Effects of enalapril and isradipine alone and in combination on blood pressure, renal function and echocardiographic parameters in mild hypertension

Aims and methods: A study was carried out to evaluate the influence of antihypertensive treatment with combined low doses of enalapril plus isradipine (5+5 mg daily) compared with those of either drug at a higher dose level (10 mg daily) by double-blind, three-way crossover study (balanced Latin square design) in 102 subjects (mean age 51.9±7.42 years) with essential hypertension. Left ventricular mass and function were evaluated by M-B mode echocardiography, renal function by glomerular filtration rate (GFR) and by serum and 24-h urinary Na+ and K+ during wash-out period and after 24 weeks of treatment. Results: The supine blood pressure for subjects given placebo was 171/103 mmHg. After 24 weeks of treatment, systolic and diastolic supine blood pressure were significantly lower with 5 mg isradipine plus 5 mg enalapril (134/84 mmHg) than with 10 mg enalapril (137/84 mmHg) or with 10 mg isradipine (144/85 mmHg). Left ventricular posterior wall and septal thickness were significantly and similarly reduced in all groups. Left ventricular systolic and diastolic end diameters were not significantly changed. Left ventricular mass (LVM) was significantly reduced in E plus I group and enalapril group. GFR was not significantly altered. The 24-h urinary Na+ significantly increased with enalapril, more so than isradipine. The combination was tolerated better than either monotherapy. We observed no clinically significant changes in laboratory variables including blood lipoproteins. Conclusions: The combination of isradipine plus enalapril reduced blood pressure more effectively and was better tolerated than other drug alone. All three groups showed similar changes in echocardiographic indices and no change in renal function.