A Review of the Adverse Effects of Peripheral Alpha-1 Antagonists in Hypertension Therapy

Obesity and hypertension: Obesity medicine association (OMA) clinical practice statement (CPS) 2023

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) provides an overview of the mechanisms and treatment of obesity and hypertension.

Methods

The scientific support for this CPS is based upon published citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

Mechanisms contributing to obesity-related hypertension include unhealthful nutrition, physical inactivity, insulin resistance, increased sympathetic nervous system activity, renal dysfunction, vascular dysfunction, heart dysfunction, increased pancreatic insulin secretion, sleep apnea, and psychosocial stress. Adiposopathic factors that may contribute to hypertension include increased release of free fatty acids, increased leptin, decreased adiponectin, increased renin-angiotensin-aldosterone system activation, increased 11 beta-hydroxysteroid dehydrogenase type 1, reduced nitric oxide activity, and increased inflammation.

Conclusions

Increase in body fat is the most common cause of hypertension. Among patients with obesity and hypertension, weight reduction via healthful nutrition, physical activity, behavior modification, bariatric surgery, and anti-obesity medications mostly decrease blood pressure, with the greatest degree of weight reduction generally correlated with the greatest degree of blood pressure reduction.

Causes of obesity: a review

Obesity research is advancing swiftly, but the increase in obesity prevalence is faster. Over the past three decades, researchers have found that biopsychosocial factors determine weight gain much more than personal choices and responsibility. Various genes have found to predispose people to obesity by interacting with our obesogenic environment. In this review, we discuss the impact of physical inactivity, excessive caloric intake, intrauterine environment, postnatal influences, insufficient sleep, drugs, medical conditions, socioeconomic status, ethnicity, psychosocial stress, endocrine disrupting chemicals and the gastrointestinal microbiome, on the occurrence of obesity.

Do adrenergic alpha-antagonists increase the risk of poor cardiovascular outcomes? A systematic review and meta-analysis

Due to concerns regarding neurohormonal activation and fluid retention, adrenergic alpha-1 receptor antagonists (A1Bs) are generally avoided in the setting of heart disease, namely, symptomatic heart failure (HF) with reduced ejection fraction (HFrEF). However, this contraindication is mainly supported by ancient studies, having recently been challenged by newer ones. We aim to perform a comprehensive meta-analysis aimed at ascertaining the extent to which A1Bs might influence cardiovascular (CV) outcomes. We systematically searched PubMed, Cochrane Central Register of Controlled Trials and Web of Science for both prospective and retrospective studies, published until 1 December 2020, addressing the impact of A1Bs on both clinical outcomes-namely, acute heart failure (AHF), acute coronary syndrome (ACS), CV and all-cause mortality-and on CV surrogate measures, specifically left ventricular ejection fraction (LVEF) and exercise tolerance, by means of exercise duration. Both randomized controlled trials (RCTs) and studies including only HF patients were further investigated separately. Study-specific odds ratios (ORs) and mean differences (MDs) were pooled using traditional meta-analytic techniques, under a random-effects model. A record was registered in PROSPERO database, with the code number CRD42020181804. Fifteen RCTs, three non-randomized prospective and two retrospective studies, encompassing 32 851, 19 287, and 71 600 patients, respectively, were deemed eligible; 62 256 patients were allocated to A1B, on the basis of multiple clinical indications: chronic HF itself [14 studies, with 72 558 patients, including seven studies with 850 HFrEF or HF with mildly reduced ejection fraction (HFmrEF) patients], arterial hypertension (four studies, with 44 184 patients) and low urinary tract symptoms (two studies, with 6996 patients). There were 25 998 AHF events, 1325 ACS episodes, 955 CV deaths and 33 567 all-cause deaths. When considering only RCTs, A1Bs were, indeed, found to increase AHF risk (OR 1.78, [1.46, 2.16] 95% CI, P < 0.00001, i² 2%), although displaying no significant effect on neither ACS nor CV or all-cause mortality rates (OR 1.02, [0.91, 1.15] 95% CI, i² 0%; OR 0.95, [0.47, 1.91] 95% CI, i² 17%; OR 1.1, [0.84, 1.43] 95% CI, i² 17%, respectively). Besides, when only HF patients were evaluated, A1Bs revealed themselves neutral towards not only ACS, CV, and all-cause mortality events (OR 0.49, [0.1, 2.47] 95% CI, i² 0%; OR 0.7, [0.21, 2.31] 95% CI, i² 21%; OR 1.09, [0.53, 2.23] 95% CI, i² 17%, respectively), but also AHF (OR 1.13, [0.66, 1.92] 95% CI, i² 0%). As for HFrEF and HFmrEF, A1Bs were found to exert a similarly inconsequential effect on AHF rates (OR 1.01, [0.5-2.05] 95% CI, i² 6%). Likewise, LVEF was not significantly influenced by A1Bs (MD 1.66, [-2.18, 5.50] 95% CI, i² 58%). Most strikingly, exercise tolerance was higher in those under this drug class (MD 139.16, [65.52, 212.8] 95% CI, P < 0.001, i² 26%). A1Bs do not seem to exert a negative influence on the prognosis of HF-and even of HFrEF-patients, thus contradicting currently held views. These drugs' impact on other major CV outcomes also appear trivial and they may even increment exercise tolerance.

A comprehensive diagnostic approach to detect underlying causes of obesity in adults

Obesity is a worldwide growing problem. When confronted with obesity, many health care providers focus on direct treatment of the consequences of adiposity. We plead for adequate diagnostics first, followed by an individualized treatment. We provide experience-based and evidence-based practical recommendations (illustrated by clinical examples), to detect potential underlying diseases and contributing factors. Adult patients consulting a doctor for weight gain or obesity should first be clinically assessed for underlying diseases, such as monogenetic or syndromic obesity, hypothyroidism, (cyclic) Cushing syndrome, polycystic ovarian syndrome (PCOS), hypogonadism, growth hormone deficiency, and hypothalamic obesity. The most important alarm symptoms for genetic obesity are early onset obesity, dysmorphic features/congenital malformations with or without intellectual deficit, behavioral problems, hyperphagia, and/or striking family history. Importantly, also common contributing factors to weight gain should be investigated, including medication (mainly psychiatric drugs, (local) corticosteroids, insulin, and specific β-adrenergic receptor blockers), sleeping habits and quality, crash diets and yoyo-effect, smoking cessation, and alcoholism. Other associated conditions include mental factors such as chronic stress or binge-eating disorder and depression.Identifying and optimizing the underlying diseases, contributing factors, and other associated conditions may not only result in more effective and personalized treatment but could also reduce the social stigma for patients with obesity.

Pharmacologic Issues in treating hypertension in CKD

Antihypertensive drugs are prescribed to patients with CKD to slow down the rate of loss of residual kidney function; to reduce proteinuria, when present; and to protect other target organs from damage that is mediated by elevated blood pressure (BP). In most patients, a diuretic and a renin system blocking drug, such as an angiotensin-converting enzyme inhibitor, angiotensin receptor antagonist, or an aldosterone receptor antagonist are used. Often, 3 or more drugs are needed to achieve BP goals. Many drugs are eliminated through the kidney and in some cases dosage reductions are advisable to avoid adverse effects from high levels of medication. This article will review the various classes of antihypertensive drugs used in the management of high BP in patients with CKD, with an emphasis on pitfalls that arise when kidney function is impaired.

Doxazosin in metabolically complicated hypertension

Metabolic syndrome, a cluster of metabolic abnormalities with visceral obesity and insulin resistance as its central component, is highly prevalent among hypertensive patients. Hypertension complicated by metabolic syndrome is associated with an increased risk of cardiovascular disease and new-onset Type II diabetes mellitus that further aggravates the prognostic outlook. Such a complex condition requires a multifactorial intervention including blood pressure lowering, improvement of the adverse metabolic profile and delayed onset of new diabetes. In this respect, doxazosin and other alpha-1 adrenoceptor blocking agents are of interest given their effect on the lipid profile in dyslipidemic, obese hypertensive patients, either diabetic or not. Doxazosin improves insulin sensitivity, apparently by accelerating insulin and glucose disposal through vasodilatation of skeletal muscle vascular beds. Whether long-term treatment with the drug might delay, or possibly prevent, incident Type II diabetes in hypertension complicated by metabolic syndrome is an intriguing possibility to be tested in appropriately designed clinical trials.

Hemodynamic Effects of α1-Adrenoceptor Antagonist, Doxazosin, in Patients With Chronic Congestive Heart Failure

PURPOSE

Non-selective alpha-adrenoceptor antagonists have not demonstrated significant beneficial effects in chronic heart failure. Previous studies with the selective alpha1-adrenoceptor antagonist, doxazosin, led to conflicting results. We assessed the hypothesis that treatment with doxazosin adjuvant to standard oral therapy results in significant increase in cardiac index in patients with chronic heart failure.

METHODS

A double-blind, randomized study was conducted on 30 patients with chronic congestive heart failure (NYHA III-IV), with cardiac index<2.5 l/minxm, and/or with pulmonary capillary wedge pressure>16 mm Hg. Of the 30 patients, 15 were treated with doxazosin and 15 with placebo, both adjuvant to stable oral therapy, which included a minimum of an ACE inhibitor and a diuretic. Hemodynamic measurements were performed on days 1 and 2, and after 12 weeks on study medication. On day 1, patients were treated with 4 mg doxazosin or placebo. On day 2 and throughout the following 12 weeks, the patients were treated with 4 mg or 8 mg doxazosin/d (the latter, if 4 mg/d did not induce an increase >0.75 l/minxm in cardiac index), or with placebo.

RESULTS

Six patients were treated with 4 mg doxazosin/d (group A), 9 patients with 8 mg doxazosin/d (group B), and 15 with placebo. Baseline values for the cardiac index on day 1, day 2, and after 12 weeks failed to disclose significant differences between patient groups and between the days of study. On day 1, the increase in cardiac index compared with baseline was significantly higher in group A than in the placebo group (P=0.004) and group B (P=0.001). On day 2, the increase in cardiac index compared with baseline on day 1 was significantly higher in group A than in group B (P=0.003) (with reference to alpha/3=0.0167 according to Bonferroni). This was no longer observed after 12 weeks. In the placebo group, following significant changes occurred in baseline values, heart rate was lower (P=0.023) and stroke volume index was higher after 12 weeks in comparison to day 1 (P=0.032).

CONCLUSIONS

In conclusion, oral application of doxazosin supplementary to standard oral medication did not induce sustained hemodynamic benefit. Significant acute increase in cardiac index was observed in a minority (40%) of patients, whereas favorable changes in baseline hemodynamic parameters after 12 weeks occurred in the placebo group.

Risk of Congestive Heart Failure in an Elderly Population Treated with Peripheral Alpha-1 Antagonists

OBJECTIVES

To compare the risk of congestive heart failure (CHF) in elderly individuals treated with any peripheral alpha-1 antagonist for hypertension with any thiazide, test whether the risk persists in subjects without cardiovascular disease (CVD) at baseline, and examine CHF risk in normotensive men with prostatism treated with alpha antagonists.

DESIGN

Prospective cohort study.

SETTING

Four U.S. sites: Washington County, Maryland; Allegheny County, Pennsylvania; Sacramento County, California; and Forsyth County, North Carolina.

PARTICIPANTS

A total of 5,888 community-dwelling subjects aged 65 and older.

MEASUREMENTS

Adjudicated incident CHF.

RESULTS

The 3,105 participants with treated hypertension were at risk for CHF; 22% of men and 8% of women took alpha antagonists during follow-up. The age-adjusted risk of CHF in those receiving monotherapy treated with alpha antagonists was 1.90 (95% confidence interval=1.03-3.50) compared with thiazides. In subjects without CVD at baseline receiving monotherapy, women taking an alpha antagonist had a 3.6 times greater age-adjusted risk of CHF, whereas men had no difference in risk. Adjustment for systolic blood pressure attenuated statistical differences in risk. There were 930 men without hypertension at risk for CHF; 5% used alpha antagonists during follow-up, with no observed increase in CHF risk.

CONCLUSION

Subjects receiving alpha antagonist monotherapy for hypertension had a two to three times greater risk of incident CHF, also seen in lower-risk subjects, but differences in blood pressure control partly explained this.