Amiloride hydrochloride
Amiloride hydrochloride (Midamor)
Amiloride hydrochloride
(ah- MILL-oh-ryd)
Pregnancy Category: B Midamor (Rx)

Classification: Diuretic, potassium-sparing

Action/Kinetics: Acts on the distal tubule to inhibit Na ⁺, K ⁺-ATPase, thereby inhibiting sodium exchange for potassium; this results in increased secretion of sodium and water and conservation of potassium. In the proximal tubule, amiloride inhibits the Na ⁺/H ⁺ exchange mechanism. Has weak diuretic and antihypertensive activity. Onset: 2 hr. Peak effect: 6-10 hr. Peak plasma levels: 3-4 hr. Duration: 24 hr. t 1/2: 6-9 hr. Twenty-three percent is bound to plasma protein. Approximately 50% is excreted unchanged by kidney and 40% by the feces unchanged.

Uses: Adjunct with thiazides or loop diuretics in the treatment of hypertension or edema due to CHF, hepatic cirrhosis, and nephrotic syndrome to help restore normal serum potassium or prevent hypokalemia. Prophylaxis of hypokalemia in clients who would be at risk if hypokalemia developed (e.g., digitalized clients or clients with significant cardiac arrhythmias). Investigational: To reduce lithium-induced polyuria. Aerosolized amiloride may slow the progression of pulmonary function reduction in adults with cystic fibrosis.

Contraindications: Hyperkalemia ( >5.5 mEq potassium/L). In clients receiving other potassium-sparing diuretics or potassium supplements. Impaired renal function. Diabetes mellitus. Use during lactation.

Special Concerns: Use with caution in metabolic or respiratory acidosis; during lactation. Geriatric clients may have a greater risk of developing hyperkalemia. Safety and efficacy have not been determined in children.

Side Effects: Electrolyte: Hyperkalemia, hyponatremia, and hypochloremia if used with other diuretics. CNS: Headache, dizziness, encephalopathy, tremors, paresthesias, mental confusion, insomnia, decreased libido, depression, sleepiness, vertigo, nervousness. GI: Nausea, anorexia, vomiting, diarrhea, changes in appetite, gas and abdominal pain, dry mouth, flatulence, abdominal fullness, GI bleeding, GI disturbance, thirst, dyspepsia, heartburn, jaundice, constipation, activation of preexisting peptic ulcer. Respiratory: Dyspnea, cough, SOB. Musculoskeletal: Weakness; muscle cramps; fatigue; joint, chest and back pain; neck or shoulder ache; pain in extremities. GU: Impotence, polyuria, dysuria, bladder spasms, urinary frequency. CV: Angina, palpitations, arrhythmias orthostatic hypotension. Hematologic: Aplastic anemia neutropenia. Dermatologic: Skin rash, itching, pruritus, alopecia. Miscellaneous: Visual disturbances, nasal congestion, tinnitus, increased intraocular pressure, abnormal liver function.

Overdose Management: Symptoms: Electrolyte imbalance, dehydration. Treatment: Induce emesis or gastric lavage. Treat hyperkalemia by IV sodium bicarbonate or oral or parenteral glucose with a rapid-acting insulin. Sodium polystyrene sulfonate, oral or by enema, may also be used.

Drug Interactions: ACE inhibitors / Risk of significant hyperkalemia Digoxin / Possible renal clearance and nonrenal clearance and possible inotropic effect of digoxin Lithium / Renal excretion of lithium chance of toxicity NSAIDs / Therapeutic effect of amiloride Potassium products / Hyperkalemia with possibility of cardiac arrhythmias or cardiac arrest Spironolactone, Triamterene / Hyperkalemia, hyponatremia, hypochloremia

How Supplied: Tablet: 5 mg

Dosage
?Tablets As single agent or with other diuretics.
Adults, initial: 5 mg/day; 10 mg/day may be necessary in some clients. Doses as high as 20 mg/day may be used, if needed, with careful monitoring of electrolytes.
Reduce lithium-induced polyuria.
10-20 mg/day.
Slow progression of pulmonary function reduction in cystic fibrosis.
Adults: Drug is dissolved in 0.3% saline and delivered by nebulizer.