Nebivolol in the treatment of cardiac failure: a double-blind controlled clinical trial

Sarcopenia and Endothelial Function in Patients With Chronic Heart Failure: Results From the Studies Investigating Comorbidities Aggravating Heart Failure (SICA-HF)

OBJECTIVES

Skeletal muscle wasting, also known as sarcopenia, has recently been identified as a serious comorbidity in patients with heart failure (HF). We aimed to assess the impact of sarcopenia on endothelial dysfunction in patients with HF with reduced ejection fraction (HFrEF) and with preserved ejection fraction (HFpEF).

DESIGN

Cross-sectional study.

SETTING

Ambulatory patients with HF were recruited at Charité Medical School, Campus Virchow-Klinikum, Berlin, Germany.

PARTICIPANTS

We assessed peripheral blood flow (arm and leg) in 228 patients with HF and 32 controls who participated in the Studies Investigating Comorbidities Aggravating HF (SICA-HF).

MEASUREMENTS

The appendicular skeletal muscle mass of the arms and the legs combined was assessed by dual energy x-ray absorptiometry (DEXA). Sarcopenia was defined as the appendicular muscle mass two standard deviations below the mean of a healthy reference group of adults aged 18 to 40 years, as suggested for the diagnosis of muscle wasting in healthy aging. All patients underwent a 6-minute walk test and spiroergometry testing. Forearm and leg blood flow were measured by venous occlusion plethysmography. Peak blood flow was assessed after a period of ischemia in the limbs to test endothelial function.

RESULTS

Sarcopenia was identified in 37 patients (19.5%). Patients with sarcopenia presented with lower baseline forearm blood flow (2.30 ± 1.21 vs. 3.06 ± 1.49 vs. 4.00 ± 1.66 mL min^-1 100 mL^-1; P = .02) than those without sarcopenia or controls. The group of patients with sarcopenia showed similar baseline leg blood flow (2.06 ± 1.62 vs. 2.39 ± 1.39 mL min^-1 100 mL^-1; P = .11) to those without but lower values when compared to controls (2.06 ± 1.62 vs. 2.99 ± 1.28 mL min^-1 100 mL^-1; P = .03). In addition, patients with and without sarcopenia presented with lower peak flow in the forearm when compared to controls (18.37 ± 7.07 vs. 22.19 ± 8.64 vs. 33.63 ± 8.57 mL min^-1 100 mL^-1; P < .001). A similar result was observed in the leg (10.89 ± 5.61 vs. 14.66 ± 7.19 vs. 21.37 ± 13.16 mL min^-1 100 mL^-1; P < .001). Peak flow in the forearm showed a significant correlation with exercise capacity (relative peak VO₂: R = 0.47; P < .001; absolute peak VO₂: R = 0.35; P < .001; and 6-min walk distance: R = 0.20; P < .01). Similar correlations were observed between peak flow in the leg and exercise capacity (absolute peak VO₂: R = 0.42, P < .001; relative peak VO₂: R = 0.41, P < .001; and 6-min walk test: R = 0.33; P < .001). Logistic regression showed peak flow in the leg to be independently associated with the 6-min walk distance adjusted for age, hemoglobin level, albumin, creatinine, presence of sarcopenia, and coronary artery disease (hazard ratio, 0.903; 95% confidence interval, 0.835-0.976; P = .01).

CONCLUSION

Patients with HF associated with sarcopenia have impaired endothelial function. Lower vasodilatation had a negative impact on exercise capacity, particularly prevalent in patients with sarcopenia.

A meta-analysis of the effects of β-adrenergic blockers in chronic heart failure

Adrenergic β-blockers are drugs that bind to, but do not activate β-adrenergic receptors. Instead they block the actions of β-adrenergic agonists and are used for the treatment of various diseases such as cardiac arrhythmias, angina pectoris, myocardial infarction, hypertension, headache, migraines, stress, anxiety, prostate cancer, and heart failure. Several meta-analysis studies have shown that β-blockers improve the heart function and reduce the risks of cardiovascular events, rate of mortality, and sudden death through chronic heart failure (CHF) of patients. The present study identified results from recent meta-analyses of β-adrenergic blockers and their usefulness in CHF. Databases including Medline/Embase/Cochrane Central Register of Controlled Trials (CENTRAL), and PubMed were searched for the periods May, 1985 to March, 2011 and June, 2013 to August, 2015, and a number of studies identified. Results of those studies showed that use of β-blockers was associated with decreased sudden cardiac death in patients with heart failure. However, contradictory results have also been reported. The present meta-analysis aimed to determine the efficacy of β-blockers on mortality and morbidity in patients with heart failure. The results showed that mortality was significantly reduced by β-blocker treatment prior to the surgery of heart failure patients. The results from the meta-analysis studies showed that β-blocker treatment in heart failure patients correlated with a significant decrease in long-term mortality, even in patients that meet one or more exclusion criteria of the MERIT-HF study. In summary, the findings of the current meta-analysis revealed beneficial effects different β-blockers have on patients with heart failure or related heart disease.

A Review of Nebivolol Pharmacology and Clinical Evidence

Nebivolol is a highly selective β1-adrenergic receptor antagonist with a pharmacologic profile that differs from those of other drugs in its class. In addition to cardioselectivity mediated via β1 receptor blockade, nebivolol induces nitric oxide-mediated vasodilation by stimulating endothelial nitric oxide synthase via β3 agonism. This vasodilatory mechanism is distinct from those of other vasodilatory β-blockers (carvedilol, labetalol), which are mediated via α-adrenergic receptor blockade. Nebivolol is approved for the treatment of hypertension in the US, and for hypertension and heart failure in Europe. While β-blockers are not recommended within the current US guidelines as first-line therapy for treatment of essential hypertension, nebivolol has shown comparable efficacy to currently recommended therapies in lowering peripheral blood pressure in adults with hypertension with a very low rate of side effects. Nebivolol also has beneficial effects on central blood pressure compared with other β-blockers. Clinical data also suggest that nebivolol may be useful in patients who have experienced erectile dysfunction while on other β-blockers. Here we review the pharmacological profile of nebivolol, the clinical evidence supporting its use in hypertension as monotherapy, add-on, and combination therapy, and the data demonstrating its positive effects on heart failure and endothelial dysfunction.

Nebivolol: vasodilator properties and evidence for relevance in treatment of cardiovascular disease

β-adrenergic blocking agents, a pharmacologically diverse class of cardiovascular medications, are recommended as first-line treatment for patients with hypertension and concomitant structural heart disease, and for angina and heart failure. Many within-class differences exist, from pharmacokinetics and pharmacodynamics to ancillary effects, such as intrinsic sympathomimetic activity, antiarrhythmic activity, α-1 adrenergic receptor blockade affinity, and direct vasodilation. Nebivolol is a third-generation, β1 selective, long acting β-blocker, which causes direct vasodilation via endothelium-dependent nitric oxide stimulation. The vasodilatory actions of nebivolol might result in clinical effects with some distinct properties. Differences from other β-blockers might include improvement of endothelial function, enhancement of forward flow in muscular resistance arteries, maintenance of exercise tolerance, and overall improved tolerability, side effect profile, and adherence. Nebivolol has been shown to be a clinically effective β-blocker for treatment as initial or add-on therapy for systemic hypertension, as an antianginal agent, and as therapy for patients with heart failure. These properties position nebivolol as a treatment option for patients with hypertension and/or structural heart disease, although its precise role in the therapeutic armamentarium remains to be clarified.

β-Blockers for the prevention of sudden cardiac death in heart failure patients: a meta-analysis of randomized controlled trials

Background

In many studies, beta-blockers have been shown to decrease sudden cardiac death (SCD) in heart failure patients; other studies reported mixed results. Recently, several large randomized control trials of beta blockers have been carried out. It became necessary to conduct a systematic review to provide an up-to-date synthesis of available data.

Methods

We conducted a meta-analysis of all randomized controlled trials examining the use of beta-blockers vs. placebo/control for the prevention of SCD in heart failure patients. We identified 30 trials, which randomized 24,779 patients to beta-blocker or placebo/control. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Eligible studies had to be randomized controlled trials and provide information on the incidence of sudden cardiac death in heart failure patients. Additional inclusion criteria included: treatment for >30 days and follow-up ≥ 3 months. Studies of patients <18 years, randomization to beta-blocker vs. an angiotensin converting enzyme (without placebo) and/or beta-blocker in both arms were excluded from the analysis. Pre-specified outcomes of interest included SCD, cardiovascular death (CVD), and all-cause mortality and were analyzed according to intention-to-treat.

Results

We found that beta-blockers are effective in the prevention of SCD [OR 0.69; 95% CI, 0.62–0.77, P < 0.00001], cardiovascular death (CVD) [OR 0.71; 95% CI, 0.64–0.79, P < 0.00001], and all-cause mortality [OR 0.67; 95% CI, 0.59–0.76, P < 0.00001]. Based on the study analysis, 43 patients must be treated with a beta-blocker to prevent one SCD, 26 patients to prevent one CVD and 21 patients to prevent all-cause mortality in one year.

Conclusion

Beta-blockers reduce the risk of sudden cardiac death (SCD) by 31%, cardiovascular death (CVD) by 29% and all-cause mortality by 33%. These results confirm the mortality benefits of these drugs and they should be recommended to all patients similar to those included in the trials.

Nebivolol: impact on cardiac and endothelial function and clinical utility

Endothelial dysfunction is a systemic pathological state of the endothelium characterized by a reduction in the bioavailability of vasodilators, essentially nitric oxide, leading to impaired endothelium-dependent vasodilation, as well as disarrangement in vascular wall metabolism and function. One of the key factors in endothelial dysfunction is overproduction of reactive oxygen species which participate in the development of hypertension, atherosclerosis, diabetes, cardiac hypertrophy, heart failure, ischemia-reperfusion injury, and stroke. Because impaired endothelial activity is believed to have a major causal role in the pathophysiology of vascular disease, hypertension, and heart failure, therapeutic agents which modify this condition are of clinical interest. Nebivolol is a third-generation β-blocker with high selectivity for β1-adrenergic receptors and causes vasodilation by interaction with the endothelial L-arginine/ nitric oxide pathway. This dual mechanism of action underscores several hemodynamic qualities of nebivolol, which include reductions in heart rate and blood pressure and improvements in systolic and diastolic function. Although nebivolol reduces blood pressure to a degree similar to that of conventional β-blockers and other types of antihypertensive drugs, it may have advantages in populations with difficult-to-treat hypertension, such as patients with heart failure along with other comorbidities, like diabetes and obesity, and elderly patients in whom nitric oxide-mediated endothelial dysfunction may be more pronounced. Furthermore, recent data indicate that nebivolol appears to be a cost-effective treatment for elderly patients with heart failure compared with standard care. Thus, nebivolol is an effective and well tolerated agent with benefits above those of traditional β-blockers due to its influence on nitric oxide release, which give it singular hemodynamic effects, cardioprotective activity, and a good tolerability profile. This paper reviews the pharmacology structure and properties of nebivolol, focusing on endothelial dysfunction, clinical utility, comparative efficacy, side effects, and quality of life in general with respect to the other antihypertensive agents.

Nebivolol for the treatment of heart failure

PURPOSE. The pharmacology, pharmacokinetics, efficacy, safety, and place in therapy of nebivolol are reviewed. SUMMARY. Nebivolol, a third-generation, highly β(1)-specific β-blocker, is labeled for the treatment of hypertension in the United States. In addition to its β-blocking effects, nebivolol has been shown to increase endothelin-dependent nitric oxide, giving it a unique peripheral vasodilatory action. Nebivolol is extensively metabolized by cytochrome P-450 isoenzyme 2D6. In patients with heart failure, certain β-blockers antagonize excessive adrenergic stimulation and can slow the progression of the disease. Clinical trials have compared nebivolol at target dosages of 5 and 10 mg once daily with placebo and, in small trials, with carvedilol in the treatment of adults with chronic heart failure. Nebivolol appears to have beneficial effects in patients with heart failure, including improvements in left ventricular ejection fraction, left ventricular volumes, and exercise capacity. In addition, the Study of the Effects of Nebivolol Intervention on Outcomes and Rehospitalisation in Seniors with Heart Failure showed a reduction in morbidity and mortality after treatment with nebivolol when compared with placebo, though this effect appeared to be less than that of other β-blockers currently recommended for the treatment of heart failure. Nebivolol was well tolerated in all clinical trials, with the most frequently reported adverse events including bradycardia, hypotension, and dizziness. To date, no large clinical trials have compared nebivolol with currently recommended β-blockers in patients with heart failure. CONCLUSION. Nebivolol has beneficial effects in heart failure but cannot be considered equivalent to other currently accepted therapies.

Nebivolol in chronic heart failure: current evidence and future perspectives

IMPORTANCE OF THE FIELD

Chronic activation of the sympathetic nervous system leads to deterioration of cardiovascular function in heart failure patients. In systolic heart failure, beta-blockers were proven to be effective in decreasing the number of deaths and improving morbidity. However, beta-blockers are a heterogeneous drug group, consisting of agents with different selectivity for adrenergic receptors and/or additional effects in heart or peripheral circulation.

AREAS COVERED IN THE REVIEW

We describe the role of the sympathetic nervous system, beta-blockers and specifically nebivolol in chronic heart failure.

WHAT THE READER WILL GAIN

Nebivolol is a third-generation beta-blocker, with high beta(1)/beta(2) selectivity. Moreover, it has important vasodilating properties, by stimulating the production of nitric oxide. Smaller studies have already shown beneficial effects of nebivolol treatment on surrogate end points in heart failure patients. The recently published SENIORS (Phase III) study in an elderly heart failure population demonstrated a decreased number of clinical events in patients treated with nebivolol. Importantly, this effect was observed in patients with both impaired and preserved left ventricular systolic function.

TAKE HOME MESSAGE

Specific beta-blockers may have distinct effects in various subgroups of heart failure patients. So far, nebivolol is the only beta-blocker to have been shown effective in elderly heart failure patients, regardless of their left ventricular ejection fraction.

[Advantages of vasodilating beta-blockers in congestive heart failure]

Beta-blockers play a pivotal role in the treatment of chronic systolic heart failure. However, the pharmacological family of beta-blockers is inhomogeneous regarding their pharmacological properties and their clinical effects can differ substantially according to different pharmacological properties. Because of vasodilator effects, the third generation of beta-blockers has additional potential across the cardiovascular diseases, from hypertension to heart failure. Nebivololol has both high selectivity for beta1-adrenergic receptors, no intrinsic sympathetic activity and ability to stimulate endothelial nitric oxide production. Such properties result in specific hemodynamic effects compared with others beta-blockers. Such properties also result in both high tolerability and positive metabolic effects which are crucial in high-risk groups. In the SENIORS trial, nebivolol demonstrated its efficacy and high tolerability in elderly patients with chronic heart failure irrespective of the left ventricular ejection fraction. More clinical trials would be useful to exhibit specific benefits of nebivolol in other high-risk groups of patients.

Nebivolol: the somewhat-different beta-adrenergic receptor blocker

Although its clinical use in Europe dates almost 10 years, nebivolol is a beta-blocker that has been only recently introduced in the U.S. market. Like carvedilol, nebivolol belongs to the third generation of beta-blockers, which possess direct vasodilator properties in addition to their adrenergic blocking characteristics. Nebivolol has the highest beta(1)-receptor affinity among beta-blockers and, most interestingly, it substantially improves endothelial dysfunction via its strong stimulatory effects on the activity of the endothelial nitric oxide synthase and via its antioxidative properties. Because impaired endothelial activity is attributed a major causal role in the pathophysiology of hypertension, coronary artery disease, and congestive heart failure, the endothelium-agonistic properties of nebivolol suggest that this drug might provide additional benefit beyond beta-receptor blockade. Although lesser beta-blocker-related side effects have been reported in patients with chronic obstructive pulmonary disease or impotence taking nebivolol, side effects and contraindications overlap those of other beta-blockers. Clinically, this compound has been proven to have antihypertensive and anti-ischemic effects as well as beneficial effects on hemodynamics and prognosis in patients with chronic congestive heart failure. Further studies are now necessary to compare the benefit of nebivolol with that of other drugs in the same class and, most importantly, its prognostic impact in patients with hypertension.

Beta-blockers in the management of hypertension: focus on nebivolol

Hypertension is a major cardiovascular risk factor but most patients remain asymptomatic for many years. Successful therapy not only needs to be effective, it also needs to be well tolerated. beta-blockers are well established as effective antihypertensive agents. However, one major drawback to the currently available beta-blockers, particularly the noncardioselective beta-blockers, is their side-effect profile, including sexual dysfunction, fatigue, depression and metabolic abnormalities such as impaired glucose tolerance and lipid abnormalities. Nebivolol (Bystolic), a novel, highly cardioselective, third-generation beta-blocker that recently received approval by the US FDA for the treatment of hypertension in the USA, is effective in treating blood pressure and has a favorable side-effect profile. Studies conducted in Europe, where nebivolol has been available for some time for the treatment of hypertension, have shown that nebivolol achieves blood pressure reductions comparable to other beta-blockers but with fewer side effects. Additionally, nebivolol has demonstrated similar efficacy in blood pressure reduction when compared with calcium channel blockers and inhibitors of the renin-angiotensin system. When combined with hydrochlorothiazide there was an additive antihypertensive effect. Lastly, nebivolol exhibits a vasodilatory property that is related to its effect on nitric oxide, an intrinsic vasodilator produced in the vascular endothelium. Nebivolol enhances nitric oxide bioavailability. Studies have also demonstrated nebivolol's ability to function as an antioxidant and decrease markers of oxidative stress. These effects are believed to ultimately produce a modulation of the endothelial dysfunction typically seen in hypertension.

Nebivolol: third-generation β-blockade

Nebivolol is a third generation beta-blocker. It is highly selective for the beta1-adrenoceptor, and has additional nitric oxide-mediated vasodilating and antioxidant properties, along with a favourable metabolic profile. Nebivolol is well tolerated by patients with hypertension and heart failure. Although several smaller studies were conducted with nebivolol in hypertensive patients, no large randomised clinical trials have been performed to prove efficacy on hard clinical end points. In patients with heart failure, a large mortality/morbidity trial was conducted, and nebivolol was shown to reduce the composite end point of mortality and hospitalisations. Nebivolol is registered, in Europe, for mild-to-moderate, uncomplicated hypertension and mild-to-moderate heart failure; and outside Europe, for hypertension. This review describes experimental and clinical data regarding this selective beta-blocker with vasodilating and antioxidant effects.

Nebivolol: new therapy update

Nebivolol is a beta-blocker under U.S. Food and Drug Administration review for the treatment of hypertension. The unique pharmacologic properties of nebivolol include high specificity for the beta-1 receptor and a nitric oxide-mediated vasodilatory effect. The agent provides significant blood pressure reduction from baseline values as compared with placebo. Clinical trials have demonstrated that nebivolol reduces blood pressure similarly to atenolol, bisoprolol, amlodipine, nifedipine, lisinopril, and hydrochlorothiazide. The tolerability of nebivolol is similar to or better than that of these agents. In elderly patients (> or = 70 years of age) with clinically stable congestive heart failure, the addition of nebivolol to the treatment regimen improved the time to all-cause mortality and cardiovascular hospital admissions over that of placebo. If approved, nebivolol would likely be a viable alternative therapy for hypertension and heart failure; however, additional studies are needed in patients having coronary artery disease.

Effects of nebivolol versus carvedilol on left ventricular function in patients with chronic heart failure and reduced left ventricular systolic function

BACKGROUND

Beta-adrenoceptor antagonist (beta-blocker) therapy results in a significant improvement in left ventricular (LV) systolic function and prognosis in patients with chronic heart failure. Both carvedilol and nebivolol produce hemodynamic and clinical benefits in chronic heart failure, but it is unknown whether their peculiar pharmacologic properties produce different effects on LV function.

OBJECTIVE

To assess the effects on LV function of nebivolol compared with carvedilol in patients with chronic heart failure and reduced LV systolic function.

METHODS

Seventy patients with a LV ejection fraction <or=40% and in New York Heart Association (NYHA) functional class II or III were randomly assigned to receive carvedilol or nebivolol therapy for 6 months. At baseline and after 6 months of treatment, all patients were assessed clinically and by biochemical and hematological investigation, ECG, 24-hour Holter monitoring, echocardiogram, measurement of ventilatory function, and a 6-minute walk test.

RESULTS

Compared with baseline values LV end-systolic volume decreased and LV ejection fraction increased in both the carvedilol (from 79 +/- 38mL to 73 +/- 43mL and from 33% +/- 6% to 37% +/- 11%) and the nebivolol group (from 72 +/- 35mL to 66 +/- 32mL and from 34% +/- 7% to 38% +/- 10%), although the between-group differences were not statistically significant. ECG data showed a decrease in resting HR in both groups (from 83 +/- 20 bpm to 66 +/- 11 bpm for carvedilol and from 81 +/- 15 bpm to 65 +/- 11 bpm for nebivolol; p < 0.001 vs baseline for both groups) but no difference in the PQ, QRS, and QT intervals. Hematologic (in particular, N-terminal pro-brain natriuretic peptide), Holter monitoring (with the exception of HR), and respiratory functional data did not show any significant variation in either group after 6 months' therapy. SBP and DBP decreased in both groups. A small reduction in mean NYHA functional class from baseline was seen in both groups (from 2.5 +/- 0.5 to 2.2 +/- 0.5 for carvedilol [p < 0.05] and from 2.3 +/- 0.4 to 2.2 +/- 0.5 for nebivolol [not significant]). The 6-minute walk test showed a trend toward an increase in the walking distance in both groups. During 6 months of treatment no significant differences in adverse events were observed between the groups.

CONCLUSION

Nebivolol is as effective as carvedilol in patients with symptomatic chronic heart failure and reduced LV systolic function.

Effects of nebivolol on left ventricular function in elderly patients with chronic heart failure: results of the ENECA study

AIM

To examine the effect of the beta(1)-selective beta-blocker nebivolol, administered as add-on therapy, on left ventricular function in 260 elderly patients (>65 years) with chronic heart failure (CHF).

METHODS

The principal inclusion criteria were (1) NYHA class II-IV CHF and (2) a left ventricular ejection fraction (LVEF) <= 35%. The primary end-point was the change in LVEF in response to nebivolol treatment for 8 months.

RESULTS

Baseline LVEF values in the two groups were as follows: nebivolol 25.41+/-7.09% and control 26.41+/-5.55%. LVEF improved significantly (p=0.027) more in the nebivolol group (6.51+/-9.15%) than in the control group (3.97+/-9.20%), the relative improvement (percentage increase in the initial value) being 35.70+/-57.62% in the nebivolol group and 19.19+/-40.96% (p=0.008) in the placebo group. Examination of different subgroups did not reveal any heterogeneity in the effects of nebivolol treatment vs. placebo treatment. There were no significant differences between the nebivolol and placebo groups as concerns the changes in clinical status, quality of life, or safety parameters.

CONCLUSION

The findings of the ENECA study confirmed that nebivolol significantly improved cardiac function and proved to be safe and well tolerated in elderly patients with signs of CHF and an impaired LVEF.

Comprehensive adrenergic receptor blockade with carvedilol is superior to beta-1-selective blockade with metoprolol in patients with heart failure: COMET

The Carvedilol or Metoprolol European Trial (COMET) compared the effects of a comprehensive adrenergic antagonist, carvedilol (target dosage 25 mg twice daily), with a beta-1-selective agent, metoprolol tartrate (target dosage 50 mg twice daily), in 3029 patients with chronic heart failure caused by left ventricular systolic dysfunction. The study showed that, compared with metoprolol, long-term treatment with carvedilol exerted a substantially greater reduction in mortality and led to improvement in well-being in these patients. The superiority of carvedilol over metoprolol is readily explained by differences in their pharmacologic profiles. There is no evidence, within the trial or from other sources, that the relative dose of each agent or their formulation explained the observed difference. The result of COMET is entirely consistent with the results of previous placebo-controlled trials of beta-1-selective blockers and carvedilol.

Protective role of nebivolol in hydroxyl radical induced injury

Increased oxidative stress has been postulated as one of the main mechanisms underlying stunned myocardium, and may play an important role in and during development of heart failure. Pharmacological interventions may attenuate or prevent detrimental effects of oxygen free radicals on the myocardium. Nebivolol has been shown to attenuate contractile dysfunction in hydroxyl radical mediated injury, but the mechanism(s) remain unknown. It was investigated whether nebivolol could partly attenuate the contractile dysfunction through a direct effect on the myofilaments. In demembranized muscles from explanted human hearts, nebivolol induced a slight desensitization of the myofilaments to calcium. Therefore, during the calcium overload that occurs during reperfusion after an ischemic event, the contractile dysfunction is less severe in the presence of nebivolol. We conclude that the protection of nebivolol in hydroxyl radical induced contractile dysfunction is mediated in part through a direct effect on the myofilaments, in addition to the previously shown preservation of sarcoplasmic reticulum function.

Beta-blockade in hypertension and congestive heart failure

Hypertension is common and increases the risk of death from coronary artery disease and cerebral vascular disease. The reason for treating hypertension is to prevent the long-term complications of this disorder. Many studies of antihypertensive therapy have produced only modest reductions in coronary events; in particular, with the use of beta-blockers. Clinical trials and meta-analyses have shown a lesser effect of these drugs on primary prevention of coronary events, cardiovascular and total mortality with respect to other antihypertensive approaches based on the use of low-dose diuretic therapy, especially in the elderly, even if the reduction of stroke and heart failure (HF) were similar. New beta-blockers with vasodilating properties due to the capacity to enhance the release of endothelial nitric oxide, then lessening a contributory mechanism to the pathogenesis of atherosclerosis as endothelial damage and dysfunction, seem to possess considerable potential in the treatment of hypertension, particularly in terms of improvement of cardiovascular outcome of patients. In HF, there is now considerable interest in the therapeutic use of beta-blockade. Some recent clinical trials have demonstrated conclusive evidence of the beneficial effects of beta-blocker therapy on survival in chronic HF. As a result of these data, beta-blocker therapy has become part of standard therapy for patients with chronic HF, in addition to angiotensin-converting enzyme-inhibitors and diuretics. The treatment is, in general, well tolerated. There are, however, some unanswered questions. One is whether some beta-blockers may be better than others. The major mortality benefit is probably a class-effect of beta1-adrenoceptor blockade, but the differences between beta-blockers might be clinically relevant. For example, it is under debate whether ancillary properties of some beta-blockers, such as the capability of exerting antioxidant effects or enhancing the nitric oxide production, may contribute to the clinical effects of these drugs. Future clinical trials will report over the next few years and help to answer the question about differences in mortality effects among types of beta-blocking agents, thus correctly defining the precise role of these drugs in the wide spectrum of cardiovascular disease.

Nebivolol in the management of essential hypertension: a review

Nebivolol is a lipophilic beta1-blocker. It is devoid of intrinsic sympathomimetic or membrane stabilising activity but appears to have nitric oxide-mediated vasodilatory effects. Nebivolol is administered as a racemic mixture of equal proportions of d- and l-enantiomers. The drug does not significantly influence glucose or plasma lipid metabolism and appears to have a protective effect on left ventricular function. At the recommended dosage (5 mg once daily) nebivolol reduces resting diastolic blood pressure as effectively as standard therapeutic dosages of atenolol, metoprolol, lisinopril and nifedipine, as shown in comparative trials. Nebivolol reduced blood pressure significantly more than enalapril 10 mg daily in the short but not the long term, although the enalapril dose may not have been optimal. Nebivolol has an additive effect in combination with hydrochlorothiazide. Standing blood pressure and/or mean 24-hour ambulatory blood pressure is significantly and similarly reduced with nebivolol, atenolol or nifedipine. Nebivolol tended to prevent increases in early morning blood pressure better than nifedipine. Overall response rates to nebivolol therapy (a decrease in sitting/supine diastolic blood pressure to < or = 90 mm Hg or a 10% or > or = 10 mm Hg fall in diastolic blood pressure) ranged from 58 to 81% after 4 to 52 weeks' treatment. In comparative studies, response rates were greater in nebivolol than in enalapril or metoprolol recipients, but not significantly different from those in atenolol or nifedipine recipients. Nebivolol 5 mg once daily is well tolerated in patients with hypertension. Adverse events are infrequent, transient and mild to moderate. Those reported most often include headache, fatigue, paraesthesias and dizziness. Several studies reported no signs of orthostatic hypotension with nebivolol. Comparative trials revealed no significant differences between the frequency and severity of adverse events in patients receiving nebivolol, atenolol, enalapril or placebo; however, the overall incidence of adverse events was greater with nifedipine or metoprolol. Some atenolol or enalapril, but not nebivolol, recipients reported impotence or decreased libido during therapy.

CONCLUSION

Current evidence indicates that nebivolol 5 mg once daily is a well tolerated beta-blocker, which is as effective as once daily atenolol and other classes of antihypertensive agents. It may therefore be recommended as a useful alternative first-line treatment option for the management of patients with mild to moderate uncomplicated essential hypertension.

The role of third-generation beta-blocking agents in chronic heart failure

Third-generation beta-blocking agents developed for the hypertension market are proving useful in the treatment of chronic heart failure (HF). These compounds share the ancillary property of vasodilation, which improves acute tolerability by unloading the failing left ventricle at a time when beta-adrenergic withdrawal produces myocardial depression. In the case of carvedilol and bucindolol, this allows for the administration of nonselective beta blockade. Because of blockade of both beta 1 and beta 2 adrenergic receptors as well as other properties, these compounds possess a more comprehensive antiadrenergic profile than second-generation, beta 1-selective compounds. For this and potentially other reasons, third-generation beta-blocking agents have theoretical efficacy advantages that have yet to be demonstrated in large-scale trials. Ongoing trials with either second- or third-generation compounds and one trial directly comparing a compound from each class will provide the answer as to whether third-generation compounds have an advantage in the treatment of chronic HF.