Acute hemodynamic effects of intravenous nicardipine in patients treated chronically with propranolol for coronary artery disease

Comparison of the Effects of Nicardipine and Sodium Nitroprusside for Control of Increased Blood Pressure after Coronary Artery Bypass Graft Surgery

We compared the haemodynamic effects of nicardipine and sodium nitroprusside after coronary artery bypass graft surgery. When post-surgery systolic blood pressure reached > 150 mmHg, patients were randomly given nicardipine (N group, n = 26) or sodium nitroprusside (S group, n = 21). The drugs were infused at a rate of 2 μg/kg per min for 10 min. If the target blood pressure (120-140 mmHg) was not achieved, the infusion rate was increased by 1 üg/kg per min every 10 min. Cardiac and stroke volume indices had increased significantly in the N group after 10 min and in both groups after 60 min. The infusion duration and total dose of drug were significantly lower in the N group compared with the S group. Nicardipine infusion controlled post-operative hypertension more rapidly and was superior to sodium nitroprusside in maintaining left ventricular performance immediately after drug infusion.

Coronary vasomotion during dynamic exercise: influence of intravenous and intracoronary nicardipine

OBJECTIVES

Our aim was to evaluate the influence of a calcium channel blocking agent of the dihydropyridine group (nicardipine) on coronary vasomotion during dynamic exercise.

BACKGROUND

Coronary vasomotion plays an important role in the pathophysiology of myocardial ischemia.

METHODS

Twenty-nine patients with coronary artery disease were studied at rest and during bicycle exercise with the use of biplane quantitative coronary angiography. Twelve patients without pretreatment (group 1) served as control subjects. Seventeen patients (group 2) received nicardipine, either 0.2 mg by intracoronary injection (n = 9) or 2.5 mg intravenously (n = 8) before exercise.

RESULTS

In the control group there was exercise-induced vasoconstriction (-29%, p < 0.001) of the stenotic segment but coronary vasodilation (+22%, p < 0.05) of the normal vessel segment. In group 2, nicardipine induced coronary vasodilation of both the normal (+16%, p < 0.001) and the stenotic vessel segment (+35%). During subsequent exercise there was some additional vasodilation of normal (+4%, p = NS) and stenotic arteries (+5%, p = NS). There was no difference between either intracoronary or intravenous nicardipine with regard to vasodilation. Application of sublingual nitroglycerin was associated with significant vasodilation of the normal vessel segment in groups 1 (+18%, p < 0.05) and 2 (+15%, p < 0.001). The stenotic vessels showed a significant increase in percent cross-sectional area after nitroglycerin in groups 1 (+12%, p = NS) and 2 (+51%, p < 0.001). Exertional angina pectoris occurred less frequently in group 2 (18%) than in group 1 (67% [p < 0.005 vs. group 2]); group 2 also had a smaller increase in mean pulmonary artery pressure (+14 vs. +21 mm Hg, p < 0.05).

CONCLUSIONS

Exercise induces vasoconstriction of stenotic, but vasodilation of normal, coronary vessel segments. Intravenous and intracoronary nicardipine prevent vasoconstriction of stenotic coronary arteries during exercise and exert a significant anti-ischemic effect. The combination of two anti-ischemic drugs, nitroglycerin and nicardipine, has an additive effect on coronary vasomotion that is seen only in the stenotic vessel segment. Thus, the anti-ischemic action of nicardipine is mainly due to a primary effect on coronary vasomotor response rather than to secondary effects such as changes in loading conditions.

Combination Therapy with Nicardipine and Beta-Adrenergic Blockade for Angina Pectoris

Nicardipine a second-generation dihidropyridine calcium antagonist, has been approved in oral formulation for use in the United States, and is under review for parenteral use. Nicardipine is the most vascular-selective agent of this class currently approved and should, on theoretical grounds, be ideal for combination therapy with beta-adrenergic blocking agents. Studies have shown that the combination of nicardipine and beta-blocking agents offers additional efficacy over monotherapy with either agent alone. The hemodynamic profile of combination therapy appears to be especially favorable in patients with diminished left ventricular function needing therapy with agents of both classes. Adverse effects are few and may be improved compared with other agents of the dihidropyridine class.

Comparison of nicardipine and sodium nitroprusside in the treatment of paroxysmal hypertension following aortocoronary bypass surgery

In an open, randomized, multicenter trial, intravenous nicardipine was compared with sodium nitroprusside in 74 patients with hypertension (mean arterial pressure [MAP] greater than or equal to 100 mm Hg) following coronary artery bypass surgery. Nicardipine was administered as a 2.5- to 12.5-mg bolus followed by a 2 to 4 mg/h infusion, and nitroprusside as a 0.5 to 6.0 micrograms/kg/min infusion. The aim was to reduce MAP to less than 90 mm Hg within 50 minutes and maintain it stable at 85 +/- 5 mm Hg. Nicardipine was effective in 35 of 38 patients (92%), and nitroprusside in 29 of 36 (81%) (NS). The decrease in MAP was not statistically different, but time until reaching the therapeutic end-point was shorter with nicardipine (P less than 0.01). Significant differences follow: increase in heart rate and decreases in mean pulmonary artery, right atrial, and pulmonary capillary wedge pressures were more marked with nitroprusside (P less than 0.01 and P less than 0.05, respectively), whereas elevation of cardiac index and depression of systemic vascular resistance were more marked with nicardipine (P less than 0.01 and P less than 0.05, respectively). Postreduction MAP was more stable with nicardipine, 51% +/- 24% of readings falling within the range 85 +/- 5 mm Hg versus 41% +/- 18% on nitroprusside (P = 0.058). Dose adjustment during the following 24 hours was less frequent with nicardipine, 1.1 +/- 1.6 versus 2.7 +/- 2.6 (P less than 0.01). Transfused blood volume was lower with nicardipine (924 +/- 644 mL) than nitroprusside (1,306 +/- 901 mL) (P = 0.08), despite similar postoperative blood losses.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute effects of intravenous nicardipine on hemodynamics and cardiac function in patients with a healed myocardial infarction and no evidence of congestive heart failure

Acute effects of intravenous nicardipine (10 micrograms/kg) on systemic hemodynamics and cardiac function were evaluated in 17 patients with a healed myocardial infarction and no evidence of congestive heart failure. Mean New York Heart Association functional class was 1.6 +/- 0.5 (mean +/- standard deviation). Aortic systolic pressure (p less than 0.001) and left ventricular end-diastolic pressure decreased (10 +/- 3 to 8 +/- 3 mm Hg, p less than 0.01), and systemic vascular resistance decreased significantly (p less than 0.001), whereas pulmonary and right atrial pressure and pulmonary arteriolar resistance did not change. Cardiac and stroke indexes showed biphasic changes. Although positive and negative maximal rate of left ventricular pressures decreased significantly (p less than 0.05 and p less than 0.01, respectively), they did not change significantly when aortic systolic pressure was corrected. There was a significant inverse correlation between the negative rate of left ventricular pressure/aortic systolic pressure before nicardipine infusion and its maximal percent increase after infusion (r = -0.56, p less than 0.05), indicating a beneficial effect on diastolic relaxation in patients with impaired diastolic function. Our data show that a low dose (10 micrograms/kg) of intravenous nicardipine exerts a favorable effect on impaired diastolic function, but depresses left ventricular pump function with much less effect on right heart circulation.

Kinetics and hemodynamic effects of intravenous nicardipine modified by previous propranolol oral treatment

Intravenous nicardipine, 5 mg, was administered in two comparable groups of eight patients with chronic coronary artery disease but no clinical signs of heart failure. One group had received no previous treatment and served as a control group, and the other had received long-term treatment with large oral doses of propranolol. Blood concentrations of nicardipine were higher, and the area under the plasma concentration curve was greater in the group previously treated by propranolol. The total clearance of nicardipine was decreased in patients taking propranolol, without a change in the half-life of the drug. Typical hemodynamic responses, namely, a decrease in aortic pressure and in arterial resistances, were greater and more lasting in patients previously treated orally by propranolol. Filling pressure remained stable in both groups. The nicardipine infusion did not induce signs of dromotropic or inotropic negative effects in either group. The greater and more lasting hemodynamic effects of nicardipine in the group previously treated orally by propranolol do not seem to be related to an overall hemodynamic action of propranolol, but are probably due to higher nicardipine plasma levels, and may be caused by a decrease in hepatic blood flow induced by propranolol, with a consequent decrease in nicardipine clearance and by a smaller nicardipine volume of distribution in the propranolol group.

Clinical pharmacology, pharmacokinetics, and hemodynamic effects of nicardipine

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 regional circulations, and there may be an important relationship between structure and activity of these compounds with respect to the predilection of the site of their action in vascular tissue. It is possible that such differences may be of clinical significance. As a class, the dihydropyridines exert reasonably distinct hemodynamic changes that may be of particular importance in the treatment of hypertension, cardiac failure, and regurgitant valvular lesions. Nicardipine hydrochloride is a newer agent that has undergone extensive evaluation in recent years. Pharmacologically and electrophysiologically, it resembles other dihydropyridines. Unlike nifedipine, however, it can be administered by both the intravenous and oral routes. There are additional differences between its properties and those of other calcium channel blockers. For example, nicardipine appears to produce a greater increase in coronary sinus blood flow than other calcium channel blockers. The clinical significance of this finding is unclear. In addition, nicardipine appears to increase myocardial contractility, even in patients with severe congestive cardiac failure. Nicardipine produces a dose-dependent decrease in blood pressure and systemic vascular resistance with increases in heart rate, left ventricular dP/dt, LV ejection fraction, cardiac output, and stroke work index, but no significant change in LV end-diastolic pressure. Clearly, the drug has negligible venodilator actions.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of nitrates, beta blockers, and calcium antagonists in stable angina pectoris

Numerous controlled studies have shown that nitrates, beta blockers, and calcium antagonists are effective in the treatment of stable angina pectoris. The pharmacokinetics, pharmacodynamics, and hemodynamic effects of these agents are different, and thus combination therapy offers additive improvement and also counterbalancing of the undesirable side effects of each drug. The choice of therapy depends on the severity of symptoms, associated diseases, compliance, side effects, and status of left ventricular function. The main mechanism of improvement is a decrease in myocardial oxygen consumption, though an increase in coronary blood flow is another potential reason for the use of calcium blockers. This review considers the properties of these drugs, their mechanism of action, and the results of randomized studies.

Calcium channel antagonists. Part IV: Side effects and contraindications drug interactions and combinations

With the correct selection of drug and patient, the calcium antagonists as a group can be remarkably effective at relatively low cost of serious side effects. Almost all side effects are dose related. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil (or diltiazem) is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine which actually has the most marked negative inotropic effect. Yet caution is required when even calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide. The most marked interaction with digoxin is that with verapamil, which may raise digoxin levels by over 50%. Combination therapy of calcium antagonists with beta-blockers is increasingly common, and is probably safest in the case of dihydropyridines. Other combinations being explored are those with angiotensin-converting enzyme inhibitors and diuretics.