Comparison of Effects of Low Dose of Spironolactone and a Thiazide Diuretic in Patients with Hypertension Treated with an Angiotensin-Converting Enzyme Inhibitor or an Angiotensin Type 1 Receptor Blocker

This study was performed to investigate the additional anti-hypertensive effects and safety of low-dose thiazide diuretic, trichlormethiazide (TCTZ), and a mineralocorticoid receptor blocker, spironolactone (SPI), as add-on therapy in 64 patients whose blood pressure (BP) at office were over 140/90 mmHg, while receiving anti-hypertensive medication including an angiotensin-converting enzyme inhibitor or angiotensin II type I receptor antagonist. After 6 months, we observed a decrease of office and home BP. Moreover, urinary albumin excretion (UAE) was reduced in SPI-treated group, but not in the TCTZ-treated group. No significant change in serum potassium, lipids, glucose, or uric acid was observed. In conclusion, low-dose thiazide diuretic or SPI provided a significant additional anti-hypertensive effect in patients in whom hypertension was not controlled by medication, and SPI-reduced UAE.