Pharmacological treatments in asthma-affected horses: A pair-wise and network meta-analysis

Effect of the Administration of a Nutraceutical Supplement in Racehorses with Lower Airway Inflammation

Mild−moderate equine asthma (MEA) is a chronic inflammatory disorder of the lower airways of the horse, characterized by tracheal mucus accumulation, cough and poor performance. The therapeutic approach is based on pharmacological treatment and environmental management. Moreover, the efficacy of the administration of antioxidant molecules has been reported. The aim of the present study was to evaluate the effect of the administration of a commercial nutraceutical supplement, composed of several herbal extracts, on lower airway inflammation in racehorses. Twelve Thoroughbreds affected by MEA were selected. All horses underwent a clinical examination with assignment of a clinical score, airway endoscopy and cytological examination of bronchoalveolar lavage fluid. In seven horses, the supplement was administered for 21 days in association with environmental changes, while in five horses only environmental changes were performed. All procedures were repeated at the end of the study. Data concerning the clinical score, the endoscopic scores and the cytology at the beginning and at the end of the study were statistically compared. Data showed a significant reduction (p < 0.0156) of the clinical score and a significant reduction (p < 0.0156) of the tracheal mucus score. The results showed the beneficial effect of the supplement on mild−moderate lower airway inflammation, probably due to its antioxidant activity.

Muscarinic receptor antagonists and airway inflammation: A systematic review on pharmacological models

Airway inflammation is crucial in the pathogenesis of many respiratory diseases, including chronic obstructive pulmonary disease (COPD) and asthma. Current evidence supports the beneficial impact of muscarinic receptor antagonists against airway inflammation from bench-to-bedside. Considering the numerous sampling approaches and the ethical implications required to study inflammation in vivo in patients, the use of pre-clinical models is inevitable. Starting from our recently published systematic review concerning the impact of muscarinic antagonists, we have systematically assessed the current pharmacological models of airway inflammation and provided an overview on the advances in in vitro and ex vivo approaches. The purpose of in vitro models is to recapitulate selected pathophysiological parameters or processes that are crucial to the development of new drugs within a controlled environment. Nevertheless, immortalized cell lines or primary airway cells present major limitations, including the inability to fully replicate the conditions of the corresponding cell types within a whole organism.

Induced animal models are extensively used in research in the attempt to replicate a respiratory condition reflective of a human pathological state, although considering animal models with spontaneously occurring respiratory diseases may be more appropriate since most of the clinical features are accompanied by lung pathology resembling that of the human condition.

In recent years, three-dimensional organoids have become an alternative to animal experiments, also because animal models are unable to fully mimic the complexity of human pulmonary diseases. Ex vivo studies performed on human isolated airways have a superior translational value compared to in vitro and animal models, as they retain the morphology and the microenvironment of the lung in vivo.

In the foreseeable future, greater effort should be undertaken to rely on more physiologically relevant models, that provide translational value into clinic and have a direct impact on patient outcomes.

Glucocorticoid treatment in horses with asthma: A narrative review

Despite substantial research efforts to improve the treatment and outcome of horses with asthma, glucocorticoids (GC) remain the cornerstone of drug treatment of this prevalent disease. The high efficacy of GC to relieve airway obstruction explains their extensive use despite potential deleterious effects. However, much is yet to be uncovered concerning GC use in horses with asthma, including the comparative efficacy of the different drugs, the determination of minimal effective doses and the mechanisms underlying their variable modulation of airway inflammation. The objectives of this structured review were to report and compare the plethora of effects of the various GC used in asthmatic horses with a focus on impact on lung function, airway inflammation, and bronchial remodeling. Adverse effects are also briefly described, with an emphasis on those that have been specifically reported in horses with asthma. Ultimately, we aimed to highlight gaps in the literature and to identify future research areas.

Nebulized dexamethasone sodium phosphate in the treatment of horses with severe asthma

Background

A study reported low systemic availability of injectable dexamethasone nebulized to healthy horses using the Flexineb mask. When used in horses with severe asthma and a different nebulizer, lack of efficacy and cortisol suppression were observed.

Hypothesis

Nebulized dexamethasone is as effective as PO administration for the treatment of severe asthma in horses.

Animals

Twelve horses with severe asthma from a research herd.

Methods

Randomized clinical trial. Horses were divided into 2 groups and received 5 mg of dexamethasone sodium phosphate by nebulization using a Flexineb mask (NE, n = 6) or PO (OR, n = 6) q24h for 7 days. Lung function and serum cortisol concentrations were evaluated at baseline, after 4 days of treatment (D4) and 1 day after the last treatment (D8). Data were analyzed using linear mixed models with Benjamini‐Hochberg adjustments.

Results

Lung resistance significantly improved at D4 (mean decrease ± SD, −1.5 ± 0.45 cm H₂O/L/s; 95% confidence interval [CI], −2; −0.6) and D8 (−1.4 ± 0.45 cm H₂O/L/s; 95% CI, −2.4; −0.5) compared to baseline in the OR group only (P = .004 and .01, respectively). Serum cortisol concentration was significantly decreased at D4 and D8 for both groups (maximum decrease, −1.2 ± 0.3 μg/dL; 95% CI, −1.9; −0.6 at D4 for NE group and −2.2 ± 0.3 μg/dL; 95% CI, −2.8; −1.6 at D8 for OR group; P < .001).

Conclusions and Clinical Importance

Oral, but not nebulized dexamethasone is an effective therapy for horses with severe asthma and both treatment modalities inhibit the hypothalamic‐pituitary‐adrenal axis.

Factors Influencing the Efficacy of COVID-19 Vaccines: A Quantitative Synthesis of Phase III Trials

To date, there is still a paucity of data from Phase III trials concerning the efficacy of vaccines against COVID-19. Furthermore, no studies investigated the variables that may modulate the efficacy of vaccination. The aim of this analysis was to assess whether there are modifying factors that may potentially influence the clinical efficacy of COVID-19 vaccines. A quantitative synthesis of data from Phase III trials was performed via pairwise and network meta-analyses, along with meta-regression analysis. Data from Phase III trials are currently available only for AZD1222, BNT162b2, mRNA-1237, and Sputnik V. Vaccination resulted to be generally effective (90.0%, 95%CI 72.6-96.4; p < 0.001), although the efficacy of AZD1222 (62.1%) introduced a significant level of heterogeneity in the meta-analysis (I2 92.17%, p < 0.001). No significant modifying factors resulted from the meta-regression analysis. However, considering the mRNA-based vaccines, a trend toward significance (p = 0.081) resulted for age. The network meta-analysis provided the following rank of effectiveness: BNT162b2 ≃ mRNA-1273 > Sputnik V >> AZD1222. In conclusion, no modifying factors seem to modulate the efficacy of vaccines against COVID-19. This quantitative synthesis will need to be updated as soon as further clinical results on the efficacy profile are available from Phase III trials for further licensed COVID-19 vaccines.

Immunoprophylaxis pharmacotherapy against canine leishmaniosis: A systematic review and meta-analysis on the efficacy of vaccines approved in European Union

Leishmania (L.) infantum is a vector-borne parasite currently endemic in several Southern countries of European Union (EU), and dogs represent the main reservoir and hosts. Data from clinical trials are inconsistent with respect to the efficacy of vaccination against L. infantum infection. Therefore, a quantitative synthesis via pairwise meta-analysis was performed in agreement with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) to increase the strength of evidence and assess the real efficacy profile of vaccines against L. infantum currently approved in EU. Data obtained from 1,394 dogs were extracted from 10 studies. The overall analysis indicated that vaccination is significantly effective in protecting against L. infantum infection (RR 0.40, 95%CI 0.23-0.72; I² 70%; P < 0.01 vs. negative controls). The subset analysis performed by excluding the effect modifiers and by considering only the studies that assessed the efficacy of vaccines currently available in EU, indicated that CaniLeish® (RR 0.38, 95%CI 0.20-0.72; I² 0%), but not Letifend® (RR 0.43, 95%CI 0.15-1.22; I² 37%), significantly protected against L. infantum infection when compared to negative controls (P < 0.05). The number needed to treat analysis showed that 3.77 (95%CI 2.59-6.94) and 10.99 (95%CI 8.28-16.34) dogs had to be treated with CaniLeish® and Letifend®, respectively, to prevent one case of infection compared to negative controls. Vaccination is effective in protecting against the risk L. infantum infection, but further studies are needed to assess whether CaniLeish® and Letifend® are characterized by similar efficacy profile.

A retrospective study of bronchoalveolar lavage fluid analysis in barrel racing horses with exercise-induced pulmonary hemorrhage and asthma in Texas from 2016 to 2018

Exercise-induced pulmonary hemorrhage (EIPH) and asthma in barrel racing horses is a common disease across the United States. Limited information is available on non-infectious respiratory diseases in this population, the interaction between these two diseases, and the occurrence of both EIPH and asthma in the horse. The purpose of this study was to evaluate the bronchoalveolar lavage (BAL) fluid cytological results of barrel racing horses with EIPH, asthma, or both. A retrospective study was conducted using the medical records of horses that presented with cough and decreased athletic performance and BAL results that met the criteria for inclusion. Data from 95 horses were included from a private practice referral hospital in Texas. No statistical difference was found in the frequency of neutrophilia, eosinophilia, or mastocytosis between diagnoses of EIPH, asthma, or concurrent diagnoses of EIPH and asthma. Bronchoalveolar lavage of horses suspected of EIPH is warranted to fully characterize the noninfectious respiratory disease of barrel racing horses.

How to Conduct a Bayesian Network Meta-Analysis

Network meta-analysis is a general approach to integrate the results of multiple studies in which multiple treatments are compared, often in a pairwise manner. In this tutorial, we illustrate the procedures for conducting a network meta-analysis for binary outcomes data in the Bayesian framework using example data. Our goal is to describe the workflow of such an analysis and to explain how to generate informative results such as ranking plots and treatment risk posterior distribution plots. The R code used to conduct a network meta-analysis in the Bayesian setting is provided at GitHub.

Adding a Second Bronchodilator in COPD: A Meta-Analysis on the Risk of Specific Cardiovascular Serious Adverse Events of Tiotropium/Olodaterol Fixed-Dose Combination

Dual bronchodilation therapy represents the cornerstone for the treatment of COPD. A large retrospective study reports that adding a second long-acting bronchodilator in patients with COPD significantly increases the risk of heart failure. Nevertheless, retrospective studies are characterized by limitations including misdiagnosis and inaccuracy of recordkeeping. This study aimed to ascertain whether tiotropium/olodaterol (T/O) 5/5 μg fixed-dose combination (FDC) may modulate the risk of main cardiovascular outcomes in COPD patients enrolled in randomized controlled trials (RCTs). A meta-analysis (CRD42017070100) was performed by selecting RCTs reporting raw data from the ClinicalTrials.gov database concerning the impact of T/O 5/5 µg FDC vs. monocomponents on the occurrence of specific cardiovascular serious adverse events: arrhythmia, heart failure, myocardial infarction, and stroke. Data were reported as relative risk and 95% Confidence Interval, and the risk of publication bias assessed via Egger's test. Eighty six full text articles were identified, and 10 RCTs published in 7 studies between 2015 and 2018 were included into the analysis. Data obtained from 12,690 COPD patients (44.47% T/O FDC, 55.53% monocomponents) were extracted. T/O 5/5 μg FDCs did not significantly modulate (p-value > 0.05) the risk of arrhythmia (1.02, 0.55 - 1.92), heart failure (0.88, 0.41 - 1.92), myocardial infarction (1.15, 0.70 - 1.87), and stroke (0.98, 0.44 - 2.16) vs. monocomponents. No significant publication bias affected the effect estimates of this meta-analysis. The results of this quantitative synthesis indicate that dual bronchodilation with T/O 5/5 μg FDC is characterized by an acceptable cardiovascular safety profile in COPD patients.

The equine asthma model of airway remodeling: from a veterinary to a human perspective

Human asthma is a complex and heterogeneous disorder characterized by chronic inflammation, bronchospasm and airway remodeling. The latter is a major determinant of the structure-function relationship of the respiratory system and likely contributes to the progressive and accelerated decline in lung function observed in patients over time. Corticosteroids are the cornerstone of asthma treatment. While their action on inflammation and lung function is well characterized, their effect on remodeling remains largely unknown. An important hindrance to the study of airway remodeling as a major focus in asthma research is the lack of reliable non-invasive biomarkers. In consequence, the physiologic and clinical consequences of airway wall thickening and altered composition are not well understood. In this perspective, equine asthma provides a unique and ethical (non-terminal) preclinical model for hypothesis testing and generation. Severe equine asthma is a spontaneous disease affecting adult horses characterized by recurrent and reversible episodes of disease exacerbations. It is associated with bronchoalveolar neutrophilic inflammation, bronchospasm, and excessive mucus secretion. Severe equine asthma is also characterized by bronchial remodeling, which is only partially improved by prolonged period of disease remission induced by therapy or antigen avoidance strategies. This review will focus on the similarities and differences of airway remodeling in equine and human asthma, on the strengths and limitations of the equine model, and on the challenges the model has to face to keep up with human asthma research.

Relaxing effects of clenbuterol, ritodrine, salbutamol and fenoterol on the contractions of horse isolated bronchi induced by different stimuli

β₂-adrenoceptor agonists are considered the most effective drugs to counteract bronchoconstriction in horses with asthma, but only clenbuterol is commonly employed in clinical practice. We evaluated the effects of different selective β₂ agonists: clenbuterol, ritodrine, salbutamol, and fenoterol on the contractions of isolated bronchial muscle of horses induced by electrical field stimulation (EFS), carbachol, histamine, and KCl. All β₂ agonists reduced the amplitude of contraction induced by the different stimuli but with variable efficacy and potency. Fenoterol and salbutamol were more effective than clenbuterol in relaxing the bronchial contractions induced by EFS and histamine, and were able to completely abolish carbachol-induced contractions, unlike clenbuterol and ritodrine. The respective potency values (pEC₅₀) of clenbuterol, ritodrine, salbutamol, and fenoterol were 7.74 ± 0.20, 7.77 ± 0.17, 7.30 ± 0.23, 8.01 ± 0.13, for EFS-induced contractions; 8.39 ± 0.26, 5.49 ± 0.28, 6.63 ± 0.14, 7.68 ± 0.11, for carbachol-induced contraction; 7.39 ± 0.27, 7.04 ± 0.28, 6.45 ± 0.34, 7.34 ± 0.22, for histamine-induced contraction; 7.15 ± 0.06, 6.07 ± 0.20, 6.48 ± 0.14, 6.70 ± 0.18, for KCl-induced contraction. Salbutamol and fenoterol showed a higher efficacy than clenbuterol in relaxing horse bronchial muscle pre-contracted by most stimuli. Clenbuterol displayed a good potency but a rather low efficacy, and this may be due to its partial agonist nature; ritodrine showed lower or not significantly different efficacy and potency compared to the other agonists. An evaluation of the clinical efficacy by fenoterol and salbutamol in horses with asthma could be of great interest to assess if they could represent more effective bronchodilators compared to clenbuterol.

Comparative Review of Asthma in Farmers and Horses

PURPOSE OF REVIEW

Farmers are routinely exposed to organic dusts and aeroallergens that can have adverse respiratory health effects including asthma. Horses are farm-reared large animals with similar exposures and can develop equine asthma syndrome (EAS). This review aims to compare the etiology, pathophysiology, and immunology of asthma in horses compared to farmers and highlights the horse as a potential translational animal model for organic dust-induced asthma in humans.

RECENT FINDINGS

Severe EAS shares many clinical and pathological features with various phenotypes of human asthma including allergic, non-allergic, late onset, and severe asthma. EAS disease features include variable airflow obstruction, cough, airway hyperresponsiveness, airway inflammation/remodeling, neutrophilic infiltrates, excess mucus production, and chronic innate immune activation. Severe EAS is a naturally occurring and biologically relevant, translational animal disease model that could contribute to a more thorough understanding of the environmental and immunologic factors contributing to organic dust-induced asthma in humans.

Clinical efficacy of bronchodilators in equine asthma: Looking for minimal important difference

BACKGROUND

Airway obstruction is the main trait of severe equine asthma that affects respiratory function and elicits detrimental effects on clinical presentation. Only few and underpowered clinical studies have investigated the impact of improvement in lung function induced by bronchodilators on the clinical signs of asthma-affected horses.

OBJECTIVES

To identify the minimal important difference (MID) in lung function elicited by bronchodilator leading to a meaningful improvement in clinical signs.

STUDY DESIGN

Pairwise meta-analysis and meta-regression analysis.

METHODS

Literature searches were performed for studies that investigated the effect of bronchodilator therapy on lung function and clinical condition of asthmatic horses. The relationship between the change in lung function variables and clinical score was analysed via random-effect meta-regression. One-point change of the Improved clinically Detectable Equine Asthma Scoring System (IDEASS) score was used to identify the MID.

RESULTS

A significant (P<0.05) relationship was found between the changes in IDEASS score and maximum change in transpulmonary pressure (ΔPpl_max ) or pulmonary resistance (R_L ). Since only the model resulting for R_L passed through the origin (Y-intercept when X = 0: -0.31, 95% CI -0.75 to 0.14), this variable was used to identify the MID correlated with a meaningful improvement in clinical signs. The resulting MID value was a change in R_L of 0.63 cm H₂ O/L/s (95% CI 0.33-0.94), representing the slope of meta-regression model (high quality of evidence).

MAIN LIMITATIONS

No long-term studies investigated the effect of bronchodilator agents on both lung function and clinical signs in asthmatic horses.

CONCLUSIONS

In conclusion, bronchodilator pharmacotherapy in equine asthma elicits clinically meaningful effect when R_L increases ≥1 cm H₂ O/L/s, a value indicating the MID. Assessing the MID based on change in R_L may improve the quality of evidence and the scientific impact of future clinical trials as it extends beyond the simple, and limiting, evaluation of statistical significance.

Insights into animal models for cell-based therapies in translational studies of lung diseases: Is the horse with naturally occurring asthma the right choice?

Human asthma is a widespread disease associated with chronic inflammation of the airways, leading to loss of quality of life, disability and death. Corticosteroid administration is the mainstream treatment for asthmatic patients. Corticosteroids reduce airway obstruction and improve quality of life, although symptoms persist despite treatment in many patients. Moreover, available therapies failed to reverse the lung pathology present in asthma. Animal models, mostly rats and mice, in which the disease is experimentally induced, have been studied to identify new therapeutic targets for human asthma. Alternative animal models could include horses in which naturally occurring asthma could represent an important step to test therapies, potentially designed around mouse studies, before being translated to human testing. Horses naturally suffer from asthma, which has striking parallels with human asthma. Severe equine asthma (SEA) is characterized by reversible bronchospasms and neutrophil accumulation in the lungs immunologically mediated mainly by Th2. Moreover, the pulmonary remodelling that occurs in SEA closely resembles that of human asthma, making the equine model unique for investigation of tissue repair and new therapies. Cell therapy, consisting on mesenchymal stromal cells (MSCs) and derivatives (conditioned medium and extracellular vesicles), could represent a novel therapeutic contribution for tissue regeneration. Cell therapy may prove advantageous over conventional therapy in that it may repair or regenerate the site of injury and reduce the reaction to allergens, rather than simply modulating the inflammatory process.

Nebulisation of dexamethasone sodium phosphate for the treatment of severe asthmatic horses

BACKGROUND

Inhaled corticosteroids are effective in the treatment of equine asthma. A recent study reported that nebulisation of injectable dexamethasone had low systemic bioavailability in healthy horses and could represent a cost-effective therapy for equine inflammatory lung diseases.

OBJECTIVES

To determine the effects of dexamethasone nebulisation on lung function in severe asthmatic horses. It was hypothesised that dexamethasone administered by nebulisation would be more effective than the same dose administered orally.

STUDY DESIGN

Randomised blinded experimental study in severe asthmatic horses.

METHODS

Twelve severe asthmatic horses in clinical exacerbation were randomly assigned to treatment with 5 mg of dexamethasone sodium phosphate by nebulisation (n = 6) or by oral administration (n = 6), once daily for 7 days. Lung function was evaluated at baseline, after four treatment days (D4) and 24 h after the last dose (D8). The presence of residual bronchospasm was assessed on D8 with N-butylscopolammonium bromide administration (0.3 mg/kg i.v.). A respiratory clinical score was performed daily. Serum cortisol concentration was measured at baseline, D4 and D8.

RESULTS

The pulmonary elastance was unchanged in both groups while pulmonary resistance was significantly improved in the oral group on D8 (mean reduction in 1 cm H₂ O/L/s [CI: 0.34-1.65, P = 0.003]). All horses had residual bronchospasm at the end of the study. There was a group difference in the respiratory clinical score as it was significantly reduced in the oral group, from D5 to D8. Serum cortisol concentration decreased in all subjects.

MAIN LIMITATIONS

Low number of horses and lack of placebo group.

CONCLUSIONS

Considering the lack of improvement of lung function and the hypothalamic-pituitary-adrenal axis suppression, the results of this study do not support aerosolisation of an injectable form of dexamethasone for the treatment of severe equine asthma at the dose and with the nebuliser evaluated.

Long-Acting β2-Agonists in Asthma: Enantioselective Safety Studies are Needed

Long-acting β2-agonists (LABAs) such as formoterol and salmeterol are used for prolonged bronchodilatation in asthma, usually in combination with inhaled corticosteroids (ICSs). Unexplained paradoxical asthma exacerbations and deaths have been associated with LABAs, particularly when used without ICS. LABAs clearly demonstrate effective bronchodilatation and steroid-sparing activity, but long-term treatment can lead to tolerance of their bronchodilator effects. There are also concerns with regard to the effects of LABAs on bronchial hyperresponsiveness (BHR), where long-term use is associated with increased BHR and loss of bronchoprotection. A complicating factor is that formoterol and salmeterol are both chiral compounds, usually administered as 50:50 racemic (rac-) mixtures of two enantiomers. The chiral nature of these compounds has been largely forgotten in the debate regarding LABA safety and effects on BHR, particularly that (S)-enantiomers of β2-agonists may be deleterious to asthma control. LABAs display enantioselective pharmacokinetics and pharmacodynamics. Biological plausibility of the deleterious effects of β2-agonists (S)-enantiomers is provided by in vitro and in vivo studies from the short-acting β2-agonist (SABA) salbutamol. Supportive clinical findings include the fact that patients in emergency departments who demonstrate a blunted response to salbutamol are more likely to benefit from (R)-salbutamol than rac-salbutamol, and resistance to salbutamol appears to be a contributory mechanism in rapid asthma deaths. More effort should therefore be applied to investigating potential enantiospecific effects of LABAs on safety, specifically bronchoprotection. Safety studies directly assessing the effects of LABA (S)-enantiomers on BHR are long overdue.

Efficacy of inhaled budesonide for the treatment of severe equine asthma

Background

Corticosteroids are the most potent drugs for the control of severe equine asthma, but adverse effects limit their chronic systemic administration. Inhaled medications allow for drug delivery directly into the airways, reducing the harmful effects of these drugs.

Objectives

To evaluate the efficacy of inhaled budesonide specifically formulated for the equine use and administered by a novel inhalation device in horses with severe asthma.

Study design

Experimental studies in horses with naturally occurring asthma with cross‐over, randomised, blinded experimental designs.

Methods

In Study 1, budesonide (1800 μg twice daily) administered using a novel Respimat^® based inhaler was compared to i.v. dexamethasone (0.04 mg/kg). In Study 2, 3 doses of budesonide (450, 900, and 1800 μg) were compared to oral dexamethasone (0.066 mg/kg). Lung function, bronchoalveolar fluid cytology (Study 1), CBC, serum chemistry, and serum cortisol and adrenocorticotropic hormone (ACTH) values were evaluated.

Results

In Study 1, there was a marked and significant improvement in the lung function of all horses treated with budesonide and dexamethasone. Neutrophil percentages in bronchoalveolar fluid decreased in all horses treated with dexamethasone and in four of six horses treated with budesonide. Serum cortisol and blood ACTH concentrations decreased with both treatments. In Study 2, there was a significant improvement in the lung function with all dosages of budesonide, and the effects of higher dosages were comparable to those of dexamethasone. Dexamethasone and budesonide at the two higher dosages induced a significant decrease of cortisol concentrations.

Main limitations

The Respimat^® based inhaler is not currently commercially available.

Conclusions

Administration of budesonide with the Respimat^® based inhaler provided dose‐dependent relief of airway obstruction in horses with severe asthma, but also a suppression of serum cortisol.

Clinical effect of corticosteroids in asthma-affected horses: A quantitative synthesis

BACKGROUND

There are limited findings from low-powered studies based on few number of subjects with equine asthma. Furthermore, no studies have been performed to assess a meaningful clinically detectable impact of corticosteroids in equine asthma.

OBJECTIVES

To assess and compare the clinical effect of inhaled and systemic corticosteroids in equine asthma and identify a quantitative clinical score suitable to assess the Minimal Important Difference (MID), expressed as the Minimally Clinically Detectable Difference (MCDD).

STUDY DESIGN

Pair-wise and network meta-analysis.

METHODS

Literature searches for studies on corticosteroid therapy in equine asthma were performed. The risk of publication bias was assessed by Funnel plots and Egger's test. The effect on changes in clinical scores vs. control was analysed via random-effects models and Bayesian networks.

RESULTS

Corticosteroids significantly improved the clinical condition (Standardised Mean Difference: -1.52, 95% CrI -2.07 to -0.98; P<0.001 vs. control). No difference was detected between inhaled and systemic corticosteroids with regard to the changes in clinical scores (Relative Effect: 0.08, 95% CrI -1.45 to 1.32; P = 0.8). An Improved clinically Detectable Equine Asthma Scoring System (IDEASS) indicated that corticosteroids improved the clinical condition of asthmatic horses by 30% compared with controls (IDEASS value: -2.36, 95% CI -3.39 to -1.33; P<0.001). A one-point change in IDEASS represented the MCDD in equine asthma.

MAIN LIMITATIONS

Moderate quality of evidence for systemic corticosteroids.

CONCLUSIONS

Inhaled corticosteroids are effective in improving the clinical condition of horses with equine asthma and prevent exacerbations. Systemic corticosteroids should be used only in selected cases with symptomatic airway hyperresponsiveness during exacerbation. IDEASS requires further validation but may represent a suitable approach to rank the level of asthma severity and assess the clinical effect of pharmacotherapy in horses with equine asthma.

Salmeterol undergoes enantioselective bronchopulmonary distribution with receptor localisation a likely determinant of duration of action

BACKGROUND

Salmeterol (a long acting beta2-agonist) is a chiral molecule. (RR)-salmeterol is responsible for pharmacological effect, but basic knowledge of enantioselective pulmonary pharmacodynamics and pharmacokinetics of salmeterol remains unknown. There are safety concerns with (S)-enantiomers of beta2-agonists, with suggestions that these enantiomers may increase bronchial hyperresponsivneness in asthma patients.

METHODOLOGY

Horses (n = 12) received racemic (rac-) salmeterol 250 μg via inhalation. Enantioselective UPLC-MS/MS was used to determine (R)- and (S)-salmeterol concentrations in pulmonary epithelial lining fluid (PELF) sampled 2, 5, 10 and 15 min after administration, in central lung (endoscopic bronchial biopsy) and peripheral lung (percutaneous pulmonary biopsy) tissues (at 20 and 25 min respectively), and in plasma samples.

RESULTS

Physiologically relevant tissue concentrations were found for both enantiomers, with median levels greater in central than peripheral lung (equivalent to 32 and 5 mM (R)-salmeterol for central and peripheral lung respectively). Levels in PELF decreased around 50% over 15 min and enantioselective distribution was observed in the central lung with levels of (R)-salmeterol around 30% higher than (S)-salmeterol.

CONCLUSION

Salmeterol distribution is enantioselective in the central lung. This suggests duration of action is more likely associated with specific B2ADR localisation effects rather than non-specific physiochemical factors which would not be enantioselective.

The impact of dual bronchodilation on cardiovascular serious adverse events and mortality in COPD: a quantitative synthesis

Objective

Long-acting β₂-agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) are burdened by the potential risk of inducing cardiovascular serious adverse events (SAEs) in COPD patients. Since the risk of combining a LABA with a LAMA could be greater, we have carried out a quantitative synthesis to investigate the cardiovascular safety profile of LABA/LAMA fixed-dose combinations (FDCs).

Methods

A pair-wise and network meta-analysis was performed by using the data of the repository database ClinicalTrials.gov concerning the impact of approved LABA/LAMA FDCs versus monocomponents and/or placebo on cardiovascular SAEs in COPD.

Results

Overall, LABA/LAMA FDCs did not significantly (P>0.05) modulate the risk of cardiovascular SAEs versus monocomponents. However, the network meta-analysis indicated that aclidinium/formoterol 400/12 µg and tiotropium/olodaterol 5/5 µg were the safest FDCs, followed by umeclidinium/vilanterol 62.5/25 µg which was as safe as placebo, whereas glycopyrronium/formoterol 14.9/9.6, glycopyrronium/indacaterol 15.6/27.5 µg, and glycopyrronium/indacaterol 50/110 µg were the least safe FDCs. No impact on mortality was detected for each specific FDC.

Conclusion

This meta-analysis indicates that LABA/LAMA FDC therapy is characterized by an excellent cardiovascular safety profile in COPD patients. However, the findings of this quantitative synthesis have been obtained from populations that participated in randomized clinical trials, and were devoid of major cardiovascular diseases. Thus, post-marketing surveillance and observational studies may help to better define the real impact of specific FDCs with regard to the cardiovascular risk.

Pharmacological characterization of the interaction between tiotropium and olodaterol administered at 5:5 concentration-ratio in equine bronchi

Equine airways represent a suitable ex vivo model to study the functional impact of pharmacological treatments on human chronic obstructive pulmonary disorders, such as asthma and chronic obstructive pulmonary disease (COPD). We aimed to characterize the pharmacological interaction between the long-acting muscarinic antagonist (LAMA) tiotropium and the long-acting β₂-agonist (LABA) olodaterol in equine airways. The effect of tiotropium and olodaterol, administered alone and in combination at the ratio of concentrations reproducing ex vivo the concentration-ratio delivered by the currently available fixed-dose combination (FDC) (5:5), was investigated on the cholinergic contractile tone induced by the parasympathetic activation of equine isolated airways. The drug interaction was analysed by using the Bliss Independence and Unified Theory models. Both tiotropium and olodaterol induced a sub-maximal concentration-dependent inhibition of bronchial contractility (E_max: tiotropium 83.6 ± 14.8%, olodaterol 76.9 ± 17.9%; pEC₅₀: tiotropium 8.2 ± 0.5; olodaterol 8.3 ± 0.6). When administered at 5:5 concentration-ratio, tiotropium plus olodaterol completely inhibited the bronchial contractility (E_max 102.7 ± 8.4%; pEC₅₀ 9.0 ± 0.7). Strong synergistic interaction was detected for tiotropium/olodaterol combination (combination index 0.011). When administered at low concentrations, the drug mixture elicited up to 94.6 ± 9.5% effect that was 36.0 ± 8.1% greater than the expected additive effect. The results of this study demonstrate that the co-administration of tiotropium plus olodaterol at 5:5 concentration-ratio leads to synergistic inhibition of equine bronchial contractility when compared with either drug administered alone. These findings suggest that the currently available LABA/LABA FDC may be effective in delivering tiotropium/olodaterol combination at equipotency concentrations of each monocomponent into the lung and, thus, inducing synergistic effect in the airways.

Withdrawal of inhaled corticosteroids in COPD: A meta-analysis

BACKGROUND

Conflicting findings exist on the benefit of withdrawal of inhaled corticosteroid (ICS) in chronic obstructive pulmonary disease (COPD). We performed a quantitative synthesis in order to assess real impact of ICS discontinuation in COPD patients.

METHODS

We carried out a meta-analysis via random-effects model on the available clinical evidence to evaluate the effect of ICS discontinuation in COPD. Randomized clinical trials and observational real-life studies investigating the effects of ICS withdrawal on the risk of COPD exacerbation, lung function (forced expiratory volume in 1 s [FEV₁]) and quality of life (St. George's Respiratory Questionnaire [SGRQ]) were identified by searching from published studies and repository databases.

RESULTS

ICS withdrawal did not significantly (P > 0.05) increase the overall rate of COPD exacerbation, although a clinically important increased risk of severe exacerbation was detected (Relative Risk >1.2). ICS withdrawal significantly (P < 0.001) impaired both lung function (-30 ml FEV₁) and quality of life (+1.24 SGRQ units), although in a non-clinically important manner. The time to the first exacerbation was significantly (P < 0.05) shorter in the patients who discontinued ICS.

CONCLUSIONS

The discrepancy between statistical analysis and clinical interpretation of this meta-analytic evaluation demonstrates the strong clinical need in understanding what is the real impact of ICS withdrawal in COPD. ICS discontinuation is a complex procedure that requires a well planned and tailored strategy. Further well designed studies on withdrawal of ICS should be performed by clustering COPD patients with regard to the phenotype characteristics, rate of exacerbations/year, decline of lung function, and quality of life.