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Amiloride Hydrochloride / Hydrochlorothiazide

Pronunciation: Uh-MILL-oh-ride HIGH-droe-KLOR-ide/high-droe-klor-oh-THIGH-uh-zide
Class: Diuretic combination

Trade Names

Moduretic
- Tablets 5 mg amiloride/50 mg hydrochlorothiazide

Apo-Amilzide (Canada)
Gen-Amilazide (Canada)
Moduret (Canada)
Nu-Amilzide (Canada)

Pharmacology

Amiloride

Interferes with sodium reabsorption at distal tubule, resulting in increased water and sodium excretion and decreased potassium excretion.

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Hydrochlorothiazide

Increases chloride, sodium, and water excretion by interfering with transport of sodium ions across renal tubular epithelium.

Indications and Usage

Treatment of hypertension or congestive heart failure in patients who develop hypokalemia when thiazide or other kaliuretic diuretics are used alone, or in patients in whom maintenance of normal serum potassium levels is clinically important (eg, digitalized patients); alone or as adjunctive treatment with other antihypertensive agents.

Contraindications

Hyperkalemia (serum potassium levels greater than 5.5 mEq/L); concurrently with other potassium-sparing diuretics (eg, spironolactone), potassium supplements (including potassium-rich diet) except in severe or refractory cases of hypokalemia; impaired renal function; sensitivity to any components of product.

Dosage and Administration

Adults

PO 1 to 2 tablets (5 mg amiloride/50 mg hydrochlorothiazide) daily with meals.

Storage/Stability

Store tablets at controlled room temperature (59° to 86°F). Protect from moisture, freezing, and excessive heat.

Drug Interactions

Amiloride ACE inhibitors (eg, captopril)

May result in severely elevated potassium levels.

Potassium preparations

May severely increase serum potassium levels, possibly resulting in cardiac arrhythmias or cardiac arrest. Do not coadminister.

Hydrochlorothiazide Bile acid sequestrants

May reduce thiazide absorption; give thiazide at least 2 h before sequestrant.

Diazoxide

May cause hyperglycemia.

Digitalis glycosides

Diuretic-induced hypokalemia and hypomagnesemia may lead to digitalis-induced arrhythmias.

Lithium

Renal excretion of lithium may be reduced.

Loop diuretics (eg, furosemide)

Synergistic effects may occur, resulting in profound diuresis and serious electrolyte abnormalities.

Sulfonylureas (eg, chlorpropamide)

Hypoglycemic effect of sulfonylurea may be decreased, necessitating an increase in sulfonylurea dosage.

Laboratory Test Interactions

Hydrochlorothiazide may decrease serum protein-bound iodine levels without signs of thyroid disturbances. May cause diagnostic interference of serum electrolyte levels, blood and urine glucose levels, serum bilirubin levels, and serum uric acid levels.

Adverse Reactions

Cardiovascular

Arrhythmia, tachycardia, palpitations (amiloride).

CNS

Headache, fatigue, tiredness, weakness, dizziness, encephalopathy, tremors, decreased libido (amiloride); restlessness (hydrochlorothiazide).

Dermatologic

Mild skin rash, pruritus, alopecia (amiloride); urticaria, purpura (hydrochlorothiazide).

EENT

Increased ocular pressure, tinnitus (amiloride); transient blurred vision, xanthopsia (hydrochlorothiazide).

GI

Nausea, anorexia, GI and abdominal pain, flatulence, activation of peptic ulcer, dyspepsia, heartburn, dry mouth (amiloride); pancreatitis, cramping, GI irritation, sialadenitis (hydrochlorothiazide).

Genitourinary

Bladder spasm, polyuria, urinary frequency (amiloride); interstitial nephritis (hydrochlorothiazide).

Hematologic

Aplastic anemia, neutropenia (amiloride); agranulocytosis, leukopenia, hemolytic anemia, thrombocytopenia (hydrochlorothiazide).

Hepatic

Jaundice.

Metabolic

Hyperkalemia, hyperglycemia, glucosuria, hyperuricemia (hydrochlorothiazide).

Respiratory

Shortness of breath, cough (amiloride); respiratory distress, including pneumonitis and pulmonary edema (hydrochlorothiazide).

Miscellaneous

Leg pain, painful extremities, neck/shoulder ache, fatigue, itching (amiloride); anaphylactic reactions, necrotizing angiitis, photosensitivity, fever (hydrochlorothiazide).

Precautions

Monitor

Electrolytes/BUN/Creatinine

Ensure that serum electrolytes, BUN, and creatinine are monitored periodically.


Pregnancy

Category B .

Lactation

Amiloride: undetermined; hydrochlorothiazide: excreted in breast milk.

Children

Safety and efficacy not established.

Hyperkalemia

Hyperkalemia may occur. The risk of hyperkalemia may be increased in patients with renal impairment or diabetes mellitus. If possible, avoid use in patients with renal impairment or diabetes mellitus.

Overdosage

Symptoms

Dehydration, electrolyte imbalance (eg, hyperkalemia), electrolyte depletion (hypokalemia, hypochloremia, hyponatremia).

Patient Information

  • Advise patient to take prescribed dose once daily in the morning with food.
  • Inform patient that drug controls, but does not cure, hypertension and to continue taking medication as prescribed even when BP is not elevated.
  • Caution patient not to change the dose or stop taking unless advised by health care provider.
  • Instruct patient to continue taking other BP medications as prescribed by health care provider.
  • Instruct patient in BP and pulse measurement skills.
  • Advise patient to monitor and record BP and pulse at home and to inform health care provider should abnormal measurements be noted. Also, advise patient to take record of BP and pulse to each follow-up visit.
  • Instruct patient to lie or sit down if experiencing dizziness or lightheadedness when standing.
  • Caution patient that inadequate fluid intake, excessive perspiration, diarrhea, or vomiting can lead to excessive fall in BP, resulting in lightheadedness or fainting.
  • Instruct diabetic patient to monitor blood glucose more frequently when drug is started or dose is changed and to inform health care provider of significant changes in readings.
  • Caution patient to avoid unnecessary exposure to UV light (sunlight, tanning booths) and to use sunscreen and wear protective clothing when exposed to UV light to avoid photosensitivity reaction.
  • Emphasize to hypertensive patient importance of other modalities on BP: weight control, regular exercise, smoking cessation, and moderate intake of alcohol and salt.
  • Instruct patient to stop taking drug and immediately report any of these symptoms to health care provider: abnormal skin sensations, muscle weakness, or slow pulse.

Copyright © 2009 Wolters Kluwer Health.

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