in treating moderate to severe heart failure. It is more effective than ACE inhibitors. Beta-blockers have been contraindicated for patients in heart failure. 

Hypotension is more common in patients with heart failure who are receiving large doses of diuretics. In a study in 124 patients with severe heart failure, all receiving furosemide (mean dose 170 mg daily range 80 to 500 mg daily) and 90 also receiving the potassium-sparing diuretic spironolactone, the addition of captopril caused transient symptomatic hypotension in 44% of subjects. The captopril dose had to be reduced, and in 8 patients it was later discontinued. In addition, four patients developed symptomatic hypotension after 1 to 2 months of treatment, and captopril was also discontinued in these patients. ... 

Hyperkalaemia with ACE inhibitors and potassium-sparing diuretics, and particularly the aldosterone antagonist spironolactone, is well documented and well established. If it occurs it can be serious and potentially life threatening. Its incidence depends on the presence of other risk factors, and clinically important hyperkalaemia usually only appears to develop if one or more of these are also present, particularly renal impairment. Other risk factors in patients with heart failure include advanced age and diabetes" (hyperkalaemia has been found to be relatively common in both non-insulin-dependent and insulin-dependent diabetics). In addition, doses of spironolactone greater than 25 mg daily increase the risk of hyperkalaemia. 

Angiotensin II receptor antagonists are potassium-sparing, via their effects on aldosterone, and their potential to cause clinically important hyperkalaemia is well established. The incidence of hyperkalaemia varies depending on the clinical indication and other disease conditions, being lowest in essential hypertension, and highest in heart failure, diabetes, and renal impairment. For example, the incidence of hyperkalaemia in clinical studies in patients with hypertension was 0.9% with eprosartan - and 1.5% with losartan in type II diabetic patients with nephropathy, the incidence was 9.9% with losartan and 18.6% with irbesartan and in those with heart failure the incidence was 6.3% with candesartan. ... 

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