Blood pressure lowering efficacy of beta-1 selective beta blockers for primary hypertension

The Usefulness of Prioritization of Ivabradine Before Beta-Blockers in a Heart Failure Patient Suffering From Intra-hemodialysis Hypotension

Depressed cardiac systolic function in hemodialysis patients occurs for a variety of reasons and is a clinical problem. Beta-blockers are a key drug in the treatment of heart failure; however, hypotension may occur, particularly in dialysis patients, thereby complicating dialysis. Ivabradine has the unique property of a negative chronotropic effect only, without the negative inotropic effect. A 55-year-old woman who underwent dialysis presented with dyspnea and fatigue even at rest due to low cardiac systolic function. The left ventricular ejection fraction (LVEF) was 30%. Medications for heart failure, such as carvedilol and enalapril, were initiated; however, they were discontinued owing to intradialytic hypotension. Subsequently, her heart rate increased to over 100 beats per minute (bpm); therefore, we administered 2.5 mg of ivabradine before beta-blockers, which reduced her heart rate by approximately 30 bpm without a significant blood pressure decrease. Moreover, her blood pressure stabilized during dialysis. After two weeks, we added 1.25 mg of bisoprolol and adjusted the dose to 0.625 mg. After seven months of treatment with 2.5 mg ivabradine and 0.625 mg bisoprolol, systolic cardiac function significantly improved to 70% of LVEF. Prioritizing ivabradine over beta-blockers may not cause intradialytic hypotension; even low doses of ivabradine and bisoprolol were considered effective heart failure therapies.

An evidence-based guide to the efficacy and safety of isometric resistance training in hypertension and clinical implications

More than 30 randomized controlled trials, supported by individual patient-level and group-level meta-analyses and a Delphi analysis of expert opinion, unequivocally show isometric resistance training (IRT) elicits antihypertensive benefits in healthy people and those with chronic illness. We aim to provide efficacy and safety evidence, and a guide for IRT prescription and delivery. Recommendations are made for the use of IRT in specific patient populations and appropriate methods for IRT delivery. Published data suggest IRT consistently elicits mean blood pressure reductions of 7.4/3.3 mmHg systolic blood pressure/diastolic blood pressure, equivalent to antihypertensive medication monotherapy. Blood pressure reductions of this size are associated with an approximate 13% to 22% reduction in major cardiovascular events. Moreover, IRT is safe in a range of patient populations. We suggest that IRT has the greatest potential benefit when used as an antihypertensive therapy in individuals unwilling and/or unable to complete aerobic exercise, or who have had limited adherence or success with it; individuals with resistant or uncontrolled hypertension, already taking at least two pharmacological antihypertensive agents; and healthy or clinical populations, as an adjunct to aerobic exercise and dietary intervention in those who have not yet attained control of their hypertension. IRT is efficacious and produces clinically meaningful blood pressure reductions (systolic blood pressure, 7 mmHg; diastolic blood pressure, 3 mmHg). IRT is safe and typical program delivery requires only about 17 min weekly. IRT should be used as an adjunct to other exercise modalities, in people unable to complete other types of exercise, or in resistant hypertension.

Blood-brain barrier permeable β-blockers linked to lower risk of Alzheimer's disease in hypertension

Alzheimer's disease is a neurodegenerative disorder in which the pathological accumulation of amyloid-β and tau begins years before symptom onset. Emerging evidence suggests that β-blockers (β-adrenergic antagonists) increase brain clearance of these metabolites by enhancing CSF flow. Our objective was to determine whether β-blocker treatments that easily cross the blood-brain barrier reduce the risk of Alzheimer's disease compared to less permeable β-blockers. Data from the Danish national registers were used to identify a retrospective cohort of individuals with hypertension, and those treated with β-blockers were included in the analysis. People with indications for β-blocker use other than hypertension (e.g. heart failure) were only retained in a sensitivity analysis. β-blockers were divided into three permeability groups: low, moderate and high. We used multivariable cause-specific Cox regression to model the effect of β-blocker blood-brain barrier permeability on time to dementia outcomes, adjusting for baseline comorbidities, demographics and socioeconomic variables. Death was modelled as a competing risk. The 10-year standardized absolute risk was estimated as the averaged person-specific risks per treatment. In a cohort of 69 081 (median age = 64.4 years, 64.8% female) people treated with β-blockers for hypertension, highly blood-brain barrier-permeable β-blockers were associated with reduced risk of Alzheimer's disease versus low permeability β-blockers (-0.45%, P < 0.036). This effect was specific to Alzheimer's diagnoses and did not extend to dementia in general. Propensity score analysis matching high and low blood-brain barrier-permeable patients also detected a decreased Alzheimer's risk (-0.92%, P < 0.001) in the high permeability group compared to the low, as did a 1-year landmark analysis (-0.57%, P < 0.029) in which events within the first year of follow-up were ignored as likely unrelated to treatment. Our results suggest that amongst people taking β-blockers for hypertension, treatment with highly blood-brain barrier permeable β-blockers reduces the risk of Alzheimer's disease compared to low permeability drugs. Our findings support the hypothesis that highly permeable β-blockers protect against Alzheimer's disease by promoting waste brain metabolite clearance.

Peculiarities of Adverse Events Manifested by Injury of Skin and Skin Derivatives and Associated with Beta-blockers Use

More than 50 years after Propranolol was introduced to the pharmaceutical market as a drug that can lower the heart rate, beta-blockers (BAB) are still widely used in the pharmacotherapy of cardiovascular diseases. However, the use of BAB has a number of limitations, first of all, due to adverse drug events (AE) that develop during their use. The purpose of our review was to study the features of the BAB AE manifested by injuries of the skin and its appendages. The clinical manifestations of them are the development or exacerbation of psoriasis, lichen planus, contact dermatitis, acrocyanosis, Raynaud's disease, alopecia, hyperhidrosis, vitiligo, anaphylaxis, and allergic skin reactions. True medicinal psoriasis occurs in patients taking BAB with no family or previous history and most often mimics erythrodermic psoriasis and palmar-plantar pustular psoriasis. Systemic use of BAB can also be accompanied by exacerbation of vitiligo. In patients with segmental vitiligo, the results of Doppler flowmetry and iontophoresis showed increased blood flow in vitiligo foci compared with normal skin. The development of anaphylactic reactions against the background of BAB therapy may be due to the modulation of adenylate cyclase, which can affect the release of anaphylactogenic mediators, as well as a decrease in the severity of cardiovascular compensatory changes. The peculiarities of the development of such reactions may be the resistance of patients to traditional treatment, which is due to the development of paradoxical reflex vagotonic effects when using adrenaline. Some of the mentioned AE may pose a potential threat to the life and health of the patient and therefore require additional discussion.

Improvement in left ventricular ejection fraction after pharmacological up-titration in new-onset heart failure with reduced ejection fraction

Objective

Recent studies have reported suboptimal up-titration of heart failure (HF) therapies in patients with heart failure and a reduced ejection fraction (HFrEF). Here, we report on the achieved doses after nurse-led up-titration, reasons for not achieving the target dose, subsequent changes in left ventricular ejection fraction (LVEF), and mortality.

Methods

From 2012 to 2018, 378 HFrEF patients with a recent (< 3 months) diagnosis of HF were referred to a specialised HF-nurse led clinic for protocolised up-titration of guideline-directed medical therapy (GDMT). The achieved doses of GDMT at 9 months were recorded, as well as reasons for not achieving the optimal dose in all patients. Echocardiography was performed at baseline and after up-titration in 278 patients.

Results

Of 345 HFrEF patients with a follow-up visit after 9 months, 69% reached ≥ 50% of the recommended dose of renin-angiotensin-system (RAS) inhibitors, 73% reached ≥ 50% of the recommended dose of beta-blockers and 77% reached ≥ 50% of the recommended dose of mineralocorticoid receptor antagonists. The main reasons for not reaching the target dose were hypotension (RAS inhibitors and beta-blockers), bradycardia (beta-blockers) and renal dysfunction (RAS inhibitors). During a median follow-up of 9 months, mean LVEF increased from 27.6% at baseline to 38.8% at follow-up. Each 5% increase in LVEF was associated with an adjusted hazard ratio of 0.84 (0.75–0.94, p = 0.002) for mortality and 0.85 (0.78–0.94, p = 0.001) for the combined endpoint of mortality and/or HF hospitalisation after a mean follow-up of 3.3 years.

Conclusions

This study shows that protocolised up-titration in a nurse-led HF clinic leads to high doses of GDMT and improvement of LVEF in patients with new-onset HFrEF.

Supplementary Information

The online version of this article (10.1007/s12471-021-01591-6) contains supplementary material, which is available to authorized users.

The impact of catecholamines on skeletal muscle following massive burns: Friend or foe?

Profound skeletal muscle wasting in the setting of total body hypermetabolism is a defining characteristic of massive burns, compromising the patient's recovery and necessitating a protracted period of rehabilitation. In recent years, the prolonged use of the non-selective beta-blocker, propranolol, has gained prominence as an effective tool to assist with suppressing epinephrine-dependent burn-induced hypermetabolism and by extension, blunting muscle catabolism. However, synthetic β-adrenergic agonists, such as clenbuterol, are widely associated with the promotion of muscle growth in both animals and humans. Moreover, experimental adrenodemedullation is known to result in muscle catabolism. Therefore, the blunting of muscle β-adrenergic signaling via the use of propranolol would be expected to negatively impair muscle protein homeostasis. This review explores these paradoxical observations and identifies the manner by which propranolol is thought to exert its anti-catabolic effects in burn patients. Moreover, we identify potential avenues by which the use of beta-blocker therapy in the treatment of massive burns could potentially be further refined to promote the recovery of muscle mass in these critically ill patients while continuing to ameliorate total body hypermetabolism.

Effects of Holding Beta-Blockers on the Vital Signs of Heart Failure Patients

Background

Heart failure with reduced ejection fraction (HFrEF) is associated with recurrent hospitalizations and high mortality. Guideline-directed medical therapy (GDMT) reduces morbidity, mortality and re-admission rates. Despite the evidence, less than 50% of patients with HFrEF are prescribed appropriate medical therapy. When hospitalized patients have these medications discontinued on admission or during hospitalization, they are less likely to have them restarted on discharge. The goal of this study was to determine the incidence of disruption of beta-blocker (BB) therapy during hospitalization for HFrEF patients admitted to an academic tertiary referral hospital.

Methods

We conducted a retrospective study in a single teaching hospital over the course of 1 year, and utilized data queried from the electronic medical record (EPIC) database. Inclusion criteria were met by patients with an ICD-10 code diagnosis of heart failure, left ventricular ejection fraction less than 40% and BB prescription prior to admission. Additional information noted included age, sex, vital signs throughout the admission and dates where BB was not given for a full 24-h period. Patients in the intensive care unit (ICU) were excluded due to uncertainty of their hemodynamics. Data were extracted from the electronic medical record database and analyzed through Python, Microsoft Excel and RStudio. The incidence of BB disruption during hospitalization was defined as a 24-h period where no BB was administered. Blood pressure (BP) and heart rate (HR) levels were compared between patients who received BB and patients who had a disruption in their BB. Measurements were also obtained to assess whether a correlation exists between holding BB therapy and time of the year, age, or sex.

Results

Between January 2018 and January 2019, 780 patient encounters met inclusion criteria for the study. Patients who were continued on BB therapy had an average BP of 120.8/68.7 mm Hg and an HR of 82.4 bpm on days they received their BB. Patients who had a disruption of BB therapy had an average BP of 117.7/67.6 mm Hg and an HR of 88.6 bpm on the days of the disruption (P < 0.001). There was no association between holding BB and age, sex, or time of year.

Conclusions

This study showed that in an academic tertiary referral center, patients with HFrEF who are not in an ICU have a 23% chance of not receiving their recommended BB therapy for 24 h. While the differences measured for BP and HR are statistically significant, they are not clinically significant.

Beta Blockers and Chronic Obstructive Pulmonary Disease (COPD): Sum of Evidence

Approximately, half a century has passed since the discovery of beta blockers. Then, their prime therapeutic purpose was to treat angina and cardiac arrhythmias, nowadays, beta blockers' usage and effectiveness is extended to treat other cardiovascular diseases, such as hypertension, congestive heart failure, and coronary artery disease. Safety concerns were raised about beta blockers and their use for chronic obstructive pulmonary disease (COPD) patients with concurrent cardiovascular disease. After a thorough research of the literature, this review summarizes the evidence proving that beta blockers not only might be well tolerated in COPD patients, but they might also have a beneficial effect in this group of patients.

Time course for blood pressure lowering of beta-blockers with partial agonist activity

BACKGROUND

Beta-blockers are commonly used in the treatment of hypertension. We do not know whether the blood pressure (BP) lowering efficacy of beta-blockers varies across the day. This review focuses on the subclass of beta-blockers with partial agonist activity (BBPAA).

OBJECTIVES

To assess the degree of variation in hourly BP lowering efficacy of BBPAA over a 24-hour period in adults with essential hypertension.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for relevant studies up to June 2020: the Cochrane Hypertension Specialised Register; CENTRAL; 2020, Issue 5; MEDLINE Ovid; Embase Ovid; the World Health Organization International Clinical Trials Registry Platform; and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We sought to include all randomised and non-randomised trials that assessed the hourly effect of BBPAA by ambulatory monitoring, with a minimum follow-up of three weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the included trials and extracted the data. We assessed the certainty of the evidence using the GRADE approach. Outcomes included in the review were end-point hourly systolic and diastolic blood pressure (SBP and DBP) and heart rate (HR), measured using a 24-hour ambulatory BP monitoring (ABPM) device.

MAIN RESULTS

Fourteen non-randomised baseline controlled trials of BBPAA met our inclusion criteria, but only seven studies, involving 121 participants, reported hourly ambulatory BP data that could be included in the meta-analysis. Beta-blockers studied included acebutalol, pindolol and bopindolol. We judged most studies at high or unclear risk of bias for selection bias, attrition bias, and reporting bias. We judged the overall certainty of the evidence to be very low for all outcomes. We analysed and presented data by each hour post-dose. Very low-certainty evidence showed that hourly mean reduction in BP and HR visually showed an attenuation over time. Over the 24-hour period, the magnitude of SBP lowering at each hour ranged from -3.68 mmHg to -17.74 mmHg (7 studies, 121 participants), DBP lowering at each hour ranged from -2.27 mmHg to -9.34 mmHg (7 studies, 121 participants), and HR lowering at each hour ranged from -0.29 beats/min to -10.29 beats/min (4 studies, 71 participants). When comparing between three 8-hourly time intervals that correspond to day, evening, and night time hours, BBPAA was less effective at lowering BP and HR at night, than during the day and evening. However, because we judged that these outcomes were supported by very low-certainty evidence, further research is likely to have an important impact on the estimate of effect and may change the conclusion.

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw general conclusions about the degree of variation in hourly BP-lowering efficacy of BBPAA over a 24-hour period, in adults with essential hypertension. Very low-certainty evidence showed that BBPAA acebutalol, pindolol, and bopindolol lowered BP more during the day and evening than at night. However, the number of studies and participants included in this review was very small, further limiting the certainty of the evidence. We need further and larger trials, with accurate recording of time of drug intake, and with reporting of standard deviation of BP and HR at each hour.

Hypertension Drug Therapy

Hypertension is still the number one global killer. No matter what causes are, lowering blood pressure can significantly reduce cardiovascular complications, cardiovascular death, and total death. Unfortunately, some hypertensive individuals simply do not know having hypertension. Some knew it but either not being treated or treated but blood pressure does not achieve goal. The reasons for inadequate control of blood pressure are many. One important reason is that we are not very familiar with antihypertensive agents and less attention has been paid to comorbidities, complications as well as the hypertension-modified target organ damage in patients with hypertension. The right antihypertensive drug was not given to the right hypertensive patients at right time. This reviewer studied comprehensively the literature, hopefully that the review will help improve antihypertensive drug selection and antihypertensive therapy.

Radio-Telemetric Assessment of Cardiac Variables and Locomotion With Experimentally Induced Hypermagnesemia in Horses Using Chronically Implanted Catheters

The objective of this study was to characterize the pharmacokinetics and pharmacodynamics of intravenous administration of magnesium sulfate to horses using a novel radio-telemetry system for physiologic signal capture. Five Horses were surgically implanted with a radio-telemetric carotid catheter. Implants were paired with a non-invasive telemetric unit which acquired a six lead ECG and 3-axis acceleration to assess activity acquired wirelessly in real-time for future analysis. Horses were exposed to a new stall environment before (baseline) and after 60 mg/kg (30 mL) of magnesium sulfate (MgSO₄), or the same volume of 0.9% saline, administered intravenously in a blinded, random crossover design. Blood for pharmacokinetics, telemetric data, and body temperature were recorded serially for 24 h. Data were analyzed across time and between treatments. Significance was set at P < 0.05. Ionized magnesium concentration (Mg²⁺) increased and the Ca²⁺ to Mg²⁺ ratio decreased and persisted for 5 h after MgSO₄ administration. Heart rate (HR) increased and mean arterial blood pressure (MAP) decreased for at least 6 h. Electrocardiogram (ECG) intervals (RR) decreased and (PR and QTc) increased in duration compared to controls indicating an increase in heart rate, and slower myocardial conduction in the MgSO₄ group. Acceleration in all planes was less in the MgSO₄ group compared to controls indicating decreased locomotion. This novel method permitted collection of physiologic signals without interference by handlers or animal restraint. An intravenous bolus of MgSO₄ produced cardiac variable changes associated with the reduction of locomotion in these horses, and in a direction that may be causal. Locomotion was decreased when horses were first introduced into a new environment which reflects the calming effect desired in sport horses. Telemetric monitoring can be used as a model to elucidate the behavior and physiologic effects of other drugs. The administration of MgSO₄ may be detected for regulatory purposes with the monitoring of Mg²⁺ and Ca²⁺ concentrations and their ratio.

Distributed Tensor Decomposition for Large Scale Health Analytics

In the past few decades, there has been rapid growth in quantity and variety of healthcare data. These large sets of data are usually high dimensional (e.g. patients, their diagnoses, and medications to treat their diagnoses) and cannot be adequately represented as matrices. Thus, many existing algorithms can not analyze them. To accommodate these high dimensional data, tensor factorization, which can be viewed as a higher-order extension of methods like PCA, has attracted much attention and emerged as a promising solution. However, tensor factorization is a computationally expensive task, and existing methods developed to factor large tensors are not flexible enough for real-world situations. To address this scaling problem more efficiently, we introduce SGranite, a distributed, scalable, and sparse tensor factorization method fit through stochastic gradient descent. SGranite offers three contributions: (1) Scalability: it employs a block partitioning and parallel processing design and thus scales to large tensors, (2) Accuracy: we show that our method can achieve results faster without sacrificing the quality of the tensor decomposition, and (3) FlexibleConstraints: we show our approach can encompass various kinds of constraints including l2 norm, l1 norm, and logistic regularization. We demonstrate SGranite's capabilities in two real-world use cases. In the first, we use Google searches for flu-like symptoms to characterize and predict influenza patterns. In the second, we use SGranite to extract clinically interesting sets (i.e., phenotypes) of patients from electronic health records. Through these case studies, we show SGranite has the potential to be used to rapidly characterize, predict, and manage a large multimodal datasets, thereby promising a novel, data-driven solution that can benefit very large segments of the population.

Acupuncture for hypertension

BACKGROUND

Elevated blood pressure (hypertension) affects about one billion people worldwide. It is important as it is a major risk factor for stroke and myocardial infarction. However, it remains a challenge for the medical profession as many people with hypertension have blood pressure (BP) that is not well controlled. According to Traditional Chinese Medicine theory, acupuncture has the potential to lower BP.

OBJECTIVES

To assess the effectiveness and safety of acupuncture for lowering blood pressure in adults with primary hypertension.

SEARCH METHODS

We searched the Hypertension Group Specialised Register (February 2017); the Cochrane Central Register of Controlled Trials (CENTRAL) 2017, Issue 2; MEDLINE (February 2017); Embase (February 2017), China National Knowledge Infrastructure (CNKI) (January 2015), VIP Database (January 2015), the World Health Organisation Clinical Trials Registry Platform (February 2017)and ClinicalTrials.gov (February 2017). There were no language restrictions.

SELECTION CRITERIA

We included all randomized controlled trials (RCTs) that compared the clinical effects of an acupuncture intervention (acupuncture used alone or add-on) with no treatment, a sham acupuncture or an antihypertensive drug in adults with primary hypertension.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies according to inclusion and exclusion criteria. They extracted data and assessed the risk of bias of each trial, and telephoned or emailed the authors of the studies to ask for missing information. A third review author resolved disagreements. Outcomes included change in systolic blood pressure (SBP), change in diastolic blood pressure (DBP), withdrawal due to adverse effects, and any adverse events. We calculated pooled mean differences (MD) with 95% confidence intervals (CI) for continuous outcomes using a fixed-effect or random-effects model where appropriate.

MAIN RESULTS

Twenty-two RCTs (1744 people) met our inclusion criteria. The RCTs were of variable methodological quality (most at high risk of bias because of lack of blinding). There was no evidence for a sustained BP lowering effect of acupuncture; only one trial investigated a sustained effect and found no BP lowering effect at three and six months after acupuncture. Four sham acupuncture controlled trials provided very low quality evidence that acupuncture had a short-term (one to 24 hours) effect on SBP (change) -3.4 mmHg (-6.0 to -0.9) and DBP -1.9 mmHg (95% CI -3.6 to -0.3). Pooled analysis of eight trials comparing acupuncture with angiotensin-converting enzyme inhibitors and seven trials comparing acupuncture to calcium antagonists suggested that acupuncture lowered short-term BP better than the antihypertensive drugs. However, because of the very high risk of bias in these trials, we think that this is most likely a reflection of bias and not a true effect. As a result, we did not report these results in the 'Summary of findings' table. Safety of acupuncture could not be assessed as only eight trials reported adverse events.

AUTHORS' CONCLUSIONS

At present, there is no evidence for the sustained BP lowering effect of acupuncture that is required for the management of chronically elevated BP. The short-term effects of acupuncture are uncertain due to the very low quality of evidence. The larger effect shown in non-sham acupuncture controlled trials most likely reflects bias and is not a true effect. Future RCTs must use sham acupuncture controls and assess whether there is a BP lowering effect of acupuncture that lasts at least seven days.

Insights on β-blockers for the treatment of hypertension: A survey of health care practitioners

A quantitative survey was completed by 103 primary care physicians (PCPs) and 59 cardiologists who regularly prescribed β-blockers to assess knowledge and use of this heterogeneous drug class for hypertension. More cardiologists than PCPs chose β-blockers as initial antihypertensive therapy (30% vs 17%, P < 0.01). Metoprolol and carvedilol were the most commonly prescribed β-blockers. Cardiologists rated "impact on energy" and "arterial vasodilation" as more important than PCPs (P < 0.05/<0.01, respectively). Awareness of vasodilation was greater for carvedilol (52%) than nebivolol (31%). Association between β-blockers and clinical variables included nebivolol with β₁ -selectivity, nebivolol and carvedilol with vasodilation and efficacy in older patients and African Americans, metoprolol with heart rate reduction, and atenolol and metoprolol with weight gain and hyperglycemia. Physicians preferred prescribing β-blockers with lower risk of incident diabetes. Clinical practice guidelines influenced physician prescribing more than formularies or performance metrics. This survey captures physicians' perceptions/use of various β-blockers and clinically relevant knowledge gaps.

Cochrane Corner: Antihypertensive efficacy of beta-1 selective beta blockers for primary hypertension

Beta blockers are commonly used to treat hypertension. This Cochrane systematic review assessed the effect of beta-1 selective beta blockers on blood pressure (BP), pulse pressure (PP), heart rate (HR) and withdrawal due to adverse effects in patients with primary hypertension. Fifty-six randomized placebo-controlled trials were included, with a total of 7812 patients. These drugs reduced systolic/diastolic BP by 10/8 mmHg, PP by 2 mmHg and HR by 11 bpm; no difference was found between treatment and placebo regarding withdrawal due to adverse effects. Differences in efficacy were observed between the various beta-1 selective beta blockers, which may be due to methodological differences in the trials. The choice of an antihypertensive drug should take into account not only its efficacy in reducing BP but also its tolerability, its efficacy in preventing cardiovascular events, and other factors such as undesirable metabolic effects.

Acupuncture Attenuates Renal Sympathetic Activity and Blood Pressure via Beta-Adrenergic Receptors in Spontaneously Hypertensive Rats

The sympathetic nervous system, via epinephrine and norepinephrine, regulates β-adrenergic receptor (β-AR) expression, and renal sympathetic activation causes sustained increases in blood pressure by enhanced renin release. In this study, we aim to investigate the effect and underlying mechanism of acupuncture at Taichong (LR3) on renal sympathetic activity in spontaneously hypertensive rats. Unanesthetized rats were subject to daily acupuncture for 2 weeks. Mean blood pressure (MBP) and heart rate variability (HRV) were monitored at days 0, 7, and 14 by radiotelemetry. After euthanasia on the 14th day, blood and the kidneys were collected and subject to the following analyses. Epinephrine and norepinephrine were detected by ELISA. The expression of β-ARs was studied by western blotting and PCR. The renin content was analyzed by radioimmunoassay. 14-day acupuncture significantly attenuates the increase of MBP. The HRV indices, the standard deviation of all normal NN intervals (SDNN), and the ratio of the low-frequency component to the high-frequency component (LF/HF) were improved following acupuncture. Renal sympathetic activation induced upregulation of epinephrine, norepinephrine, and renin content were attenuated by acupuncture. In addition, acupuncture decreased β1-AR expression and improved β2-AR expression. These results indicated that acupuncture relieves the increased MBP via the regulation of renal sympathetic activity and β-ARs.

Blood pressure lowering efficacy of dual alpha and beta blockers for primary hypertension

BACKGROUND

Drugs with combined alpha and beta blocking activity are commonly prescribed to treat hypertension. However, the blood pressure (BP) lowering efficacy of this class of beta blockers has not been systematically reviewed and quantified.

OBJECTIVES

To quantify the dose-related effects of various types of dual alpha and beta adrenergic receptor blockers (dual receptor blockers) on systolic and diastolic blood pressure versus placebo in patients with primary hypertension.

SEARCH METHODS

We searched the Cochrane Hypertension Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and ClinicalTrials.gov for randomized controlled trials up to October 2014. The WHO International Clinical Trials Registry Platform (ICTRP) is searched for inclusion in the Group's Specialised Register.

SELECTION CRITERIA

Randomized double blind placebo controlled parallel or cross-over trials. Studies contained a beta blocker monotherapy arm with a fixed dose. Patients enrolled in the studies had primary hypertension at baseline. Duration of the studies was from three to 12 weeks. Drugs in this class of beta blockers are carvedilol, dilevalol and labetalol.

DATA COLLECTION AND ANALYSIS

Two review authors (GW and AL) confirmed the inclusion of studies and extracted the data independently. RevMan 5.3 was used to synthesize data.

MAIN RESULTS

We included eight studies examining the blood pressure lowering efficacy of carvedilol and labetalol in 1493 hypertensive patients. Five of the included studies were parallel design; three were cross-over design. The two largest included studies were unpublished carvedilol studies. The estimates of BP lowering effect (systolic BP/diastolic BP millimeters of mercury; SPB/DBP mm Hg) were -4 mm Hg (95% confidence intervals (CI) -6 to -2)/-3 mm Hg (95% CI -4 to -2) for carvedilol (>1000 subjects) and -10 mm Hg (95% CI -14 to -7)/-7 mm Hg (95% CI -9 to -5) for labetalol (110 subjects). The effect of labetalol is likely to be exaggerated due to high risk of bias. Carvedilol, within the recommended dose range, did not show a significant dose response effect for SBP or DBP. Carvedilol had little or no effect on pulse pressure (-1 mm Hg) and did not change BP variability. Overall, once and twice the starting dose of carvedilol and labetalol lowered BP by -6 mm Hg (95% CI -7 to -4) /-4 mm Hg (95% CI -4 to -3) (low quality evidence) and lowered heart rate by five beats per minute (95% CI -6 to -4) (low quality evidence). Five studies (N = 1412) reported withdrawal due to adverse effects; the risk ratio was 0.88 (95% CI 0.54 to 1.42) (moderate quality evidence).

AUTHORS' CONCLUSIONS

This review provides low quality evidence that in patients with mild to moderate hypertension, dual receptor blockers lowered trough BP by an average of -6/-4 mm Hg and reduced heart rate by five beats per minute. Due to the larger sample size from the two unpublished studies, carvedilol provided a better estimate of BP lowering effect than labetalol. The BP lowering estimate from combining carvedilol once and twice the starting doses is -4/-3 mm Hg. Doses higher than the recommended starting dose did not provide additional BP reduction. Higher doses of dual receptor blockers caused more bradycardia than lower doses. Based on indirect comparison with other classes of drugs, the blood pressure lowering effect of dual alpha- and beta-receptor blockers is less than non-selective, beta1 selective and partial agonist beta blockers, as well as thiazides and drugs inhibiting the renin angiotensin system. Dual blockers also had little or no effect on reducing pulse pressure, which is similar to the other beta-blocker classes, but less than the average reduction of pulse pressure seen with thiazides and drugs inhibiting the renin angiotensin system. Patients taking dual receptor blockers were not more likely to withdraw from the study compared to patients taking placebo.

Blood pressure lowering efficacy of partial agonist beta blocker monotherapy for primary hypertension

BACKGROUND

Partial agonists are a subclass of beta blockers used to treat hypertension in many countries. Partial agonist act by stimulating beta receptors when they are quiescent and blocking beta receptors when they are active. The blood pressure (BP) lowering effect of partial agonist beta blockers has not been quantified.

OBJECTIVES

To quantify the dose-related effects of various partial agonists beta blockers on systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate versus placebo in patients with primary hypertension.

SEARCH METHODS

We searched the Hypertension Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, EMBASE and ClinicalTrials.gov for randomized controlled trials up to October 2014. The WHO International Clinical Trials Registry Platform (ICTRP) is searched for inclusion in the Group's Specialised Register.

SELECTION CRITERIA

Randomized double-blinded placebo-controlled parallel or cross-over trials. Studies must contain a partial agonist monotherapy arm with fixed dose. Patients enrolled into the studies must have primary hypertension at baseline (defined as SBP/DBP > 140/90 mmHg). Duration of studies must be between three to 12 weeks.

DATA COLLECTION AND ANALYSIS

Two authors (GW and HB) confirmed the inclusion of studies and extracted the data independently.

MAIN RESULTS

Thirteen randomized double-blinded placebo-controlled trials that examined the blood pressure lowering efficacy of six partial agonists in 605 hypertensive patients were included in this review. Five of the included studies were parallel studies and the other eight were cross-over studies. The overall risk of bias is high in this review due to the small sample size and high risk of detection bias. Pindolol, celiprolol and alprenolol lowered SBP and DBP compared to placebo. Acebutolol lowered SBP but there was no clear evidence that it lowered DBP. There was no clear evidence that pindolol and oxprenolol lowered SBP or DBP. Other than for celiprolol, sample sizes were generally small increasing the uncertainty in findings for individual agents versus placebo. In patients with moderate to severe hypertension, partial agonists (considered as a subclass) lowered peak BP by an average of 8 mmHg systolic (95% CI, -10 to -6, very low quality evidence), 4 mmHg diastolic (95%CI, -5 to -3, very low quality evidence) and reduced heart rate by five beats per minute (95%CI, -6 to -4, very low quality evidence). Higher dose partial agonists did not appear to provide additional BP lowering effects compared to lower dose. The maximum BP lowering effect of the overall subclass occurred at the starting dose. Partial agonists reduced pulse pressure by 4 mmHg (95% CI, -5 to -2, very low evidence). Only one study reported withdrawal due to adverse effects, the risk ratio (95% confidence interval) was 0.72 (0.07, 7.67).

AUTHORS' CONCLUSIONS

There was very low quality evidence that in patients with moderate to severe hypertension, partial agonists lowered peak BP by an average of 8/4 mmHg and reduced heart rate by five beats per minute. There was no evidence of a greater effect at doses higher than the initial doses. This estimate was probably exaggerated as it was subject to a high risk of bias. Based on the indirect comparison of the results in this review and two Cochrane reviews on angiotensin-converting-enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), which also used similar inclusion criteria as this review, the BP lowering effect appeared to be less than the effect in patients with mild to moderate elevated BP who were taking ACE inhibitors and ARBs based on an indirect comparison. Withdrawals due to adverse effects were only reported in one trial so it is impossible to assess the harm of these drugs.