Drug information of Amiloride

Mechanism of effect

Amiloride works by inhibiting sodium reabsorption in the distal convoluted tubules and collecting ducts in the kidneys by binding to the amiloride-sensitive sodium channels. This promotes the loss of sodium and water from the body, but without depleting potassium. Amiloride 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.

Pharmacodynamic

Amiloride, an antikaliuretic-diuretic agent, is a pyrazine-carbonyl-guanidine that is unrelated chemically to other known antikaliuretic or diuretic agents. It is an antihypertensive, potassium-sparing diuretic that was first approved for treat hypertension and congestive heart failure.

The drug is often used in conjunction with thiazide or loop diuretics. 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.

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%

Drug indications

polyuria , cystic fibrosis patients

It is used to treat or prevent low potassium levels in ongestive heart failure or hypertension

Dosage

Usual Adult Dose for Ascites, Congestive Heart Failure, Edema, Hypertension,

Initial dose: 5 mg orally once a day.
Maintenance dose: 5-10 mg once a day.

Renal Dose Adjustments

CrCl< 25 mL/min: Not recommended.

CrCl 25-80 mL/min: The usual dose is decreased by 50%.

Amilorideis used to prevent hypokalemia in patients receiving diuretics or digoxin. Doses as high as 15-20 mg divided 1-2 times a day have been used.

Thiazide-Induced Hypokalemia

5-10 mg/day divided 1-2 times a day

Geriatric:

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

Pediatric:

Hypertension (Off-label)

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

Drug contraindications

diabetes , impairment of renal function , hypersensitivity to this drug , 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])

Side effects

Diarrhea , Headache , nausea , constipation , dizziness , vomiting , vertigo , asthenia , impotence , anorexia , flatulence , Muscle cramps , tiredness , Restlessness , Abdominal pain

Interactions

Amlodipine/Atorvastatine , Triamterene-H , eplerenone , Spironolactone , Drospirenone , Cyclosporine , Triamterene , potassium citrate , ethacrynic acid , Trimethoprim , Bumetanide , Eprosartan , Perindopril , Canagliflozin , Telmisartan , Sacubitril and valsartan , Azilsartan , Irbesartan , Olmesartan , Treprostinil , Benorilate , Blonanserin , xipamide

Alerts

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.

Monitoring serum potassium levels carefully in any patient receiving amiloride is essential.

Cautions

Anuria, DM, diabetic nephropathy, electrolyte imbalance and increases BUN, metabolic or respiratory acidosis

Points of recommendation

Take with food

Monitor: Serum potassium

Pregnancy level

B

Related drugs

Triamterene-H , Spironolactone , eplerenone , Triamterene