Effects of felodipine, metoprolol and their combination on blood pressure at rest and during exercise and on volume regulatory hormones in hypertensive patients

The effects on blood pressure (BP) and heart rate (HR), at rest and during bicycle exercise, of the vascular selective calcium antagonist felodipine, the cardio-selective beta-blocker metoprolol, and of the two drugs in combination, were assessed in a double-blind, three-way cross-over study comprising 23 patients with essential, mild to moderate hypertension. All three treatment regimens were given to each patient in randomised order for 4 weeks after a 4 week placebo run-in period. Felodipine 10-20 mg daily, metoprolol 100-200 mg daily and the combination of felodipine 10-20 mg plus metoprolol 100 mg daily were all effective antihypertensive treatments both at rest and during exercise. The two drugs seemed to have additive effects and the effect on BP of the combination was greater than that of either drug given as monotherapy. The mean sitting BP was 148/103 mmHg at randomisation, after 4 weeks of placebo treatment, and 134/88, 134/94 and 121/84 mmHg, respectively, after 4 weeks' treatment with felodipine, metoprolol and the combination. Maximal exercise capacity was similar irrespective of treatment regimen, and the normal response to exercise BP and HR was maintained during all active treatments. Changes observed in volume regulatory hormones (PRA, aldosterone and ANP) were consistent with a direct tubular natriuretic-diuretic effect of felodipine and of beta-blocker attenuated release of renin. All treatment regimens were well tolerated and adverse events reported were usually mild and transient.

Metoprolol treatment for two years after coronary bypass grafting: effects on exercise capacity and signs of myocardial ischaemia

OBJECTIVE

To evaluate whether prophylactic treatment with metoprolol for two years after coronary artery bypass grafting improves working capacity and reduces the occurrence of myocardial ischaemia in patients with coronary artery disease.

METHODS

After coronary artery bypass grafting, patients were randomised to treatment with metoprolol or placebo for two years. Two years after randomisation, a computerised 12-lead electrocardiogram was obtained during a standardised bicycle exercise test in 618 patients (64% of all those randomised).

RESULTS

The median exercise capacity was 140 W in the metoprolol group (n = 307) and 130 W in the placebo group (n = 311) (P > 0.20). An ST depression of > or = 1 mm at maximum exercise was present in 34% of the patients in the metoprolol group and 38% in the placebo group (P > 0.20) and an ST depression of > or = 2 mm at maximum exercise was present in 11% in the metoprolol group and 16% in the placebo group (P = 0.09). The median values for maximum systolic blood pressure were 200 mm Hg in the metoprolol group and 210 mm Hg in the placebo group (P < 0.0001), while the median values for maximum heart rate were 126 beats/min in the metoprolol group and 143 beats/min in the placebo group (P < 0.0001). The occurrence of cardiac and neurological clinical events two years postoperatively among exercised patients was comparable in the treatment groups.

CONCLUSIONS

Treatment with metoprolol for two years after coronary artery bypass grafting did not significantly change exercise capacity or electrocardiographic signs of myocardial ischaemia.

Primary prevention in patients with coronary heart disease: the APSIS study

Symptomatic treatment of patients with angina pectoris is well established and consists of nitrates, calcium antagonists, or beta-blockers. All these drugs improve symptomatology and reduce signs of ischemia on exercise test or long-term electrocardiogram recordings. It is not known, however, whether these drugs also improve prognosis. The only drug shown to improve prognosis is aspirin. In order to study the prognostic effect of calcium antagonists and beta-blockers, these two drugs were compared in the APSIS study.

Effects of beta receptor antagonists in patients with clinical evidence of heart failure after myocardial infarction: double blind comparison of metoprolol and xamoterol

OBJECTIVE

To evaluate whether xamoterol, a partial agonist, would improve exercise time more than metoprolol in patients with mild to moderate heart failure after a myocardial infarction.

DESIGN

Single-centre double blind randomised parallel group comparison of metoprolol 50-100 mg and xamoterol 100-200 mg twice daily.

PATIENTS

210 patients aged 40-80 years (173 men) with clinical evidence of heart failure early after a myocardial infarction. 106 were given metoprolol and 104 xamoterol.

MAIN OUTCOME MEASURES

Exercise test results and performance at three months; the exercise test, quality of life, and clinical assessments at baseline (5-7 days after the infarction) and after 3, 6, and 12 months.

RESULTS

Exercise time increased at three months by 22% in the metoprolol group and 29% in the xamoterol group, but with no significant difference between the groups. Patients taking xamoterol showed overall non-significantly higher mean values of exercise time achieved with higher heart rates at rest and exercise. Improvements in quality of life, clinical signs of heart failure, and New York Heart Association functional class were seen in both treatment groups over one year, with minor benefits of xamoterol on breathlessness, peripheral oedema, and functional class. Eighteen patients taking metoprolol and 22 taking xamoterol withdrew from the study during one year, with a low mortality, reinfarction rate, and progress of heart failure in both treatment groups. Mean dose from baseline to 3 months was 135 mg metoprolol and 347 mg xamoterol.

CONCLUSION

beta 1 Receptor antagonists with or without partial agonist activity are safe to use in mild to moderate heart failure after a myocardial infarction. Exercise tolerance, quality of life, and clinical signs and functional class of heart failure improve, and few patients show deterioration in their condition. Exercise tolerance is no better with xamoterol than metoprolol.

Improving the therapeutic balance between efficacy and tolerability in antihypertensive drugs--the rationale and benefits of combining felodipine and metoprolol

Several studies, most recently the Starnberg Study on Epidemiology of Parkinsonism and Hypertension in the Elderly (STEPHY), have shown that BP is not adequately controlled in a substantial proportion of treated hypertensive patients. This finding highlights the need for new treatment strategies that are sufficiently effective throughout the dosing interval, well tolerated, and available in a convenient, once-daily regimen. Monotherapy with any individual drug class is often unable to fulfil all of these criteria in more than a minority of patients. In contrast, once-daily therapy with rational combinations of antihypertensive drugs offers a promising approach to improving treatment of hypertension. The highly vascular selective calcium antagonist felodipine and the cardioselective beta-blocker metoprolol have complementary mechanisms of action, making them appropriate for use together in the management of hypertension. A new extended-release (ER) formulation, combining felodipine, 5 mg, and metoprolol, 50 mg*, has therefore been developed. This formulation has been shown to provide significantly greater reductions and higher antihypertensive response rates than either agent used alone. This high efficacy is achieved with maintained good tolerability. In comparative trials, felodipine-metoprolol has also been shown to be more effective than combination treatment with nifedipine and atenolol, or captopril and hydrochlorothiazide. It is concluded that the felodipine-metoprolol ER tablet offers predictably high 24 h antihypertensive response rates from a convenient and well-tolerated once-daily dose.

New directions in the treatment of heart failure: some paradoxical observations

The alpha-agonist drug phenylephrine has been generally considered to be contraindicated in patients with heart failure for the reason that increased afterload produced by the vasoconstriction should decrease ventricular function; the beta-adrenergic blocking drugs generally have been considered to be contraindicated in heart failure because of the dependence of the failing heart on beta-sympathetic agonism; the angiotensin converting enzyme inhibitors have been indicted recently as causing undesirable cardiovascular depression in patients for coronary artery bypass surgery. Yet recently, phenylephrine has been shown to have positive cardiac inotropic effects in a variety of experimental preparations including intact humans; the beta-adrenergic blocking drugs have been shown to be therapeutically effective in treating patients with chronic congestive heart failure (CHF); and the "gold standard" for treating chronic CHF at present are the ACEI. Consequently, the clinician caring for patients with cardiac disease needs to reevaluate the use of classic drugs whose original pharmacological properties may either have changed because of advances in technology or may be producing effects that were unanticipated previously.

Utility of beta-blockade treatment for older postinfarction patients

OBJECTIVE

The prevalence of myocardial infarction (MI) in older people is high. Whereas use of beta-blockers after MI is known to lower MI mortality in younger adults, its efficacy for adults more than 75 years of age remains less clear. We hypothesized that use of beta-blockers after MI in older adults would improve clinical outcomes.

DESIGN

Retrospective cohort study.

SETTING

A community-based, tertiary-care teaching hospital.

METHODS

A total of 1011 consecutive MI patients aged 60 to 89 were admitted to Boston's Beth Israel Hospital between January 1988 and September 1989 and were screened for this study. One hundred eighteen patients met eligibility criteria, of whom 76 received metoprolol, > or = 25 mg/day for at least 5 days after their MI. Forty-two age and clinically matched patients were similarly suitable for beta-blocker therapy, but it was omitted by their physicians during and after hospitalization. The latter group served as controls.

MEASUREMENTS

Mortality, reinfarction, and subsequent hospital admissions were measured.

RESULTS

MI patients aged 60 to 89 years who were treated with metoprolol had an age-adjusted mortality reduction of 76% (RR 0.24; P < .001; 95% CI 0.11-0.54). Multivariate logistic regression analysis showed a 12% mortality reduction (95% CI 0.75-1.00) among older MI patients, attributable to metoprolol therapy. Reinfarction rates were unchanged in patients receiving metoprolol therapy, and subsequent rehospitalizations were significantly increased among the metoprolol patients.

CONCLUSIONS

Use of metoprolol significantly reduced mortality in older MI patients. The fact that metoprolol-treated patients had neither reduced reinfarctions or rehospitalizations may relate to methologic limitations of this study. The mortality data support the hypothesis that older patients benefit from postinfarction beta-blockade.

[The effect of treatment with propafenone, metoprolol and amiodarone on lymphocyte sodium efflux and level of cAMP in serum]

The effect of long-term treatment with propafenone, metoprolol and amiodarone was studied on the activity of Na,K-adenosine triphosphatase in lymphocytes and the plasma level of cAMP in patients with ventricular arrhythmias. The investigations were carried out in 86 patients with cardiac dysrhythmias caused by coronary artery disease, hypertension, post-inflammatory and alcohol cardiomyopathy and preexcitation syndrome. Propafenone was used in treatment in 31 patients, metoprolol in 30, amiodarone in 25. The activity of of Na,K-adenosine triphosphatase in lymphocytes was estimated by the method of Heagerty et al. The plasma level of cAMP was measured radioimmunologically. Disappearance of ventricular arrhythmias after treatment was accompanied by increase in activity of of Na,K-adenosine triphosphatase and decrease in plasma level of cAMP regardless of which drug was used. Ineffective treatment did not affect both parameters.

Antifibrillary action of class I-IV antiarrhythmic agents in the model of ventricular fibrillation threshold of anesthetized guinea pigs

We compared the effects of class I-IV antiarrhythmic agents on the ventricular fibrillation threshold (VFT) induced by electrical stimulation directly on the myocardium in anesthetized, open-chest guinea pigs. VFT was assessed by determining the intensity (mA) of electrical current required to induce ventricular fibrillation (VF) and is expressed as a percentage change of the baseline premedication value. The following antiarrhythmic agents or their solvent were administered intravenously (i.v.) to pentobarbital-anesthetized animals (n = 6-12 per group): class I antiarrhythmic agent encainide (1.5 mg/kg); class II antiarrhythmic agents atenolol (2.5 mg/kg), metoprolol (2.5 mg/kg), and nebivolol (2.5 mg/kg); class III antiarrhythmic agents dofetilide (0.08 mg/kg), terikalant (0.04 mg/kg), and DL-sotalolol (10 mg/kg); and class IV antiarrhythmic agent verapamil (0.16 mg/kg). The antiarrhythmic compounds or their solvents resulted in the following changes in the VFT at 15 min after treatment: saline control, 1 +/- 14% (mean +/- SEM) from its baseline value; 10% hydroxypropyl-beta-cyclodextrine (CD), 4 +/- 13%; encainide, 183 +/- 46% (p < 0.05 vs. saline); atenolol, 66 +/- 23% (p > 0.05 vs. saline); metoprolol, 89 +/- 25% (p > 0.05 vs. saline); nebivolol, 224 +/- 58% (p < 0.05 vs. 10% CD); DL-sotalol, 485 +/- 119% (p < 0.05 vs. saline); dofetilide, 357 +/- 69% (p < 0.05 vs. saline); terikalant, 487 +/- 183% (p < 0.05 vs. saline), and verapamil, -17 +/- 21% (p > 0.05 vs. saline). At the doses used, all compounds significantly reduced heart rate (HR).(ABSTRACT TRUNCATED AT 250 WORDS)

A felodipine-metoprolol extended-release tablet: its properties and clinical development

The current failure of antihypertensive therapy to control BP in many hypertensive patients highlights the need for new treatment strategies. Ideally, these new strategies should provide reliable, effective 24 h BP control in all types of patients with a convenient, well-tolerated regimen. Logimax, an extended-release tablet containing felodipine and metoprolol, has been developed, which provides more effective control of BP in a wider range of patients than either component as monotherapy, without compromising tolerability. This combination increases the likelihood of achieving target BP and is therefore likely to provide further reductions in cardiovascular risk.

[The effect of hypotensive drugs on left ventricular mass and diastolic function]

Chronic left ventricular hypertrophy (LVH) is associated with depressed contractile performance, abnormal compliance of the chamber, and ultimately, the development of a left ventricular failure. Thus the presence of LVH carries a particularly ominous prognosis in patients with essential hypertension. Finally, regression of LVH appears to be a worthwhile goal of an antihypertensive therapy along with blood pressure control. Of particular importance, is whether the functional derangements associated with hypertrophy will also be reversed. The present study was undertaken to determine whether antihypertensive therapy reduced ventricular mass, and whether these changes were accompanied by improved diastolic function. 47 patients with mild-to-moderate essential hypertension were divided into two groups. Group I--included 21 patients whose blood pressure responded to nifedipine monotherapy. Group II--included 26 patients whose normalization of blood pressure required combined therapy with nifedipine and metoprolol. 40 healthy volunteers comprised a control group. To assess the effects of antihypertensive therapy on the heart, left ventricular mas (LVM), systolic and diastolic function, by M-mode, 2-D and pulsed wave Doppler echocardiography had been evaluated. Measurements were performed before therapy and every 3rd month during first year, and every 40th month during the second year of observation. RESULTS. At baseline all hypertensive patients had significantly increased LVM compared to the controls. Indexes of systolic function in studied patients were normal, while indexes of LV diastolic filling were significantly abnormal compared to the controls. In the group treated with nifedipine, starting from the 9th month of observation, small but significant decrease in posterior wall thickness was noted but LVM did not change during the whole time of the observation. Similarly, there was no significant change in indexes of left ventricular diastolic filling. Contrary to patients treated with nifedipine, in group of patients treated with combination of nifedipine and metoprolol, significant reduction of LVM and improvement of LV diastolic filling was observed. Of particular interest was the fact, that improvement in diastolic, performance appeared earlier, and preceded regression of LVM. Most striking was the improvement in Ev/Av ratio which increased by 16% after 6 months and by 35% after 24 months of the therapy. CONCLUSION. 1. Combined therapy with nifedipine and metoprolol contrary to monotherapy with nifedipine alone, results in the regression of left ventricular mass and the improvement of left ventricular diastolic function. 2. Improvement of left ventricular diastolic function appears earlier, preceding the regression of left ventricular hypertrophy.

[Analysis of heart rhythm variability in evaluation of treatment for unstable angina pectoris]

Unstable angina pectoris is accompanied by several unfavourable autonomic disturbances. A noninvasive assessment of the autonomic cardiac control is possible by means of heart rate variability analysis (HRV). 26 patients with unstable angina pectoris were enrolled in the study. All patients received obligatory nitroglycerin and heparin intravenously within two days, and gallopamil (G) or metoprolol (M) together with aspirin or ticlopidine orally randomly, which were continued for 3 month or shorter if coronary revascularization was earlier performed. 512 R-R intervals was registered in each patient at 7th day of hospitalization and in 14th at the time of admission. Kardioassist v.1.0 system was used for heart rate variability analysis. After analog to digital conversion, with 12 bit resolution and 1000 Hz of sampling rate, seriogram of R-R intervals was obtained, and then power spectrum density was computed with the Fast Fourier Transform. Time-domain analysis provided mean (basic) R-R interval (BCL) and its standard deviation (SD-RR). In frequency-domain the following spectral variables were analysed: power spectral density (s2/Hz) of the high frequency component (aHF, 0.15-035 Hz), low frequency component (aLF, 0.05-0.15 Hz) and very low frequency component (aVLF, 0.004-0.05 Hz), percentage power of respective components (%HF, %LF and %VLF) and autonomic balance indices: aLF:aHF and %LF:%HF. These variables were compared in patients treated with G (13 patients) against those with M (13 patients). Additionally, the effects of treatment regimen was evaluated also in 14 patients, in whom HRV analysis was performed at admission and 7 days later.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection of medical treatment in stable angina pectoris: results of the International Multicenter Angina Exercise (IMAGE) Study

OBJECTIVES

The present study was designed to investigate which characteristics of anginal symptoms or exercise test results could predict the favorable anti-ischemic effect of the beta-adrenergic blocking agent metoprolol and the calcium antagonist nifedipine in patients with stable angina pectoris.

BACKGROUND

The characteristics of anginal symptoms and the results of exercise testing are considered of great importance for selecting medical treatment in patients with chronic stable angina pectoris. However, little information is available on how this first evaluation may be used to select the best pharmacologic approach in individual patients.

METHODS

In this prospective multicenter study, 280 patients with stable angina pectoris were enrolled in 25 European centers. After baseline evaluation, consisting of an exercise test and a questionnaire investigating patients' anginal symptoms, the patients were randomly allocated to double-blind treatment for 6 weeks with either metoprolol (Controlled Release, 200 mg once daily) or nifedipine (Retard, 20 mg twice daily) according to a parallel group design. At the end of this period, exercise tests were repeated 1 to 4 h after drug intake.

RESULTS

Both metoprolol and nifedipine prolonged exercise tolerance over baseline levels; the improvement was greater in the patients receiving metoprolol (p < 0.05). Multivariate analysis revealed that low exercise tolerance was the only variable associated with a more favorable effect within each treatment group. Metoprolol was more effective than nifedipine in patients with a lower exercise tolerance or with a higher rate-pressure product at rest and at ischemic threshold. None of the characteristics of anginal symptoms or exercise test results predicted a greater efficacy of nifedipine over metoprolol.

CONCLUSIONS

The results of a baseline exercise test, but not the characteristics of anginal symptoms, may offer useful information for selecting medical treatment in stable angina pectoris.

[Akinetic mutism in decompensated triventricular hydrocephalus]

The case of a 21-year-old man with obstructive hydrocephalus who suffered multiple shunt failures is presented. The patient developed a syndrome of akinetic mutism that improved after administration of bromocriptine and metoprolol.

Time course of improvement in left ventricular function, mass and geometry in patients with congestive heart failure treated with beta-adrenergic blockade

OBJECTIVES

We examined the time course of ventricular functional improvement in patients with dilated cardiomyopathy who received beta-blockade and the long-term effects of beta-blockade on ventricular mass and geometry in these patients.

BACKGROUND

Previous studies have shown that beta-adrenergic blocking agents when administered long term improve ventricular function in patients with heart failure. However, the time course of improvement in ventricular function and the long-term effects of beta-blockade on ventricular mass and geometry are not known.

METHODS

Twenty-six men with dilated cardiomyopathy underwent serial echocardiography on days 0 and 1 and months 1 and 3 of either metoprolol (n = 16) or standard therapy (n = 10). At 3 months all patients on standard therapy were crossed over to metoprolol, and late echocardiograms were obtained after 18 +/- 5 (mean +/- SD) months of metoprolol therapy. All echocardiograms were read in blinded manner.

RESULTS

Patients treated with metoprolol had an initial decline (day 1 vs. day 0) in ventricular function (increase in end-systolic volume and decrease in ejection fraction). Ventricular function improved between months 1 and 3 (p = 0.013, metoprolol vs. standard therapy). Left ventricular mass regressed at 18 months (333 +/- 85 to 275 +/- 53 g, p = 0.011) but not at 3 months. Left ventricular shape became less spherical and assumed a more normal elliptical shape by 18 months (major/minor axis ratio 1.5 +/- 0.2 to 1.7 +/- 0.2, p = 0.0001).

CONCLUSIONS

Patients with heart failure treated with metoprolol do not demonstrate an improvement in systolic performance until after 1 month of therapy and may have a mild reduction in function initially. Long-term therapy with metoprolol results in a reversal of maladaptive remodeling with reduction in left ventricular volumes, regression of left ventricular mass and improved ventricular geometry by 18 months.

Angiotensin-converting enzyme inhibitors and beta-blockers in long-term treatment of dilated cardiomyopathy

This double-blind, randomized, long-term study investigated the effects of the angiotensin-converting enzyme inhibitor enalapril and the beta-blocker metoprolol on clinical, hemodynamic, angiographic, and neurohormonal parameters in patients with dilated cardiomyopathy and moderate cardiac functional impairment (left ventricular ejection fraction [LVEF] 35% +/- 6%). After 12 months of treatment, a 12% reduction in 24-hour heart rate was observed in both groups (p < 0.05), whereas heart rate during exercise was reduced only in the metoprolol group. Echocardiographic fractional shortening increased (enalapril: 17% +/- 6% to 21% +/- 7%; metoprolol: 21% +/- 9% to 29% +/- 7%; both p < 0.05), as did the angiographic LVEF (enalapril: 35% +/- 7% to 43% +/- 12%, p = 0.1; metoprolol: 34% +/- 7% to 44% +/- 9%, p < 0.05), whereas ventricular volume decreased. Initially, both groups were comparable in terms of all parameters investigated. After 12 months fractional shortening was greater, and the heart rate at 50 W was lower in the beta-blocker group. At the doses used, the effect of the beta-blocker on dilated cardiomyopathy with moderate functional impairment was at least as great as that of the angiotensin-converting enzyme inhibitor.

[Adrenergic betablockers and heart failure]

Several studies have shown that beta-blockade could provide functional benefit in heart failure, suggesting a deleterious role for the compensatory sympathetic stimulation. Betablockers induced benefit could result from either antagonism of myocardial beta-adrenergic stimulation or, on the contrary a paradoxical increased cardiac beta-adrenergic responsiveness secondary to beta-adrenergic receptor up-regulation. Two recently completed large scale multicentric placebo controlled studies, the MDC trial with metoprolol and CIBIS with bisoprolol, have confirmed that beta-blockade could functionally improve patients with heart failure. The observed survival improvement in non-ischaemic patients was observed only in the CIBIS trial. This result requires confirmation by additional studies.

Failure of intravenous metoprolol to limit acute myocardial infarct size in a nonreperfused porcine model

The usefulness of intravenous beta-adrenergic receptor blockade in limiting infarct size when neither reperfusion nor collateral flow occurs is unknown. The effect of intravenous metoprolol on limiting myocardial infarct size was therefore examined in a nonreperfused porcine model. Closed-chest techniques were used to occlude the left anterior descending coronary artery, after which animals were randomized at 20 minutes to receive intravenous metoprolol, 0.75 mg/kg, or placebo. Infarct size examined at 5 hours with Evans blue and triphenyltetrazolium staining techniques was expressed as a percentage of total ventricular myocardium at ischemic risk. This percentage was not significantly different between the groups (84% +/- 5% with metoprolol vs 90% +/- 4% with placebo; p = 0.4). Myocardial infarct size was not significantly decreased at 5 hours by early administration of intravenous metoprolol when the infarct artery remained occluded and collateral flow was minimal.

Left ventricular and aortic root structure and function changes with beta blocker antihypertensive therapy. A one-year double blind study of celiprolol and metoprolol

Using echocardiographic and Doppler methodology, we evaluated the effects of celiprolol 200-400 mg/day and metoprolol 100-200 mg/day, given for one year, on haemodynamics, left ventricular structure and function, and aortic root distensibility in 40 hypertensive patients. Total peripheral resistance was unchanged with metoprolol (-1.7%) but decreased with celiprolol (-11.2%), a significant difference between the two treatments (P = 0.01). Left ventricular mass index was reduced by 5.7% in those patients receiving metoprolol and by 11.8% in those receiving celiprolol (P < 0.001). Cardiac index fell significantly with metoprolol and marginally with celiprolol (-13.9% vs. 5.9%, P = 0.003). Left ventricular diastolic function-as shown by the transmitral early to late peak filling velocity ratio-was not altered with metoprolol, but a significant increase (17%, P = 0.2) was seen with celiprolol. Both metoprolol and celiprolol increased aortic root distensibility, with celiprolol having a significantly greater effect (80% vs. 30%, P < 0.01). We conclude that, in comparison to metoprolol, long term antihypertensive therapy with celiprolol improves left ventricular diastolic and aortic root function, whilst reducing total peripheral resistance and left ventricular hypertrophy.

Lymphocyte beta 2-receptor activity, metoprolol kinetics, and response to metoprolol in hypertensive black men

STUDY OBJECTIVES

To evaluate whether variability in S-metoprolol kinetics and lymphocyte beta 2-receptor-mediated cyclic adenosine monophosphate (cAMP) accumulation is related to the variability in antihypertensive response to metoprolol of black men.

DESIGN

Prospective, unblinded study.

SETTING

University-based preventive medicine clinic.

PATIENTS

Twelve hypertensive black men.

MEASUREMENTS AND MAIN RESULTS

Ambulatory blood pressure was measured over 24 hours before and after metoprolol administration. Ex vivo responsiveness of lymphocyte beta 2-receptors to isoproterenol was established for each subject before initiating metoprolol therapy. Plasma samples were collected over 12 hours at the conclusion of the study, from which metoprolol enantiomer concentrations were determined by chiral high-performance liquid chromatography, and kinetic values were calculated. The 24-hour ambulatory blood pressure responses to metoprolol were highly variable, with systolic blood pressure responses ranging from -13 to +33 mm Hg and diastolic blood pressure responses ranging from -15 to +15 mm Hg. There was a significant relationship between the metoprolol-induced change in systolic blood pressure and the maximum lymphocyte beta 2-receptor cAMP production (y = 0.47x-7.79; r2 = 0.49, p < 0.05) such that those with the highest maximum cAMP production had the greatest blood pressure increases during metoprolol therapy. There was no relationship between S-metoprolol concentration and blood pressure response. Mean oral clearance values for S- and R-metoprolol were 1320 and 2346 ml/minute, respectively.

CONCLUSIONS

Lymphocyte beta 2-receptor data suggest that individuals most responsive to beta-receptor stimulation may be at greatest risk of blood pressure elevation during beta 2-receptor blockade. The metoprolol enantiomer kinetic data are markedly different from previously published data and may represent racial differences in pharmacokinetics.

[The antihypertensive effect of the new cardioselective prolonged-action beta-adrenoblocker bisoprolol compared with propranolol, metoprolol and placebo]

The antihypertensive effect of daily doses of three beta-adrenoblockers (Bisoprolol, 10 mg once a day, propranolol, 80 mg twice a day, and methoprolol, 100 mg twice a day), and placebo was examined in 14 patients with persistent mild and moderate hypertension during a double blind cross-over study by using 24-hour monitoring of blood pressure and its routine measurements. The latter made by a mercury sphygmomanometer indicated that the antihypertensive and negative chronotropic effect of Bisoprolol in a dose of 10 mg remained 24 hours after its administration and it did not significantly differ from that of the two other agents given in the above doses. The application of 24-hour blood pressure monitoring allows a more pronounced antihypertensive effect of bisoprolol to be revealed during 24 hours than that displayed by the two agents. Bisoprolol is an effective and safe antihypertensive agent.

Metoprolol minimizes nighttime blood pressure dip in hypertensive black males

Twelve hypertensive black males completed the study, which was conducted to evaluate the effect of metoprolol on 24-h ambulatory blood pressure (ABP). Study participants took 50 mg to 100 mg metoprolol twice daily for a minimum of 3 weeks. Metoprolol had no significant effect on blood pressure (147/90 +/- 11/8 mm Hg v 151/88 +/- 16/8 mm Hg, baseline v treated, respectively) in spite of causing significant reductions in heart rate (87 +/- 9 beats/min v 69 +/- 7 beats/min, P < .001). Only one subject had a > or = 10 mm Hg decrease in 24-h diastolic blood pressure. The nighttime fall in blood pressure was minimized by metoprolol and clinically significant increases in daytime or nighttime blood pressure were noted in 58% of patients. Metoprolol therapy failed to lower blood pressure and eliminated the normal nighttime decline in blood pressure. Since the nighttime decline in blood pressure is thought to protect against target organ damage, it may be important to identify antihypertensive agents which preserve or enhance the nighttime blood pressure dip.

Hemodynamic and energetic comparison of bucindolol and metoprolol for the treatment of congestive heart failure

Although beta blockers have demonstrated a salutary effect on ventricular function in patients with heart failure, it is unclear whether a nonselective third-generation beta blocker produces different hemodynamic and energetic effects than a second-generation beta 1 selective agent. In 30 male patients with heart failure, we retrospectively analyzed hemodynamic data from 2 protocols examining the effects of a nonselective beta antagonist bucindolol (n = 15), and a highly selective beta 1 antagonist metoprolol (n = 15). Both studies were conducted in a similar fashion with patients undergoing cardiac catheterization before and after receiving 3 months of beta blockade. Both groups were matched at baseline in terms of ventricular function. beta blockade resulted in similar reductions in heart rate and similar improvements in ejection fraction, ventricular volumes, stroke and minute work, peak +dP/dt, and isovolumic relaxation in both groups. Only patients taking bucindolol had a significant within-group decrease in resting left ventricular end-diastolic pressure. The metoprolol group had a greater decrease in coronary sinus blood flow and myocardial oxygen consumption. Bucindolol increased cardiac index more than metoprolol, but did not increase stroke volume index more than metoprolol. The bucindolol group had an increase in systolic elastance, whereas the metoprolol group had a parallel left shift in this relation. Thus, metoprolol reduces coronary blood flow and myocardial oxygen consumption more than bucindolol, whereas bucindolol produces slightly more favorable improvements in resting cardiac index and end-diastolic pressure. Otherwise, these 2 agents produced similar hemodynamic changes.