Amiloride


Generic Medicine Info
Indications and Dosage
Oral
Oedema
Adult: Initially, 10 mg as a single dose or 5 mg bid, may be increased if necessary, to a Max of 20 mg daily.

Oral
CHF (congestive heart failure), Hypertension
Adult: As adjunct to thiazide or loop diuretics to conserve K: Initially, 2.5 mg daily, may increase gradually to a Max of 10 mg daily.

Oral
Hepatic cirrhosis with ascites and oedema
Adult: As adjunct to thiazide or loop diuretics to conserve K: Initially, 5 mg daily, may increase gradually to a Max of 10 mg daily.
Renal Impairment
Severe: Contraindicated.
Administration
Should be taken with food.
Contraindications
Hyperkalaemia (serum K levels >5.5 mEq/L), anuria, diabetic nephropathy, Addison’s disease, acute or chronic renal insufficiency. Concomitant use with other K-conserving agents (e.g. spironolactone, triamterene), K supplements, K-containing salt substitutes, or K-rich diet.
Special Precautions
Patient with diabetes mellitus, adrenal insufficiency, risk factors for metabolic or respiratory acidosis (e.g. poorly controlled diabetes, cardiopulmonary disease). Hepatic impairment. Elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Electrolyte imbalance (e.g. hyponatraemia, hypochloraemia); increased BUN, serum creatinine; metabolic or respiratory acidosis; hepatic encephalopathy (with severe liver impairment).
Blood and lymphatic system disorders: Aplastic anaemia, neutropenia.
Cardiac disorders: Angina pectoris, palpitation, chest pain.
Ear and labyrinth disorders: Tinnitus.
Eye disorders: Minor visual disturbances, increased IOP.
Gastrointestinal disorders: Nausea, vomiting, diarrhoea, constipation, abdominal pain, dyspepsia, flatulence, heartburn, thirst, dry mouth, gastrointestinal bleeding.
General disorders and administration site conditions: Weakness, fatigue, malaise.
Hepatobiliary disorders: Jaundice.
Investigations: Increased serum uric acid, abnormal LFT(s).
Metabolism and nutrition disorders: Anorexia, dehydration.
Musculoskeletal and connective tissue disorders: Muscle cramps, joint pain, back pain, neck or shoulder pain, pain in extremities.
Nervous system disorders: Headache, dizziness, paraesthesia, tremor, vertigo.
Psychiatric disorders: Nervousness, agitation, mental confusion, insomnia, somnolence, depression, minor psychiatric changes.
Renal and urinary disorders: Urinary disturbances (e.g. polyuria, dysuria, bladder spasms, urinary frequency).
Reproductive system and breast disorders: Sexual dysfunction, impotence.
Respiratory, thoracic and mediastinal disorders: Cough, dyspnoea, nasal congestion.
Skin and subcutaneous tissue disorders: Mild skin rashes, pruritus, alopecia.
Vascular disorders: Orthostatic hypotension.
Potentially Fatal: Hyperkalaemia and increased risk of cardiac arrhythmias.
Monitoring Parameters
Monitor serum electrolyte (especially K), blood pressure, renal function, fluid status, and ECG abnormalities (if hyperkalaemia occurred). Assess for signs and symptoms of hyperkalaemia.
Overdosage
Symptoms: Dehydration and electrolyte imbalance. Management: Symptomatic and supportive treatment. May induce emesis or perform gastric lavage. If severe hyperkalaemia occurs, may administer IV Na bicarbonate, or oral or parenteral administration of glucose with a rapid-acting insulin preparation to decrease serum K levels. May also consider administration of Na polystyrene sulfonate given orally or via enema. Patients with persistent hyperkalaemia may require dialysis.
Drug Interactions
Increased risk of hyperkalaemia with other K-sparing diuretics (e.g. spironolactone, triamterene), K supplements, ARBs, ACE inhibitors, ciclosporin, tacrolimus, aliskiren, trimethoprim, pentamidine, drospirenone, trilostane, and indometacin. Hyponatraemia and hypochloraemia may occur with other diuretics. May reduce the renal clearance of lithium, hence may increase the risk of toxicity. May reduce the inotropic effect of digoxin. Increased risk of hyponatraemia with carbamazepine, and chlorpropamide. Increased risk of nephrotoxicity and ototoxicity with platinum compounds. Antagonised diuretic effect with NSAIDs (e.g. ketorolac), corticosteroids, and estrogens. Enhanced hypotensive effect with diazoxide, aldesleukin, alprostadil, baclofen, tizanidine, levodopa, co-beneldopa, co-careldopa, anaesthetics, anxiolytics/hypnotics, and other antihypertensives. Increased risk of postural hypotension with TCAs or MAOIs. May reduce the ulcer healing properties of carbenoxolone.
Food Interaction
Food reduces the extent of absorption or bioavailability. Increased risk of hyperkalaemia with K-rich diet. Enhanced hypotensive effects with alcohol.
Action
Description:
Mechanism of Action: Amiloride is a K-sparing diuretic that has weak natriuretic, diuretic, and antihypertensive activity It blocks the epithelial Na channels in the late distal convoluted tubules (DCT) and collecting duct, leading to the inhibition of Na reabsorption from the lumen which efficiently decreases intracellular Na and reduces Na+/K+-ATPase function resulting in K retention and diminished excretion of Ca, Mg, and hydrogen.
Onset: Within 2 hours.
Duration: Approx 24 hours.
Pharmacokinetics:
Absorption: Incompletely absorbed from the gastrointestinal tract. Food reduces the extent of absorption and bioavailability. Bioavailability: Approx 50%. Time to peak plasma concentration: 3-4 hours.
Distribution: Volume of distribution: 350-380 L.
Excretion: Via urine (50% as unchanged drug); faeces (approx 40%). Elimination half-life: 6-9 hours. Terminal half-life: Approx ≥20 hours.
Chemical Structure

Chemical Structure Image
Amiloride

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 16231, Amiloride. https://pubchem.ncbi.nlm.nih.gov/compound/Amiloride. Accessed Dec. 20, 2023.

Storage
Store between 20-25°C.
MIMS Class
Diuretics
ATC Classification
C03DB01 - amiloride ; Belongs to the class of other potassium-sparing agents. Used as diuretics.
References
Amiloride 5 mg/5 mL Oral Solutions (Essential Pharma Limited). MHRA. https://products.mhra.gov.uk. Accessed 19/09/2023.

Amiloride Hydrochloride 5 mg Tablets (Genethics Europe Limited). MHRA. https://products.mhra.gov.uk. Accessed 19/09/2023.

Amiloride Hydrochloride Tablet (Sigmapharm Laboratories, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/09/2023.

Anon. Amiloride Hydrochloride. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 19/09/2023.

Anon. Amiloride. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 19/09/2023.

Buckingham R (ed). Amiloride Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 19/09/2023.

Joint Formulary Committee. Amiloride Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 19/09/2023.

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