amiloride hydrochloride

amiloride hydrochloride

[am′ilôr′īd]

a potassium-sparing diuretic with antihypertensive activity. Its prototype is spironolactone.

indication It is prescribed as an adjunct in the treatment of congestive heart failure or hypertension. It is often given with a thiazide medication.

contraindications Concurrent use of potassium-conserving agents, hyperkalemia, impaired renal function, or known hypersensitivity to this drug prohibit its use.

adverse effects Among the most serious adverse reactions are headache, diarrhea, nausea and vomiting, anorexia, hyperkalemia, dizziness, encephalopathy, impotence, muscle cramps, photosensitivity, irregular heart rhythm, confusion, and paresthesia.

---

amiloride hydrochloride

Amilamont (UK)

Pharmacologic class: Pyrazine-carbonyl-guanidine

Therapeutic class: Potassium-sparing diuretic

Pregnancy risk category B

FDA Boxed Warning

• Drug may cause hyperkalemia (serum potassium level above 5.5 mEq/L), which can be fatal if uncorrected. Hyperkalemia incidence is about 10% when drug is used without kaliuretic diuretic; incidence increases in renal impairment, diabetes mellitus, and elderly patients. (When drug is given along with a thiazide diuretic in patients without these complications, hyperkalemia risk drops to about 1% to 2%.) Monitor serum potassium levels carefully, particularly when therapy begins, when diuretic dosage is adjusted, and during illness that could affect renal function.

Action

Inhibits sodium reabsorption at distal convoluted renal tubule, cortical collecting tubule, and collecting duct, thereby causing sodium and fluid loss and potassium retention

Availability

Tablets: 5 mg

⊘Indications and dosages

➣ Adjunctive therapy (with thiazide or other potassium-wasting diuretics) to help restore a normal serum potassium level; to prevent hypokalemia in patients at risk (such as those receiving cardiac glycosides )

Adults: 5 mg P.O. daily as adjunct to usual antihypertensive or diuretic; may increase to 20 mg daily with careful electrolyte monitoring

➣ Monotherapy in patients with heart failure or hypertension

Adults: Initially, 5 mg P.O. daily; if needed, increase to 10 mg P.O. daily. In persistent hypokalemia, may increase to 15 to 20 mg P.O. daily with careful electrolyte monitoring.

Contraindications

• Hypersensitivity to drug
• Impaired renal function
• Concurrent use or ingestion of potassium supplements or other potassium-sparing diuretics
• Serum potassium level > 5.5 mEq/L
• Children

Precautions

Use cautiously in:
• hepatic insufficiency, cardiopulmonary disease, diabetes mellitus, renal disease
• elderly patients
• pregnant patients.

Administration

• Administer with meals.
☞ Never give to patient concurrently receiving potassium supplements or other potassium-sparing diuretics.

Route	Onset	Peak	Duration
P.O.	2 hr	6-10 hr	24 hr

Adverse reactions

CNS: headache, weakness, fatigue, dizziness, paresthesia, encephalopathy

GI: nausea, vomiting, constipation, abdominal pain, flatulence

GU: polyuria, erectile dysfunction

Metabolic: electrolyte imbalances (when used with other diuretics), hyperkalemia

Musculoskeletal: muscle cramps

Respiratory: cough, dyspnea

Skin: rash

Other: appetite changes

Interactions

Drug-drug. Angiotensin-converting enzyme (ACE) inhibitors, cyclosporine, potassium supplements, other potassium-sparing diuretics, tacrolimus: increased risk of severe hyperkalemia

Digoxin: decreased digoxin efficacy

Lithium: reduced lithium clearance and increased risk of lithium toxicity

Nonsteroidal anti-inflammatory drugs (NSAIDs): reduced diuretic and antihypertensive effects of amiloride

Drug-diagnostic tests. Blood urea nitrogen, potassium: increased levels

Chloride, hemoglobin, magnesium, neutrophils, sodium: decreased levels

Liver function tests: decreased values

Drug-food. Foods high in potassium, salt substitutes containing potassium: hyperkalemia

Drug-herbs. Licorice: increased risk of hypokalemia

Patient monitoring

• Monitor blood chemistry and liver and kidney function test results, CBC, and electrolyte levels (especially potassium).
• Assess for signs and symptoms of hyperkalemia, especially in patients also taking ACE inhibitors or indomethacin.
• Evaluate patient for orthostatic hypertension.

Patient teaching

☞ Instruct patient to immediately report signs and symptoms of hyperkalemia (tingling, fatigue, muscle weakness or paralysis).
• Tell patient to avoid high-potassium salt substitutes and foods.
• Advise patient to minimize GI upset by taking drug with meals; eating small, frequent servings of healthy food; and drinking plenty of fluids.
• Encourage patient to discuss activity recommendations and pain management with prescriber. Advise him to avoid NSAIDs, which interfere with drug's action.
• Caution patient to avoid driving and other hazardous activities until he knows how the drug affects concentration and alertness.
• Inform patient that he'll undergo regular blood testing during therapy.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.