Amiloride

U.S. BRAND NAMES — Midamor® [DSC]
PHARMACOLOGIC CATEGORY Diuretic, Potassium Sparing
DOSING: ADULTS — Hypertension, edema (to limit potassium loss): Oral: Initial: 5-10 mg/day (up to 20 mg) Hypertension (JNC 7): 5-10 mg/day in 1-2 divided doses
DOSING: PEDIATRIC — Edema, hypertension: Oral: Although safety and efficacy in children have not been established by the FDA, a dosage range of 0.4-0.625 mg/kg/day (maximum: 20 mg/day) has been used in children weighing 6-20 kg.
(For additional information see "Amiloride: Pediatric drug information")
DOSING: ELDERLY — Oral: Initial: 5 mg once daily or every other day
DOSING: RENAL IMPAIRMENT — Oral:
Clcr 10-50 mL/minute: Administer 50% of normal dose.
Clcr <10 mL/minute: Avoid use.
DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, as hydrochloride: 5 mg
DOSAGE FORMS: CONCISE Tablet: 5 mg
GENERIC EQUIVALENT AVAILABLE — Yes
ADMINISTRATION — Administer with food or meals to avoid GI upset.
USE — Counteracts potassium loss induced by other diuretics in the treatment of hypertension or edematous conditions including CHF, hepatic cirrhosis, and hypoaldosteronism; usually used in conjunction with more potent diuretics such as thiazides or loop diuretics
USE - UNLABELED / INVESTIGATIONAL — Investigational: Cystic fibrosis; reduction of lithium-induced polyuria
ADVERSE REACTIONS SIGNIFICANT 1% to 10%: Central nervous system: Headache, fatigue, dizziness Endocrine & metabolic: Hyperkalemia (up to 10%; risk reduced in patients receiving kaliuretic diuretics), hyperchloremic metabolic acidosis, dehydration, hyponatremia, gynecomastia Gastrointestinal: Nausea, diarrhea, vomiting, abdominal pain, gas pain, appetite changes, constipation Genitourinary: Impotence Neuromuscular & skeletal: Muscle cramps, weakness Respiratory: Cough, dyspnea
<1% (Limited to important or life-threatening): Alopecia, arrhythmia, bladder spasms, chest pain, dyspnea, dysuria, GI bleeding, intraocular pressure increased, jaundice, orthostatic hypotension, palpitation, polyuria
CONTRAINDICATIONS — Hypersensitivity to amiloride or any component of the formulation; presence of elevated serum potassium levels (>5.5 mEq/L); if patient is receiving other potassium-conserving agents (eg, spironolactone, triamterene) or potassium supplementation (medicine, potassium-containing salt substitutes, potassium-rich diet); anuria; acute or chronic renal insufficiency; evidence of diabetic nephropathy. Patients with evidence of renal impairment or diabetes mellitus should not receive this medicine without close, frequent monitoring of serum electrolytes and renal function.
WARNINGS / PRECAUTIONS Box warnings: Hyperkalemia: See "Concerns related to adverse effects" below.
Concerns related to adverse effects: Fluid/electrolyte loss: Excess amounts can lead to profound diuresis with fluid and electrolyte loss; close medical supervision and dose evaluation are required. Watch for and correct electrolyte disturbances; adjust dose to avoid dehydration. Hyperkalemia: [U.S. Boxed Warning]: Hyperkalemia can occur; patients at risk include those with renal impairment, diabetes, the elderly, and the severely ill. Serum potassium levels must be monitored at frequent intervals especially when dosages are changed or with any illness that may cause renal dysfunction.
Disease-related concerns: Cirrhosis: In cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy. Diabetes: Use with extreme caution in patients with diabetes mellitus; monitor closely. Discontinue amiloride 3 days prior to glucose tolerance testing. Metabolic/respiratory acidosis: Use with caution in patients who are at risk for metabolic or respiratory acidosis (eg, cardiopulmonary disease, uncontrolled diabetes).
DRUG INTERACTIONS Amoxicillin's absorption may be reduced; avoid concurrent use or observe for clinical response.
ACE inhibitors or angiotensin receptor antagonists can cause hyperkalemia, especially in patients with renal impairment, potassium-rich diets, or on other drugs causing hyperkalemia; avoid concurrent use or monitor closely.
Cyclosporine or tacrolimus: Risk of hyperkalemia may be increased by concurrent therapy.
NSAIDs: May decrease the effect of diuretics.
Potassium supplements may further increase potassium retention and cause hyperkalemia; avoid concurrent use.
Quinidine and amiloride together may increase risk of malignant arrhythmias; avoid concurrent use.
ETHANOL / NUTRITION / HERB INTERACTIONS — Food: Hyperkalemia may result if amiloride is taken with potassium-containing foods.
PREGNANCY RISK FACTOR — B (show table)
LACTATION — Excretion in breast milk unknown/contraindicated
DIETARY CONSIDERATIONS — Take with food or meals to avoid GI upset. Do not use salt substitutes or low salt milk without checking with your healthcare provider; too much potassium can be as harmful as too little.
PRICING — (data from drugstore.com)Tablets (Amiloride HCl) 5 mg (30): $22.41
Tablets (Midamor) 5 mg (30): $18.99
MONITORING PARAMETERS — I & O, daily weights, blood pressure, serum electrolytes, renal function
TOXICOLOGY / OVERDOSE COMPREHENSIVE — Clinical signs are consistent with dehydration and electrolyte disturbance. Large amounts may result in life-threatening hyperkalemia (>6.5 mEq/L). This can be treated with I.V. glucose (dextrose 25% in water), with rapid-acting insulin, with concurrent I.V. sodium bicarbonate and, if needed, Kayexalate® oral or rectal solutions in sorbitol. Persistent hyperkalemia may require dialysis.
CANADIAN BRAND NAMES — Apo-Amiloride®
INTERNATIONAL BRAND NAMES — Amiclaran (CZ); Amikal (SE); Amilo 5 (KR); Amilozid (HU); Apo-Amiloride (CA); Kaluril (AU, TW); Medamor (FI); Midamor (NZ)
MECHANISM OF ACTION — Interferes with potassium/sodium exchange (active transport) in the distal tubule, cortical collecting tubule, and collecting duct by inhibiting sodium, potassium-ATPase; decreases calcium excretion; increases magnesium loss
PHARMACODYNAMICS / KINETICS Onset of action: 2 hours
Duration: 24 hours
Absorption: ~15% to 25%
Distribution: Vd: 350-380 L
Protein binding: 23%
Metabolism: No active metabolites
Half-life elimination: Normal renal function: 6-9 hours; End-stage renal disease: 8-144 hours
Time to peak, serum: 6-10 hours
Excretion: Urine and feces (equal amounts as unchanged drug)
PATIENT INFORMATION — Report any muscle cramps, weakness, nausea, or dizziness. Use caution operating machinery or performing other tasks requiring alertness.