beta-Blockers in hypertension: is carvedilol different?

The β2-adrenergic receptor in the apical membrane of intestinal enterocytes senses sugars to stimulate glucose uptake from the gut

The presence of sugar in the gut causes induction of SGLT1, the sodium/glucose cotransporter in intestinal epithelial cells (enterocytes), and this is accompanied by stimulation of sugar absorption. Sugar sensing was suggested to involve a G-protein coupled receptor and cAMP - protein kinase A signalling, but the sugar receptor has remained unknown. We show strong expression and co-localization with SGLT1 of the β2-adrenergic receptor (β ₂-AR) at the enterocyte apical membrane and reveal its role in stimulating glucose uptake from the gut by the sodium/glucose-linked transporter, SGLT1. Upon heterologous expression in different reporter systems, the β ₂-AR responds to multiple sugars in the mM range, consistent with estimated gut sugar levels after a meal. Most adrenergic receptor antagonists inhibit sugar signaling, while some differentially inhibit epinephrine and sugar responses. However, sugars did not inhibit binding of I¹²⁵-cyanopindolol, a β ₂-AR antagonist, to the ligand-binding site in cell-free membrane preparations. This suggests different but interdependent binding sites. Glucose uptake into everted sacs from rat intestine was stimulated by epinephrine and sugars in a β ₂-AR-dependent manner. STD-NMR confirmed direct physical binding of glucose to the β ₂-AR. Oral administration of glucose with a non-bioavailable β ₂-AR antagonist lowered the subsequent increase in blood glucose levels, confirming a role for enterocyte apical β ₂-ARs in stimulating gut glucose uptake, and suggesting enterocyte β ₂-AR as novel drug target in diabetic and obese patients. Future work will have to reveal how glucose sensing by enterocytes and neuroendocrine cells is connected, and whether β ₂-ARs mediate glucose sensing also in other tissues.

Clinical impact of beta-blockers at discharge on long-term clinical outcomes in patients with non-reduced ejection fraction after acute myocardial infarction

BACKGROUND

Beta-blockers are associated with several clinical benefits in patients with reduced left ventricular ejection fraction (REF) after acute myocardial infarction (AMI), such as lower rates of mortality, recurrence of myocardial infarction, and heart failure. However, the long-term prognosis of beta-blockers has rarely been investigated in patients with non-REF after AMI. This study aimed to investigate the clinical benefits of beta-blockers in these patients.

METHODS

A total of 3281 consecutive patients who were hospitalized within 48 h after AMI were registered in the J-MINUET study. Patients who underwent primary percutaneous coronary intervention (PCI) and had a left ventricular ejection fraction ≥40 % were enrolled, and patients who died during admission were excluded. Included patients were divided into two groups according to the prescription of beta-blockers at discharge. Their characteristics and clinical outcomes were compared.

RESULTS

The number of AMI patients treated with beta-blockers was 1353 (70.4 %). Patients who received beta-blockers were younger and had a higher incidence of hypertension, dyslipidemia, and ST-segment elevation myocardial infarction than those who did not receive beta-blockers. The peak creatine kinase level after primary PCI was significantly higher in patients who received beta-blockers. These patients also had a lower incidence of a composite of all-cause death, myocardial infarction, and stroke compared to those that did not receive beta-blockers (7.3 % vs. 11.9 %, p = 0.001). Multivariate analysis showed that beta-blocker use was an independent factor for better clinical outcomes.

CONCLUSIONS

The J-MINUET study revealed the clinical benefit of beta-blockers in AMI patients with non-REF after primary PCI.

Enhanced purification protocol for the angiotensin-converting enzyme from bovine systems and investigation of the in vitro effect of some active substances

Angiotensin-converting enzyme (ACE, EC 3.4.15.1) synthesized by endothelial cells and responsible for the regulation of blood pressure was purified from the bovine lung with affinity chromatography method. The purification rate of the ACE of the bovine lung was calculated as 1748- fold. Optimum pH and optimum temperature for the purified ACE were found to be 7.6 and 35-40 °C, respectively. The purity and molecular weight of the ACE were designated with SDS-PAGE. The ACE was found to have three subunits with molecular weights of 57 kDa, 66 kDa, and 190 kDa. Then, the total molecular weight of the ACE was designated as 303 kDa with gel filtration chromatography. The effects of ACE inhibitors captopril, fosinopril, lisinopril, and beta-blockers propranolol, atenolol, and diuretic triamterene on ACE activity were studied. ACE inhibitors lisinopril, captopril, fosinopril, and diuretic triamterene demonstrated an inhibition effect on ACE activity. Beta-blockers indicated no effect on ACE. IC₅₀ values of captopril, fosinopril, lisinopril, and triamterene from the graphical equation were calculated as 0.835 nM, 1.159 μM, 4.085 nM, and 227 μM, respectively. The inhibition type and K_i values of these compounds were determined from Lineweaver-Burk plots. Captopril, fosinopril, lisinopril, and triamterene demonstrated a non-competitive inhibition effect on ACE activity. K_i constants were found as 1.057 nM, 1.675 μM, 6.449 nM, and 419.5 μM, respectively. Captopril indicated the highest inhibitor effect with an IC₅₀ value of 0.835 nM.

Association of beta blocker use and hearing ability in adults: a cross-sectional study

OBJECTIVES

To investigate the potential association between beta blocker use and hearing ability in adults and to discern whether this effect is dose-dependent.

DESIGN

Cross-sectional analyses. Multiple linear regression was performed with hearing ability as the dependent variable and beta blocker use as the independent variable. The independent variable was classified into three dose categories for secondary analysis. Adjustments were made for age, gender, educational level, and tobacco smoking status.

STUDY SAMPLE

1636 adults, 75 of whom reported being on beta blockers, from the internet-based Netherlands Longitudinal Study on Hearing (NL-SH).

RESULTS

No significant association was found between beta blocker use and hearing ability in noise. In the adjusted regressions, beta blocker use changed the speech reception threshold in noise (SRT) by -0.04 dB signal-to-noise ratio (SNR) (95%CI [-0.67 to 0.58], p = 0.890). Medium dose beta blocker use changed SRT by -0.42 dB SNR (95%CI [-1.38 to 0.71], p = 0.433), while a high dose changed it by -0.26 dB SNR (95%CI [-1.74 to 1.4], p = 0.767).

CONCLUSIONS

No evidence was found for beta blocker-induced changes in hearing ability. Future studies on this topic should favour case-control and cohort study designs, while focussing on a hypertensive population to minimise confounding by indication.

Study protocol for the randomized controlled EVA (early vascular adjustments) trial: tailored treatment of mild hypertension in pregnancy to prevent severe hypertension and preeclampsia

BACKGROUND

In contrast to severe gestational hypertension, it is questioned whether antihypertensive medication for mild to moderate gestational hypertension prevents adverse maternal and offspring outcomes. Hypertensive drugs halve the risk of severe hypertension, but do not seem to prevent progression to preeclampsia or reduce the risk of complications in offspring. In fact, beta-blockers, a first line therapy option, are suspected to impair foetal growth. Disappointing effects of antihypertensive medication can be anticipated when the pharmacological mode of action does not match the underlying haemodynamic imbalance. Hypertension may result from 1) high cardiac output, low vascular resistance state, in which beta blockade is expected to be most effective, or 2) low cardiac output, high vascular resistance state where dihydropyridine calcium channel blockers or central-acting alpha agonists might be the best corrective medication. In the latter, beta-blockade might be maternally ineffective and even contribute to impaired foetal growth by keeping cardiac output low. We propose a randomized controlled trial to determine whether correcting the haemodynamic imbalance in women with mild to moderate hypertension reduces the development of severe hypertension and/or preeclampsia more than non-pharmacological treatment does, without alleged negative effects on foetal growth.

METHODS

Women diagnosed with mild to moderate hypertension without proteinuria or signs of other organ damage before 37 weeks of pregnancy are invited to participate in this randomized controlled trial. Women randomized to the intervention group will be prescribed tailored antihypertensive medication, using a simple diagnostic and treatment algorithm based on the mean arterial pressure/heart rate ratio, which serves as an easy-to-determine proxy for maternal circulatory state. Women randomized to the control group will receive non-pharmacological standard care according to national and international guidelines. In total, 208 women will be randomized in a 1:1 ratio. The primary outcome is progression to severe hypertension and preeclampsia and the secondary outcomes are adverse maternal and neonatal outcomes.

DISCUSSION

This trial will provide evidence of whether tailoring treatment of mild to moderate gestational hypertension to the individual haemodynamic profile prevents maternal disease progression.

TRIAL REGISTRATION

NCT02531490 , registered on 24 August 2015.

Epidural anesthesia and hypotension in pheochromocytoma and paraganglioma

Postoperative hypotension frequently occurs after resection of pheochromocytoma and/or paraganglioma (PPGLs). Epidural anesthesia (EA) is often used for pain control in open resection of these tumors; one of its side effects is hypotension. Our aim is to determine if EA is associated with an increased risk of postoperative hypotension after open resection of PPGLs. We conducted a retrospective review of patients who underwent open resection of PPGLs at the National Institutes of Health from 2004 to 2019. Clinical and perioperative parameters were analyzed by the use of EA. The primary endpoint was postoperative hypotension. Ninety-seven patients (46 female and 51 male; mean age, 38.5 years) underwent open resection of PPGLs and 69 (71.1%) received EA. Patients with EA had a higher rate beta-blocker use (79.7% vs 57.1%, P = 0.041), metastasis (69.6% vs 39.3%, P = 0.011), and were more frequently hypotensive after surgery (58.8% vs 25.0%, P = 0.003) compared to those without EA. Patients with postoperative hypotension had higher plasma normetanephrines than those without (7.3 fold vs 4.1 fold above the upper limit of normal, P = 0.018). Independent factors associated with postoperative hypotension include the use of beta-blockers (HR = 3.35 (95% CI: 1.16-9.67), P = 0.026) and EA (HR = 3.49 (95% CI: 1.25-9.76), P = 0.017). Data from this retrospective study suggest that, in patients with open resection of PPGLs, EA is an independent risk factor for early postoperative hypotension. Special caution is required in patients on beta-blockade. A prospective evaluation with standardized protocols for the use of EA and management of hemodynamic variability is necessary.

Enantioselective determination of 1-[4-(2-methoxyethyl)phenoxy]-3-[2-(2-methoxyphenoxy)ethylamino]-2-propanol hydrochloride, a novel antihypertensive agent, in rat plasma and tissues by liquid chromatography-tandem mass spectrometry

Enantioselective biodistribution studies of 1-[4-(2-methoxyethyl)phenoxy]-3-[2-(2-methoxyphenoxy)ethylamino]-2-propanol hydrochloride (TJ0711), a novel antihypertensive agent, require the accurate and precise quantification of each TJ0711 enantiomer in biological fluids and tissues. Here we report a simple and sensitive liquid chromatography with tandem mass spectrometry method for simultaneous determination of (R)-TJ0711 and (S)-TJ0711 in rat plasma and tissue samples using protein precipitation. The influence of column type, temperature, mobile phase composition, and flow rate on the retention and enantioselectivity was evaluated. The separation of the TJ0711 enantiomers was ultimately achieved on a SUMICHIRAL OA-2500 column in 15 min using isocratic elution with ethanol/hexane (40:60) at a flow rate of 0.8 mL/min. Good linearities of spiked analyte concentration from 5 to 2000 ng/mL were achieved and the correlation coefficients (R) were greater than 0.99. The intra- and inter-day accuracy and precision for both analytes were <15% at all concentration levels, and the extraction recoveries were consistent among the five quality control concentrations. This assay was successfully applied to quantify plasma and tissue concentrations of TJ0711 enantiomers in a preclinical study.

Protective Effects of Vasodilatory Βeta-Blockers Carvedilol and Nebivolol against Glycerol Model of Rhabdomyolysis-Induced Acute Renal Failure in Rats

BACKGROUND

Rhabdomyolysis (RM)-induced acute renal failure (ARF) accounts for about 10-40% of all cases of ARF.

AIM

The present study investigated the possible protective effect of two nitric oxides (NO)-releasing third generation β-blockers, carvedilol (Carv) and nebivolol (Nebi), against RM-mimicking glycerol (Gly)-induced ARF in rats.

MATERIAL AND METHODS

After 24 h dehydration, rats received a single dose of 50% Gly (8 ml/kg, im). They were treated with vehicle, Carv (2.5 mg/kg/day, po) or Nebi (10 mg/kg, po) for 3 successive days starting from an hour prior to Gly injection. Evaluation of blood pressure and locomotor activity was performed during the experiment. 72 h following Gly administration, total protein in the urine, serum levels of creatinine, blood urea nitrogen, sodium and potassium as well as the renal contents of malondialdehyde, reduced glutathione and NO were assessed, together with a histopathological examination of renal tissues.

RESULTS

Carv and Nebi attenuated Gly-induced renal dysfunction and histopathological alterations. They decreased the Gly-induced oxidative stress and increased renal NO concentration. Restoration of normal blood pressure and improvement of locomotor activity were also observed.

CONCLUSION

The results clearly demonstrate protective effects of Carv and Nebi against renal damage involved in RM-induced ARF and suggest a role of their antioxidant and NO-releasing properties.

Effectiveness comparison of cardio-selective to non-selective β-blockers and their association with mortality and morbidity in end-stage renal disease: a retrospective cohort study

Background

Within-class comparative effectiveness studies of β-blockers have not been performed in the chronic dialysis setting. With widespread cardiac disease in these patients and potential mechanistic differences within the class, we examined whether mortality and morbidity outcomes varied between cardio-selective and non-selective β-blockers.

Methods

Retrospective observational study of within class β-blocker exposure among a national cohort of new chronic dialysis patients (N = 52,922) with hypertension and dual eligibility (Medicare-Medicaid). New β-blocker users were classified according to their exclusive use of one of the subclasses. Outcomes were all-cause mortality (ACM) and cardiovascular morbidity and mortality (CVMM). The associations of cardio-selective and non-selective agents on outcomes were adjusted for baseline characteristics using Cox proportional hazards.

Results

There were 4938 new β-blocker users included in the ACM model and 4537 in the CVMM model: 77 % on cardio-selective β-blockers. Exposure to cardio-selective and non-selective agents during the follow-up period was comparable, as measured by proportion of days covered (0.56 vs. 0.53 in the ACM model; 0.56 vs 0.54 in the CVMM model). Use of cardio-selective β-blockers was associated with lower risk for mortality (AHR = 0.84; 99 % CI = 0.72–0.97, p = 0.0026) and lower risk for CVMM events (AHR = 0.86; 99 % CI = 0.75–0.99, p = 0.0042).

Conclusion

Among new β-blockers users on chronic dialysis, cardio-selective agents were associated with a statistically significant 16 % reduction in mortality and 14 % in cardiovascular morbidity and mortality relative to non-selective β-blocker users. A randomized clinical trial would be appropriate to more definitively answer whether cardio-selective β-blockers are superior to non-selective β-blockers in the setting of chronic dialysis.

Carvedilol-induced hyperkalemia in a patient with chronic kidney disease

A 69-year-old male was admitted to the hospital with a chief complaint of abdominal pain, nausea, and vomiting. He had an extensive past medical history, including diabetes mellitus type 2 and chronic kidney disease stage III. Prior to admission, the patient was taking carvedilol 3.125 mg twice daily with no abnormality in his serum potassium. During hospitalization, his carvedilol was increased to 6.25 mg twice daily. The patient's serum potassium then rose from 4.8 to 6.7 mEq/L, with no improvement following administration of sodium polystyrene sulfonate. Nephrology concluded the carvedilol could be contributing to the hyperkalemia. The dose was decreased back to 3.125 mg twice daily, leading to the potassium normalizing to 4.4 mEq/L. The reported incidence of beta-blocker-induced hyperkalemia is less than 5%. A literature search revealed several cases of beta-blocker-induced hyperkalemia, but to the authors' knowledge, this is the first case describing carvedilol specifically. Utilization of the Naranjo probability scale indicated a possible probability that the carvediol was the cause.

Effect of β-blockers on platelet aggregation: a systematic review and meta-analysis

AIMS

Platelets play an important role in cardiovascular disease, and β-blockers are often prescribed for cardiovascular disease prevention. β-Blockers may directly affect platelet aggregation, because β-adrenergic receptors are present on platelets. There is uncertainty about the existence and magnitude of an effect of β-blockers on platelet aggregation. The aim of this study was to perform a systematic review and meta-analysis of the effect of β-blockers on platelet aggregation.

METHODS

MEDLINE and EMBASE were searched until April 2014. Two reviewers independently performed data extraction and risk of bias assessment. Type of β-blocker, population, treatment duration and platelet aggregation were extracted. Standardized mean differences were calculated for each study and pooled in a random-effects meta-analysis.

RESULTS

We retrieved 31 studies (28 clinical trials and three observational studies). β-Blockers decreased platelet aggregation (standardized mean difference -0.54, 95% confidence interval -0.85 to -0.24, P < 0.0001). This corresponds to a reduction of 13% (95% confidence interval 8-17%). Nonselective lipophilic β-blockers decreased platelet aggregation more than selective nonlipophilic β-blockers.

CONCLUSIONS

Clinically used β-blockers significantly reduce platelet aggregation. Nonselective lipophilic β-blockers seem to reduce platelet aggregation more effectively than selective nonlipophilic β-blockers. These findings may help to explain why some β-blockers are more effective than others in preventing cardiovascular disease.

Clinical utility of fixed-dose combinations in hypertension: evidence for the potential of nebivolol/valsartan

Despite significant advances in pharmacologic approaches to treat hypertension during the last decades, hypertension- and hypertension-related organ damage are still a high health and economic burden because a large proportion of patients with hypertension do not achieve optimal blood pressure control. There is now general agreement that combination therapy with two or more antihypertensive drugs is required for targeted blood pressure accomplishment and reduction of global cardiovascular risk. The goals of combination therapies are to reduce long-term cardiovascular events by targeting different mechanism underlying hypertension and target organ disease, to block the counterregulatory pathways activated by monotherapies, to improve tolerability and decrease the adverse effects of up-titrated single agents, and to increase persistence and adherence with antihypertensive therapy. Multiple clinical trials provide evidence that fixed-dose combinations in a single pill offer several advantages when compared with loose-dose combinations. This review discusses the advances in hypertension control and associated cardiovascular disease as they relate to the prospect of combination therapy targeting a third-generation beta (β) 1-adrenergic receptor (nebivolol) and an angiotensin II receptor blocker (valsartan) in fixed-dose single-pill formulations.

Antihypertensive drugs and glucose metabolism

Hypertension plays a major role in the development and progression of micro- and macrovascular disease. Moreover, increased blood pressure often coexists with additional cardiovascular risk factors such as insulin resistance. As a result the need for a comprehensive management of hypertensive patients is critical. However, the various antihypertensive drug categories have different effects on glucose metabolism. Indeed, angiotensin receptor blockers as well as angiotensin converting enzyme inhibitors have been associated with beneficial effects on glucose homeostasis. Calcium channel blockers (CCBs) have an overall neutral effect on glucose metabolism. However, some members of the CCBs class such as azelnidipine and manidipine have been shown to have advantageous effects on glucose homeostasis. On the other hand, diuretics and β-blockers have an overall disadvantageous effect on glucose metabolism. Of note, carvedilol as well as nebivolol seem to differentiate themselves from the rest of the β-blockers class, being more attractive options regarding their effect on glucose homeostasis. The adverse effects of some blood pressure lowering drugs on glucose metabolism may, to an extent, compromise their cardiovascular protective role. As a result the effects on glucose homeostasis of the various blood pressure lowering drugs should be taken into account when selecting an antihypertensive treatment, especially in patients which are at high risk for developing diabetes.

Hypertension in the elderly: unique challenges and management

Elderly individuals, worldwide, are on the rise, posing new challenges to care providers. Hypertension is highly prevalent in elderly individuals, and multiple challenges face care providers while managing it. In addition to treating hypertension, the physician must treat other modifiable cardiovascular risk factors in patients with or without diabetes mellitus or chronic kidney disease to reduce cardiovascular events and mortality. This review discusses some of the unique characteristics of high blood pressure in the elderly and provides an overview of the challenges facing care providers, as well as the current recommendations for management of hypertension in the elderly.

Diabetic cardiomyopathy: mechanisms and new treatment strategies targeting antioxidant signaling pathways

Cardiovascular disease is the primary cause of morbidity and mortality among the diabetic population. Both experimental and clinical evidence suggest that diabetic subjects are predisposed to a distinct cardiomyopathy, independent of concomitant macro- and microvascular disorders. 'Diabetic cardiomyopathy' is characterized by early impairments in diastolic function, accompanied by the development of cardiomyocyte hypertrophy, myocardial fibrosis and cardiomyocyte apoptosis. The pathophysiology underlying diabetes-induced cardiac damage is complex and multifactorial, with elevated oxidative stress as a key contributor. We now review the current evidence of molecular disturbances present in the diabetic heart, and their role in the development of diabetes-induced impairments in myocardial function and structure. Our focus incorporates both the contribution of increased reactive oxygen species production and reduced antioxidant defenses to diabetic cardiomyopathy, together with modulation of protein signaling pathways and the emerging role of protein O-GlcNAcylation and miRNA dysregulation in the progression of diabetic heart disease. Lastly, we discuss both conventional and novel therapeutic approaches for the treatment of left ventricular dysfunction in diabetic patients, from inhibition of the renin-angiotensin-aldosterone-system, through recent evidence favoring supplementation of endogenous antioxidants for the treatment of diabetic cardiomyopathy. Novel therapeutic strategies, such as gene therapy targeting the phosphoinositide 3-kinase PI3K(p110α) signaling pathway, and miRNA dysregulation, are also reviewed. Targeting redox stress and protective protein signaling pathways may represent a future strategy for combating the ever-increasing incidence of heart failure in the diabetic population.

Use of carvedilol in hypertension: an update

β-blockers are effective antihypertensive agents and, together with diuretics, have been the cornerstone of pioneering studies showing their benefits on cardiovascular morbidity and mortality as a consequence of blood pressure reduction in patients with hypertension. However, evidence from recent meta-analyses have demonstrated no benefit afforded by atenolol compared with placebo in risk of mortality, myocardial infarction, or stroke, and a higher risk of mortality and stroke with atenolol/propranolol compared with other antihypertensive drug classes. Thus, the effect of these agents on cardiovascular morbidity and mortality in hypertensive patients, especially their use in uncomplicated hypertension, has remained largely controversial. However, it is recognized that the clinical studies used in these meta-analyses were mainly based on the older second-generation β-blockers, such as atenolol and metoprolol. Actually, considerable heterogeneity in, eg, pharmacokinetic, pharmacological, and physicochemical properties exists across the different classes of β-blockers, particularly between the second-generation and newer third-generation agents. Carvedilol is a vasodilating noncardioselective third-generation β-blocker, without the negative hemodynamic and metabolic effects of traditional β-blockers, which can be used as a cardioprotective agent. Compared with conventional β-blockers, carvedilol maintains cardiac output, has a reduced prolonged effect on heart rate, and reduces blood pressure by decreasing vascular resistance. Studies have also shown that carvedilol exhibits favorable effects on metabolic parameters, eg, glycemic control, insulin sensitivity, and lipid metabolism, suggesting that it could be considered in the treatment of patients with metabolic syndrome or diabetes. The present report provides an overview of the main clinical studies concerning carvedilol administered as either monotherapy or in combination with another antihypertensive or more frequently a diuretic agent, with particular focus on the additional benefits beyond blood pressure reduction.

The role of Beta-blockers as first-line therapy in hypertension

National and international guidelines still recommend β-blockers (BBs) as first-line agents in uncomplicated prevention of hypertension. However, it has been shown that BBs reduce blood pressure less than other drugs, specifically with regard to central aortic pressure. More importantly, recent meta-analyses have highlighted that in primary prevention BBs are associated with a relatively weak effect in reducing stroke compared to placebo or no treatment and, compared with other drugs, show evidence of a worse cardiovascular outcome. Several reasons might explain their mild cardioprotective effect, such as their unfavorable metabolic properties, a lack of efficacy on left ventricular hypertrophy regression and endothelial dysfunction, and reduced patient compliance. Thus, the available evidence does not support the use of BBs as first-line drugs in the treatment of uncomplicated hypertension. It remains to be determined whether newer BBs, such as nebivolol and carvedilol, will be more effective than older compounds in improving cardiovascular prognosis.

Beta-blockers in hypertension

Beta blockers have been used in the treatment of cardiovascular conditions for decades. Despite a long history and status as a guideline-recommended treatment option for hypertension, recent meta-analyses have brought into question whether β blockers are still an appropriate therapy given outcomes data from other antihypertensive drug classes. However, β blockers are a heterogenous class of agents with diverse pharmacologic and physiologic properties. Much of the unfavorable data revealed in the recent meta-analyses were gleaned from studies involving nonvasodilating, traditional β blockers, such as atenolol. However, findings with traditional β blockers may not be extrapolated to other members of the class, particularly those agents with vasodilatory activity. Vasodilatory β blockers (i.e., carvedilol and nebivolol) reduce blood pressure in large part through reducing systemic vascular resistance rather than by decreasing cardiac output, as is observed with traditional β blockers. Vasodilating ability may also ameliorate some of the concerns associated with traditional β blockade, such as the adverse effects on metabolic and lipid parameters, including an increased risk for new-onset diabetes. Furthermore, vasodilating ability is physiologically relevant and important in treating a condition with common co-morbidities involving metabolic and lipid abnormalities such as hypertension. In patients with hypertension and diabetes or coronary artery disease, vasodilating β blockers provide effective blood pressure control with neutral or beneficial effects on important parameters for the co-morbid disease. In conclusion, it is time for a reexamination of the clinical evidence for the use of β blockers in hypertension, recognizing that there are patients for whom β blockers, particularly those with vasodilatory actions, are an appropriate treatment option.

Hypertension, dyslipidemia, and insulin resistance in patients with diabetes mellitus or the cardiometabolic syndrome: benefits of vasodilating β-blockers

Hypertension frequently coexists with diabetes and the cardiometabolic syndrome. β-Blockers have been a mainstay for controlling blood pressure for nearly 4 decades. However, β-blockers are perceived to cause glucose and lipid metabolism dysregulation, including hypoglycemia masking, reduced glycemic control, insulin resistance, and dyslipidemia. It should be noted, however, that β-blockers are diverse in their effects on glucose and lipid metabolism. Potential mechanisms that contribute to these metabolic effects include hemodynamic differences, anti-inflammatory and anti-oxidative pathways, and/or weight changes. Traditional β-blockers decrease cardiac output while peripheral vascular resistance increases or remains unchanged, which may result in glucose and lipid abnormalities. In contrast, vasodilating β-blockers reduce peripheral vascular resistance but have little effect on cardiac output. Vasodilating β-blockers may therefore result in less impact on insulin sensitivity and glycemic control, a reduced new-onset diabetes risk, and improved dyslipidemia compared with traditional β-blockers. Because of these effects, vasodilating β-blockers may represent a favorable option in the treatment of high-risk patients with hypertension.

Heart rate control with adrenergic blockade: clinical outcomes in cardiovascular medicine

The sympathetic nervous system is involved in regulating various cardiovascular parameters including heart rate (HR) and HR variability. Aberrant sympathetic nervous system expression may result in elevated HR or decreased HR variability, and both are independent risk factors for development of cardiovascular disease, including heart failure, myocardial infarction, and hypertension. Epidemiologic studies have established that impaired HR control is linked to increased cardiovascular morbidity and mortality. One successful way of decreasing HR and cardiovascular mortality has been by utilizing β-blockers, because their ability to alter cell signaling at the receptor level has been shown to mitigate the pathogenic effects of sympathetic nervous system hyperactivation. Numerous clinical studies have demonstrated that β-blocker-mediated HR control improvements are associated with decreased mortality in postinfarct and heart failure patients. Although improved HR control benefits have yet to be established in hypertension, both traditional and vasodilating β-blockers exert positive HR control effects in this patient population. However, differences exist between traditional and vasodilating β-blockers; the latter reduce peripheral vascular resistance and exert neutral or positive effects on important metabolic parameters. Clinical evidence suggests that attainment of HR control is an important treatment objective for patients with cardiovascular conditions, and vasodilating β-blocker efficacy may aid in accomplishing improved outcomes.

Optimal use of beta-blockers in high-risk hypertension: a guide to dosing equivalence

Hypertension is the number one diagnosis made by primary care physicians, placing them in a unique position to prescribe the antihypertensive agent best suited to the individual patient. In individuals with diabetes mellitus, blood pressure (BP) levels >130/80 mmHg confer an even higher risk for cardiovascular and renal disease, and these patients will benefit from aggressive antihypertensive treatment using a combination of agents. β-blockers are playing an increasingly important role in the management of hypertension in high-risk patients. β-blockers are a heterogeneous class of agents, and this review presents the differences between β-blockers and provides evidence-based protocols to assist in understanding dose equivalence in the selection of an optimal regimen in patients with complex needs. The clinical benefits provided by β-blockers are only effective if patients adhere to medication treatment long term. β-blockers with proven efficacy, once-daily dosing, and lower side effect profiles may become instrumental in the treatment of hypertensive diabetic and nondiabetic patients.

Why beta-blockers should not be used as first choice in uncomplicated hypertension

In the past 4 decades, beta blockers (BBs) have been widely used in the treatment of uncomplicated hypertension and are still recommended as first-line agents in national and international guidelines. Their putative cardioprotective properties, however, derive from the extrapolation into primary prevention of data relative to the reduction of mortality observed in the 1970s in patients with previous myocardial infarctions. In the past 5 years, a critical reanalysis of older trials, together with several meta-analyses, has shown that in patients with uncomplicated hypertension BBs exert a relatively weak effect in reducing stroke compared to placebo or no treatment, do not have any protective effect with regard to coronary artery disease and, compared to other drugs, such as calcium channel blockers, renin-angiotensin-aldosterone system inhibitors or thiazide diuretics, show evidence of worse outcomes, particularly with regard to stroke. Several reasons can explain their reduced cardioprotection: their suboptimal effect in lowering blood pressure compared to other drugs; their "pseudoantihypertensive" efficacy (failure to lower central aortic pressure); their undesirable adverse effects, which reduce patients' compliance; their unfavorable metabolic effects; their lack of an effect on regression of left ventricular hypertrophy and endothelial dysfunction. In conclusion, the available evidence does not support the use of BBs as first-line drugs in the treatment of hypertension. Whether newer BBs, such as nebivolol and carvedilol, which show vasodilatory properties and a more favorable hemodynamic and metabolic profile, will be more efficacious in reducing morbidity and mortality remains to be determined.

Current role of beta-blockers in the treatment of hypertension

IMPORTANCE OF THE FIELD

It is important to know which patients with hypertension will benefit from beta-blocker therapy and which beta-blockers should be used in the treatment of hypertension to reduce cardiovascular events and mortality.

AREAS COVERED IN THIS REVIEW

Studies between 1981 and 2009 using a Medline search are reported. Beta-blockers should be used to treat hypertension in patients with previous myocardial infarction, acute coronary syndromes, angina pectoris, congestive heart failure, ventricular arrhythmias, supraventricular tachyarrhythmias, diabetes mellitus, after coronary artery bypass graft surgery, and in patients who are pregnant, have thyrotoxicosis, glaucoma, migraine, essential tremor, perioperative hypertension, or an excessive blood pressure response after exercise.

WHAT THE READER WILL GAIN

The use of beta-blockers as first-line therapy in patients with primary hypertension has been controversial. However, the 2009 guidelines of the European Society of Hypertension state that large-scale meta-analyses of available data confirm that diuretics, beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and calcium channel blockers do not significantly differ in their ability to lower blood pressure and to exert cardiovascular protection both in elderly and in younger patients.

TAKE HOME MESSAGE

The key message of this paper is that atenolol should not be used as an antihypertensive drug and that the degree of reduction of mortality, myocardial infarction, stroke and congestive heart failure by antihypertensive therapy is dependent on the degree of lowering of aortic blood pressure. Newer vasodilator beta-blockers such as carvedilol and nebivolol may be more effective in reducing cardiovascular events than traditional beta-blockers, but this needs to be investigated by controlled clinical trials.

Effects of beta-blockers on glucose and lipid metabolism

BACKGROUND

Activation of the sympathetic nervous system (SNS) has been linked to hypertension. Beta-blockers, which decrease SNS activation via beta-adrenergic receptor antagonism, are effective in lowering blood pressure and reducing cardiovascular morbidity and mortality in several conditions, including post-myocardial infarction and heart failure. Despite these clinical benefits, many physicians are reluctant to prescribe beta-blockers because of perceived negative metabolic effects, including reduced glycemic control, masking of hypoglycemia, insulin resistance, and dyslipidemia.

OBJECTIVE

This article reviews the pathophysiology of hypertension and either insulin resistance or dyslipidemia as well as treatment effects from glucose- and lipid-lowering regimens on cardiovascular morbidity and mortality. Based on a PubMed literature search from January 1980 to December 2008, the effects of nonvasodilating (atenolol, metoprolol, and propranolol) and vasodilating beta-blockers (carvedilol, labetalol, and nebivolol) on parameters of glucose and lipid metabolism in hypertension are presented. Preference for clinical trial inclusion was given to randomized, controlled trials with at least 100 patients. Limitations of a drug class literature review may include trial inclusion bias with associated result skewing and underrepresentation of an individual agent, which may give different results.

RESULTS

Beta-blockers differ in terms of their mechanism of action and their effects on glucose and lipid metabolism. Nonvasodilating beta-blockers reduce blood pressure in association with a cardiac output reduction and may increase or have no appreciable effect on peripheral vascular resistance. As a result, nonvasodilating beta-blockers are associated with a worsening of glycemic and lipidic control. In contrast, vasodilating beta-blockers reduce peripheral vascular resistance but have little or no effect on cardiac output. Numerous studies have established that vasodilating beta-blockers are associated with more favorable effects on glucose and lipid profiles than nonvasodilating beta-blockers.

CONCLUSIONS

Improvements in glucose and lipid metabolism mediated by vasodilating beta-blockers may help reduce coronary artery disease risk among high-risk patients with hypertension.

Controlled-release carvedilol in the management of systemic hypertension and myocardial dysfunction

Cardiovascular disease is the leading cause of death worldwide. Within the treatment armamentarium, beta-blockers have demonstrated efficacy across the spectrum of cardiovascular disease--from modification of a risk factor (ie, hypertension) to treatment after an acute event (ie, myocardial infarction). Recently, the use of beta-blockers as a first-line therapy in hypertension has been called into question. Moreover, beta-blockers as a class are saddled with a misperception of having poor tolerability. However, vasodilatory beta-blockers such as carvedilol have a different hemodynamic action that provides the benefits of beta-blockade with the addition of vasodilation resulting from alpha 1-adrenergic receptor blockade. Vasodilation reduces total peripheral resistance, which may produce an overall positive effect on tolerability. Recently, a new, controlled-release carvedilol formulation has been developed that provides the clinical efficacy of carvedilol but is indicated for once-daily dosing. This review presents an overview of the clinical and pharmacologic carvedilol controlled-release data.

Are tolerability concerns a class effect of beta-blockers in treating patients with hypertension?

Beta-blockers (beta-blockers) have demonstrated their value across the cardiovascular disease spectrum. Beta-blockers effectively lower blood pressure in patients with hypertension and provide symptomatic or mortality benefits in patients with heart failure and in post-myocardial infarction patients. However, despite their utility, beta-blockers remain underused. There have been recent concerns that beta-blockers as a class are not as effective as once thought in uncomplicated hypertension due to a relatively weak effect on reduction of stroke and the absence of an effect on coronary heart disease when compared with placebo or no treatment. Underuse can, in part, be related to tolerability concerns. Beta-blockers have been traditionally associated with side effects including depression, fatigue, sexual dysfunction, and cold extremities, which limit their acceptance by patients and physicians and may lead to discontinuation of therapy. Because of inherent heterogeneity of the beta-blocker class in terms of adrenergic receptor selectivity, intrinsic sympathomimetic activity, and vasodilatory activity, these agents vary in tolerability profile. Recently, more attention has been focused on the third-generation vasodilatory beta-blockers (ie, carvedilol, labetalol, and nebivolol), with the recognition that these agents may diverge in meaningful ways from the traditional beta-blockers. By examining the differences among members of the beta-blocker class, it may be possible to determine whether and which tolerability issues are indeed a class effect of beta-blockers or whether these agents should be evaluated on a case-by-case basis.

Carvedilol in hypertension treatment

Although β-blockers have been previously shown to effectively reduce blood pressure (BP) and have been used for hypertension treatment for over 40 years, their effect on cardiovascular morbidity and mortality in hypertensive patients remains controversial and its use in uncomplicated hypertension is currently under debate. However, data on the above field derive mainly from studies which were conducted with older agents, such as atenolol and metoprolol, while considerable pharamacokinetic and pharmacodynamic heterogeneity is present within the class of β-blockers. Carvedilol, a vasodilating non-cardioselective β-blocker, is a compound that seems to give the opportunity to the clinician to use a cardioprotective agent without the concerning hemodynamic and metabolic actions of traditional β-blocker therapy. In contrast with conventional β-blockers, carvedilol maintains cardiac output, has a less extended effect on heart rate and reduces BP by decreasing vascular resistance. Further, several studies has shown that carvedilol has a beneficial or at least neutral effect on metabolic parameters, such as glycemic control, insulin sensitivity, and lipid metabolism, suggesting that they could be used in subjects with the metabolic syndrome or diabetes without negative consequences. This article summarizes the distinct pharmacologic, hemodynamic, and metabolic properties of carvedilol in relation to conventional β-blockers, attempting to examine the potential use of this agent for hypertension treatment.

Nebivolol: pharmacologic profile of an ultraselective, vasodilatory beta1-blocker

Beta-blockers are well-established therapeutic agents in the treatment of hypertension and cardiovascular disease. However, these agents are highly heterogeneous. Beta-blockers differ in their ancillary pharmacologic properties, which are clinically important. Nebivolol is a highly selective beta(1)-adrenergic receptor blocker that induces vasodilation through stimulation of the endothelial nitric oxide/L-arginine pathway. As a racemic mixture of d- and l-enantiomers, nebivolol is highly lipophilic and rapidly absorbed. Nebivolol undergoes extensive hepatic metabolism through the cytochrome P450 2D6 (CYP2D6) system. As a result of genetic polymorphisms, CYP2D6 has variable activity, manifested by extensive and poor metabolizers of nebivolol. Time to maximum concentration is 0.5 to 2 hours, and half-life is 11 hours in extensive metabolizers; these values are about 3 times longer in poor metabolizers. Urinary and fecal excretion of unchanged nebivolol is less than 0.5% of the dose. Nebivolol has a unique hemodynamic profile of reduced systemic vascular resistance and increased left ventricular function. These properties are attributed to its vasodilating action and contrast with the hemodynamic effects of conventional beta-blockers. Nebivolol is thus a novel beta-blocker with several important pharmacologic properties that distinguish it from traditional beta-blockers. These unique properties may confer clinical benefits beyond simple blood pressure lowering.

The effect of carvedilol on metabolic parameters in patients with metabolic syndrome

The objective of the present study was to explore the effect of carvedilol treatment on metabolic parameters in patients with metabolic syndrome. A total of 77 patients > or = 20 years of age (59 females, 18 males, mean age, 52.3 +/- 10.3) with stage 1 hypertension who fulfilled at least 3 of the metabolic syndrome criteria proposed by NCEP-ATP III were included in this prospective, randomized, controlled study. Patients were randomly assigned to receive daily treatment with carvedilol (n = 27, 12.5 mg/day orally for the first 2 days and 25 mg/day thereafter), atenolol (n = 26, 50 mg/day orally), or doxazosin (n = 24, 2 mg/day orally) for 90 days. Doses were doubled at the end of the 3rd week in patients whose blood pressure was inadequately controlled and amlodipine 10 mg was added to the treatment if the target blood pressure was still not reached at the end of week 6. The biochemical parameters and insulin sensitivity based on the HOMA-IR model were evaluated at baseline and at the end of treatment. Similar reductions in systolic and diastolic blood pressure were observed in all groups (P > 0.05). A significant decrease in HDL cholesterol levels occurred in the doxazosin and atenolol groups compared to the carvedilol group (percent change: -5.6 +/- 13.5 and -8 +/- 9.8 versus -0.1 +/- 12.2, respectively; P < 0.05) and a significant increase in apolipoprotein A1 level was observed in the carvedilol group compared to the doxazosin and atenolol groups (percent change: + 4.3 +/- 9.6 versus - 0.5 +/- 10.6 and -2.3 +/- 6.6, respectively; P < 0.05). There were no significant differences among the groups with respect to other parameters. It is concluded antihypertensive treatment with carvedilol in patients with metabolic syndrome effectively reduces blood pressure without adversely affecting metabolic parameters.

Abnormal pressure passive dilatation of cerebral arterioles in the elderly with isolated systolic hypertension

The aim of this study was to investigate the cerebrovascular adaptability to 2 sequential pressor stimuli in elderly patients with isolated systolic hypertension. Ten healthy elderly normotensive subjects (68 to 82 years), 10 elderly subjects with isolated systolic hypertension (63 to 82 years), and 10 young normotensive subjects (24 to 40 years) took part in the study. A pressor reaction, using sequential cold pressor and handgrip stimulation, was induced. The cerebrovascular response to the pressor stimulation was measured by transcranial Doppler determination of the mean flow velocity in the middle cerebral arteries. In all of the subjects, blood pressure increased during handgrip (+12 mm Hg, P<0.001 in the young; +18 mm Hg, P<0.01 in the elderly normotensive subjects; +19 mm Hg, P<0.001 in the hypertensive patients versus baseline). In the hypertensive subjects, the pressure increase persisted well into the recovery period. The pressure increase caused a significant increase in mean flow velocity in the middle cerebral arteries only in the elderly subjects. Cold pressor test increased blood pressure in all of the subjects during stimulation and the first 2 minutes of the recovery period (at whole-curve ANOVA: F=22.03, P<0.001 in the young participants; F=18.3, P<0.001 in the normotensive elderly; and F=13.04, P<0.001 in the hypertensive elderly). Mean flow velocity in the middle cerebral arteries significantly increased only in the hypertensive subjects. In the elderly hypertensive patients, the cerebrovascular reaction to adrenergic stimuli was more impaired than in the elderly normotensive subjects. This event can amplify the pressure insult on cerebral hemodynamics and increase the predisposition to cerebral damage, such as vascular cognitive impairment or stroke.

β-Blockers for Primary Prevention in Hypertension: Era Bygone?

Beta-blockers are used commonly worldwide in clinical practice for lowering blood pressure. Most of the agents in this class are efficacious in reducing blood pressure, although they vary widely in their pharmacokinetic and pharmacodynamic properties. This variability may confer significant differences in clinical benefits associated with use of specific agents. Although commonly used in managing hypertension, the role of beta-blockers for primary prevention in uncomplicated hypertension has been controversial. Evidence from recent trials suggest relatively poor efficacy toward primary prevention and worse outcomes for certain end points, when compared with other blood pressure-lowering agents, Recently updated National Institute for Health and Clinical Excellence guidelines for England and Wales reflect this concern and have changed the indication for beta-blockers for blood pressure control from primary agents to use as an add-on agent in patients requiring multiple therapy. In this review, considering the extended debate on this topic, we discuss the general properties of beta-blockers and evidence from clinical trials supporting or refuting their use in various clinical scenarios. Newer beta-blockers have additional properties which may be beneficial. Although, whether these additional benefits will help in primary prevention is not clear.