Amiloride

Amiloride

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Systematic (IUPAC) name
3,5-diamino-6-chloro-N-(diaminomethylene)pyrazine-2-carboxamide
Clinical data
Pregnancy category	US: B (No risk in non-human studies)
Routes of administration	oral
Legal status
Legal status	US: ℞-only
Pharmacokinetic data
Bioavailability	Readily absorbed
Metabolism	none
Biological half-life	6 to 9 hours
Excretion	unchanged in urine
Identifiers
CAS Number	2016-88-8
ATC code	C03DB01 (WHO)
PubChem	CID 16231
IUPHAR/BPS	2421
DrugBank	APRD00790
ChemSpider	15403
Chemical data
Formula	C6H8ClN7O
Molar mass	229.627 g/mol[[]]
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Amiloride is a potassium-sparing diuretic, first approved for use in 1967 (then known as MK 870), used in the management of hypertension and congestive heart failure.

Structure

Amiloride is a guanidinium group containing pyrazine derivative.

Mechanism of action

Amiloride works by directly blocking the epithelial sodium channel (ENaC) thereby inhibiting sodium reabsorption in the late distal convoluted tubules, connecting tubules, and collecting ducts in the kidneys (this mechanism is the same for triamterene). This promotes the loss of sodium and water from the body, but without depleting potassium. The drug is often used in conjunction with thiazide (e.g. co-amilozide) or loop diuretics (e.g. co-amilofruse). Due to its potassium-sparing capacities, hyperkalemia (high blood potassium levels) are occasionally observed in patients taking amiloride. The risk is high in concurrent use of ACE inhibitors or spironolactone. Patients are also advised not to use potassium-containing salt replacements. Amiloride also carries the risk of developing an acidosis.

A fraction of the effects of amiloride is inhibition of cyclic GMP-gated cation channels in the inner medullary collecting duct.

Amiloride has a second action on the heart, blocking Na+/H+ exchangers Sodium-hydrogen antiporter 1 or NHE-1. This minimizes reperfusion injury in ischemic attacks.

See also

• Benzamil

References

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