Amiloride

MIDAMOR

What it isEpithelial sodium channel blocker in the collecting duct; potassium-sparing diuresis and Liddle syndrome.

Why this oneIt spares potassium and magnesium, and it is the specific treatment for Liddle syndrome and lithium-induced diabetes insipidus.

What limits itHyperkalemia, especially with an ACE inhibitor or ARB. Weak as a diuretic alone.

FDA-approved for

FDA dosing	Population	Start	Target	Max
Potassium-conserving adjunct to kaliuretic diuretics in hypertension/CHF (or when used alone)	Adult	5 mg QD	5–10 mg QD	20 mg/day

Renal Contraindicated in anuria, acute or chronic renal insufficiency, and diabetic nephropathy.

Hepatic Undefined

Administer with food.
Monitor serum potassium closely; risk of hyperkalemia (especially with renal impairment or diabetes).

Hyperkalemia (serum potassium >5.5 mEq/L)
Concomitant other potassium-conserving agents (spironolactone, triamterene) or potassium supplementation (except in severe/refractory hypokalemia)
Impaired renal function: anuria, acute or chronic renal insufficiency, diabetic nephropathy

Hyperkalemia—accentuated in renal impairment and diabetes; monitor electrolytes, creatinine, BUN

Pregnancy Category B; no evidence of fetal harm in animal studies—use during pregnancy only if clearly needed.

Lactation Undefined

⚠ BOXED WARNING

Principal riskHyperkalemia

Cost, est. cash$10–$300/month

Generic entry1986

Therapeutic safety burden2 / 4

Overdose danger3 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk2 / 4

Legacy pregnancy categoryB

Defining liabilityHyperkalemia and kidney dysfunction; useful for lithium-induced nephrogenic diabetes insipidus.

Box: minimal PK interactions