hydrochlorothiazide × spironolactone

Opposing effects on potassium: thiazide depletes, spironolactone retains. The combination is used in resistant hypertension and ascites. In CKD or diabetes, spironolactone dominates – with hyperkalemia risk.

Check potassium, sodium, and creatinine at 7–14 days after initiation, then every 1–3 months. Target potassium is 4.0–5.0 mmol/L. For hyponatremia (Na+ < 130 mmol/L), reassess therapy.