Comparison of hypersensitivity to adrenergic stimulation after abrupt withdrawal of propranolol and nadolol: influence of half-life differences

Distinct outcomes of labetalol exposed infants: case reports and systematic review

BACKGROUND

The adverse effects of long-term maternal exposure of labetalol on neonates have been recognized clinically. But there are few systematic studies on their clinical demonstrations and potential mechanisms.

METHODS

A death case of an infant with long-term maternal labetalol exposure was reported and compared with two case reports from the literature. A systematic literature review was carried out followed by a retrospective analysis on neonatal labetalol withdrawal effects.

RESULTS

It was discovered that labetalol withdrawal effects initially cause various degrees of hypotension, hypoglycemia, and bradycardia among exposed neonates. Some life-threatening cases can also occur within 1 week after birth. Long-term maternal exposure of labetalol, preterm infants with birth asphyxia, acidosis, hypoalbuminemia, and cardiac defects are their primary features. Possible mechanisms were concluded as labetalol-induced effects on the vascular and sympathetic nervous system as well as tissue oxygen extraction.

CONCLUSIONS

Neonatal labetalol withdrawal effects include early-onset and late-onset demonstrations, the latter can be life-threatening. A possible mechanism is multiple factors induced imbalance of sympathetic homeostasis increases neonatal vulnerability to common stresses. Long-term exposed preterm infants complicated with asphyxia, acidosis, hypoalbuminemia and cardiac defects, should be provided with intense care during the first week after birth. Further work is necessary to enrich this hypothesis.

Usefulness of universal beta-blocker therapy in patients after ST-elevation myocardial infarction

The use of beta-blockers (BB) in the context of ST-segment elevation myocardial infarction (STEMI) was a universal practice in the pre-reperfusion era. Since then, evidence of their use for secondary prevention after STEMI is scarce. Our aim is to determine treatment results associated with BB therapy after a STEMI at 1-year follow-up in a contemporary nationwide cohort.A prospective analysis involving 49 national centers, including patients admitted with STEMI, enrolled between October 2010 and September 2019 was conducted. The primary outcome was defined as the composite of all-cause mortality or hospital re-admission for a cardiovascular (CV) cause in the first year after STEMI. The patients were distributed into 2 groups, depending on whether they received therapy with BB at hospital discharge or not (BB and NB group, respectively).A total of 3145 patients were included in the analysis, of which 2526 (80.3%) in the BB group. A total of 12.2% of patients reached the primary outcome. Regarding the univariate Cox regression analysis, the BB group presented lower mortality or re-admission for CV cause at 1-year follow-up [hazard ratio (HR) 0.69, confidence interval (CI) 95% 0.55-0.87, P = .001]. However, after adjustment for significant covariates, this association was lost (HR 0.73, CI 95% 0.51-1.04, P = .081). In patients with preserved (HR 0.73, CI 95% 0.51-1.04, P = .081) and mid-range (HR 1.01, CI 95% 0.64-1.61, P = .959) left ventricular ejection fraction (LVEF), the primary outcome was similar between the 2 groups, while in patients with reduced LVEF, the BB group presented a better prognosis, with fewer patients reaching the primary outcome (HR 0.431, CI 95% 0.262-0.703, P = .001).BB universal therapy after STEMI has not proved useful, but it seems to be beneficial in patients with reduced LVEF.

Iatrogenic hypertension: a bioinformatic analysis

It is well known that a myriad of medications and substances can induce side effects that are related to blood pressure (BP) regulation. This study aims to investigate why certain drugs tend to cause iatrogenic hypertension (HTN) and focus on drug targets that are implicated in these conditions.Databases and resources such as SIDER, DrugBank, and Genomatix were utilized in order to bioinformatically investigate HTN-associated drug target-genes for which HTN is a side effect. A tree-like map was created, representing interactions between 198 human genes that relate to the blood pressure system. 72 HTN indicated drugs and 160 HTN-inducing drugs were investigated. HTN-associated genes affected by these drugs were identified. HTN indicated drugs, which target nearly all branches of the interaction tree, were shown to exert an effect on most functional sub-systems of the BP regulatory system; and specifically, for the adrenergic and dopaminergic receptor pathways. High prevalence (25 genes) of shared targets between the HTN indicated and HTN-inducing drug categories was demonstrated. We focus on six drug families which are not indicated for HTN treatment, yet are reported as a major cause for blood pressure side effects. We show the molecular mechanisms that may lead to this iatrogenic effect. Such an analysis may have clinical implications that could allow for the development of tailored medicine with fewer side effects.

Nadolol for the treatment of infantile hemangioma

PURPOSE

The successful use of nadolol as an alternative to propranolol therapy in three cases of infantile hemangioma is reported.

SUMMARY

Infantile hemangioma is a benign vascular neoplastic disorder that affects up to 10% of newborns and can lead to deformity or local complications in severe cases. Propranolol, administered alone or in combination with corticosteroids, is increasingly used to treat infantile hemangioma, but its ability to cross the blood-brain barrier and potentially cause central nervous system adverse effects has prompted research on alternative β-blocker therapies for the disorder that have more favorable safety profiles, including nadolol. This article describes the use of nadolol to treat three pediatric patients with a buccal or genital hemangioma who developed adverse reactions (mainly, irritability and sleep disturbances) or resistance to initial treatment with propranolol. The patients were 10 months, 12 months, and 4 years of age, respectively, when hemangioma treatment was initiated. The results of nadolol therapy were favorable, with involution of lesions and gradual disappearance of propranolol-associated adverse effects occurring in all three cases. As with any use of β-blocker therapy in a pediatric patient, a cardiac workup is advised before the start of nadolol therapy; blood pressure and heart rate monitoring should be performed at one and two hours after the first dose and continued during dose escalation.

CONCLUSION

Nadolol was an effective alternative to propranolol in three pediatric patients with hemangiomas.

The changing role of beta-blocker therapy in patients with cirrhosis

Cirrhosis is a leading cause of death in the United States and worldwide. Beta-blockers have been established in numerous studies as part of the cornerstone of the medical management of cirrhosis, particularly in the primary and secondary prevention of variceal hemorrhage. However, new evidence has cautioned the use of beta-blockers in patients with end-stage cirrhosis and refractory ascites. In this article, we review the beneficial effects of beta-blocker therapy, the potential harms of aggressive beta-blocker therapy, and provide suggestions regarding the appropriate use of this class of medications in patients with cirrhosis.

Risk Factors for Post-Coronary Artery Bypass Grafting (CABG) Atrial Fibrillation and the Role of Aspirin and Beta Blockers in its Prevention

Background: Atrial fibrillation/flutter (AF) is the most common arrhythmia following coronary artery bypass grafting (CABG) and it increases morbidity and mortality associated with this procedure. The purpose of this study was to evaluate the predictability of this arrhythmia using previously identified risk factors and to assess the efficacy of recommended prophylactic beta blocker (BB) therapy in the prevention of post CABG AF. Methods: We performed a retrospective chart analysis of consecutive patients undergoing elective CABG during 1 year period. Patients who developed new onset AF after the surgery were designated as cases and those who did not, as controls. 41 different variables were analyzed using Chi-square test and independent sample t-test. Multivariate analysis was carried out using logistic regression model. Results: 23% patients undergoing CABG developed AF during post-operative period. Statistically significant differences were observed between the two groups in terms of age, use of peri-operative Aspirin (ASA), current smoking, previous history of AF, left atrial size, history of congestive heart failure (CHF) and brain natriuretic peptide (BNP) levels. In terms of prophylactic therapy, preoperative BB did not independently protect against post CABG AF. On multivariate analysis, only age, use of ASA and previous history of AF remained as independent predictors of post CABG AF. Conclusion: In our study population, the use of preoperative BB did not independently decrease the risk of post-CABGAF. Age, peri-operative ASA use and previous history of AF remained strong independent predictors of post- operative AF.

Prevention of post-coronary artery bypass grafting (CABG) atrial fibrillation: efficacy of prophylactic beta-blockers in the modern era: a meta-analysis of latest randomized controlled trials

BACKGROUND

Atrial fibrillation/flutter (AF) is a common complication of open heart surgery and ACC/AHA guidelines strongly recommend the use of prophylactic beta-blockers (BB) for its prevention. Several recent studies, however, have failed to show the desired protective effects of BB against post-coronary artery bypass grafting (CABG) AF. As the protocols of CABG, medical management of CAD (coronary artery disease) and demographic features of the patients undergoing open heart surgery have evolved significantly over the last two decades, we decided to perform a review of evidence from latest randomized controlled trials (RCTs) to confirm the efficacy of prophylactic BB.

METHODS

We searched for RCTs comparing the efficacy of prophylactic BB versus placebo/control against post-CABG AF. We limited our search to 1995 till present to reflect ongoing advancements in the protocols of CABG and the medical management of CAD. Initially, 34 trials were selected; however after certain exclusions only 10 RCTs were included in the final analysis.

RESULTS

Prophylactic BB decreased the incidence of post-CABG AF from 32.8% in the control group to 20% in the prophylactic group with risk ratio (RR) of 0.50 with 95% CI of 0.36-0.69, P value < 0.001. In a subgroup analysis, carvedilol appears to be superior to metoprolol for the prevention of postoperative AF.

CONCLUSIONS

Despite several limitations, this analysis confirms the efficacy of prophylactic BB against post-CABG AF in this era. We recommend continuing perioperative BB in the open heart surgery patients in the absence of contraindications.

Efficacy and tolerability of nebivolol compared with other antihypertensive drugs: a meta-analysis

BACKGROUND AND OBJECTIVE

Lowering BP to normal levels without quality of life deterioration is the most important means of reducing cardiovascular risk. Recent studies have challenged the position of beta-adrenoceptor antagonists (beta-blockers) as first-line antihypertensive drugs. Nebivolol is a third-generation, highly selective beta(1)-blocker that causes vasodilation through nitric oxide (NO) release. This meta-analysis investigates the efficacy and tolerability of nebivolol compared with other antihypertensive drugs and placebo in patients with hypertension.

METHODS

Twelve randomized controlled studies were included in which nebivolol 5 mg once daily was compared with the recommended clinical doses of other antihypertensive drugs (n = 9), placebo (n = 2), and both (n = 1). The clinical studies were selected after a MEDLINE search up to 2007 using the key words 'nebivolol' and 'hypertension.'

RESULTS

Antihypertensive response rates (the percentage of patients achieving target BP levels or a defined DBP reduction) were higher with nebivolol than with ACE inhibitors (odds ratio [OR] 1.92; p = 0.001) and all antihypertensive drugs combined (OR 1.41; p = 0.001) and similar to beta-blockers, calcium channel antagonists (CCAs) and the angiotensin receptor antagonist (ARA) losartan. Moreover, a higher percentage of patients receiving nebivolol achieved target BP levels compared with patients treated with losartan (OR 1.98; p = 0.004), CCAs (OR 1.44; p = 0.024), and all antihypertensive drugs combined (OR 1.35; p = 0.012). The percentage of patients experiencing adverse events did not differ between nebivolol and placebo; adverse event rates were significantly lower with nebivolol than losartan (OR 0.52; p = 0.016), other beta-blockers (OR 0.56; p = 0.007), nifedipine (OR 0.49; p < 0.001), and all antihypertensive drugs combined (OR 0.59; p < 0.001).

CONCLUSION

Results of previous pharmacokinetic studies suggest that nebivolol 5 mg may not conform completely to the definition of a classic beta-blocker demonstrating additional antihypertensive effect due to endothelial NO release-mediated vasodilation. This meta-analysis showed that nebivolol 5 mg achieved similar or better rates of treatment response and BP normalization than other drug classes and other antihypertensive drugs combined, with similar tolerability to placebo and significantly better tolerability than losartan, CCAs, other beta-blockers, and all antihypertensive drugs combined. Although not definitive, this meta-analysis suggests that nebivolol 5 mg is likely to have advantages over existing antihypertensives and may have a role in the first-line treatment of hypertension.

Secondary hypertension due to drugs and toxins

This review summarizes the current state of knowledge about drugs, other chemical substances, and toxins on blood pressure. Many classes of drugs, such as steroids, sympathomimetic amines, immunosuppressive agents, nonsteroidal anti-inflammatory agents, antidepressants, erythropoietin, substances of abuse and other agents can induce transient or sustained hypertension, exacerbate well-controlled hypertension, antagonize the effects of antihypertensive therapy, or precipitate hypertensive emergencies. Heightened awareness on the part of the physician is important to avoid unnecessary tests in search for other etiologies, and to reduce antihypertensive medication prescriptions by eliminating contributing agents whenever possible. These agents represent an important modifiable cause of secondary or resistant hypertension.

Beta blockers for elective surgery in elderly patients: population based, retrospective cohort study

OBJECTIVE

To test whether atenolol (a long acting beta blocker) and metoprolol (a short acting beta blocker) are associated with equivalent reductions in risk for elderly patients undergoing elective surgery.

DESIGN

Population based, retrospective cohort analysis.

SETTING

Acute care hospitals in Ontario, Canada, over one decade.

PARTICIPANTS

Consecutive patients older than 65 who were admitted for elective surgery, without symptomatic coronary disease.

MAIN OUTCOME MEASURE

Death or myocardial infarction.

RESULTS

37,151 patients were receiving atenolol or metoprolol before surgery, of which the most common operations were orthopaedic or abdominal procedures. As expected, the two groups were similar in demographic characteristics, medical therapy, and type of surgery. 1038 patients experienced a myocardial infarction or died, a rate that was significantly lower for patients receiving atenolol than for those receiving metoprolol (2.5% v 3.2%, P < 0.001). The decreased risk with atenolol persisted after adjustment for measured demographic, medical, and surgical factors; extended to comparisons of other long acting and short acting beta blockers; was accentuated in analyses that focused on patients with the clearest evidence of beta blocker treatment; and reflected the immediate postoperative interval.

CONCLUSIONS

Patients receiving metoprolol do not have as low a perioperative cardiac risk as patients receiving atenolol, in accord with possible acute withdrawal after missed doses.

Beta-adrenergic signalling and threshold adrenaline concentration for induction of fibrillation in the perfused heart pretreated with antihypertensive drugs

Recent investigations have shown that antihypertensive drug treatment leads to enhanced myocardial beta-adrenoceptor sensitivity. This study was therefore conducted to establish whether or not such hypersensitivity might trigger myocardial arrhythmia subsequent to adrenaline exposure. Adult male Wistar rats (n = 6 per group) were treated with either placebo (vehicle), metoprolol (2.40 mg.kg-1.day-1), timolol (0.075 mg.kg-1.day-1), verapamil (5.50 mg.kg-1.day-1) or enalapril (0.50 mg.kg-1.day-1) for 20 consecutive days. Hearts were excised and perfused ad modum Langendorff in the presence of an adrenaline gradient (0-300 nM) for 20 min with either 3.0 mM or 5.9 mM of potassium in the perfusion buffer. Adrenaline threshold concentration (ATC, nanomolar) at myocardial fibrillation was recorded, as well as tissue cAMP contents, beta-adrenoceptor number, G-protein levels and signalling effector enzyme activities. The main findings were: (1) ATC and cAMP levels were affected in hearts perfused with low-concentration potassium buffer only. In terms of ATC, the beneficial effect of each drug regimen appeared to be in the rank order of: placebo = enalapril > verapamil > timolol > metoprolol. There was an inverse correlation between ATC and myocardial cAMP contents at the start of fibrillation; (2) Subsequent to fibrillation, beta-adrenoceptor number, hormone-elicited adenylate cyclase activities and Gs alpha:Gi2 alpha-ratio were no different from preperfusion values; (3) Significant inverse correlations between beta 1-adrenoceptor numbers and ATC were observed. We conclude that alterations in beta-adrenoceptor number, G proteins and cAMP induced by antihypertensive drugs are predictive of the myocardial sensitivity to adrenaline in terms of time to continuous and irrevocable fibrillation.

Pharmacokinetics of nadolol in children with supraventricular tachycardia

The pharmacokinetics of intravenous and oral nadolol, a long-acting beta-adrenoceptor blocking agent, were investigated in six children receiving the drug for treatment of supraventricular tachycardia. In the youngest patient (age 3 months), no distribution phase was seen. In children younger than 22 months of age, nadolol is more rapidly eliminated (t1/2 = 4.3 hours or less) than in older children, in whom elimination is more similar to that in adults (t1/2 approximately 7.3-15.7 hours). After intravenous administration, nadolol displayed two-compartment pharmacokinetics with a distribution phase (t1/2 = 0.2-1.1 hours) followed by elimination. Large changes in nadolol pharmacokinetics may occur during the first year of life. Nadolol should be used cautiously in infants.

Efficacy and safety of intravenous and oral nadolol for supraventricular tachycardia in children

The efficacy and safety of oral nadolol in supraventricular tachycardia were evaluated prospectively in 27 children (median age 5.5 years). Fifteen patients had an unsuccessful trial of digoxin therapy. Intravenous nadolol was given to seven patients during electrophysiologic study; five of these had an excellent response and two had a partial response (25% decrease in tachycardia rate). Six of these patients had a similar response to oral nadolol. Twelve patients received both propranolol and nadolol. Among six patients, intravenous propranolol was successful in four and unsuccessful in two; all six had a similar response to oral nadolol. With oral propranolol, tachycardia was well controlled in four patients and persistent in two; five of five patients had a similar response to oral nadolol. Twenty-six patients were treated with oral nadolol; the arrhythmia was well controlled in 23, 2 had recurrent tachycardia and 1 patient had tachycardia at a 25% slower rate. The effective dose of nadolol ranged between 0.5 and 2.5 mg/kg body weight once daily (median dose 1 mg/kg per day). During follow-up (3 to 36 months), compliance and tolerance were excellent; excluding 2 patients with reactive airway disease who developed wheezing, only 3 (12%) of 24 had side effects necessitating a change in drug therapy. Once a day nadolol is a safe and effective agent in the management of supraventricular tachycardia in children. Its long-term efficacy can be predicted by the short-term response to intravenous nadolol or propranolol during programmed electrophysiologic study.