Effect of nifedipine on plasma renin, aldosterone and catecholamines in arterial hypertension

Effects of the calcium antagonist felodipine on the sympathetic and renin-angiotensin-aldosterone systems in essential hypertension

Studies were performed in 10 male patients with untreated essential hypertension, WHO grade I-II, aged 25-62 years, to explore the acute (single dose) and long-term (8 weeks) effects of felodipine on sympathetic activity--evaluated by plasma and urinary catecholamines--as related to blood pressure, heart rate and the activity in the renin-angiotensin-aldosterone system. The patients were hospitalized for 8 (acute) and 6 (long-term) days and were maintained on a standardized daily intake of sodium (150 mmol), potassium (75 mmol) and water (2,500 ml). Acute felodipine administration (10 mg) significantly reduced blood pressure and increased heart rate. Plasma and urinary noradrenaline, plasma renin activity and angiotensin II increased, whereas plasma and urinary adrenaline, dopamine, aldosterone and plasma vasopressin were unaltered. Long-term felodipine treatment, 10 mg twice daily, reduced blood pressure to a similar extent as acute felodipine administration, but heart rate was not significantly changed. Plasma noradrenaline 3 and 12 hours after the last dose and urinary noradrenaline were increased, whereas plasma and urinary adrenaline and dopamine were unchanged. Plasma renin activity and angiotensin II were increased 3 hours, but unchanged 12 hours after the last dose. Plasma aldosterone was unchanged but urinary aldosterone increased. Plasma vasopressin was unchanged. The changes in plasma noradrenaline as related to blood pressure, heart rate, plasma renin activity and angiotensin II during long-term felodipine treatment may reflect decreased cardiac and renal beta-adrenoceptor-mediated responses. Increased renal clearance of aldosterone could partly explain the unaltered plasma aldosterone level in spite of increased plasma angiotensin II following long-term felodipine treatment.

Antihypertensive effects at rest and during exercise of a calcium blocker, nifedipine, alone and in combination with metoprolol

The effects of metoprolol and/or nifedipine on blood pressure were studied in 12 hypertensive males at rest and during standardized exercise on an ergometer bicycle. Metoprolol (100 mg X 2) and nifedipine (10 mg X 3) gave similar blood pressure reductions both at rest and during exercise. When the drugs were combined, the antihypertensive effect was potentiated. The PQ interval was not affected during any treatment period. No adverse reactions to the combined treatment were noted. The combination of a calcium blocker with vasodilating properties with a beta-blocker, which reduces cardiac output, thus seems a logical and promising therapeutic approach in the treatment of hypertension.

Antihypertensive, haemodynamic and metabolic effects of nifedipine slow-release tablets in elderly patients

In a double-blind, cross-over study for 8 weeks, including 10 non-hospitalized elderly hypertensives (average age 73.2 years), WHO stage I-II, the antihypertensive effect of nifedipine slow-release tablets, 20 mg twice daily, was compared with placebo. Nifedipine reduced supine and standing blood pressure values significantly, and no signs of orthostatic hypotension were noted. An initial increment in heart rate was found after 1 week with a subsequent fall towards control values after 8 weeks of nifedipine administration. Heart rate pressure product in the supine position was reduced, and this reduction became statistically significant at the 8th week. Cardiac output measured non-invasively in 8 patients after 6-8 weeks' nifedipine therapy, using an Irex echocardiograph, was on an average 34% higher than in the placebo period (p less than 0.05). Serum electrolytes, cholesterol, HDL cholesterol, blood glucose and renal function were not affected by the drug. Side-effects were few and mild. It is concluded that nifedipine is a potent antihypertensive agent which may represent an attractive first choice alternative in the treatment of elderly hypertensive patients.

Calcium channel blockade and renal function

Since calcium channel blocking agents were introduced into the treatment of hypertension their influence on renal function has become an important issue. In animal experiments calcium channel blocking agents have been shown to increase renal blood flow and glomerular filtration rate and to augment urine flow and electrolyte excretion. In human acute studies the administration of calcium channel blocking agents have elicited similar renal hemodynamic and diuretic effects. Clinical studies on the renal effects of long-term treatment are however still lacking. Studies on the effect on renin release have given divergent results. In acute experiments renin release is increased by calcium channel blocking agents. In long-term treatment, however, no change in peripheral plasma levels of renin has been demonstrated. The influence of decreased renal function on the pharmacokinetics of calcium channel blocking agents has been studied in patients with renal disease. For verapamil the volume of distribution is smaller in uremic patients than in normals and both metabolic and renal clearances are decreased. For nifedipine, on the other hand, similar plasma levels, plasma half life and total plasma clearance are found in uremic patients and normal subjects.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is characterized by a hypertrophic and non-dilated left ventricle with disproportionate involvement of the intraventricular septum compared to the free walls, and by varying degrees of outflow obstruction during systole. Its symptoms and clinical course, pathogenesis and treatment are briefly discussed. It is speculated whether hypertrophic cardiomyopathy and hypertension are both caused by systemic disorders of calcium channels and calcium uptake and binding by cardiac and smooth muscle membranes, respectively.

The intrarenal renin-angiotensin system: from physiology to the pathobiology of hypertension and kidney disease

In recent years, the focus of interest on the role of the renin-angiotensin system (RAS) in the pathophysiology of hypertension and organ injury has changed to a major emphasis on the role of the local RAS in specific tissues. In the kidney, all of the RAS components are present and intrarenal angiotensin II (Ang II) is formed by independent multiple mechanisms. Proximal tubular angiotensinogen, collecting duct renin, and tubular angiotensin II type 1 (AT1) receptors are positively augmented by intrarenal Ang II. In addition to the classic RAS pathways, prorenin receptors and chymase are also involved in local Ang II formation in the kidney. Moreover, circulating Ang II is actively internalized into proximal tubular cells by AT1 receptor-dependent mechanisms. Consequently, Ang II is compartmentalized in the renal interstitial fluid and the proximal tubular compartments with much higher concentrations than those existing in the circulation. Recent evidence has also revealed that inappropriate activation of the intrarenal RAS is an important contributor to the pathogenesis of hypertension and renal injury. Thus, it is necessary to understand the mechanisms responsible for independent regulation of the intrarenal RAS. In this review, we will briefly summarize our current understanding of independent regulation of the intrarenal RAS and discuss how inappropriate activation of this system contributes to the development and maintenance of hypertension and renal injury. We will also discuss the impact of antihypertensive agents in preventing the progressive increases in the intrarenal RAS during the development of hypertension and renal injury.

Ambulatory blood pressure monitoring and active renin in menopausal women treated with amlodipine and hormone replacement therapy

The aim of this study was to follow up the effect of an 8-week treatment with amlodipine given alone or in combination with hormone replacement therapy (HRT) on blood pressure and active renin in postmenopausal women with mild to moderate arterial hypertension using both conventional clinical blood pressure measurements and ambulatory blood pressure monitoring. Twenty-nine hypertensive menopausal women were divided randomly into two groups according to the treatment regimens: amlodipine and amlodipine plus HRT. The combination with HRT led to normalization of 24-h and daytime systolic and diastolic blood pressure. In contrast to the group treated with amlodipine alone, where a significant fall only of systolic night-time blood pressure was observed, in the group treated with amlodipine plus HRT both systolic and diastolic night-time blood pressure decreased significantly. Active renin did not change significantly after treatment in both groups. Triglycerides decreased significantly and high-density lipoprotein-cholesterol increased significantly only after amlodipine treatment. There were no significant differences in serum total cholesterol and low-density lipoprotein-cholesterol after HRT plus amlodipine. In conclusion, amlodipine is effective in reducing blood pressure in postmenopausal women. The maintenance of a normal circadian blood pressure pattern was influenced by HRT.

Acute hypotensive, natriuretic, and hormonal effects of nifedipine in salt-sensitive and salt-resistant black normotensive and hypertensive subjects

In a randomized double-blind study, we compared the short-term effects of nifedipine (10 mg 3x daily for 1 day) versus placebo on 24-h blood pressure, diuresis, natriuresis, urinary excretion of dopamine and metabolites, and on plasma renin activity (PRA) and plasma aldosterone levels in 18 black hypertensive (HT) patients [eight salt-resistant (HT-SR) and 10 salt-sensitive (HT-SS)], and in 20 black normotensive (NT) subjects (12 NT-SR and eight NT-SS) who were studied randomly with both a high- (HS) and a low-salt (LS) diet. In comparison to placebo, nifedipine significantly decreased 24-h mean BP in all groups either with HS or LS diets (all p<0.05). With HS, greater hypotensive effects were achieved in NT-SS (-10+/-2 mm Hg) versus NT-SR (-3+/-1 mm Hg; p<0.05) and in HT-SS (-18+/-2 mm Hg) versus HT-SR (-12+/-2 mm Hg; p<0.05). In NT-SS and HT-SS, nifedipine induced greater (p<0.05) BP decrease with HS (-10+/-2 and -18+/-2 mm Hg) than with LS (-4+/-1 and -9+/-1 mm Hg, respectively), whereas in NT-SR and HT-SR, the hypotensive effect did not differ between HS and LS. Nifedipine versus placebo significantly increased natriuresis and fractional excretion of sodium in all groups only with HS (p<0.05) but not with LS diets. Only in HT-SS were the hypotensive and natriuretic effects of nifedipine significantly correlated (r = -0.77; p<0.01). Nifedipine produced a similar increase of the urinary excretion of dopamine, L-DOPA, and of DOPAC in all subjects, which did not correlate with hypotensive and natriuretic effects. Nifedipine did not modify plasma levels of renin and of aldosterone except in NT-SS with HS, in whom nifedipine increased PRA levels (p <0.05). We conclude that although nifedipine reduces BP in all groups of NT and HT with LS and HS diets, the effect is greater in salt-sensitive subjects with HS. Although in HT-SS with HS, the short-term natriuretic response to nifedipine may contribute to its hypotensive effects, the diuretic-natriuretic effect of nifedipine is not necessary for the expression of its hypotensive effect. Moreover, it is unlikely that any short-term effects of nifedipine either on the renal dopaminergic system or on the secretion of aldosterone explain nifedipine short-term hypotensive and diuretic-natriuretic effects.

Effects of amlodipine and cilnidipine on cardiac sympathetic nervous system and neurohormonal status in essential hypertension

N-Type calcium channel antagonists may suppress sympathetic activity. The purpose of this study was to assess the effects of amlodipine and cilnidipine on the cardiac sympathetic nervous system and the neurohormonal status of essential hypertension. 123I-metaiodobenzylguanidine (MIBG) cardiac imaging was performed and blood samples were taken to determine plasma renin activity and plasma norepinephrine concentration before and 3 months after drug administration in 47 patients with mild essential hypertension. Twenty-four of the patients were treated with 5 to 10 mg/d of amlodipine; the other 23 were treated with 10 to 20 mg/d of cilnidipine. For comparison, 12 normotensive subjects were also studied. No significant differences were found in the basal characteristics between the 2 hypertensive groups. In both hypertensive groups, both the systolic and diastolic blood pressures were significantly reduced to similar levels 3 months after drug treatment. Before the drug treatment, the 2 hypertensive groups had a significantly higher washout rate and lower heart-to-mediastinum (H/M) ratio compared with the normotensive subjects. The H/M ratio significantly increased (P<0.05) in combination with a decreased washout rate (P<0.02) after drug treatment in the cilnidipine group. In the amlodipine group, a significant decrease in washout rate (P<0. 04) was noted, without an increase in the H/M ratio. However, no significant changes were found in plasma renin activity and plasma norepinephrine concentration in either group. Thus, in patients with essential hypertension, cilnidipine suppressed cardiac sympathetic overactivity and amlodipine had a little suppressive effect. Cilnidipine may provide a new strategy for treatment of cardiovascular diseases with sympathetic overactivity.

A prospective, randomized trial of nifedipine vs. ritodrine in threatened preterm labor

OBJECTIVES

To compare the tocolytic efficacy and maternal tolerance of nifedipine with ritodrine in the management of threatened preterm labor.

METHODS

Prospective randomized study of 52 singleton pregnancies with preterm labor between 26 and 34 week's gestation. The capacity to delay delivery 48 h, 7 days, until week 36 or until fetal weight reached 2500 g were the outcome variables assessed. Doppler ultrasound studies were performed on the fetal umbilical artery as control.

RESULTS

No significant differences were found in the delay of delivery, but significantly fewer maternal side-effects were found in the nifedipine group. Doppler ultrasound results were similar in both groups.

CONCLUSIONS

Nifedipine is a valid and well-tolerated alternative among the tocolytic drugs, and apparently does not significantly alter fetal vascular blood flow.

The effect of nifedipine on ventriculoarterial coupling in old myocardial infarction

The effect of nifedipine on ventriculoarterial coupling was examined in 8 patients with old myocardial infarction who showed a depressed ejection fraction (37 +/- 7%). Left ventricular (LV) pressure and LV volume were determined simultaneously by micromanometer and conductance catheter, respectively. We measured the slope (Ees) of the end-systolic pressure-volume relation during transient inferior vena caval occlusion, the slope (Ea) of the end-systolic pressure-stroke volume relation, the ratio of Ea to Ees (Ea/Ees), and the work efficiency (the ratio of external work to the systolic pressure-volume area) at baseline and after the sublingual administration of nifedipine (10 mg). Nifedipine slightly increased the heart rate from 71 +/- 14 to 78 +/- 17 beats/min. Although nifedipine had little effect on Ees (2.54 +/- 0.68 vs 2.47 +/- 0.62 mmHg/ml/m2, ns), it significantly decreased Ea from 3.47 +/- 1.16 to 2.37 +/- 0.54 mmHg/ml/m2. Consequently, Ea/Ees decreased from 1.42 +/- 0.47 to 0.97 +/- 0.31 and work efficiency increased from 48 +/- 12 to 59 +/- 13% after nifedipine administration. These data suggest that nifedipine reduces afterload (Ea) and improves left ventriculoarterial coupling without depressing left ventricular contractility in patients with failing hearts due to old myocardial infarction.

Effects of tetrandrine on left ventricle hypertrophy in deoxycorticosterone acetate-salt hypertensive rats

The effect of regression of left ventricular hypertrophy was studied in deoxycorticosterone-acetate-salt hypertensive rats (DOCA-salt hypertensive rats) treated with tetrandrine. Treatment with tetrandrine (by gastric intubation, 50 mg/kg per day for 9 weeks) lowered systolic blood pressure, left ventricular weight, Ca2+ of mitochondria, and markedly decreased the density (Bmax) and total number of dihydropyridine binding sites in hypertrophic left ventricle (P < 0.001). There was no difference between groups in dissociation constant (Kd) values of dihydropyridine binding sites. These facts indicate that tetrandrine decreased cardiac mass in DOCA-salt hypertensive rats through mechanisms that may be associated with the density and the total number of dihydropyridine binding sites, Ca2+ and blood pressure control.

Relevance of plasma noradrenaline concentrations to estimate autonomic effects of antihypertensive drugs

The sympathetic nervous system is important in regulating cardiovascular function. It is therefore of interest to study the influence of antihypertensive drugs on sympathetic nerve activity. For this purpose, measurements of noradrenaline concentrations in forearm venous plasma have often been used. For several reasons, this provides limited information: i) the sympathetic nervous system is highly differentiated, i.e. activity may be high in some organs and low in others; ii) noradrenaline in forearm venous plasma is largely derived from sympathetic activity to the forearm skeletal muscle; iii) plasma noradrenaline concentrations are determined not only by noradrenaline spillover from sympathetic nerve endings, which is related to sympathetic nerve activity, but also by noradrenaline clearance. Under most circumstances plasma noradrenaline concentrations are not high enough to produce hormonal effects. Many types of antihypertensive drugs may cause acute and long-term increases in forearm venous noradrenaline concentrations. The mechanisms underlying these increases are not fully understood but seem to differ between drug classes: Diuretics increase renal noradrenaline spillover; beta-blockers do not affect spillover but reduce total noradrenaline clearance; calcium antagonists and alpha-blockers probably increase noradrenaline spillover, but it is not known which organs are involved, particularly during long-term treatment. ACE inhibitors seem to have a sympatholytic action, which counteract reflex increases in sympathetic nerve activity during blood pressure reduction, and plasma noradrenaline concentrations are generally not affected. To be able to judge the possible clinical consequences of changes in plasma noradrenaline concentrations during chronic antihypertensive treatment, assessments of noradrenaline spillover from individual organs are needed.

A comparative assessment of the duration of action of amlodipine and nifedipine GITS in normotensive subjects

1 This study in normotensive subjects compared the duration and consistency of action of amlodipine (5 mg) and nifedipine GITS (60 mg) by assessment of the attenuation of pressor responses to noradrenaline and angiotensin II. 2 Both drugs significantly attenuated pressor responses to both vasoconstrictors at 6 and 24 h post-dose with rightward shifts of up to 2.3-fold in the dose-response curves. 3 There was significantly less pharmacokinetic variability with amlodipine: for example, intra-subject variability was 33% with amlodipine and 59% with nifedipine GITS. 4 There were no significant differences in the pressor dose ratios up to 48 h post-dose with amlodipine whereas there was a significant and progressive reduction in the pressor dose ratios with nifedipine. 5 These results suggest that both drugs are broadly comparable as once daily treatments but amlodipine displayed less intra- and inter-subject variability and provided a significantly more sustained effect with a reserve of pharmacological activity up to 48 h post-dose.

Efficacy and mode of action of manidipine: a new calcium antagonist

Clinical studies were performed on patients with mild-to-moderate essential hypertension to elucidate the efficacy and mode of action of manidipine. Augmentation of diuresis and natriuresis during the short- and long-term phases of manidipine treatment was found in essential hypertensive patients. Manidipine partly inhibited sympathetic nerve activity and suppressed the mean arterial pressure response to infused norepinephrine. This drug also inhibited aldosterone secretion. Natriuresis and suppression of pressor responses may contribute to the depressor mechanisms of this drug. After manidipine administration, increases in both urinary calcium and uric acid were observed. Both parameters were positively correlated with urinary excretion of sodium, and the inhibition of tubular reabsorption may contribute to this mechanism. The increase in plasma parathyroid hormone may also be involved in the calciuresis produced by manidipine. Patients with lower plasma renin activity or lower plasma ionized calcium levels showed a greater reduction in blood pressure after manidipine administration. Thus the hypotensive action of manidipine was more pronounced in low renin essential hypertension.

The acute effect of nicardipine on the renin-angiotensin-aldosterone system in salt-sensitive essential hypertension

To determine the role of the renin-angiotensin-aldosterone (RAA) system in the acute effect of calcium channel blockers, we examined the acute effect of 40 mg nicardipine in 21 essential hypertensive patients. Nine patients whose mean blood pressure (MBP) decreased more than 5% at 2 hours after 20 mg furosemide i.v. were classified as salt-sensitive (SS); the remainder as salt-resistant (SR). The percentage decrease of MBP with nicardipine was not different between the two subgroups (12.4 +/- 2.5% for SS, and 17.7 +/- 4.1% for SR). The percentage decrease of MBP correlated with the pretreatment MBP (r = 0.67, p < 0.001), but not with the basal plasma renin activity (PRA), plasma aldosterone concentration (PAC), or natriuretic response. A significant increase of heart rate was noted in SR (31.2%) but not in SS (6.5%), and was associated with a higher increase of PRA in SR (90.7%) than in SS (25.5%). A correlation between the increase of PRA and the percentage increase of heart rate was noted (r = 0.77 p < 0.001). Decrease of PAC was observed in SS but not in SR until the third hour. The 3-hour sodium excretion was slightly greater in SR than in SS (59.9 +/- 9.1 vs. 35.1 +/- 3.0 mEq; p < 0.05). In summary, the acute hypotensive effect of nicardipine is dependent upon the vascular tone regardless of the status of the RAA system. An increase in PRA by nicardipine resulting from a baroreflex mechanism may counteract the inhibitory effect of aldosterone secretion by nicardipine. The unchanged PRA in SS is due to their blunted baroreflex control of heart rate. Mechanisms other than the change in the RAA system by nicardipine may account for the acute natriuretic effect.

Effects of sustained-release nicardipine on regression of left ventricular hypertrophy in systemic hypertension

The effects of a sustained-release formulation of the calcium antagonist nicardipine on left ventricular (LV) mass, Doppler transmitral velocity profiles and plasma neurohumoral studies were analyzed in patients with mild to moderate systemic hypertension. A double-blind placebo control phase in 28 patients was carried out for 6 weeks with a subgroup of 13 subsequently entering an open-label long-term phase for 1 year. Nicardipine produced a significant decrease in systolic and diastolic pressure over the 6-week phase (158 +/- 15 to 142 +/- 9 mm Hg, and 100 +/- 5 to 89 +/- 9 mm Hg, respectively, both p less than 0.001). No significant differences in Doppler measures of mitral inflow or echocardiographic measures of LV function, wall thickness or mass were noted in the 6-week phase of the study. Although nicardipine increased both norepinephrine and renin values after the first dose, these levels had returned to baseline in most patients after 6 weeks. In addition, there was no evidence for stimulation of adrenomedullary activity because nicardipine had no effect on epinephrine or dopamine-B-hydroxylase levels at first dose or after 6 weeks. In the 13 patients treated for 1 year, systolic and diastolic pressure remained significantly decreased compared with pressure before therapy (135 +/- 9 vs 147 +/- 15 mm Hg, and 85 +/- 6 vs 97 +/- 9 mm Hg, both p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrendipine and renal tubular function in human volunteers

Nine normotensive, water-loaded subjects received 10 mg oral nitrendipine, and eight subjects received placebo in a double-blind randomized manner. Urine and plasma were collected at fixed time points for 1 hour before and for 4 hours after drug administration for biochemical measurements. Glomerular filtration rate was measured by inulin clearance and effective renal blood flow was measured by para-amino hippurate clearance. Absolute sodium excretion increased by 25.9% from 0.27 +/- 0.03 mmol/min to 0.34 +/- 0.02 mmol/min (P = .02), and fractional sodium excretion increased by 32.3% from 18.9 +/- 3.0% to 25.0 +/- 1.9% (P = .03) after nitrendipine, but both were unchanged after placebo. There was no change in inulin clearance, para-amino hippurate clearance, urine volume, or fractional excretion of uric acid, which made an effect on glomerular filtration, renal blood flow, or proximal tubular function an unlikely explanation of the natriuresis. Fractional excretion of magnesium increased after both placebo and nitrendipine administration, from 5.0 +/- 0.6% to 6.8 +/- 0.7% (P = .027) and 5.7 +/- 0.8% to 8.8 +/- 1.0% (P = .006), respectively. Fractional excretion of phosphate also increased after both placebo and nitrendipine, from 9.5 +/- 2.3% to 12.9 +/- 3.9% (P = .05) and 9.7 +/- 1.7% to 14.2 +/- 1.9% (P = .002), respectively. These changes are likely to be due to the effects of the water load rather than due to a drug effect. There was no change in clearance of solute free water, which made a direct effect on the loop of Henle or cortical diluting segment unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration of slow-release nifedipine does not affect lactate threshold, hormone release during exercise, and quality of life in normal subjects

In a double-blind crossover study of 10 normal healthy subjects, we examined the effects of slow-release nifedipine (nifedipine-SR, 10 mg b.i.d) administration on exercise capacity, hormone levels during exercise, and quality of life (QOL) after a 2-week treatment. Two exercise tests, a progressive exercise test and a constant work-rate exercise test, were performed. Maximal oxygen uptake (VO2max) and blood lactate concentration were measured during the progressive exercise test and the exercise intensity corresponding to half lactate threshold (LT), LT, and 4 mmol/l of lactate concentration was determined. Subjects underwent 20 minutes of constant work-rate exercise at each work load, and blood lactate, plasma epinephrine, plasma norepinephrine, plasma renin activity, plasma aldosterone, atrial natriuretic peptide, plasma beta-endorphin, and met-enkephalin were measured. Taking nifedipine-SR had no effect on the responses of blood pressure, heart rate, VO2max, maximal work load, and LT compared to taking placebo. Blood lactate, plasma catecholamine, plasma renin activity, aldosterone, atrial natriuretic peptide, and beta-endorphin levels increased during exercise, and there was no difference between nifedipine-SR and placebo. Met-enkephalin did not increase with either treatment. In the QOL questionnaires, no differences were noted between the two treatments. These findings suggest nifedipine-SR to be a potentially useful drug in view of the lack of effect on exercise capacity, hormone release, and QOL.

Differential effects of nifedipine on plasma atrial natriuretic peptide in normal subjects and hypertensive patients

The physiology of atrial natriuretic peptide (ANP) secretion was studied in normotensive subjects and hypertensive patients both young and old. Basal plasma ANP concentration was least in young normotensives, intermediate in old normotensives and young hypertensives, and highest in old hypertensives. Nifedipine, a known stimulator of ANP secretion, acutely increased plasma ANP in young and old normotensive subjects but not in young hypertensive patients and half of the old hypertensive patients. Increase in serum ANP level in response to nifedipine did not augment its hypotensive effect. However, the increase of aldosterone in response to nifedipine-induced rise in plasma renin activity (PRA) seemed to be suppressed by elevated ANP.

Sustained release nifedipine formulations. An appraisal of their current uses and prospective roles in the treatment of hypertension, ischaemic heart disease and peripheral vascular disorders

Nifedipine antagonises influx of calcium through cell membrane slow channels, and sustained release formulations of the calcium channel blocker have been shown to be effective in the treatment of mild to moderate hypertension and both stable and variant angina pectoris. Preliminary findings also indicate that these formulations are effective in the treatment of Raynaud's phenomenon and hypertension in pregnancy, and that they reduce the frequency of ischaemic episodes in some patients with silent myocardial ischaemia. The exact mechanism of action of nifedipine in all of these disorders has not been defined. However, its potent peripheral and coronary arterial dilator properties, together with improvements in oxygen supply/demand, are of particular importance. A major goal of sustained release therapy is to permit reductions in the frequency of nifedipine administration, preferably to once daily, and thus improve patient compliance. Two new once-daily formulations--the nifedipine gastrointestinal therapeutic system (GITS) and a fixed combination capsule comprising sustained release nifedipine 20 mg and atenolol 50 mg--have exhibited marked antihypertensive efficacy. The GITS preparation has also been used effectively in the treatment of stable angina pectoris, and both formulations appear to be well tolerated. Sustained release nifedipine formulations are generally better tolerated than their conventionally formulated counterparts, particularly with regard to reflex tachycardia. Adverse effects seem to be dose related, are mainly associated with the drug's potent vasodilatory action, and include headache, flushing and dizziness. Generally, these effects are mild to moderate in severity and transient, usually diminishing with continued treatment. Thus, sustained release nifedipine formulations are useful and established cardiovascular therapeutic agents which have demonstrable efficacy in various forms of angina, mild to moderate hypertension and Raynaud's phenomenon. Further, promising results shown by the nifedipine GITS formulation, with its advantage of once daily administration suggest that it is likely to become one of the preferred nifedipine formulations for the treatment of hypertension and the various forms of angina.

Short-term effects of atenolol and nifedipine on atrial natriuretic peptide, plasma renin activity, and plasma aldosterone in patients with essential hypertension

The short-term effects of atenolol and nifedipine on plasma levels of atrial natriuretic peptide (ANP), plasma renin activity (PRA), and plasma aldosterone (PA) were studied in two groups of patients with uncomplicated essential hypertension. Urinary catecholamines, and sodium and potassium excretion were also studied. A group of 20 patients with hypertension, after a wash-out period of at least 10 days, was randomly subdivided into two protocol therapy subgroups. One group (six men and four women) received atenolol (100 mg/d), and the other group (six men and four women) received nifedipine (30 mg/d). Circulating plasma levels of ANP, PRA, and PA were determined by radioimmunoassay, and other variables were determined by routine laboratory techniques before therapy and at day 3 and day 7 after the treatment began. Arterial blood pressure and heart rate were monitored during the study. Both drugs reduced arterial blood pressure (P less than .001) significantly. The atenolol therapy decreased heart rate (P less than .001), increased plasma ANP levels and urinary catecholamine excretion, and decreased PRA and circulating PA levels. Nifedipine treatment did not modify plasma ANP values, whereas it increased PRA and PA circulating levels and urinary catecholamine excretion. No differences were shown for urinary volume, urinary sodium, and potassium excretions during the two different treatments. These findings suggest that the increased plasma ANP levels could contribute to the antihypertensive effects of the beta-adrenoreceptor blockers, by a reduction in PRA and PA levels and a vasodilatative effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Nisoldipine--effects on the renin-angiotensin-aldosterone system and catecholamines. Studies in normotensive and hypertensive subjects

We have studied the effects of nisoldipine, a new calcium channel antagonist, on the renin-angiotensin-aldosterone system and on plasma catecholamines in 10 healthy volunteers and in 29 patients with primary essential hypertension. Of these 29 patients, thirteen had normal renin hypertension (NRH), and sixteen had low renin hypertension (LRH). Eight healthy volunteers received placebo. Short-term (24 h) effects were measured in all subjects and long-term (up to 6 months) effects of 10-40 mg nisoldipine daily were monitored in the 29 hypertensive patients. Plasma renin activity (PRA) increased slightly, although this rise was not statistically significant, 1 h after the first dose of nisoldipine in both normotensive subjects and hypertensive patients. After 2 h PRA had returned to the pre-treatment level. No change in PRA was observed after administration of placebo. Plasma angiotensin II (AII) levels showed considerable variation after nisoldipine administration. Plasma aldosterone levels decreased despite the increase in PRA and AII concentrations. However, no concomitant reduction in urinary aldosterone excretion was observed. Plasma noradrenaline levels increased slightly 2-4 h after administration of nisoldipine, and decreased again thereafter, but no changes in plasma adrenaline levels were seen. Nisoldipine had no long-term effects on the renin-angiotensin-aldosterone system or on serum catecholamine levels.

Co-dergocrine mesylate inhibits the increase in plasma catecholamines caused by nifedipine in essential hypertension

Co-dergocrine mesylate (Cod), which inhibits norepinephrine secretion by stimulating presynaptic dopamine receptors, and has no known metabolic side effect, has an additive antihypertensive effect to that of Nifedipine (Nif). Plasma norepinephrine, epinephrine, renin activity and aldosterone have been measured after acute administration of Nif and Cod alone and in combination to 18 patients with a diastolic blood pressure greater than 105 mmHg in a cross-over, randomized, double-blind study. Every patient received 4 mg Cod then 20 mg Nif, placebo then 20 mg Nif and 4 mg Cod then placebo. The second treatment was always given 1 h after the first medication. Blood pressure was measured before and every 15 min during the study period. Blood for measurement of catecholamines, aldosterone and renin activity was collected before medication, 1 h after the first dose and 90 min after the second treatment. Blood pressure was significantly lower (P less than 0.05) where Cod preceded Nif. Cod caused a significant decrease in plasma norepinephrine from 293 to 202 pg.ml-1 and in epinephrine from 67 to 55 pg.ml-1. The Nif-induced increase in norepinephrine from a pre-treatment value of 293 pg.ml-1 with preceding Cod to 331 pg.ml-1 was much less than the increase with placebo as premedication, from 284 to 440 pg.ml-1. Nif caused an increase in renin activity but no increase in aldosterone. Nif-related side effects, such as flushing and headache, occurred in 6 patients of whom 5 had no received Cod as premedication.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute coronary vasomotor effects of nifedipine and therapeutic correlates in syndrome X

In 18 patients (12 women) presenting with effort-induced chest pain and normal coronary angiograms (syndrome X), 10 mg sublingual nifedipine increased the lumen of major coronary arteries (quantitative angiography) by 13 +/- 10% (p less than 0.01), coronary blood flow (thermodilution) by 23 +/- 26% (p less than 0.05), norepinephrine plasma concentration by 60 +/- 42% (p less than 0.01) and decreased the global ST-segment shift during the effort stress test from 8.8 +/- 4.1 to 7 +/- 6.8 mm (p less than 0.03) at comparable maximal workload and at unchanged double product. There was a correlation (positive) of changes in flow with changes in coronary lumen diameter (r = 0.65, p less than 0.01) with ST-segment response to exercise (r = 0.83, p less than 0.001) and with (inverse) norepinephrine plasma concentration (r = -0.70, p less than 0.01); no correlation was found between ST-segment response and changes in arterial lumen diameter. In a few cases, nifedipine did not improve or even worsened the response to exercise; coronary flow was unchanged or decreased and norepinephrine plasma levels were modestly or greatly increased, respectively. After 4 weeks of treatment with nifedipine (10 to 20 mg 4 times daily), the effort ST-segment shift was further decreased to 4.4 +/- 3.5 mm (p less than 0.03) despite a slightly increased double product. Plasma norepinephrine values, as compared to those after acute nifedipine, were decreased by 40% in patients with further improvement and were unchanged in patients whose exercise performance did not vary.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive effect of CS-905, a novel dihydropyridine calcium blocker, in conscious hypertensive dogs

CS-905, (+-)-3-(1-diphenylmethylazetidin-3-yl)5-isopropyl 2-amino-1,4-dihydro-6-methyl-4-(m-nitrophenyl)-3,5-pyridine-dicarboxy lat e, is a novel dihydropyridine calcium blocker. Both CS-905 and nicardipine, when administered orally, produced a dose-dependent fall of blood pressure in conscious perinephritic hypertensive dogs. Unlike the hypotensive effect of nicardipine, that of CS-905 has a gradual onset and is long-lasting, with little increase in the heart rate and plasma renin activity (PRA). The lack of both tachycardia and increase of PRA is probably mostly due to the slow onset of antihypertensive action following CS-905.

Behavioral performance effects of nifedipine in normotensive and renovascular hypertensive baboons

Behavioral performances of normotensive and hypertensive adult male baboons were tested before, during, and following chronic oral dosing with nifedipine. Performances during a five-color simultaneous match-to-sample task were measured during three dosing schedules (0.20, 0.68, and 1.14 mg/kg/day) and vehicle. Each dose was administered for 21 consecutive days preceded and followed by 14-day baseline and recovery periods, respectively. Choice reaction times increased by 191 ms over baseline at the 0.68 mg/kg dose. Choice reaction times above the 95th percentile (i.e., the slowest reaction times) were the most slowed by nifedipine. Accuracy of color matching was decreased at 0.20 and 0.68 mg/kg by an average range of 2-4%. The yellow and white stimuli were the most difficult to discriminate correctly, and were also the most impaired by nifedipine. Nifedipine's behavioral effects were not modulated by blood pressure changes because daily changes in choice reaction time and systolic blood pressure were not correlated, and hypertensive status did not determine the behavioral effects. Potential sources of nifedipine's behavioral performance effects are discussed, with blood pressure changes excluded as a probable mechanism.

Effects of nifedipine on renal responses to human atrial natriuretic peptide in healthy subjects and normoglycemic patients with type 1 diabetes mellitus

We examined renal responses to a pharmacological dosage of human atrial natriuretic peptide (hANP) and the potential interference of nifedipine administration with the effects of hANP on kidney function in healthy subjects and normoglycemic patients with type 1 diabetes mellitus. Ten healthy volunteers (age, 28 +/- 1 years) and ten patients (age, 33 +/- 2 years; diabetes duration; 14 +/- 3 years; HbAI 7.2% +/- 0.2%) were studied. According to a double-blind, randomized, placebo-controlled trial design, three experiments were performed in each subject using the double-dummy technique: placebo only, hANP only, and nifedipine + hANP. As i.v. bolus injection 100 micrograms hANP was given; nifedipine was applied buccally, at a dose of 10 mg 90 min before and at a dose of 5 mg together with hANP injection. At base-line and in the placebo only experiment, patients did not differ from controls. In the hANP only experiment, in both groups hANP resulted in increased urinary volume and both sodium and chloride excretion (P less than 0.05 vs placebo only experiment). In patients, hANP-induced increase in electrolyte excretion was greater than in controls (P less than 0.05). In the nifedipine + hANP experiment, hANP-induced changes in renal indexes were enhanced in controls (P less than 0.05 vs hANP only experiment) but not in patients. Thus, diuretic response to nifedipine + hANP in patients was decreased in comparison with controls (P less than 0.05). In patients, however, nifedipine administration decreased the hANP-induced increase in urinary albumin excretion (P less than 0.05 vs hANP only experiment). Creatinine clearance was uninfluenced throughout the experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular and metabolic effects associated with nifedipine and ritodrine tocolysis

Recent investigations have indicated that nifedipine, a calcium channel entry blocker, may be useful in the treatment of preterm labor. This prospective, randomized study compares cardiovascular and metabolic effects measured in association with sublingual and oral administration of nifedipine with those noted with the intravenous and oral administration of the beta-adrenergic agent ritodrine. Serial measurements of cardiovascular parameters, hematocrit, electrolytes, glucose, blood urea nitrogen, creatinine, calcium, and serum glutamic-oxaloacetic and glutamic-pyruvic transaminase were compared between groups. Sublingual and oral nifedipine caused minimal cardiovascular alterations. At doses sufficient to achieve tocolysis, ritodrine caused more pronounced cardiovascular changes than nifedipine. Both agents had a hemodilutional effect, but nifedipine was not associated with alterations in serum electrolytes or a dramatic hyperglycemia. On the basis of this study, it appears that the use of nifedipine for preterm labor management is associated with hemodilutional changes but not the adverse cardiovascular or metabolic effects often associated with ritodrine tocolysis.

Long-term effects of isradipine on blood pressure and renal function

The hemodynamic and renal effects of isradipine were investigated in 10 hypertensive patients treated for 3.5 months and in a further nine patients treated for two years. Both groups achieved significant and sustained reductions in systolic blood pressure/diastolic blood pressure (-15 percent/-12 percent and -15 percent/-20 percent, respectively; p less than 0.001). Renal parameters were investigated two to three hours after the morning dose of isradipine, using a water-loading procedure. After 3.5 months of treatment, the glomerular filtration rate and renal plasma flow showed small increases (+6 percent and +9 percent, respectively, p less than 0.05), whereas, after two years, these changes were no longer present (+4 percent and 0 percent). Clearance of sodium and uric acid was increased by 40 percent (p less than 0.01) and 21 percent (p less than 0.01), respectively, after 3.5 months, and by 45 percent (p less than 0.05) and 23 percent (p less than 0.01), respectively, after two years. Lithium clearance studies revealed the natriuretic effect to be located in the proximal tubule. After 3.5 months, a significant relationship was found between the blood pressure response and the change in sodium excretion, but this relationship also was no longer present after two years. In conclusion, because of a maintained blood pressure-lowering effect while preserving renal function, and sustained natriuretic and uricosuric actions, isradipine can be considered a promising agent in the long-term treatment of arterial hypertension.

Hemodynamic and endocrine effects of acute and chronic administration of nifedipine

Although it is well known that calcium channel blockers can influence contraction of vascular smooth muscle, there is less knowledge on its effect on excitation contraction coupling in the endocrine glands and more specifically on insulin and glucagon release. In this study, nifedipine was administered in doses of 40 to 80 mg/day to 14 patients with essential hypertension, and its hemodynamic effects were evaluated by non-invasive methods, and its effect on glucose metabolism by an arginine infusion test. Nifedipine produced a significant reduction in systolic and diastolic blood pressure, both after the first dose (30/12 mm Hg) and after 8 weeks of administration (19/12 mm Hg). There were no significant changes in cardiac output (5.1 to 4.9 L/min), muscle (2.4 to 3.2 mL/sec/min) or cutaneous basal flow (9.8 to 8.6 mL/100 mL) as measured non-invasively by echocardiogram and by plethysmography. Insulin and glucagon release were evaluated by the arginine infusion test. Nifedipine produced a tendency towards an increase in glucagon release and a reduction in insulin release although these changes did not reach statistical significance. In this group of patients, nifedipine produced a significant reduction in systolic and diastolic pressure, but no significant changes in insulin or glucagon plasma levels.

Hemodynamic and endocrine effects of acute and chronic administration of nifedipine

Although it is well known that calcium channel blockers can influence contraction of vascular smooth muscle, there is less knowledge on its effect on excitation contraction coupling in the endocrine glands and more specifically on insulin and glucagon release. In this study, nifedipine was administered in doses of 40 to 80 mg/day to 14 patients with essential hypertension, and its hemodynamic effects were evaluated by non-invasive methods, and its effect on glucose metabolism by an arginine infusion test. Nifedipine produced a significant reduction in systolic and diastolic blood pressure, both after the first dose (30/12 mm Hg) and after 8 weeks of administration (19/12 mm Hg). There were no significant changes in cardiac output (5.1 to 4.9 L/min), muscle (2.4 to 3.2 mL/sec/min) or cutaneous basal flow (9.8 to 8.6 mL/100 mL) as measured non-invasively by echocardiogram and by plethysmography. Insulin and glucagon release were evaluated by the arginine infusion test. Nifedipine produced a tendency toward an increase in glucagon release and a reduction in insulin release although these changes did not reach statistical significance. In this group of patients, nifedipine produced a significant reduction in systolic and diastolic pressure, but no significant changes in insulin or glucagon plasma levels.

Acute calcium entry blockade inhibits the blood pressure but not the hormonal responses to angiotensin II

The effects of acute calcium entry blockade by isradipine (IS) and placebo (P) on the haemodynamic and humoral responses to angiotensin II (A II) have been compared in two groups of 9 patients with essential hypertension. During 4 sequential periods each of 20 min, an i.v. infusion of A II 0, 2, 4 and 8 ng.kg-1.min-1 was given before (control) and 30 min after the oral administration either of IS or P. After IS, both the blood pressure and the angiotensin II-induced pressor effect were significantly reduced. Isradipine increased the heart rate and this cardio-acceleration was potentiated by A II. In contrast, when A II was infused in the absence of IS, heart rate tended to decrease. IS stimulated plasma renin activity and reduced plasma aldosterone. However, it did not affect either the inhibition of plasma renin activity or the rise in plasma aldosterone in response to A II. In conclusion, acute calcium entry blockade in patients with essential hypertension reduces the pressor response to A II, but not the A II-induced inhibition of renin and increase in plasma aldosterone.

The effect of nisoldipine on renal function in the long-term treatment of hypertension in patients with and without renal impairment

The effect of nisoldipine on renal function after 6 weeks treatment was investigated in hypertensive patients with and without renal impairment. Nisoldipine was well tolerated and an effective antihypertensive agent when administered over a period of 6 weeks. There were no significant changes in glomerular filtration, cardiac output, plasma renin activity or serum biochemistry during nisoldipine administration. Effective renal plasma flow was unaffected by treatment in the patients with normal renal function, but in the patients with renal insufficiency, the value decreased by a mean of 12%. Nisoldipine had no major untoward effects on renal function after 6 weeks administration, but minor changes in renal haemodynamics in the patients with renal insufficiency would suggest that careful monitoring of renal function is indicated in such patients.

Nifedipine: individual responses and concentration-effect relationships

Dynamic and kinetic variability account for the large intersubject differences in the antihypertensive response to nifedipine, and a clear concentration-effect relationship has not been established. The effects of placebo, first dose, and chronic (1 and 6 weeks) treatment with nifedipine were studied in 14 subjects with essential hypertension using an integrated kinetic-dynamic model to calculate individual subject responsiveness in terms of fall in blood pressure per unit change in drug concentration. Nifedipine concentrations were well correlated with the fall in systolic blood pressure in individual subjects, and the mean responsiveness was -0.48 mm Hg/ng/ml after the first dose, -0.45 mm Hg/ng/ml after 1 week, and -0.49 mm Hg/ng/ml after 6 weeks. The responsiveness to the first dose of nifedipine was significantly correlated with the responsiveness after 1 (r = 0.83) and 6 weeks (r = 0.78) of therapy and with the height of the pretreatment blood pressure (r = 0.6). This study incorporated kinetic as well as dynamic information to characterize the antihypertensive response to nifedipine and identify nifedipine concentration-effect relationships in individual hypertensive subjects.

Calcium channel blockers in systemic hypertension

Alterations in transmembrane flux of calcium ions may be playing a role in the pathophysiology of systemic hypertension. Calcium channel blockers have been shown to be effective antihypertensive drugs with excellent safety profiles. They are efficacious in the long term treatment of systemic hypertension in all population subgroups, and have special applicability for treating patients with hypertensive urgencies and individuals with concomitant diseases such as angina pectoris and arrhythmias.

Addition of chlorthalidone to slow-release nifedipine in the treatment of arterial hypertension: a controlled study versus placebo

The use of calcium antagonists and diuretics in combination for treatment of hypertension is controversial. In a single-blind study 16 patients (8 men, 8 women, age range 39 to 62 years) with primary hypertension of mild to moderate degree were given slow-release nifedipine 20 mg twice daily for 6 weeks, thereafter either chlorthalidone 25 mg (Group A) or placebo (group B) daily was randomly added for a further 6-week period. Blood pressure (BP), heart rate, plasma renin activity (PRA), aldosterone, and 24 hour urinary electrolytes were evaluated. Nifedipine decreased supine BP from 159/92 +/- 16/8 to 151/89 +/- 10/6 mmHg in group A and from 162/94 +/- 20/12 to 145/85 +/- 14/6 mmHg in group B. A further fall to 139/84 +/- 7/6 mmHg (p less than .05) was observed after addition of chlorthalidone. PRA significantly increased with combined treatment compared to baseline (3.3 +/- 0.8 to 9.9 +/- 3.3 ng/ml/hr; p less than 0.05). A slight reduction of 24-hour urinary calcium was observed after the addition of chlorthalidone. These data indicate that the combination of nifedipine and chlorthalidone might be beneficial in the treatment of arterial hypertension.

Hormonal and metabolic effects of calcium channel antagonists in man

Calcium is a component of many metabolic reactions. By blocking calcium transport across cell membranes, calcium channel antagonists can therefore theoretically affect numerous metabolic and hormonal processes. In vitro studies have often documented just such an effect. Because of the expanding use and prevalence of calcium antagonists in clinical practice, a review of their in vivo effects on hormones and metabolism is warranted. The effect on glucoregulatory hormones, calcium regulatory hormones, anterior and posterior pituitary secretion, the renin-angiotensin axis, plasma catecholamines, and plasma lipids and lipoproteins is herein reviewed. The various calcium antagonists, by virtue of their distinct chemical structures, influence metabolism in their own unique manner. Despite the widespread involvement of calcium in hormone action, however, calcium channel antagonists have little dramatic impact on hormone regulation. This is, in part, due to the drug dosage used in clinical practice and to the inherent compensatory mechanisms built into normal endocrine function. The development of agents with greater and more potent metabolic specificity, however, coupled with the ability to target drug action, holds promise for expanded therapeutic application in the future.

Multicenter comparison of the nifedipine gastrointestinal therapeutic system and long-acting propranolol in patients with mild to moderate systemic hypertension receiving diuretics. A preliminary experience

The efficacy and safety of nifedipine in a gastrointestinal therapeutic system (GITS) push-pull osmotic pump formulation was compared with long-acting propranolol in 49 patients with mild to moderate hypertension already receiving diuretics. Using a two-week placebo run-in, double-blind study design, patients were randomly assigned to receive nifedipine GITS (n = 24) in doses of 30 mg, 60 mg, or 90 mg once daily; or long-acting propranolol (n = 25) in doses of 80, 160, or 240 mg once daily. Previous diuretic therapy was continued. Sitting and five-minute standing blood pressure and heart rate measurements were made 24 hours after dosing. At the endpoint of treatment, both nifedipine GITS and sustained-release propranolol reduced blood pressure compared with placebo (p less than 0.001) in the sitting and standing positions. Nifedipine GITS was more effective in lowering standing systolic blood pressure than was propranolol (p less than 0.02). Propranolol caused a greater reduction in resting heart rate than did nifedipine GITS (p less than 0.003). Both drugs were well tolerated. Nifedipine GITS is an effective and safe once-daily drug for use in patients with hypertension who are already receiving diuretics, may be more effective than sustained-release propranolol, and may be better tolerated than conventional nifedipine capsules.

Acute effects of nitrendipine in pregnancy-induced hypertension

The acute effects of a single, 20 mg oral dose of nitrendipine were studied in 10 women at between 32 and 42 weeks gestation with stable pregnancy-induced hypertension (PIH). Blood pressure (BP), maternal heart rate and fetal heart rate (FHR) were assessed for 8 h after nitrendipine intake together with the plasma levels of nitrendipine, noradrenaline, adrenaline, plasma renin activity (PRA) and vasopressin. The mean initial systolic/diastolic BP was 158 (SEM 3.7)/108 (SEM 2.7) mmHg. Within 1 h stable, reduced mean BP-levels of 141-145/90-95 mmHg were reached and maintained for 4 h after medication. This antihypertensive effect was closely related to the maternal plasma concentration of nitrendipine, which reached a maximum of 9.1 (SEM 2.6) ng/ml 3 h after tablet intake. After 4 h, systolic and diastolic BPs slowly increased in parallel to a successive decrease in plasma concentrations of nitrendipine. Maternal heart rate increased by less than 10%, while FHR remained unchanged. No hypotensive incidents occurred. The initial mean plasma concentrations of noradrenaline, adrenaline, vasopressin and PRA did not change during the treatment. No major maternal and no fetal side-effects were observed. Three of 10 patients experienced mild, transient facial flushing.

Short- and long-term effects of calcium entry blockers on the kidney

The renal effects of the calcium entry-blocking drugs diltiazem, nifedipine, nitrendipine, nicardipine and verapamil are reviewed. Although nifedipine may acutely increase plasma renin activity, most of the calcium entry blockers have no sustained effect on any of the components of the renin-angiotensin-aldosterone system. Although all of the calcium entry blockers effectively lower blood pressure, none adversely affects renal function: Glomerular filtration rate and effective renal plasma flow are maintained. Diltiazem may increase glomerular filtration rate via attenuation of the intrarenal effects of angiotensin II or norepinephrine. Although all of the calcium entry blockers acutely increase salt and water excretion, most of the calcium entry blockers have no clinically sustained effect on salt and water excretion; serum electrolytes, urinary sodium and potassium excretion, body fluid composition and body weight are usually unchanged. Calcium entry blockers can be expected to assume a prominent role in the treatment of hypertension because of their ability to lower blood pressure while preserving renal perfusion and function.

Effect of the calcium antagonist nilvadipine on haemodynamics at rest and during cold stimulation in essential hypertension

The immediate haemodynamic effects of the calcium antagonist nilvadipine have been studied in ten patients with established mild essential hypertension. Nilvadipine 4 mg p.o. reduced both the systolic and diastolic blood pressures within 60 min, associated with a fall in total peripheral resistance and an increase in heart rate and cardiac index. The peak of blood pressure and total peripheral resistance reached during a cold pressor test were reduced by nilvadipine, but it did not affect the haemodynamic responsiveness to cold stimulation. Plasma renin activity was unaltered and the plasma noradrenaline concentration was increased only slightly. Thus, nilvadipine lowered blood pressure at rest and during cold stimulation as a result of arteriolar dilatation. The hypotensive effect at rest was associated with a reflex increase in heart rate and cardiac index.

Clinical evaluation of felodipine in patients with refractory hypertension

The calcium antagonist, felodipine, was used to treat 21 patients with severe uncontrolled hypertension: 13 had renoparenchymatous hypertension, 5 essential hypertension and 3 renovascular hypertension. Mean arterial blood pressure of patients was 195 +/- 8/122 +/- 3mm Hg in spite of treatment with 3 or more antihypertensive drugs. The majority of the patients (n = 17) were treated with an ACE inhibitor. Mean glomerular filtration rate (GFR) for 20 patients was 39 +/- 6 ml/min/1.73m2 body surface area (Cr-EDTA clearance) before felodipine administration. All patients had an immediate blood pressure fall after 5-10mg of felodipine administered orally. This fall persisted when the drug was given 2 or 3 times daily in combination with previous medication except the former vasodilating drugs. 15 patients are on long term treatment with felodipine and their blood pressure after 1 year (n = 14) was 152 +/- 4/89 +/- 2mm Hg. Patients with moderately impaired renal function and no signs of progressive kidney disease (n = 8) improved their GFR significantly after 1 year on felodipine. Six patients stopped felodipine therapy within 3 months (4 because of adverse reactions, 1 died of scleroderma and 1 became normotensive after the start of dialysis treatment). In patients with renoparenchymatous disease and documented progressive deterioration of renal function the addition of felodipine did not prevent a decline in filtration rate but did slow the rate of deterioration (from 9 +/- 2 to 5 +/- 1 ml/min/year).(ABSTRACT TRUNCATED AT 250 WORDS)