The place of isradipine in the treatment of hypertension

Nanostructured lipid carriers of isradipine for effective management of hypertension and isoproterenol induced myocardial infarction

The objective of the present paper is to formulate nanostructured lipid carriers (NLCs) of a calcium channel blocker, isradipine, to enhance its oral bioavailability and prolong its antihypertensive effect apart from evaluating efficacy of the formulation in isoproterenol induced myocardial infarction in rats. Formulation was optimized using quality by design (QbD)-based approach. Three factors i.e., total lipid concentration (%), homogenization pressure (bar), and number of cycles were optimized through Box-Behnken design to estimate their effect on critical quality attributes (CQAs) viz., size (nm), % entrapment efficiency, and in vitro % drug release which were found to be 80.9 ± 1.7 nm, 83.51 ± 2.15%, and 83.3 ± 3.86% after 24 h, respectively. In vivo pharmacokinetic study indicated 4.207 and 1.907 times increase in the oral bioavailability of optimized nanostructured lipid carrier without and with cycloheximide (lymphatic transport inhibitor), respectively. Treatment with ISO (isoproterenol) significantly diverges the levels of antioxidant marker, TBARS (thiobarbituric acid), and ultrastructure of the cardiac tissue indicating significant myocardial damage. Pretreatment of nanostructured lipid carrier of isradipine (ISD-NLCs) significantly prevented the antioxidant status and ultrastructural changes in the heart. In conclusion, this study confirms that optimized NLCs can substantially improve oral bioavailability of isradipine and presents a promising strategy in the management of hypertension for longer duration of time apart from demonstrating its preclinical efficacy in cardioprotection.

Comparison of isradipine and enalapril effects on regional carotid circulation in patients with hypertension with unilateral internal carotid artery stenosis

This randomized, double-blind, placebo-controlled study was aimed at detecting cerebrovascular effects of isradipine and enalapril in patients with moderate hypertension depending on the presence and grade on unilateral stenosis of internal carotid artery (ICA). We evaluated carotid vascular resistance by using Doppler analysis and regional cerebral blood flow (rCBF) by using 133Xe-clearance technique before and after a single 5-mg oral dose of isradipine, enalapril, or placebo. Their effects were randomly and consecutively tested in 73 patients with essential hypertension subdivided into three groups: without carotid occlusive lesions, with moderate (50-75%), and with severe (76-99%) unilateral asymptomatic ICA stenosis. There were no differences in age, gender, and antihypertensive effects of the drugs between these three subgroups. Three major variants of cerebrovascular drug effects were observed: absence of changes (variant I), decrease in carotid vascular resistance with increase in rCBF and elimination of side-to-side asymmetry (variant II), and increase in carotid vascular resistance with further reduction of rCBF ipsilaterally ICA stenosis, and increased side-to-side asymmetry (variant III). Frequency of variant III was significantly higher in patients with severe ICA stenosis. Enalapril produced variant I of cerebrovascular effects in most patients examined; variant III was observed only in 13% of patients with severe ICA stenosis. Isradipine produced variant I of cerebrovascular effects much less frequently than did enalapril. For this drug, variant II was most typical in patients without ICA stenosis and with moderate ICA stenosis. In 43.5% of patients with severe ICA stenosis, however, isradipine produced reduction of cerebral perfusion. Presumably the presence of ICA stenosis, especially >75%, increases the risk of cerebrovascular disorders in antihypertensive therapy. In patients with severe ICA stenosis, treatment with enalapril appears to be safer than that with isradipine.

Isradipine versus captopril in patients with essential hypertension

We conducted a double-blind, crossover study comparing the antihypertensive effects of isradipine versus captopril in patients with essential hypertension. Seventeen patients (8 men, 9 women; 6 whites, 11 blacks) completed both phases of the study, which consisted of two 5-week treatment periods separated by 2 weeks of placebo treatment. Each drug was randomly allocated to half the patients as the first drug and half as the second drug they received. Ambulatory blood pressure (BP) monitoring was carried out on the day before treatment and the last day of each active treatment. Both drugs were effective and well tolerated but isradipine was more effective overall than captopril in lowering BP (9.4% vs 3.9%, respectively; P < 0.02). Black patients had significantly higher BP at baseline than white patients; furthermore, black patients responded better to isradipine than to captopril. White patients had a smaller decrease in blood pressure with both drugs than did black patients, but white patients still attained a lower diastolic BP with captopril than did black patients (88 +/- 2 mm Hg vs 96 +/- 9 mm Hg; P < 0.01). There was no correlation between the pretreatment plasma levels of pressor hormones (plasma renin activity, catecholamines, and arginine vasopressin) and the magnitude of BP response to either drug, but the decrease in BP in response to captopril correlated significantly with the increase in plasma renin activity during treatment (r = -.84; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Evaluation of the effectiveness of isradipine SRO in the treatment of hypertensive patients with left ventricular hypertrophy

Myocardial hypertrophy is a response to many diseases, above all hypertension, that involves morphological and functional damage and may be the basis for the development of myocardial dysfunction. We attempted to verify the effectiveness of a new calcium antagonist, isradipine 5 mg SRO, on the reversal of left ventricular hypertrophy. For this purpose 13 hypertensive patients (pts) were treated for 12 weeks, which is the minimum period described in the literature for the regression of hypertrophy. At the end of the study, blood pressure in all patients returned to normal levels (mean blood pressure from 120.15 +/- 4.4 to 108 +/- 6.4 mmHg, p < 0.001); end-systolic stress (from 128 +/- 30 to 65 +/- 14 g/cm2, p < 0.001), and left ventricular mass index (from 142 +/- 31 to 97 +/- 23 g/m2, p < 0.001) showed significant reduction. Moreover, Doppler-derived indexes of left ventricular filling improved, particularly early to late peak velocity of the mitral valve (E/A ratio) and deceleration time (from 235 +/- 37 to 198 +/- 17 msec, p < 0.001), which were normalized after 12 weeks. In conclusion isradipine shows rapid effects in the reversal of morphofunctional damage in hypertension. For this reason it also appears to be useful for the treatment of myocardial hypertrophy in the absence of chronic hypertension.