The effect of low-dose spironolactone on resistant hypertension

Our objective was to estimate the effect of addition of low-dose spironolactone to previous antihypertensive therapy in patients with resistant hypertension. Patients had 25 to 50 mg of spironolactone once daily added to the treatment of hypertension that was uncontrolled despite previous treatment with three classes of antihypertensive drugs. The effect on blood pressure was estimated by office measurements together with serum potassium and adverse effects. The data were analyzed retrospectively. A total of 544 patients were identified; 200 were excluded because of secondary hypertension, other indications for spironolactone than hypertension, previous antihypertensive therapy with less than three drugs unless demonstrated intolerance to a third drug, insufficient compliance, and lack of follow-up data. Thus, 344 cases were included in the analysis. The population was 62.1 ± 12.8 years old, 45.1% were males, and 43% had cardiovascular comorbidity. Mean blood pressure before the addition of spironolactone was 169/88 mm Hg. At 1, 3, and 6 months after the addition, blood pressure was decreased by an average of 16.6/7.0, 23.9/9.7, and 26.0/10.7 mm Hg (all P < .001). Serum potassium increased from an average of 3.7 mmol/L to 4.1 mmol/L (P < .001). Spironolactone was discontinued because of hyperkalemia in 4.1% of the cases. A total of 18% of all patients had adverse effects, which in 9.9% led to discontinuation of the drug. A total of 5.2% of the males developed gynecomastia. In conclusion, low-dose spironolactone is highly effective when added to previous treatment of patients with resistant hypertension.