Diuretics potassium levels

Symptomatic hypotension may occur when an angiotensin II receptor antagonist is started in patients taking high-dose diuretics. Potassium levels may be either increased, decreased or not affected. No clinically relevant pharmacokinetic interactions appear to occur between candesartan, eprosartan, irbesartan, losartan, telmisartan or valsartan and hydrochlorothiazide, although the bioavailability of hydrochlorothiazide may be modestly reduced. Similarly, there is no clinically significant pharmacokinetic interaction between valsartan and furosemide. 

Diuretics (see Chap. 46) may be ordered for some patients receiving a cardiotonic drug. Diuretics, as well as odier conditions or factors, such as gastrointestinal suction, diarrhea, and old age, may produce low serum potassium levels (hypokalemia). The primary care provider may order a potassium salt to be given orally or IV. 

POTASSIUM-SPARING DIURETICS. Ratients taking the potassium-sparing diuretics are at risk for hyperkalemia Serum potassium levels are monitored frequently, particularly during initial treatment. 

Monitor electrocardiogram continuously in patients with cardiac abnormalities until serum potassium levels drop below 5 mEq/L (5 mmol/L) or cardiac abnormalities resolve. Evaluate serum potassium and glucose levels within 1 hour in patients who receive insulin and dextrose therapy. Evaluate serum potassium levels within 2 to 4 hours after treatment with SPS or diuretics. Repeat doses of diuretics or SPS if necessary until serum potassium levels fall below 5 mEq/L (5 mmol/L). Monitor blood pressure and serum potassium levels in 1 week in patients who receive fludrocortisone. 

Lithium reduces the kidney s ability to concentrate urine and may cause a nephrogenic diabetes insipidus with low urine specific gravity and low osmolality polyuria (urine volume greater than 3 L/day). This may be treated with loop diuretics, thiazide diuretics, or triamterene. If a thiazide diuretic is used, lithium doses should be decreased by 50% and lithium and potassium levels monitored. 

Hypokalaemia occurs when the plasma-potassium level falls below 3.0 mmol/L Hypokalaemia may occur following loop or thiazide diuretic therapy. Patients at risk of developing hypokalaemia are often prescribed potassium supplements to counteract the potassium loss caused by the diuretic therapy. Symptoms of hypokalaemia include muscle weakness and cramps. Severe cases may lead to muscle paralysis and respiratory failure. 

As a result of the narrow therapeutic range overdosage of digoxin readily occurs, in particular in patients with low plasma potassium levels. Special attention should therefore be paid to the combination of digoxin with drugs causing hypokalemia, such as diuretics. 

The hypotensive response to captopril is accompanied by a fall in plasma aldosterone and angiotensin II levels and an increase in plasma renin activity. Serum potassium levels are not affected unless potassium supplements or potassium-sparing diuretics are used concomitantly this can result in severe hyperkalemia. 

Contraindications Concurrent use of potassium supplements or potassium-sparing diuretics (such as amiloride, spironolactone, and triamterene), or strong inhibitors of the cytochrome P450 3A4 enzyme system (including ketoconazole and itraconazole), creatinine clearance less than 50 ml/min, serum creatinine level greater than 2 mg/dl in males or 1.8 mg/dl in females, serum potassium level greater than 5.5 mEq/L, type 2 diabetes mellitus with microalbuminuria... 

The use of diuretics, such as a thiazide or amiloride, with careful attention paid to lithium and potassium levels ( 318, 319)... 

Alterations in the serum potassium level are hazardous because they can result in cardiac arrhythmias. Drugs that may cause hyperkalemia despite normal renal function include potassium itself, 13 blockers, digitalis glycosides, potassiumsparing diuretics, and fluoride. Drugs associated with hypokalemia include barium, 13 agonists, caffeine, theophylline, and thiazide and loop diuretics. 

Drugs that are also known to decrease potassium levels, such as glucocorticoids and digoxin, should be avoided by anyone taking potassium-depleting diuretics. If they are prescribed, a physician should closely monitor the potassium levels of the patient. Potassium deficiency, or hypokalemia, can cause serious and potentially dangerous side effects (see Harmful side effects section). 

Adverse effects Renal function may deteriorate with the decreased circulating fluid volume, especially after the addition of another diuretic drug acting on the RAAS system, and careful monitoring of serum creatinine is essential. Serum potassium should be monitored within one week of initiation and at least every four weeks for the first three months and every three months thereafter. It should also be monitored at any dose change in spironolactone or if there is a change in concomitant medications that affects the potassium balance. The spironolactone dose (standard 25 mg per day) should be reduced if potassium levels are <5.4 mEq/L, and treatment should be discontinued if painful gynecomastia or serious renal dysfunction or hyperkalemia result. 

Adverse effects Thiazide diuretics induce hypokalemia and hyperuricemia in 70% of patients, and hyperglycemia in 10% of patients. Serum potassium levels should be monitored closely in patients who are predisposed to cardiac arrhythmias (particularly individuals with left ventricular hypertrophy, ischemic heart disease, or chronic congestive heart failure) and who are concurrently being treated with both thiazide diuretics and digitalis glycosides (see p. 160). Diuretics should be avoided in the treatment of hypertensive diabetics or patients with hyperlipidemia. 

AMIODARONE CARBONIC ANHYDRASE ANTAGONISTS, LOOP DIURETICS, THIAZIDES Risk of arrhythmias Cardiac toxicity directly related to hypokalaemia Monitor potassium levels eveiy 4-6 weeks until stable, then at least annually... 

MEXILETINE DIURETICS-CARBONIC ANHYDRASE INHIBITORS, LOOP DIURETICS, THIAZIDES Effect of mexiletine 1 by hypokalaemia Uncertain Normalize potassium levels before starting mexiletine... 

SOTALOL DIURETICS-CARBONIC ANHYDRASE INHIBITORS, LOOP DIURETICS, THIAZIDES t risk of ventricular arrhythmias, particularly torsades de pointes ventricular tachycardia, caused by sotalol Hypokalaemia, a side-effect of these diuretics, predisposes to arrhythmias during sotalol therapy Normalize potassium levels before starting sotalol in patients already taking these diuretics. When starting these diuretics in patients already taking sotalol, monitor potassium levels eveiy 4-6 weeks until stable... 

LOOP DIURETICS BRONCHODILATORS -BETA-2 AGONISTS, THEOPHYLLINE Risk of hypokalaemia Additive effects Monitor blood potassium levels prior to concomitant administration and during therapy. Administer potassium supplements to prevent hypokalaemia... 

LOOP DIURETICS CARDIAC GLYCOSIDES Risk of digoxin toxicity t due to hypokalaemia Uncertain Monitor potassium levels closely. Watch for digoxin toxicity and check levels... 

LOOP DIURETICS CNS STIMULANTS -ATOMOXETINE t risk of arrhythmias with hypokalaemia These diuretics may cause hypokalaemia Monitor potassium levels closely... 

POTASSIUM-SPARING DIURETICS TRIMETHOPRIM Risk of hyperkalaemia when trimethoprim is co-administered with eplerenone Additive effect Monitor potassium levels closely... 

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