AMILORIDE HYDROCHLORIDE
(a-mill'oh-ride)
Midamor
Classifications: electrolyte and water balance agents; diuretics, potassium-sparing
Prototype: Spironolactone
Pregnancy Category: B
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5 mg tablets
Potassium-sparing diuretic with mild diuretic and antihypertensive action. Diuretic action is independent of aldosterone and
carbonic anhydrase.
Induces urinary excretion of sodium and reduces excretion of potassium and hydrogen ions by direct action on distal renal
tubules.
Potassium-sparing effect in prevention or treatment of diuretic-induced hypokalemia in patients with CHF, hepatic cirrhosis,
or hypertension. Also used in management of primary hyperaldosteronism. Usually combined with a potassium-wasting (kaliuretic)
diuretic such as a thiazide or loop diuretic.
With hydrochlorothiazide for recurrent calcium nephrolithiasis, lithium-induced polyuria.
Elevated serum potassium (>5.5 mEq/L), concomitant use of other potassium-sparing diuretics; anuria, acute or chronic renal
insufficiency; evidence of diabetic nephropathy; type 1 diabetes mellitus; metabolic or respiratory acidosis; hepatic function
impairment. Safety during pregnancy (category B), lactation, or in children is not established.
Debilitated patients; diet-controlled or uncontrolled diabetes mellitus; cardiopulmonary disease; the older adult.
Diuretic
Adult: PO 5 mg/d, may increase up to 20 mg/d in 1–2 divided doses
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Oral
- Give once/d dose in the morning and schedule the second b.i.d. dose early to avoid interrupting sleep.
- Give with food to reduce possibility of gastric distress.
- Store at 15°–30° C (59°–86° F) in a tightly closed container unless otherwise directed.
Body as a Whole: Generally well tolerated. CNS:
Headache, dizziness, nervousness, confusion, paresthesias, drowsiness. CV: Cardiac arrhythmias. Metabolic: Hyperkalemia, hyponatremia, positive Coombs' test. Hematologic:
Aplastic anemia. Special Senses: Tinnitus; nasal congestion. Visual disturbances, increased intraocular pressure. GI:
Diarrhea or constipation, anorexia, nausea, vomiting, abdominal cramps, dry mouth, thirst. Urogenital: Polyuria, dysuria, bladder spasms, urinary frequency, impotence, decreased libido. Respiratory: Dyspnea, shortness of breath. Skin: Rash, pruritus, photosensitivity reactions. Other: Weakness, fatigue, muscle cramps.
Manufacturer advises discontinuing amiloride in patients with diabetes mellitus at least 3 d before glucose tolerance test.
Drug: Blood from blood banks, ace inhibitors (e.g., captopril), spironolactone,
triamterene,
potassium supplements may cause hyperkalemia with cardiac arrhythmias; possibility of increased lithium toxicity (decreased renal elimination); possibility of altered digoxin response; nsaids may attenuate antihypertensive effects. Food:
potassium-containing salt substitutes increase risk of hyperkalemia.
Absorption: 50% absorbed from GI tract. Onset: 2 h. Peak: 6–10 h. Duration: 24 h. Elimination: 20–50% excreted unchanged in urine, 40% in feces. Half-Life: 6–9 h.
Assessment & Drug Effects
- Monitor for S&S of hyperkalemia and hyponatremia (see Appendix F). Hyperkalemia occurs in about 10% of patients receiving
amiloride and serum potassium can rise suddenly and without warning. It is more common in older adults and patients with diabetes
or renal disease.
- Lab tests: Serum potassium levels, particularly when therapy is initiated, whenever dosage adjustments are made, and during
any illness that may affect kidney function. Intermittent evaluations of BUN, creatinine, and ECG for patients with renal
or hepatic dysfunction, diabetes mellitus, older adults, or the debilitated.
Patient & Family Education
- Learn S&S of hyperkalemia and hyponatremia (see Appendix F) and report to physician immediately.
- Do not take potassium supplements, salt substitutes, high intake of dietary potassium unless prescribed by physician.
- Do not drive or engage in potentially hazardous activities until response to drug is known.
- Do not breast feed while taking this drug without consulting physician.
1%)
Canadian drug name; 
Prototype drug