Spironolactone (Resistant Hypertension in CKD)

How it works

It is a competitive aldosterone (mineralocorticoid) receptor antagonist, promoting sodium and water excretion while retaining potassium. Blocking aldosterone counters the sodium retention that drives treatment-resistant hypertension.

Prescribing in practice

• In CKD the risk of severe hyperkalaemia is markedly increased, especially when combined with ACE inhibitors, ARBs or potassium supplements — check potassium and renal function before and shortly after starting.
• Reduced eGFR diminishes the natriuretic response and raises hyperkalaemia risk, so use with caution and avoid in advanced renal impairment unless closely supervised.
• Anti-androgenic effects such as gynaecomastia and menstrual disturbance may limit tolerability; eplerenone is an alternative if these occur.

Monitoring

Monitor serum potassium and renal function before initiation, soon after starting or dose changes, and regularly thereafter, stopping if potassium rises significantly.

Counselling the patient

• Avoid potassium-based salt substitutes and high-potassium supplements.
• Attend blood tests as arranged to check kidney function and potassium.
• Report breast tenderness or swelling so an alternative can be considered.

Evidence & guidelines

The PATHWAY-2 trial established spironolactone as the most effective fourth-line agent for resistant hypertension, with NICE recommending it where potassium permits.