Renal effects of the new calcium channel blocking drug isradipine

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.

Calcium-channel entry blocker therapy for hypertensive patients with concomitant renal impairment: a focus on isradipine

In the treatment of hypertension in renally impaired patients, normalization of blood pressure alone may not be sufficient to prevent significant morbidity to the kidneys. Treatment must reduce pressure in the renal vasculature, otherwise glomerular filtration rate and renal plasma flow will continue to deteriorate. Isradipine a dihydropyridine calcium-channel blocker, has been investigated as a suitable treatment in this setting. Isradipine maintains glomerular filtration rate, preserves or enhances renal plasma flow, decreases renal vascular resistance, maintains or reduces filtration fraction, and exerts a sustained natriuretic effect, all of which may enable isradipine to slow the rate of progression of renal deterioration. In addition, isradipine may decrease proteinuria and may decrease glomerular capillary pressure by dilating both the efferent and afferent arterioles. Unlike older calcium-channel blockers, isradipine exhibits minimal cardiodepressant activity and is not associated with any negative inotropic effects. It is metabolized in the liver and dosage adjustments may not be necessary when administered to patients with renal insufficiency. Isradipine has a favorable renal effect profile and also has several properties that meet the requirements of other patient populations where an extra measure of antihypertensive safety is required, such as diabetics, dialysis patients, and transplant recipients. Side effects with isradipine are usually mild and transient, occurring in a dose-dependent manner.