Intravenous verapamil infusion reduced the arterial pressure (AP) in 13 out of 71 (76.5%) patients with severe arterial hypertension (AH) refractory to a two-week, three-step oral antihypertensive medication. Investigations including echo- and radio-cardiography were performed: in the control period before starting the three-step treatment; after two weeks before intravenous verapamil ...

Circadian phase dependency in pharmacokinetics and hemodynamic effects on blood pressure and heart rate of different galenic formulations of nifedipine (immediate-release, sustained-release, and i.v. solution) were studied in healthy subjects or in hypertensive patients. Pharmacokinetics of immediate-release but not sustained-release and i.v. nifedipine were dependent on time of day: immediate-release ...

In anesthetized rabbits, we can induce a significant degree of spontaneous activity in the urinary bladder by placing a ligature around the proximal portion of the external urethra. Previous studies characterized the activity as primarily reflex in nature, since intravesical hexamethonium selectively inhibited the hyperreflexia. In this current study we ...

The effects of oral nifedipine pretreatment on subjective and cardiovascular responses to intravenous cocaine infusions were studied in cocaine-using volunteers. Nifedipine, 10 mg or placebo, was administered 20-25 min before placebo, 20 mg, or 40 mg cocaine, using a repeated measures randomized double-blind design. The variables measured were self-reported subjective ...

In the present study we have compared the effect of intravenous infusion of a calcium channel blocker, nifedipine (1.0 micrograms.kg-1.min-1 for 20 min), with that of isoproterenol (0.1 micrograms.kg-1.min-1 for 20 min) on the hemodynamic parameters and the vascular response of different locations and tissue layers of the gastrointestinal tract. ...

Nifedipine, in the gastrointestinal therapeutic system (GITS) formulation, a controlled-release formulation for once-a-day administration, was evaluated in the Modern Approach to the Treatment of Hypertension (MATH) trial. In this study conducted at 127 centers, 1155 patients with mild-to-moderate hypertension representative of the spectrum seen in practice were included in the ...

Twenty patients with preeclampsia at a gestational age of 26 to 35 weeks were treated with oral nifedipine until delivery. The mean oral daily dose was 45.1 +/- 11 mg/day (range, 40 to 80 mg/day). Fetal aorta, internal carotid artery, umbilical artery, and uteroplacental Doppler flow velocity waveforms were recorded ...

The Modern Approach to the Treatment of Hypertension (MATH) trial was conducted to determine the therapeutic safety and efficacy of the once-a-day nifedipine gastrointestinal therapeutic system (GITS) formulation in a large and diverse cohort of patients with mild-to-moderate hypertension. One of the goals of the MATH study was to evaluate ...

1. This multicentre hospital study compared the antihypertensive efficacy and the tolerability of once daily felodipine extended release (ER) with twice daily nifedipine retard (R) in hypertensive patients inadequately controlled on metoprolol monotherapy. 2. One hundred patients, aged 20-70 years, whose seated diastolic blood pressure was 100-115 mmHg after 4 ...

Calcium is important in the maintenance of arterial smooth muscle function and its alteration from normal may predispose to atherogenesis and hypertension. Slow channel inhibitors such as nifedipine and calcium salts have been used separately to modulate arterial calcium in patients with hypertension. This study included 41 patients with essential ...

The acute effects of single doses of captopril (C) 12.5 mg, of nifedipine (N) 10 mg, or of their combination (C + N) on parameters of left ventricular (LV) function were assessed in 18 elderly hypertensive subjects using radionuclide ventriculography. Blood pressure (BP) was lowered by C from 177/100 to ...

The short-term effect of 20 mg of oral nifedipine on maternal and fetal hemodynamics was investigated in ten healthy, normotensive women at 38 weeks' gestation admitted to the hospital for elective cesarean delivery. Within 1 hour after nifedipine administration, mean arterial pressure had decreased by 10% and a slight increase ...

In a double-blind cross-over study, 10 patients with stable angina pectoris owing to coronary heart disease were investigated in supine position during rest and bicycle exercise for the effect of 0.4 mg of intravenous (i.v.) isradipine in comparison to 2 mg i.v. nifedipine on cardiac hemodynamics and myocardial ischemia. At ...

The blood pressure response to a new sustained-release formulation of nifedipine was evaluated in an 8-week, double-blind, placebo-controlled study. Twenty-nine patients with mild essential hypertension were randomized to receive placebo (N = 9), 30 mg nifedipine (N = 10), or 60 mg nifedipine (N = 10). During treatment, 30-mg and ...

The effects of ryanodine on the action potential and induction of early afterdepolarization (EAD) were studied in the atrial fibers of mouse heart. Under treatment with ryanodine, the duration of the action potential (ADP) was prolonged. The percentage of the prolongation of ADP25, APD50 and ADP100 were 83, 49 and ...

Dipyridamole has liberalized referrals for stress TI-201 chloride (thallium) studies at the Iowa City Veterans Administration Medical Center. Seventy-five percent of referrals now receive dipyridamole and, unlike patients who tolerate conventional exercise testing, these patients are often quite debilitated. Therefore, the hemodynamic consequences of dipyridamole were reviewed in 120 consecutive, ...

Forty-one elderly patients with mild to moderate hypertension (resting diastolic blood pressure 100-130 mmHg after an eight week placebo run-in phase) were randomised to a double-blind parallel group comparison of nifedipine retard 10 mg twice daily or atenolol 50 mg once daily. If the resting diastolic pressure exceeded 95 mmHg ...

Marked prolongation of cardiac action potentials and of QT intervals has been associated with early afterdepolarizations and triggered activity in vitro and with ventricular tachycardia in vivo. Because the antihypertensive potassium channel activators pinacidil and cromakalim are known to accelerate repolarization in cardiac tissues, we performed in vitro and in ...

OBJECTIVE: To assess the changes in sodium excretion and sodium balance after withdrawal of long term nifedipine. DESIGN: Single blind, placebo controlled study in patients receiving fixed sodium and potassium intakes. SETTING: Blood pressure unit of a teaching hospital in south London. PATIENTS: Eight patients with mild to moderate uncomplicated ...

1. Aspects of quality of life (symptoms, psychological well-being and activity) were evaluated by self-administered questionnaires in a 4 month randomised double-blind trial of titrated doses of verapamil slow release (n = 41) compared with nifedipine retard (n = 40). An untreated diastolic blood pressure of 95-115 mm Hg was ...

Ten spinal-cord-injured males who exhibited autonomic dysreflexia during electroejaculation were given sublingual calcium channel blocker nifedipine pretreatment to prevent this complication. Nifedipine was successful in decreasing peak systolic, diastolic, and mean blood pressures during the procedure. The use of nifedipine resulted in fewer aborted trials and allowed higher energy delivery ...

STUDY OBJECTIVE: The aim of the study was (1) to determine the difference in aortic input impedance and derived parameters between hypertensives and normotensives; and (2) to assess the acute effects of nifedipine on the aortic impedance, compliance, and resistance in patients with hypertension. DESIGN: A high fidelity multisensor catheter ...

The regional haemodynamic profiles of Ro 31-6930, cromakalim and nifedipine were compared using pulsed Doppler flowmetry in the anaesthetised rat. In order of potency, Ro 31-6930 (0.1-300 micrograms/kg), cromakalim (1-300 micrograms/kg) and nifedipine (1-1000 micrograms/kg) produced dose related falls in mean arterial pressure. The hypotensive effects of Ro 31-6930 and ...

1. In a double-blind, randomised, parallel group study, 128 patients with sitting diastolic blood pressure between 95 and 125 mm Hg (Phase V) after 2-4 weeks run-in on placebo, received enalapril 10-40 mg once daily (65 patients) or nifedipine retard 10-40 mg twice daily (63 patients), utilising a double dummy ...

IV verapamil is the preferred drug for the acute management of supraventricular tachyarrhythmias (SVTs) in the absence of contraindications to its use. SVT complicated by hypotension has been considered a relative contraindication for the use of IV verapamil. However, the efficacy of IV verapamil in the management of "rate-related" hypotension ...

Twelve of 40 consecutive patients with effort angina, documented coronary artery disease, and a positive exercise stress test had a positive ergonovine test. ST-segment depression (0.1 mV) occurred in ten and ST elevation (0.1 mV) in two patients. During the ergonovine maleate test the rate-pressure product recorded at the onset ...

The dihydropyridine calcium antagonist (+/-)-nicardipine shares some of the pharmacologic properties of the dihydropyridine prototype nifedipine. To compare them, serum concentrations and cardiovascular effects of 10 mg nifedipine and 20 mg (+/-)-nicardipine were evaluated at 1, 2, and 3 hours after oral intake in a randomized, crossover, single-blind study involving ...

This randomised, parallel group study was designed to compare the efficacy of nifedipine (40 mg once daily) combined with either the dopamine agonist, co-dergocrine mesilate (4 mg once daily) or the diuretic mefruside (25 mg once daily) in 40 patients with essential arterial hypertension and a diastolic blood pressure greater ...

The acute hypotensive effect of nifedipine was evaluated, and the possibility of its long-term use in hypertensives over 60 years of age was studied. Sublingual nifedipine in a dose of 20 mg was given to 28 patients, mean age 73.1 yrs, and blood pressure, heart rate, and plasma drug concentration ...

The reduction of transmembranous calcium influx into vascular smooth muscle cells by calcium antagonists leads to a reduction of tension development and vascular tone. Nifedipine reduces forearm vascular resistance dose-dependently when infused into the brachial artery in patients with essential hypertension, attesting to its potent arterial vasodilator effects. This effect ...

In this article a new model of peripheral occlusive arterial disease is described. The lower hindlimb of an anesthetized ferret was fixed to a holder, the distal end of the Achilles tendon attached to an isometric force transducer, and a passive preload of 100 g was applied to the muscle ...

The prehospital management of severe hypertension is limited by a paucity of pharmacologic agents suitable for field use. This prospective study was designed to test the safety and efficacy of intraoral nifedipine therapy in 50 patients with severe hypertension being transported by an urban emergency medical service system. Ten milligrams ...

The magnitude and time course of the hemodynamic effect of a new formulation of an aqueous solution of isosorbide dinitrate (ISDN) spray were compared with those of sublingual nitroglycerin (NTG) tablets in 12 patients with chronic congestive heart failure. The patients received, in a random order, ISDN spray, 2.5 mg, ...

The calcium antagonist verapamil was intravenously infused after plasma volume expansion with dextran-70 in nine patients with severe gestational proteinuric hypertension. The hemodynamic response of these patients was monitored using a flow-directed pulmonary artery catheter. Verapamil produced a statistically significant reduction in mean arterial pressure and systemic vascular resistance without ...

It is known that calcium antagonists may produce a natriuresis and diuresis but the mechanisms are unknown and there have been few studies of the relative potencies of different drugs. This paper reports a study designed to measure the effect of nifedipine and nitrendipine on urine volume, sodium and potassium ...

Representative calcium antagonists from proposed class I (nifedipine), class II (verapamil) and class III (flunarizine) have been examined for effects on blood pressure, heart rate, ventricular pressures, ECG, cardiac output and regional blood flow in pentobarbitone-anaesthetized rats. Flow was measured by the microsphere technique. Low and high infusion rates of ...

The effects of 5 mg sublingual nifedipine on a standardized cold provocation test were compared with that of placebo in a double-blind, cross-over trial in 10 patients with Raynaud's disease. The percentage decrease of finger systolic pressure in the cooled finger (as compared with the contralateral control finger) was significantly ...

The aim of the present study was to further validate our method for the determination of minimal forearm vascular resistance after ischemia (13 min arterial occlusion and 1 min hand exercise) in patients with hypertension. This parameter, calculated as the ratio of mean blood pressure (intra-arterial recordings on the experimental ...

1. The influence of hypoventilation or hyperventilation on blood pressure and pulse rate responses to verapamil and nifedipine was studied in chloralose-anaesthetized rats. 2. Artificial ventilation with room air at a fixed volume of 10 ml kg-1 successfully induced combinations of hypoxaemia, hypercarbia and acidosis at a ventilator rate of ...

Both human endothelin 1 (ET1) and rat endothelin 3 (ET3) produced dose-dependent pressor effects in the pithed rat. The pressor actions of ET3 and arginine vasopressin (AVP) were compared with one another in pithed rats in the presence of the calcium channel activator BAY K 8644 or the calcium channel ...

In patients with hypertension persisting on combined diuretic and beta-blocker therapy, the effects of an additional 9-week therapy with a calcium antagonist (nifedipine) versus a classical arterial vasodilator (hydralazine) were compared for changes in blood pressure (BP), plasma catecholamines (n = 15), and left ventricular (LV) systolic and diastolic function ...

Many of the newer antiarrhythmic agents are said to cause minimal myocardial depression, but their hemodynamic effects have not been invasively evaluated and compared in patients with severe chronic heart failure. In a randomized, crossover study, the hemodynamic responses to single oral doses of procainamide (750 mg), tocainide (600 mg), ...

Nifedipine is a calcium channel blocker that reduces blood pressure and increases renal blood flow. This double-blind investigation evaluated the effect of nifedipine in postpartum patients with severe preeclampsia. Thirty-one patients were randomized to receive either nifedipine (10 mg) or placebo every 4 hours beginning immediately after delivery. Data analysis ...

Experiments were performed in pentobarbital-anesthetized rats to evaluate the dependence of the effector limb of the tubuloglomerular feedback mechanism on transmembrane calcium flux through potential-operated calcium channels. Peritubular capillary infusions of the calcium channel blockers, verapamil and nifedipine, were used to achieve high intrarenal levels without influencing arterial blood pressure. ...

The dihydropyridine derivatives constitute a distinct subcategory of calcium channel blockers that have marked peripheral vascular effects with minimal or no electrophysiologic actions when administered to intact animals or humans. These dihydropyridine derivatives are structurally similar to nifedipine, the most widely studied dihydropyridine. The derivatives have varying affinities for different ...

We assessed the efficacy of long-acting nifedipine as monotherapy in 52 patients with mild to moderate essential hypertension in a randomized, controlled crossover study. Good blood pressure control was achieved in 34 of 40 patients (85%) receiving nifedipine (mean daily dose, 52 mg in 2 divided doses) compared with 23 ...

Hypertensive crises require immediate therapy, usually by parenteral drug administration. Sublingual nifedipine has been shown to be highly effective. However, the blood pressure fall following nifedipine is frequently associated with side-effects. The use of sublingual captopril has recently been indicated in hypertensive crisis, assuming that by this route, there would ...

We investigated the acute effects of nifedipine (10 mg orally) on renin and systemic hemodynamics in twelve patients who had severe hypertension (diastolic values averaging 114 mm Hg) with unilateral renal artery stenosis (angiography) and hyperreninemia. Plasma renin activity was determined from blood samples drawn from the aorta and from ...

The results of a variety of studies that have investigated the effect of age on the pharmacokinetics and pharmacodynamics of calcium antagonist drugs have produced the following conclusions. Primarily, as a result of an age-dependent decline in plasma drug clearance, there is a tendency for elderly patients to have higher ...

Haemodynamic effects of nifedipine (NIF) tablets were studied for 12 h in 10 patients with severe congestive heart failure due to ischaemic heart disease. A significant reduction (p less than 0.001) in systemic and pulmonary vascular resistances and pulmonary capillary wedge pressure, was observed, at rest and after hand grip ...