AMILORIDE

Midamor

Reviewed at Senior Paediatric Meeting
July 2012
Administration Newborn Drug Protocol Index Newborn Services Home Page

Dose and Administration

Any variation in dosing, to be discussed with Cardiologist/Neonatal Specialist

Indications

  1. Adjunct to thiazides or furosemide to conserve potassium.
  2. Not used as primary diuretic.

Contraindications and Precautions

  1. Infants with hyperkalaemia.
  2. Caution in renal or hepatic impairment.
  3. Caution in renal impairment in infants receiving digoxin therapy. Possible increase in serum digoxin levels.
  4. Caution with concomitant administration of IVN. May cause possible metabolic acidosis.
  5. Avoid supplemental potassium.

Clinical Pharmacology

Amiloride hydrochloride is a weak diuretic with potassium sparing properties. It also exhibits natriuretic and hypotensive effects. It is chemically unrelated to other known diuretics. Amiloride acts directly on the distal renal tubule of the nephron to inhibit sodium-potassium ion exchange. Unlike spironolactone, amiloride does not competitively inhibit aldosterone and its diuretic activity is independent of aldosterone.

It is completely absorbed from the gastrointestinal tract. Simultaneous administration of food decreases gastrointestinal absorption from about 50% to about 30%. The drug has large extravascular distribution. It is not significantly bound to human plasma protein. Amiloride is not metabolised and is eliminated by the kidney (50%) and in the faeces (about 40%).

Onset of action about 2 hours and its diuretic action reaches a peak in 6 - 10 hours and may persist for about 24 hours.

Possible Adverse Effects

  1. Hyperkalaemia (signs and symptoms: lethargy, paralysis of the extremities, bradycardia, shock and ECG abnormalities.
  2. Hyponatraemia.
  3. Gastrointestinal disturbances (nausea, vomiting, diarrhoea or constipation).
  4. Metabolic acidosis.
  5. Transient elevation in BUN and serum creatinine.
  6. Rash.

Special Considerations

  1. Monitor urea and electrolytes frequently when commenced. Anticipate hyperkalaemia, hyponatraemia.
  2. It should be given with care to patients likely to develop metabolic acidosis.
  3. Amiloride has been shown to increase serum digoxin levels.
  4. Safety and efficacy of amiloride in children alone or in combination with hydrochlorothiazide has not been established.
  5. Avoid supplemental potassium.
  6. Decreased diuretic effectiveness with NSAIDS avoid concomitant use.

References

1 Paediatric Pharmacopoeia, Royal Children’s Hospital, Melbourne 2002
2 British National Formulary 2012-13. BMJ Group, the Royal Pharmaceutical Society of Great Britain, and RCPCH Publications Ltd 2012