Risk of all-cause mortality or hospitalization for pneumonia associated with inhaled β2-agonists in patients with asthma, COPD or asthma-COPD overlap

β2-agonists provide necessary bronchodilatory action, are recommended by existing clinical practice guidelines and are widely prescribed for patients with these conditions. We examined the risk of all-cause mortality and hospitalization for pneumonia associated with long-or short-acting β2-agonists (LABA or SABA) or ICS (inhaled corticosteroids)/LABA use. In a nested case-control of 185,407 patients, we found no association between β2-agonist use and the risk of pneumonia in patients with asthma, COPD, or asthma-COPD overlap. In contrast, new SABA [HR 1.82 (95% CI 1.04-3.20)] or LABA [HR 2.77 (95% CI 1.22-6.31)] use was associated with an increased risk of all-cause mortality compared to ICS use in COPD patients.

Congenital myasthenic syndrome due to mutations in MUSK suggests that the level of MuSK phosphorylation is crucial for governing synaptic structure

MUSK encodes the muscle‐specific receptor tyrosine kinase (MuSK), a key component of the agrin‐LRP4‐MuSK‐DOK7 signaling pathway, which is essential for the formation and maintenance of highly specialized synapses between motor neurons and muscle fibers. We report a patient with severe early‐onset congenital myasthenic syndrome and two novel missense mutations in MUSK (p.C317R and p.A617V). Functional studies show that MUSK p.C317R, located at the frizzled‐like cysteine‐rich domain of MuSK, disrupts an integral part of MuSK architecture resulting in ablated MuSK phosphorylation and acetylcholine receptor (AChR) cluster formation. MUSK p.A617V, located at the kinase domain of MuSK, enhances MuSK phosphorylation resulting in anomalous AChR cluster formation. The identification and evidence for pathogenicity of MUSK mutations supported the initiation of treatment with β2‐adrenergic agonists with a dramatic improvement of muscle strength in the patient. This work suggests uncharacterized mechanisms in which control of the precise level of MuSK phosphorylation is crucial in governing synaptic structure.

The Neuromuscular Junction and Wide Heterogeneity of Congenital Myasthenic Syndromes

Congenital myasthenic syndromes (CMS) are genetic disorders characterised by impaired neuromuscular transmission. This review provides an overview on CMS and highlights recent advances in the field, including novel CMS causative genes and improved therapeutic strategies. CMS due to mutations in SLC5A7 and SLC18A3, impairing the synthesis and recycling of acetylcholine, have recently been described. In addition, a novel group of CMS due to mutations in SNAP25B, SYT2, VAMP1, and UNC13A1 encoding molecules implicated in synaptic vesicles exocytosis has been characterised. The increasing number of presynaptic CMS exhibiting CNS manifestations along with neuromuscular weakness demonstrate that the myasthenia can be only a small part of a much more extensive disease phenotype. Moreover, the spectrum of glycosylation abnormalities has been increased with the report that GMPPB mutations can cause CMS, thus bridging myasthenic disorders with dystroglycanopathies. Finally, the discovery of COL13A1 mutations and laminin α5 deficiency has helped to draw attention to the role of extracellular matrix proteins for the formation and maintenance of muscle endplates. The benefit of β2-adrenergic agonists alone or combined with pyridostigmine or 3,4-Dyaminopiridine is increasingly being reported for different subtypes of CMS including AChR-deficiency and glycosylation abnormalities, thus expanding the therapeutic repertoire available.

Long-Acting Bronchodilator Use in the Management of Stable COPD

OBJECTIVE

To review the management of chronic obstructive pulmonary disease (COPD), with a focus on updated information regarding the use of long-acting bronchodilators in the prevention of exacerbations and outcomes associated with this disease.

DATA SOURCES

A literature search of the MEDLINE databases through November 2017 was conducted. All published articles regarding use of bronchodilator therapy in the management of COPD were evaluated. References of selected articles, data from poster presentations, and abstract publications were additionally reviewed.

STUDY SELECTION AND DATA EXTRACTION

Available English-language data from reviews, abstracts, presentations, and clinical trials of the treatment of stable COPD with bronchodilator therapy in humans were reviewed; relevant clinical data were selected and included.

DATA SYNTHESIS

COPD is a prevalent medical condition worldwide that results in functional impairment, and worsened quality of life and overall health status. Numerous treatment options are available; the rationale for the optimal agents to utilize in a particular patient case is dependent on a multitude of patient-specific factors and severity of disease. In this review, a discussion of the role of long-acting bronchodilators, including long-acting β agonists and long-acting muscarinic antagonists will be explored. Additionally, an update on the roles of novel delivery devices for delivering respiratory medications in this medical condition will be described.

CONCLUSION

Although numerous treatment options are available, management of COPD remains a clinical challenge. Long-acting bronchodilators represent a significant class of medications that have the potential to reduce exacerbations and related hospitalizations and improve overall health outcomes.

Risk of Cardiovascular and Cerebrovascular Events in COPD Patients Treated With Long-Acting β2-Agonist Combined With a Long-Acting Muscarinic or Inhaled Corticosteroid

BACKGROUND

The recent approval of several fixed-dose combination long-acting β₂-agonist (LABA) and long-acting muscarinic antagonist (LAMA) products has increased the use of dual bronchodilators in the treatment of chronic obstructive pulmonary disease (COPD). Understanding the comparative safety of this combination is important for informing treatment decisions.

OBJECTIVE

To compare the risk of cardiovascular and cerebrovascular (CCV) events associated with LABA/LAMA compared with a combination of LABA and inhaled corticosteroid (ICS).

METHODS

This was a retrospective, observational cohort study using health insurance claims data to identify COPD patients initiating LABA/LAMA or LABA/ICS. CCV outcomes included hospitalizations with a primary diagnosis for acute coronary syndrome, heart failure, cardiac dysrhythmia, stroke, or transient ischemic attack. Patients were followed until they experienced an event, discontinued treatment, initiated medication from the opposite cohort, or lost enrollment. Patients were matched 1:4 on propensity scores, and time to event was compared using Cox proportional hazards models.

RESULTS

After matching, there were 3842 patients in the LABA/LAMA cohort and 15 225 in the LABA/ICS cohort. Cardiovascular events in the LABA/LAMA cohort were lower than in the LABA/ICS: hazard ratio (HR) = 0.794; 95% CI = 0.623-0.997. No significant difference in the risk of cerebrovascular events (HR = 1.166; 95% CI = 0.653-1.959) was observed.

CONCLUSIONS

Despite concerns about the CCV effects of LAMA and LABA monotherapy, the LABA/LAMA combination had similar or lower risk of these events in comparison to LABA/ICS. Further studies are recommended to confirm these findings.

Role of Long-Acting Muscarinic Antagonist/Long-Acting β2-Agonist Therapy in Chronic Obstructive Pulmonary Disease

OBJECTIVE

To compare the available literature regarding the use of long-acting muscarinic antagonist (LAMA)/long-acting β₂ agonists (LABA) and inhaled corticosteroid (ICS)/LABA combination inhaler therapy in chronic obstructive pulmonary disease (COPD) maintenance therapy management.

DATA SOURCES

A MEDLINE literature search from database inception to February 2017 was conducted using the search terms chronic obstructive pulmonary disease, adrenergic beta-agonist, muscarinic antagonist, and inhaled corticosteroid. References from extracted sources were further searched for any relevant, missed data sources.

STUDY SELECTION AND DATA EXTRACTION

All English-language randomized-controlled trials comparing LAMA/LABA and ICS/LABA combination inhaler therapy were evaluated.

DATA SYNTHESIS

A total of 10 randomized controlled trials have reviewed the use of LAMA/LABA compared with ICS/LABA therapy for COPD maintenance therapy. Results of clinical trials that evaluated LAMA/LABA and ICS/LABA maintenance therapy demonstrated superior improvements in pulmonary function tests via spirometry and improved clinical outcomes with LAMA/LABA therapy, specifically reduction in COPD exacerbation rates. The safety of LAMA/LABA combination therapy also is favorable compared with ICS/LABA combination therapy because of the increased infection risk with ICS therapy.

CONCLUSIONS

COPD is a disease state with significant morbidity and mortality in the United States and is the third leading cause of death. Long-acting inhalers are recommended for the majority of COPD severities, and combination therapy is typically utilized. LAMA/LABA combination therapy has demonstrated superior improvements in pulmonary function and reduction in COPD exacerbation rates compared with ICS/LABA. LAMA/LABA combination therapy will have a larger future role in COPD maintenance management.

Urinary Excretion of the β-Adrenergic Feed Additives Ractopamine and Zilpaterol in Breast and Lung Cancer Patients

β₂-Adrenergic agonists (β-agonists) have been legally used in the U.S. for almost two decades to increase lean muscle mass in meat animals. Despite a cardiotoxic effect after high-dose exposure, there has been limited research on human β-agonist exposures related to meat consumption. We quantified urinary concentrations of ractopamine and zilpaterol, two FDA-approved β-agonist feed additives, and examined the extent to which the concentrations were associated with estimated usual meat intake levels. Overnight urine samples from 324 newly diagnosed breast cancer patients and spot urine samples from 46 lung cancer patients at the time of diagnosis, prior to treatment, were collected during 2006-2010 and 2014-2015, respectively. Urinary ractopamine and zilpaterol concentrations were measured by LC-MS/MS. Ractopamine and zilpaterol, respectively, were detected in 8.1% and 3.0% of the urine samples collected (n = 370). Only 1.1% (n = 4) of the urine samples had zilpaterol concentrations above the limit of quantification, with the mean value of 0.07 ng/mL in urine. The presence of detectable ractopamine and zilpaterol levels were not associated with meat consumption estimated from a food frequency questionnaire, including total meat (P = 0.13 and 0.74, respectively), total red meat (P = 0.72 and 0.74), unprocessed red meat (P = 0.74 and 0.73), processed red meat (P = 0.72 and 0.15), and poultry intake (P = 0.67 for ractopamine). Our data suggest that the amount of meat-related exposure of β-agonists was low.