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Amiloride and Hydrochlorothiazide

Pronunciation

(a MIL oh ride & hye droe klor oh THYE a zide)

Index Terms

  • Hydrochlorothiazide and Amiloride

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet: 5/50: Amiloride hydrochloride 5 mg and hydrochlorothiazide 50 mg

Pharmacologic Category

  • Antihypertensive
  • Diuretic, Combination

Use: Labeled Indications

Heart failure, Hypertension: For the treatment of patients with congestive heart failure (CHF) or hypertension who develop hypokalemia when thiazides or other kaliuretic diuretics are used alone, or in whom maintenance of normal potassium levels is considered to be clinically important (eg, digitalized patients or patients with significant cardiac arrhythmias).

Contraindications

Hypersensitivity to amiloride, hydrochlorothiazide, any component of the formulation, or sulfonamide-derived drugs; presence of elevated serum potassium levels (>5.5 mEq/L); if patient is receiving other potassium-sparing agents (eg, spironolactone, triamterene), potassium-containing salt substitutes, potassium-rich diet, or potassium supplements (except in cases of severe and/or refractory hypokalemia); anuria; acute or chronic renal insufficiency; evidence of diabetic nephropathy. Patients with evidence of renal impairment (serum creatinine >1.5 mg/dL, BUN >30 mg/dL) or diabetes mellitus should not receive this medicine without close, frequent monitoring of serum electrolytes and renal function.

Dosing: Adult

Heart failure, hypertension: Oral: Initial: One tablet daily; usual dose: 1 to 2 tablets daily as a single daily dose or in divided doses.

Dosing: Geriatric

Lower initial doses should be considered; use with caution.

Dosing: Renal Impairment

Use with caution; contraindicated in patients with anuria, acute or chronic renal insufficiency, or evidence of diabetic nephropathy. For additional considerations, also see individual agents.

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.

Administration

Oral: Administer with food.

Dietary Considerations

Take with food.

Storage

Store at 20°C to 25°C (68°F to 77°F); protect from light.

Drug Interactions

ACE Inhibitors: Potassium-Sparing Diuretics may enhance the hyperkalemic effect of ACE Inhibitors. Monitor therapy

ACE Inhibitors: Thiazide and Thiazide-Like Diuretics may enhance the hypotensive effect of ACE Inhibitors. Thiazide and Thiazide-Like Diuretics may enhance the nephrotoxic effect of ACE Inhibitors. Monitor therapy

Ajmaline: Sulfonamides may enhance the adverse/toxic effect of Ajmaline. Specifically, the risk for cholestasis may be increased. Monitor therapy

Alcohol (Ethyl): May enhance the orthostatic hypotensive effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Alfuzosin: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Allopurinol: Thiazide and Thiazide-Like Diuretics may enhance the potential for allergic or hypersensitivity reactions to Allopurinol. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Allopurinol. Specifically, Thiazide Diuretics may increase the concentration of Oxypurinol, an active metabolite of Allopurinol. Monitor therapy

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. Consider therapy modification

Aminolevulinic Acid: Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid. Monitor therapy

Ammonium Chloride: Potassium-Sparing Diuretics may enhance the adverse/toxic effect of Ammonium Chloride. Specifically the risk of systemic acidosis. Consider therapy modification

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Analgesics (Opioid): May enhance the adverse/toxic effect of Diuretics. Analgesics (Opioid) may diminish the therapeutic effect of Diuretics. Monitor therapy

Angiotensin II Receptor Blockers: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Monitor therapy

Anticholinergic Agents: May increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Antidiabetic Agents: Thiazide and Thiazide-Like Diuretics may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Antidiabetic Agents: Hyperglycemia-Associated Agents may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Barbiturates: May enhance the orthostatic hypotensive effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Benazepril: HydroCHLOROthiazide may enhance the hypotensive effect of Benazepril. HydroCHLOROthiazide may enhance the nephrotoxic effect of Benazepril. Benazepril may decrease the serum concentration of HydroCHLOROthiazide. Monitor therapy

Beta2-Agonists: May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Bile Acid Sequestrants: May decrease the absorption of Thiazide and Thiazide-Like Diuretics. The diuretic response is likewise decreased. Consider therapy modification

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

BuPROPion: May increase the serum concentration of OCT2 Substrates. Monitor therapy

Calcium Salts: Thiazide and Thiazide-Like Diuretics may decrease the excretion of Calcium Salts. Continued concomitant use can also result in metabolic alkalosis. Monitor therapy

Canagliflozin: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Canagliflozin may enhance the hypotensive effect of Potassium-Sparing Diuretics. Monitor therapy

CarBAMazepine: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of CarBAMazepine. Specifically, there may be an increased risk for hyponatremia. Monitor therapy

Cardiac Glycosides: Potassium-Sparing Diuretics may diminish the therapeutic effect of Cardiac Glycosides. In particular, the inotropic effects of digoxin appear to be diminished. Potassium-Sparing Diuretics may increase the serum concentration of Cardiac Glycosides. This particular effect may be unique to Spironolactone. Monitor therapy

Cardiac Glycosides: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Cardiac Glycosides. Specifically, cardiac glycoside toxicity may be enhanced by the hypokalemic and hypomagnesemic effect of thiazide diuretics. Monitor therapy

Corticosteroids (Orally Inhaled): May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Corticosteroids (Systemic): May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Cyclophosphamide: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Cyclophosphamide. Specifically, granulocytopenia may be enhanced. Monitor therapy

CycloSPORINE (Systemic): Potassium-Sparing Diuretics may enhance the hyperkalemic effect of CycloSPORINE (Systemic). Avoid combination

Dexketoprofen: May enhance the adverse/toxic effect of Sulfonamides. Monitor therapy

Diazoxide: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Diazoxide. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Dofetilide: Thiazide and Thiazide-Like Diuretics may enhance the QTc-prolonging effect of Dofetilide. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Dofetilide. Avoid combination

Drospirenone: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Eplerenone: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Management: This combination is contraindicated in patients receiving eplerenone for treatment of hypertension. Consider therapy modification

Heparin: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Management: Monitor serum potassium concentrations closely. The spironolactone Canadian product monograph lists its combination with heparin or low molecular weight heparins as contraindicated. Monitor therapy

Heparin (Low Molecular Weight): May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Management: Monitor serum potassium concentrations closely. The spironolactone Canadian product monograph lists its combination with heparin or low molecular weight heparins as contraindicated. Monitor therapy

Herbs (Hypertensive Properties): May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Ivabradine: Thiazide and Thiazide-Like Diuretics may enhance the arrhythmogenic effect of Ivabradine. Monitor therapy

Levodopa: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa. Monitor therapy

Levosulpiride: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Levosulpiride. Avoid combination

Licorice: May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Lithium: Thiazide and Thiazide-Like Diuretics may decrease the excretion of Lithium. Consider therapy modification

Mecamylamine: Sulfonamides may enhance the adverse/toxic effect of Mecamylamine. Avoid combination

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Multivitamins/Fluoride (with ADE): May enhance the hypercalcemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Multivitamins/Minerals (with ADEK, Folate, Iron): Thiazide and Thiazide-Like Diuretics may enhance the hypercalcemic effect of Multivitamins/Minerals (with ADEK, Folate, Iron). Monitor therapy

Multivitamins/Minerals (with AE, No Iron): Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Multivitamins/Minerals (with AE, No Iron). Specifically, thiazide diuretics may decrease the excretion of calcium, and continued concomitant use can also result in metabolic alkalosis. Monitor therapy

Naftopidil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicergoline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicorandil: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nitroprusside: Blood Pressure Lowering Agents may enhance the hypotensive effect of Nitroprusside. Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: Thiazide and Thiazide-Like Diuretics may enhance the nephrotoxic effect of Nonsteroidal Anti-Inflammatory Agents. Nonsteroidal Anti-Inflammatory Agents may diminish the therapeutic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: May diminish the antihypertensive effect of Potassium-Sparing Diuretics. Nonsteroidal Anti-Inflammatory Agents may enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

OXcarbazepine: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of OXcarbazepine. Specifically, there may be an increased risk for hyponatremia. Monitor therapy

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Monitor therapy

Potassium Salts: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Consider therapy modification

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

QuiNIDine: Potassium-Sparing Diuretics may diminish the therapeutic effect of QuiNIDine. Monitor therapy

Reboxetine: May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Selective Serotonin Reuptake Inhibitors: May enhance the hyponatremic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Sodium Phosphates: Diuretics may enhance the nephrotoxic effect of Sodium Phosphates. Specifically, the risk of acute phosphate nephropathy may be enhanced. Management: Consider avoiding this combination by temporarily suspending treatment with diuretics, or seeking alternatives to oral sodium phosphate bowel preparation. If the combination cannot be avoided, hydrate adequately and monitor fluid and renal status. Consider therapy modification

Spironolactone: AMILoride may enhance the hyperkalemic effect of Spironolactone. Avoid combination

Tacrolimus (Systemic): Potassium-Sparing Diuretics may enhance the hyperkalemic effect of Tacrolimus (Systemic). Avoid combination

Tolvaptan: May enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Monitor therapy

Topiramate: Thiazide and Thiazide-Like Diuretics may enhance the hypokalemic effect of Topiramate. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Topiramate. Management: Monitor for increased topiramate levels/adverse effects (e.g., hypokalemia) with initiation/dose increase of a thiazide diuretic. Closely monitor serum potassium concentrations with concomitant therapy. Topiramate dose reductions may be necessary. Consider therapy modification

Toremifene: Thiazide and Thiazide-Like Diuretics may enhance the hypercalcemic effect of Toremifene. Monitor therapy

Valsartan: HydroCHLOROthiazide may enhance the hypotensive effect of Valsartan. Valsartan may increase the serum concentration of HydroCHLOROthiazide. Monitor therapy

Verteporfin: Photosensitizing Agents may enhance the photosensitizing effect of Verteporfin. Monitor therapy

Vitamin D Analogs: Thiazide and Thiazide-Like Diuretics may enhance the hypercalcemic effect of Vitamin D Analogs. Monitor therapy

Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Test Interactions

Hydrochlorothiazide may interfere with parathyroid function tests and may decrease serum iodine (protein bound) without signs of thyroid disturbance.

Adverse Reactions

Also see individual agents.

1% to 10%:

Cardiovascular: Cardiac arrhythmia (>1%)

Central nervous system: Dizziness (3% to 8%), headache (3% to 8%), fatigue (>1%)

Dermatologic: Skin rash (3% to 8%), pruritus (>1%)

Endocrine & metabolic: Hyperkalemia (1% to 2%), increased serum potassium (>1%; >5.5 mEq/L)

Gastrointestinal: Nausea (3% to 8%), abdominal pain (>1%), diarrhea (>1%), gastrointestinal pain (>1%)

Neuromuscular & skeletal: Leg pain (>1%), weakness (3% to 8%)

Respiratory: Dyspnea (>1%)

<1% (Limited to important or life-threatening): Anorexia, arthralgia, chest pain, confusion, dehydration, depression, digitalis intoxication, erythema multiforme, exfoliative dermatitis, gastrointestinal hemorrhage, gout, hyponatremia (symptomatic), impotence, orthostatic hypertension, renal failure, renal insufficiency, Stevens-Johnson syndrome, syncope, toxic epidermal necrolysis, urinary incontinence, visual disturbance

ALERT: U.S. Boxed Warning

Hyperkalemia:

Amiloride and hydrochlorothiazide may cause hyperkalemia (serum potassium levels greater than 5.5 mEq/L). In patients without renal impairment or diabetes mellitus, the risk of hyperkalemia with this combination product is about 1% to 2%. This risk is higher in patients with renal impairment or diabetes mellitus (even without recognized diabetic neuropathy). Because hyperkalemia, if uncorrected, is potentially fatal, it is essential to monitor serum potassium levels carefully in any patient receiving amiloride/hydrochlorothiazide, particularly when it is first introduced, at the time of dosage adjustments, and during any illness that could affect renal function.

Warnings/Precautions

Concerns related to adverse effects:

• Electrolyte disturbances: Hypochloremic alkalosis, hypomagnesemia, and hyponatremia can occur.

• Gout: In certain patients with a history of gout, a familial predisposition to gout, or chronic renal failure, gout can be precipitated by hydrochlorothiazide. This risk may be increased with doses ≥25 mg (Gurwitz 1997).

• Hyperkalemia: [US 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. Discontinue if hyperkalemia develops. Patients who are severely ill (eg, cardiopulmonary disease, uncontrolled diabetes) may develop respiratory or metabolic acidosis which may be associated with rapid elevations in serum potassium concentrations; use caution in these patients.

• Hypersensitivity reactions: Hypersensitivity reactions may occur with hydrochlorothiazide. Risk is increased in patients with a history of allergy or bronchial asthma.

• Ocular effects: Hydrochlorothiazide may cause acute transient myopia and acute angle-closure glaucoma, typically occurring within hours to weeks following initiation; discontinue therapy immediately in patients with acute decreases in visual acuity or ocular pain. Additional treatments may be needed if uncontrolled intraocular pressure persists. Risk factors may include a history of sulfonamide or penicillin allergy.

• Photosensitivity: Photosensitization may occur with hydrochlorothiazide.

• Sulfa allergy: Chemical similarities are present among sulfonamides, sulfonylureas, carbonic anhydrase inhibitors, thiazides, and loop diuretics (except ethacrynic acid). Use in patients with sulfonamide allergy is specifically contraindicated in product labeling, however, a risk of cross-reaction exists in patients with allergy to any of these compounds; avoid use when previous reaction has been severe. Discontinue if signs of hypersensitivity are noted.

Disease-related concerns:

• Diabetes: Use with extreme caution in patients with diabetes mellitus; may see a change in glucose control. Monitor closely; discontinue amiloride 3 days prior to glucose tolerance testing.

• Hepatic impairment: Use hydrochlorothiazide with caution in patients with severe hepatic dysfunction. In progressive or severe liver disease, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy/coma.

• Hypercholesterolemia: Use hydrochlorothiazide with caution in patients with moderate or high cholesterol concentrations.

• Parathyroid disease: Thiazide diuretics reduce calcium excretion; pathologic changes in the parathyroid glands with hypercalcemia and hypophosphatemia have been observed with prolonged use; should be discontinued prior to testing for parathyroid function.

• Renal impairment: Avoid use of hydrochlorothiazide in severe renal disease (ineffective). Cumulative effects may develop, including azotemia, in patients with impaired renal function.

• Systemic lupus erythematosus (SLE): Hydrochlorothiazide can cause SLE exacerbation or activation.

Pregnancy Risk Factor

B

Pregnancy Considerations

Adverse events have not been observed in animal reproduction studies. See individual agents.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience headache, lack of appetite, nausea, or loss of strength and energy. Have patient report immediately to prescriber signs of high potassium (abnormal heartbeat, confusion, dizziness, passing out, weakness, shortness of breath, numbness or tingling feeling), signs of high blood sugar (confusion, fatigue, increased thirst, increased hunger, polyuria, flushing, fast breathing, or breath that smells like fruit), signs of fluid and electrolyte problems (mood changes, confusion, muscle pain or weakness, abnormal heartbeat, severe dizziness or passing out, tachycardia, increased thirst, seizures, loss of strength and energy, lack of appetite, urinary retention or change in the amount of urine passed, dry mouth, dry eyes, or nausea or vomiting), severe dizziness, passing out, vision changes, or eye pain (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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