Amiloride Hydrochloride

How it works

It blocks epithelial sodium channels in the distal nephron, producing a mild natriuresis while reducing potassium and hydrogen ion excretion.

Prescribing in practice

• Its main hazard is hyperkalaemia, so it should be avoided with other potassium-sparing agents, potassium supplements, and used cautiously with ACE inhibitors, ARBs, or in renal impairment.
• It is most often prescribed in combination with a potassium-losing diuretic to balance potassium handling.
• Renal function and potassium must be checked before starting and during treatment, particularly in older or renally impaired patients.

Monitoring

Monitor serum potassium and renal function before and during treatment, especially when combined with other drugs affecting potassium.

Counselling the patient

• Advise the patient to avoid potassium-containing salt substitutes and over-the-counter potassium supplements unless told otherwise.
• Explain that blood tests will check kidney function and potassium levels.
• Suggest taking the dose earlier in the day to limit night-time urination.

Evidence & guidelines

Amiloride is an established potassium-sparing diuretic used to offset diuretic-induced hypokalaemia, with potassium monitoring advised in standard UK prescribing references.