amiloride (Rx)

Brand and Other Names:Midamor
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 5mg

Congestive Heart Failure

5-10 mg/day PO qDay OR divided q12hr

Hypertension

5-10 mg/day PO qDay OR divided q12hr

Thiazide-Induced Hypokalemia

5-10 mg/day PO qDay OR divided q12hr

Renal Impairment

CrCl 10-50 mL/minute: 50% normal dose

CrCl <10 mL/minute: Not recommended

Overdose Management

May use normal saline for volume replacement

May use dopamine or norepinephrine to treat hypotension

Treat hyperkalemia with IV glucose (dextrose 25% in water) with rapid acting insulin with concurrent IV sodium bicarbonate and use oral or rectal solutions of kayexalate in sorbitol if needed

If dysrhythmia due to decreased K+ or Mg+ suspected replace aggressively

Discontinue treatment if no symptoms after 6hr

Other Information

Take with food

Monitor: Serum potassium

See also combo with hydrochlorothiazide

Other Indications & Uses

Off-label: cystic fibrosis, Li-induced polyuria

Dosage Forms & Strengths

tablet

  • 5mg

Hypertension (Off-label)

0.4-0.625 mg/kg/day PO; not to exceed 20 mg/day

5-10 mg/day PO qDay OR every other day

Maximum dosage limit: 20 mg PO qDay; 40 mg PO qDay has been used

Elderly patients may be more sensitive to the diuretic effects of the drug and are more likely to have age-associated renal dysfunction

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Interactions

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            Adverse Effects

            1-10%

            Hyperkalemia (10%)

            Anorexia (3-8%)

            Diarrhea (3-8%)

            Headache (3-8%)

            Nausea (3-8%)

            Vomiting (3-8%)

            Abdominal pain (<3%)

            Appetite changes (<3%)

            Constipation (<3%)

            Cough (<3%)

            Dizziness (<3%)

            Dyspnea (<3%)

            Encephalopathy (<3%)

            Fatigue (<3%)

            Gas pain (<3%)

            Impotence (<3%)

            Muscle cramps (<3%)

            Weakness (<3%)

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            Warnings

            Black Box Warnings

            Like other potassium-conserving agents, amiloride may cause hyperkalemia (serum potassium levels greater than 5.5 mEq/L), which, if not corrected, is potentially fatal.

            Hyperkalemia occurs commonly (about 10%) when amiloride is used without a kaliuretic diuretic.

            This incidence is greater in patients with renal impairment, diabetes mellitus (with or without recognized renal insufficiency), and in elderly persons.

            When amiloride is used concomitantly with a thiazide diuretic in patients without these complications, the risk of hyperkalemia is reduced to about 1-2%. Monitoring serum potassium levels carefully in any patient receiving amiloride is essential, particularly when it is first introduced, at the time of diuretic dosage adjustments, and during any illness that could affect renal function.

            Contraindications

            Hypersensitivity to amiloride

            Hyperkalemia (K+ >5.5 mEq/L [5.5 mmol/L])

            Concomitant use with K+-sparing diuretic, or K supplementation

            Impaired renal function (Scr >1.5 mg/dL [132.6 umol/L], or BUN >30 mg/dL [10.7 mmol/L]) diabetes

            Cautions

            Hyperkalemia

            • The risk of hyperkalemia may be increased when potassium-conserving agents, including amiloride hydrochloride are administered concomitantly with an angiotensin-converting enzyme inhibitor, an angiotensin II receptor antagonist, cyclosporine or tacrolimus
            • Warning signs or symptoms of hyperkalemia include paresthesias, muscular weakness, fatigue, flaccid paralysis of the extremities, bradycardia, shock, and ECG abnormalities; monitoring of the serum potassium level is essential because mild hyperkalemia is not usually associated with an abnormal ECG
            • When abnormal, the ECG in hyperkalemia is characterized primarily by tall, peaked T waves or elevations from previous tracings; there may also be lowering of the R wave and increased depth of the S wave, widening and even disappearance of the P wave, progressive widening of the QRS complex, prolongation of the PR interval, and ST depression
            • If hyperkalemia occurs the drug should be discontinued immediately; if serum potassium level exceeds 6.5 mEq per liter, active measures should be taken to reduce it; such measures include the intravenous administration of sodium bicarbonate solution or oral or parenteral glucose with a rapid-acting insulin preparation; if needed, a cation exchange resin such as sodium polystyrene sulfonate may be given orally or by enema; patients with persistent hyperkalemia may require dialysis

            Diabetes Mellitus

            • In diabetic patients, hyperkalemia has been reported with the use of all potassium-conserving diuretics, including amiloride hydrochloride, even in patients without evidence of diabetic nephropathy; therefore, amiloride should be avoided, if possible, in diabetic patients and, if it is used, serum electrolytes and renal function must be monitored frequently; amiloride should be discontinued at least 3 days before glucose tolerance testing

            Metabolic or Respiratory Acidosis

            • Antikaliuretic therapy should be instituted only with caution in severely ill patients in whom respiratory or metabolic acidosis may occur, such as patients with cardiopulmonary disease or poorly controlled diabetes
            • If therapy is administered to these patients, frequent monitoring of acid-base balance necessary; shifts in acid-base balance alter ratio of extracellular/intracellular potassium, and development of acidosis may be associated with rapid increases in serum potassium levels
            • In patients with renal disease, diuretics may precipitate azotemia; cumulative effects of the components of amiloride hydrochloride may develop in patients with impaired renal function; if renal impairment becomes evident discontinue therapy

            Drug interaction overview

            • In some patients, the administration of a non-steroidal anti-inflammatory agent can reduce the diuretic, natriuretic, and antihypertensive effects of loop and potassium-sparing diuretics
            • When amiloride and non-steroidal anti-inflammatory agents are used concomitantly, the patient should be observed closely to determine if the desired effect of the diuretic is obtained
            • Since indomethacin and potassium-sparing diuretics, including this product, may each be associated with increased serum potassium levels, the potential effects on potassium kinetics and renal function should be considered when these agents are administered concurrently
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            Pregnancy & Lactation

            Pregnancy

            Teratogenicity studies in rabbits and mice given 20 and 25 times maximum human dose, respectively, revealed no evidence of harm to fetus, although studies showed that the drug crossed the placenta in modest amounts; reproduction studies in rats at 20 times the expected maximum daily dose for humans showed no evidence of impaired fertility

            At approximately 5 or more times the expected maximum daily dose for humans, some toxicity was seen in adult rats and rabbits and a decrease in rat pup growth and survival occurred

            Lactation

            Studies in rats have shown that amiloride is excreted in milk in concentrations higher than those found in blood, but it is not known whether amiloride hydrochloride is excreted in human milk

            Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.

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            Pharmacology

            Mechanism of Action

            Exerts its potassium sparing effect through the inhibition of sodium reabsorption at the distal convoluted tubule, cortical collecting tubule and collecting duct; this decreases the net negative potential of the tubular lumen and reduces both potassium and hydrogen secretion and their subsequent excretion. This mechanism accounts in large part for the potassium sparing action of amiloride.

            Inhibits Na/K-ATPase, decreases Ca++, Mg++ and hydrogen excretion

            Pharmacokinetics

            Half-Life: 6-9 hr

            Duration: 24 hr

            Onset: initial effect: 2-3 hr, max effect: 6-10 hr

            Peak Plasma Time: 3-4 hr

            Bioavailability: 30-90%

            Protein Bound: 23%

            Vd: 350-380 L

            Metabolism: NOT metabolized in the liver; no active metabolites

            Excretion

            • Urine: 50%
            • Feces: 40-50%
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            Images

            BRAND FORM. UNIT PRICE PILL IMAGE
            amiloride oral
            -
            5 mg tablet
            amiloride oral
            -
            5 mg tablet
            amiloride oral
            -
            5 mg tablet

            Copyright © 2010 First DataBank, Inc.

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            Patient Handout

            Patient Education
            amiloride oral

            AMILORIDE - ORAL

            (a-MIL-oh-ride)

            COMMON BRAND NAME(S): Midamor

            WARNING: This medication can cause high potassium levels (hyperkalemia). This effect is more likely to occur in older adults and in patients with kidney disease, diabetes, or a serious illness. Potassium levels must be closely monitored on a regular basis while taking this medication. If not treated, very high potassium levels can sometimes be fatal. Tell your doctor right away if you develop any symptoms of high potassium levels, including muscle weakness, slow/irregular heartbeat, numb/tingling skin.

            USES: Amiloride is used with other "water pills"/diuretics (such as furosemide, thiazide diuretics like hydrochlorothiazide) to treat high blood pressure (hypertension), heart failure, or extra fluid in the body (edema). Amiloride also helps to treat or prevent low blood potassium levels caused by the other diuretics. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.Amiloride is called a "water pill" (diuretic) and causes your body to get rid of extra salt and water while also preventing the kidneys from getting rid of too much potassium.

            HOW TO USE: Take this medication by mouth with food as directed by your doctor, usually once daily.If you take this drug too close to bedtime, you may need to wake up to urinate. It is best to take this medication at least 4 hours before your bedtime. If you have any questions about how and when to take this medication, ask your doctor or pharmacist.The dosage is based on your medical condition and response to treatment.Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick.Tell your doctor if your condition does not improve or if it worsens (such as your blood pressure readings remain high or increase).

            SIDE EFFECTS: See also Warning section.Headache, dizziness, nausea, vomiting, loss of appetite, stomach/abdominal pain, gas, or diarrhea may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.When given with other diuretics, amiloride may cause dehydration and electrolyte imbalance. Tell your doctor right away if you have any of these unlikely but serious symptoms of dehydration or mineral loss: very dry mouth, extreme thirst, muscle cramps, weakness, fast heartbeat, severe dizziness, confusion, fainting, seizures.Tell your doctor right away if you have any serious side effects, including: nausea/vomiting that doesn't stop, signs of kidney problems (such as change in the amount of urine), yellowing eyes/skin, dark urine.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

            PRECAUTIONS: See Also Warning section.Before taking amiloride, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: untreated salt/mineral imbalance (such as high potassium, low sodium level), kidney disease, liver disease, diabetes, dehydration.Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Dehydration from too much sweating, vomiting, or diarrhea can also lower your blood pressure and worsen dizziness. Drink plenty of fluids to prevent these effects and dehydration. If you are on restricted fluid intake, consult your doctor for further instructions. Contact your doctor if you are unable to drink fluids or if you have diarrhea/vomiting that doesn't stop.This drug may increase the potassium levels in your blood. Limit foods high in potassium such as bananas and orange juice. Consult your doctor or pharmacist before using any products containing potassium (such as potassium supplements, salt substitutes).During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is unknown if this drug passes into breast milk. Discuss the risks and benefits with your doctor before breast-feeding.

            DRUG INTERACTIONS: See also Precautions section.Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug are: lithium, sodium phosphate products, other products that may increase potassium levels (such as eplerenone, tacrolimus, cyclosporine, birth control pills containing drospirenone, potassium-sparing diuretics like spironolactone/triamterene, ACE inhibitors like benazepril/captopril, angiotensin receptor antagonists like losartan/valsartan).Some products have ingredients that could raise your blood pressure or worsen your heart failure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen).This medication may interfere with certain laboratory tests (including glucose tolerance testing), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

            OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe dizziness, fainting, slow/irregular heartbeat.

            NOTES: Do not share this medication with others.Lifestyle changes such as stress reduction programs, exercise, and dietary changes may increase the effectiveness of this medicine. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.Lab and/or medical tests (including kidney function, blood mineral levels such as potassium) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.Check your blood pressure regularly while taking this medication, especially when you first start this drug or when your dose is changed. Learn how to monitor your own blood pressure at home, and share the results with your doctor.

            MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

            STORAGE: Store at room temperature away from light and moisture. Protect from freezing. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

            Information last revised December 2022. Copyright(c) 2022 First Databank, Inc.

            IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.