Schedule H

Oral

• Tablets: 5 mg

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

1. Hypertension (usually in combination with thiazides)

Parameter Recommendation

Starting dose 5 mg once daily

Titration Increase to 5 mg twice daily after 1–2 weeks if response inadequate

Usual maintenance dose 5–10 mg/day in 1–2 divided doses

Maximum dose 20 mg/day

Clinical notes Typically combined with hydrochlorothiazide or other thiazides to offset potassium loss; not recommended as monotherapy

1. Oedema (cardiac failure, hepatic cirrhosis, nephrotic syndrome)

Parameter Recommendation

Starting dose 5 mg once daily

Titration Increase by 5 mg increments every 1–2 weeks based on clinical response

Usual maintenance dose 5–10 mg/day

Maximum dose 20 mg/day

Clinical notes Use lowest effective dose to minimise hyperkalemia risk; combine with loop or thiazide diuretic for synergistic effect

1. Hypokalemia Prevention/Treatment (diuretic-induced)

Parameter Recommendation

Starting dose 5 mg once daily, given alongside thiazide or loop diuretic

Titration Adjust based on serum potassium levels (recheck within 3–5 days)

Usual maintenance dose 5–10 mg/day

Maximum dose 15 mg/day

Clinical notes Do not initiate if baseline serum potassium >5.0 mEq/L; discontinue if hyperkalemia develops

Secondary Indications — Adults (Off-label)

Indication Dose Duration Notes

Lithium-induced nephrogenic diabetes insipidus (OFF-LABEL) 5–10 mg once daily Long-term under supervision Specialist only; Evidence: Case series, nephrology specialist practice; Reduces urine output by blocking ENaC in collecting duct

PAEDIATRIC DOSING (Specialist Only)

⚠️ Not routinely used in paediatric practice. Use ONLY under specialist supervision (paediatric nephrology/cardiology) when potassium-sparing diuresis is specifically indicated.

Primary Indications

Edematous States with Hypokalemia (e.g., nephrotic syndrome, cardiac failure)

≥1 year to 12 years 0.3 mg/kg/day PO once daily Increase by 0.1 mg/kg/day based on serum K+ response 0.6 mg/kg/day OR 20 mg/day (whichever is lower)

≥12 years 5 mg once daily As per adult dosing 20 mg/day

Safety Monitoring:

• Serum potassium and creatinine at baseline, within 3–5 days of initiation, then weekly during titration

• Use short-term alongside loop/thiazide diuretics

• Discontinue promptly if serum K+ exceeds 5.5 mEq/L

Secondary Indications — Paediatrics (Off-label)

Indication Status

Hypertension in children Not routinely recommended; use only under nephrology/cardiology guidance if strong indication exists

Other off-label uses NOT AVAILABLE — insufficient paediatric data in Indian sources

Age Restriction: Not recommended below 1 year of age except under direct paediatric nephrology supervision with documented justification.

60 No dose adjustment required

30–60 Use with caution; start at lowest dose; monitor potassium within 3–5 days and weekly thereafter

<30 Avoid — high risk of severe hyperkalemia

Haemodialysis Contraindicated

Peritoneal dialysis Contraindicated

• Hyperkalemia (serum K+ >5.5 mEq/L) or conditions predisposing to hyperkalemia

• Severe renal impairment (eGFR <30 mL/min/1.73 m²)

• Anuria

• Concurrent use with other potassium-sparing diuretics (spironolactone, triamterene, eplerenone)

• Concurrent potassium supplementation

• Known hypersensitivity to amiloride or any excipient

• Addison's disease (untreated)

• Diabetes mellitus — impaired potassium excretion increases hyperkalemia risk

• Elderly patients — higher susceptibility to electrolyte disturbances

• Concurrent ACE inhibitor or ARB therapy — additive hyperkalemia risk

• Metabolic or respiratory acidosis — shifts potassium extracellularly

• Hepatic cirrhosis — risk of electrolyte derangement precipitating encephalopathy

• Dehydration or hypovolaemia

• Pregnancy and lactation (limited human safety data)

Parameter Recommendation

Risk category Limited human data; use only if potential benefit justifies risk to fetus

Preferred alternatives Labetalol, methyldopa, or nifedipine for hypertension; loop diuretics for severe refractory oedema under specialist supervision

When it may be used Refractory oedema not responding to safer diuretics — specialist obstetric/nephrology input mandatory

What to monitor Maternal serum potassium, creatinine, blood pressure; fetal growth monitoring via ultrasound

Parameter Recommendation

Compatibility Unknown; likely excreted in breast milk in small quantities — avoid prolonged use

Expected drug levels in milk Low (estimated, based on pharmacokinetic profile)

Preferred alternatives Low-dose thiazides if diuretic necessary during breastfeeding

What to monitor in infant Adequate weight gain, signs of dehydration, urine output

Parameter Recommendation

Starting dose 2.5–5 mg once daily

Titration Slow — increase dose no more frequently than every 2 weeks

Key risks Hyperkalemia (due to age-related decline in renal function), hyponatraemia, orthostatic hypotension

Monitoring Serum potassium and creatinine within 3–5 days of initiation and after any dose change; more frequent if combined with ACE inhibitors/ARBs

Dose recommendation Maintain at lower end of therapeutic range

Interacting Drug Mechanism / Effect Action

ACE inhibitors (enalapril, ramipril) / ARBs (losartan, telmisartan) Additive hyperkalemia due to reduced aldosterone effect Avoid combination or use only with strict K+ monitoring (within 3–5 days and regularly)

Potassium supplements Additive increase in serum potassium Contraindicated — risk of severe, life-threatening hyperkalemia

Other potassium-sparing diuretics (spironolactone, triamterene, eplerenone) Additive hyperkalemia Contraindicated

Ciclosporin / Tacrolimus Both cause hyperkalemia via renal tubular effects Avoid combination

Trimethoprim (especially high-dose) Blocks ENaC-mediated potassium excretion Monitor potassium closely; avoid if possible in elderly or renal impairment

Interacting Drug Mechanism / Effect Action

Lithium Reduced lithium clearance; risk of lithium toxicity Monitor lithium levels; consider dose reduction of lithium

NSAIDs (ibuprofen, diclofenac, naproxen) Reduce renal perfusion; may worsen renal function and increase serum potassium Monitor renal function and potassium; use short-term if unavoidable

Loop diuretics (furosemide) / Thiazides (hydrochlorothiazide) Used together therapeutically but risk of excessive volume depletion Monitor blood pressure, volume status, and electrolytes

Beta-blockers Additive hypotensive effect; beta-blockers can mask hypoglycaemia and impair potassium regulation Monitor blood pressure and potassium

Digoxin Amiloride may alter digoxin renal clearance Monitor digoxin levels if co-administered

• Hyperkalemia (especially in renal impairment or with interacting drugs)

• Nausea

• Abdominal discomfort / flatulence

• Headache

• Dizziness

• Muscle cramps

• Fatigue

Adverse Effect Clinical Significance

Severe hyperkalemia May cause cardiac arrhythmias (peaked T waves, widened QRS, ventricular fibrillation) — potentially fatal; requires immediate discontinuation and urgent correction

Severe electrolyte imbalances Hyponatraemia, hypochloraemia — may cause confusion, weakness, cardiac dysfunction

Hepatic encephalopathy In patients with cirrhosis — triggered by electrolyte shifts; requires discontinuation

Aplastic anaemia / Neutropenia Rare; requires blood count monitoring if unexplained fever or infection

Long-term maintenance Serum potassium, creatinine, and eGFR every 4–6 weeks; more frequently in elderly, diabetics, or patients on ACE inhibitors/ARBs

Additional Blood pressure, volume status, symptoms of hyperkalemia (muscle weakness, palpitations)

• Enamide

• Lymin

Note: Plain amiloride 5 mg tablets have limited standalone availability; most commonly available as fixed-dose combinations with thiazide or loop diuretics.

NPPA Status: Not currently under DPCO price control as plain amiloride.

• Rarely used as monotherapy — almost always combined with thiazide or loop diuretic to counterbalance potassium loss while enhancing natriuresis

• Always check baseline serum potassium before initiating; do not start if K+ >5.0 mEq/L

• Recheck potassium within 3–5 days of initiation, especially in elderly, diabetics, or those on ACE inhibitors/ARBs — this is when hyperkalemia is most likely to manifest

• HYPERKALEMIA is the most dangerous adverse effect — educate patients about symptoms (muscle weakness, fatigue, palpitations) and importance of follow-up

• Avoid in dialysis-dependent patients — drug accumulates and hyperkalemia risk is unacceptable

• In cirrhotic patients, use with extreme caution — electrolyte shifts can precipitate hepatic encephalopathy

Amiloride; potassium-sparing; diuretic; ENaC-inhibitor; hypertension; edema; hyperkalemia-risk; renal-caution; cirrhosis; Schedule H; NLEM

RxIndia v1.0 — 14 May 2025

• CDSCO approved product information

• Indian Pharmacopoeia

• National Formulary of India

• API Textbook of Medicine

• AIIMS Drug Formulary

• NLEM 2022

• Goodman & Gilman's: The Pharmacological Basis of Therapeutics

• Indian nephrology and cardiology consultant protocols

• Indian package inserts (Frumil, Amifru, Moduretic)