Evaluation of the effects of the R- and S-enantiomers of salbutamol on equine isolated bronchi

Inflammatory and contractile profile in LPS-challenged equine isolated bronchi: Evidence for IL-6 as a potential target against AHR in equine asthma

BACKGROUND

Airway inflammation and airway hyperresponsiveness (AHR) are pivotal characteristics of equine asthma. Lipopolysaccharide (LPS) may have a central role in modulating airway inflammation and dysfunction. Therefore, the aim of this study was to match the inflammatory and contractile profile in LPS-challenged equine isolated bronchi to identify molecular targets potentially suitable to counteract AHR in asthmatic horses.

METHODS

Equine isolated bronchi were incubated overnight with LPS (0.1-100 ng/ml). The contractile response to electrical field stimulation (EFS) and the levels of cytokines, chemokines, and neurokinin A (NKA) were quantified. The role of capsaicin sensitive-sensory nerves, neurokinin-2 (NK₂) receptor, transient receptor potential vanilloid type 1 receptors (TRPV1), and epithelium were also investigated.

RESULTS

LPS 1 ng/ml elicited AHR to EFS (+238.17 ± 25.20% P < 0.001 vs. control). LPS significantly (P < 0.05 vs. control) increased the levels of IL-4 (+36.08 ± 1.62%), IL-5 (+38.60 ± 3.58%), IL-6 (+33.79 ± 2.59%), IL-13 (+40.91 ± 1.93%), IL-1β (+1650.16 ± 71.16%), IL-33 (+88.14 ± 8.93%), TGF-β (22.29 ± 1.03%), TNF-α (+56.13 ± 4.61%), CXCL-8 (+98.49 ± 17.70%), EOTAXIN (+32.26 ± 2.27%), MCP-1 (+49.63 ± 4.59%), RANTES (+36.38 ± 2.24%), and NKA (+112.81 ± 6.42%). Capsaicin sensitive-sensory nerves, NK₂ receptor, and TRPV1 were generally involved in the LPS-mediated inflammation. Epithelium removal modulated the release of IL-1β, IL-33, and TGF-β. Only the levels of IL-6 fitted with AHR to a wide range of EFS frequencies, an effect significantly (P < 0.05) inhibited by anti-IL-6 antibody; exogenous IL-6 induced significant (P < 0.05) AHR to EFS similar to that elicited by LPS.

CONCLUSION

Targeting IL-6 with specific antibody may represent an effective strategy to treat equine asthma, especially in those animals suffering from severe forms of this disease.

Indacaterol, glycopyrronium, and mometasone: pharmacological interaction and anti-inflammatory profile in hyperresponsive airways

LABA/ICS and LABA/LAMA/ICS combinations elicit beneficial effects in asthma. Specific evidence concerning the impact of combining indacaterol acetate (IND), glycopyrronium bromide (GLY), and mometasone furoate (MF) on human airway hyperresponsiveness (AHR) and airway inflammation is still missing. The aim of this study was to characterize the synergy of IND/MF and IND/GLY/MF combinations, both once-daily treatments for asthma, in hyperresponsive airways. Passively sensitized human medium and small airways were stimulated by histamine and treated with IND/MF (molar ratio: 100/45, 100/90) and IND/GLY/MF (molar ratio: 100/37/45, 100/37/90). The effect on contractility and airway inflammation was tested. Drug interaction was assessed by Bliss Independence equation and Unified Theory. IND/MF 100/90 elicited middle-to-very strong synergistic relaxation in medium and small airways (+≈20-30% vs. additive effect, P<0.05), for IND/MF 100/45 the synergy was middle-to-very strong in small airways (+≈20% vs. additive effect, P<0.05), and additive in medium bronchi (P>0.05 vs. additive effect). IND/GLY/MF 100/37/45 and 100/37/90 induced very strong synergistic relaxation in medium and small airways (+≈30-50% vs. additive effect, P<0.05). Synergy was related with significant (P<0.05) reduction in IL-4, IL-5, IL-6, IL-9, IL-13, TNF-α, TSLP, NKA, SP, and non-neuronal ACh, and enhancement in cAMP. IND/MF and IND/GLY/MF combinations synergistically interact in hyperresponsive medium and small airways and modulate the levels of cytokines, neurokinins, ACh, and intracellular cAMP. The concentrations of MF in the combinations modulate the effects in the target tissue.

Can bronchoconstriction and bronchodilatation in horses be detected using electrical impedance tomography?

BACKGROUND

Electrical impedance tomography (EIT) generates images of the lungs based on impedance change and was able to detect changes in airflow after histamine challenge in horses.

OBJECTIVES

To confirm that EIT can detect histamine-provoked changes in airflow and subsequent drug-induced bronchodilatation. Novel EIT flow variables were developed and examined for changes in airflow.

METHODS

Bronchoconstriction was induced using stepwise histamine bronchoprovocation in 17 healthy sedated horses. The EIT variables were recorded at baseline, after saline nebulization (control), at the histamine concentration causing bronchoconstriction (Cmax ) and 2 and 10 minutes after albuterol (salbutamol) administration. Peak global inspiratory (PIFEIT ) and peak expiratory EIT (PEFEIT ) flow, slope of the global expiratory flow-volume curve (FVslope ), steepest FVslope over all pixels in the lung field, total impedance change (surrogate for tidal volume; VTEIT ) and intercept on the expiratory FV curve normalized to VTEIT (FVintercept /VTEIT ) were indexed to baseline and analyzed for a difference from the control, at Cmax , 2 and 10 minutes after albuterol. Multiple linear regression explored the explanation of the variance of Δflow, a validated variable to evaluate bronchoconstriction using all EIT variables.

RESULTS

At Cmax , PIFEIT , PEFEIT , and FVslope significantly increased whereas FVintercept /VT decreased. All variables returned to baseline 10 minutes after albuterol. The VTEIT did not change. Multivariable investigation suggested 51% of Δflow variance was explained by a combination of PIFEIT and PEFEIT .

CONCLUSIONS AND CLINICAL IMPORTANCE

Changes in airflow during histamine challenge and subsequent albuterol administration could be detected by various EIT flow volume variables.

Generation of soluble, disulfide-rich JEV NS1 protein recognizable by anti-NS1 antibodies through a simplified, in vitro refolding approach

Co-existence of Japanese Encephalitis virus (JEV) with highly homologous antigenic epitopes results in antibody-based serodiagnosis being inaccurate at detecting and distinguishing JEV from other flaviviruses. This often causes misdiagnosis and inefficient treatments of flavivirus infection. Generation of JEV NS1 protein remains a challenge as it is notably expressed in the form of inactive aggregates known as inclusion bodies using bacterial expression systems. This study evaluated two trxB and gor E. coli strains in producing soluble JEV NS1 via a cold-shock expression system. High yield of JEV NS1 inclusion bodies was produced using cold-shocked expression system. Subsequently, a simplified yet successful approach in generating soluble, active JEV NS1 protein through solubilization, purification and in vitro refolding of JEV NS1 protein from inclusion bodies was developed. A step-wise dialysis refolding approach was used to facilitate JEV NS1 refolding. The authenticity of the refolded JEV NS1 was confirmed by specific antibody binding on indirect ELISA commercial anti-NS1 antibodies which showed that the refolded JEV NS1 was highly immunoreactive. This presented approach is cost-effective, and negates the need for mammalian or insect cell expression systems in order to synthesize this JEV NS1 protein of important diagnostic and therapeutic relevance in Japanese Encephalitis disease.

Beclomethasone dipropionate, formoterol fumarate and glycopyrronium bromide: Synergy of triple combination therapy on human airway smooth muscle ex vivo

BACKGROUND AND PURPOSE

Combining inhaled corticosteroids (ICSs), long-acting β₂ -adrenoceptor agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) is recommended to treat severe forms of asthma and chronic obstructive pulmonary disease (COPD). Clinical benefits have been demonstrated for ICS/LABA/LAMA combinations. This study characterized the interaction between the ICS beclomethasone dipropionate, the LABA formoterol fumarate and the LAMA glycopyrronium bromide in human airways.

EXPERIMENTAL APPROACH

Human passively sensitized airways and bronchi from COPD donors were stimulated with histamine or carbachol. Tissues were incubated overnight with beclomethasone and then treated with formoterol and glycopyrronium, alone or in triple combination. The interaction was assessed by using Bliss Independence and Unified Theory theorems.

KEY RESULTS

Beclomethasone/formoterol/glycopyrronium combination synergistically relaxed medium bronchi and small airways. Beclomethasone/formoterol/glycopyrronium combination at 100:6:12.5 combination ratio was a balanced drug mixture leading to very strong synergistic effect on relaxation of medium bronchi (Combination Index: from 0.042 to 0.96) and middle to very strong synergy in small airways (Combination Index: from 0.018 to 0.310). The synergy was related with the activation of intracellular glucocorticoid receptors and G_sα subunit G-protein of β₂ -adrenoceptors, leading to the modulation of cyclic AMP-dependent PKA pathway.

CONCLUSION

Triple beclomethasone/formoterol/glycopyrronium combination induces synergistic bronchorelaxant effect in medium and small human airways, at least in ex vivo experiments. Further research is needed to confirm these findings in clinical studies in patients with asthma or COPD.

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.

Isolated airways in equine respiratory pharmacology: They never lie

Pre-clinical studies on human isolated bronchi have relevant translational value in human in vivo, conversely no investigation has been performed to assess whether data resulting from equine isolated airways can have any translational application in asthmatic horses. Thus, a meta-regression analysis via random-effect method was carried out to correlate the pharmacological characteristics of bronchodilators resulting from experiments performed in equine isolated bronchi with their impact on the lung function outcomes in asthmatic horses. Data on the potency of different bronchodilators were extracted from four ex vivo studies involving 68 horses, and related with the maximum change in transpulmonary pressure (ΔPpl_max), pulmonary resistance (R_L), and dynamic lung compliance (C_dyn) resulting from the meta-analysis of clinical trials aimed to assess the effect of different bronchodilator classes, namely antimuscarinic agents and β₂-adrenoreceptor (β₂-AR) agonists, on lung function of asthmatic horses. The potency (pEC₅₀) detected in equine isolated bronchi for each specific bronchodilator did not significantly (P > 0.05) influence the bronchorelaxant effect resulting from clinical trials. R_L was characterized by a flatter meta-regression line (slope 0.01, 95%CI -0.25 - 0.28) with respect to ΔPpl_max (slope 0.90, 95%CI -4.06 - 2.26) and C_dyn (slope 0.09, 95%CI -0.21 - 0.04). The quality of evidence was moderate for R_L and ΔPpl_max and low for C_dyn. This quantitative synthesis provides the indirect evidence that pre-clinical investigations performed by using equine isolated airways may produce useful data to predict the impact of bronchodilators on the R_L of asthmatic horses. Further translational studies are needed to directly confirm the results of this research.

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.

The Crystal Structure of N-(1-Arylethyl)-4-methyl- 2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxamides as the Factor Determining Biological Activity Thereof

In order to detect new structural and biological patterns in a series of hetaryl-3-carboxylic acid derivatives, the optically pure (S)- and (R)-enantiomers of N-(1-arylethyl)-4-methyl- 2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxamides, their true racemates, and mechanical racemic mixtures have been synthesized in independent ways. The particular features of the 1Н- and 13С-NMR spectra of all synthesized substances, liquid chromato-mass spectrometric behavior thereof under electrospray ionization conditions, and also the results of polarimetric and X-ray diffraction studies have been discussed. Pharmacological screening on a model of carrageenan inflammation has found a clear relationship between the spatial structure of the studied objects and biological activity thereof. Enantiomers with chiral centers having (S)-configuration showed weak inhibition of pain and inflammatory reactions, while their mirror (R)-isomers exhibited very powerful analgesic and antiphlogistic properties under the same conditions, with the level of specific activity exceeding that of Lornoxicam and Diclofenac. Taking obtained data into account, a noticeable decrease in the activity of mechanical racemic mixtures, consisting of one-half of the “wrong” (S)-enantiomers, is quite natural. The true racemate of N-(1-phenylethyl)-amide proved itself in a similar way, while 4-methoxy-substituted analog thereof stood out against this background with unexpectedly high analgesic and anti-inflammatory activities. A comparative analysis of X-ray diffraction data has found that crystalline and molecular structure of racemic N-[1-(4-methoxyphenyl)ethyl]-4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxamide is completely different from that of the original enantiomers and, moreover, very unusual for racemates. Obviously, it is the factor determining the unique character of the biological effects of the said substance.

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.

Beclomethasone dipropionate and formoterol fumarate synergistically interact in hyperresponsive medium bronchi and small airways

Background

Corticosteroids increase the expression of β₂-adrenoceptors (β₂-ARs) and protect them against down-regulation. Conversely, β₂-AR agonists improve the anti-inflammatory action of corticosteroids. Nevertheless, it is still uncertain whether adding a long-acting β₂-AR agonist (LABA) to an inhaled corticosteroid (ICS) results in an additive effect, or there is true synergy.

Therefore, the aim of this study was to pharmacologically characterize the interaction between the ICS beclomethasone diproprionate (BDP) and the LABA formoterol fumarate (FF) in a validated human ex vivo model of bronchial asthma.

Methods

Human medium and small airways were stimulated by histamine and treated with different concentrations of BDP and FF, administered alone and in combination at concentration-ratio reproducing ex vivo that of the currently available fixed-dose combination (FDC; BDP/FF 100:6 combination-ratio). Experiments were performed in non-sensitized (NS) and passively sensitized (PS) airways. The pharmacological interaction was assessed by using Bliss Independence and Unified Theory equations.

Results

BDP/FF synergistically increased the overall bronchorelaxation in NS and PS airways (+ 15.15% ± 4.02%; P < 0.05 vs. additive effect). At low-to-medium concentrations the synergistic interaction was greater in PS than in NS bronchioles (+ 16.68% ± 3.02% and + 7.27% ± 3.05%, respectively). In PS small airways a very strong synergistic interaction (Combination Index: 0.08; + 20.04% ± 2.18% vs. additive effect) was detected for the total concentrations of BDP/FF combination corresponding to 10.6 ng/ml.

Conclusion

BDP/FF combination synergistically relaxed human bronchi; the extent of such an interaction was very strong at low-to-medium concentrations in PS small airways.

Trial registration

Not applicable.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0770-7) contains supplementary material, which is available to authorized users.

Combining long-acting bronchodilators with different mechanisms of action: A pharmacological approach to optimize bronchodilation of equine airways

The ultra long-acting β₂ -adrenoceptor agonist olodaterol plus the ultra long-acting muscarinic antagonist tiotropium bromide are known to relax equine airways. In human bronchi combining these drugs elicits a positive interaction, thus we aimed to characterize this information further in equine isolated airways stimulated by electrical field stimulation (EFS) and using the Concentration-Reduction Index (CRI) and Combination Index (CI) equations. The drugs were administered alone and together by reproducing ex vivo the concentration-ratio delivered by the currently available fixed-dose combination (1:1). The single agents elicited a significant (p < .05) concentration-dependent reduction in the EFS-induced contractility, that was synergistically improved (CI 0.18) when administered in combination (0.9 logarithms more potent, 24% more effective than the monocomponents). The drugs mixture allowed a reduction in the concentration of olodaterol from ≃1 to ≃2.3 logarithms. A favorable CRI was detected also for tiotropium bromide, whose concentration can be reduced ≃1 logarithm at medium effect levels, remaining positive up to submaximal relaxant effect in the presence of olodaterol. The combination of tiotropium bromide/olodaterol allows the reduction in the concentration of the monocomponents to achieve airway smooth muscle relaxation, thus potentially decreases the risk of adverse events when these drugs are used to treat severe asthmatic horses.

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.

Effect of lipopolysaccharide on the responsiveness of equine bronchial tissue

Recurrent airway obstruction (RAO) is a main characteristic of horses with severe equine asthma syndrome. The presence of bacterial lipopolysaccharide (LPS) in the airways of horses is thought to play a crucial role in the clinical expression of this disorder. This study pharmacologically characterized the effect of LPS on the responsiveness of equine bronchial tissue. Equine isolated bronchi were incubated overnight with LPS (0.1-100 ng/ml) and then stimulated by electrical field stimulation (EFS). The role of capsaicin sensitive-sensory nerves (capsaicin desensitization treatment), neurokinin-2 (NK₂) receptors (blocked by GR159897), transient receptor potential vanilloid type 1 receptors (TRPV1; blocked by SB366791), and neurokinin A (NKA) were investigated. Untreated bronchi were used as control tissues. LPS (1 ng/ml) significantly increased the EFS-evoked contractility of equine bronchi compared with control tissues (+742 ± 123 mg; P < 0.001). At higher concentrations LPS induced desensitization to airways hyperresponsiveness (AHR; EC₅₀: 5.9 ± 2.6 ng/ml). Capsaicin desensitization and GR159897 significantly prevented AHR induced by LPS at EFS_1-50Hz (-197 ± 25%; P < 0.01). SB366791 inhibited AHR at very low EFS frequency (EFS_1Hz -193 ± 29%; P < 0.01 vs. LPS-treated bronchi). LPS (1 ng/ml) significantly (P < 0.01) increased 3.7 ± 0.7 fold the release of NKA compared with control bronchi. LPS induces biphasic dysfunctional bronchial contractility due to the stimulation of capsaicin sensitive-sensory nerves, increased release of NKA, and activation of NK₂ receptors, whereas TRPV1 receptors appear to play a marginal role in this response. The overnight challenge with low concentrations of LPS represents a suitable model to investigate pharmacological options that may be of value in the treatment of equine RAO.

Chiral Drug Analysis in Forensic Chemistry: An Overview

Many substances of forensic interest are chiral and available either as racemates or pure enantiomers. Application of chiral analysis in biological samples can be useful for the determination of legal or illicit drugs consumption or interpretation of unexpected toxicological effects. Chiral substances can also be found in environmental samples and revealed to be useful for determination of community drug usage (sewage epidemiology), identification of illicit drug manufacturing locations, illegal discharge of sewage and in environmental risk assessment. Thus, the purpose of this paper is to provide an overview of the application of chiral analysis in biological and environmental samples and their relevance in the forensic field. Most frequently analytical methods used to quantify the enantiomers are liquid and gas chromatography using both indirect, with enantiomerically pure derivatizing reagents, and direct methods recurring to chiral stationary phases.

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.

Bronchopulmonary pharmacokinetics of (R)-salbutamol and (S)-salbutamol enantiomers in pulmonary epithelial lining fluid and lung tissue of horses

AIMS

Salbutamol is usually administered as a racemic mixture but little is known about the enantioselectivity of salbutamol pharmacokinetics in the lung. This study was designed to investigate enantiomer concentrations in lung tissue after inhaled dosing.

METHODS

Horses (n = 12) received racemic salbutamol 1000 μg via inhalation. Enantioselective ultra performance liquid chromatography-tandem mass spectrometry was used to determine salbutamol 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

Mean ± 95% confidence interval (CI) yield of PELF was 57 ± 10 mg. Initial mean ± 95%CI (R)- and (S)-salbutamol PELF concentrations were 389 ± 189 ng g^-1 and 378 ± 177 ng g^-1 respectively, and both reduced approximately 50% by 15 min. Mean ± 95%CI central lung levels of drug were higher than peripheral lung tissue for both (R)-salbutamol (875 ± 945 vs. 49.5 ± 12 ng g^-1 ) and (S)-salbutamol (877 ± 955 vs. 50.9 ± 12 ng g^-1 ) respectively. There was no evidence of enantioselectivity in PELF or central lung but minor (~2%) enantioselectivity was observed in the peripheral lung. Enantioselectivity was clearly evident in plasma with (S):(R) ratio of 1.25 and 1.14 for both area under the concentration-time curve (0-25 min) and C_max respectively.

CONCLUSIONS

PELF sampling in horses offers sufficient yield allowing direct detection of drug and, combined with tissue sampling, is a valuable model to investigate bronchopulmonary pharmacokinetics. Salbutamol did not demonstrate enantioselectivity in PELF or central lung tissue uptake following acute dosing, however, enantioselective plasma concentrations were demonstrated, with minor enantioselectivity in the peripheral lung.

Pharmacological characterisation of the interaction between glycopyrronium bromide and indacaterol fumarate in human isolated bronchi, small airways and bronchial epithelial cells

BACKGROUND

Nowadays, there is a considerable gap in knowledge concerning the mechanism(s) by which long-acting β2-agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) interact to induce bronchodilation. This study aimed to characterise the pharmacological interaction between glycopyrronium bromide and indacaterol fumarate and to identify the mechanism(s) leading to the bronchorelaxant effect of this interaction.

METHODS

The effects of glycopyrronium plus indacaterol on the contractile tone of medium and small human isolated bronchi were evaluated, and acetylcholine and cAMP concentrations were quantified. The interaction was assessed by Bliss Independence approach.

RESULTS

Glycopyrronium plus indacaterol synergistically inhibited the bronchial tone (medium bronchi, +32.51 % ± 7.86 %; small bronchi, +28.46 % ± 5.35 %; P < 0.05 vs. additive effect). The maximal effect was reached 140 min post-administration. A significant (P < 0.05) synergistic effect was observed during 9 h post-administration on the cholinergic tone, but not on the histaminergic contractility. Co-administration of glycopyrronium and indacaterol reduced the release of acetylcholine from the epithelium but not from bronchi, and enhanced cAMP levels in bronchi and epithelial cells (P < 0.05 vs. control), an effect that was inhibited by the selective KCa(++) channel blocker iberiotoxin. The role of cAMP-dependent pathway was confirmed by the synergistic effect elicited by the adenylate cyclase activator forskolin on glycopyrronium (P < 0.05 vs. additive effect), but not on indacaterol (P > 0.05 vs. additive effect), with regard of the bronchial relaxant response and cAMP increase.

CONCLUSIONS

Glycopyrronium/indacaterol co-administration leads to a synergistic improvement of bronchodilation by increasing cAMP concentrations in both airway smooth muscle and bronchial epithelium, and by decreasing acetylcholine release from the epithelium.

Efficacy of Inhaled Levalbuterol Compared to Albuterol in Horses with Recurrent Airway Obstruction

Background

The (R)‐enantiomer of racemic albuterol (levalbuterol) has bronchodilatory properties whereas the (S)‐enantiomer causes adverse effects in human airways, animal models, and isolated equine bronchi. Levalbuterol is commercially available and improves pulmonary function of asthmatic patients with a longer duration of effect than albuterol.

Objective

To determine the dose at which inhaled levalbuterol produces maximal bronchodilatory effect (EDmax) and determine its duration of action in recurrent airway obstruction (RAO)‐affected horses in comparison to racemic albuterol.

Animals

Nine horses with inducible and reversible RAO.

Methods

Randomized, crossover trial. Horses were challenged with moldy hay to induce airway obstruction. Horses were treated with nebulized albuterol or levalbuterol chosen randomly. Pulmonary function testing (PFT) was measured before and for up to 3 hours after bronchodilatation challenge. Maximum change in transpulmonary pressure (DP_max) was measured to assess the dose effect and duration of action of each drug. After a 24 hours washout period, the bronchodilatation challenge was repeated with the second bronchodilator.

Results

The duration of effect was 60 minutes for albuterol and 120 minutes for levalbuterol. The dose of bronchodilator EDmax was not significantly different between albuterol and levalbuterol (EDmax = 125.0 [125–125 μg] and EDmax = 188 [125–188 μg] respectively; P = .068). The magnitude of bronchodilatation was not significantly different between the 2 treatments (61.1 and 59.9% decrease in DP_max for albuterol and levalbuterol respectively; P = .86).

Conclusions and clinical importance

Levalbuterol is as effective a bronchodilator as albuterol; although levalbuterol lasts twice as long as albuterol, its duration of action is still too short to make it practical for RAO treatment.

Chiral liquid chromatography-mass spectrometry (LC-MS/MS) method development for the detection of salbutamol in urine samples

A sequential solid-phase extraction (SPE) method was developed and validated using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the detection and quantification of salbutamol enantiomers in porcine urine. Porcine urine samples were hydrolysed with β-glucuronidase/arylsulfatase from Helix pomatia and then subjected to a double solid-phase extraction (SPE) first using the Abs-Elut Nexus SPE and then followed by the Bond Elut Phenylboronic Acid (PBA) SPE. The salbutamol enantiomers were separated using the Astec CHIROBIOTIC™ T HPLC column (3.0mm×100mm; 5μm) maintained at 15°C with a 15min isocratic run at a flow rate of 0.4mL/min. The mobile phase constituted of 5mM ammonium formate in methanol. Salbutamol and salbutamol-tert-butyl-d9 (internal standard, IS) was monitored and quantified with the multiple reaction monitoring (MRM) mode. The method showed good linearity for the range of 0.1-10ng/mL with limit of quantification at 0.3ng/mL. Analysis of the QC samples showed intra- and inter-assay precisions to be less than 5.04%, and recovery ranging from 83.82 to 102.33%.

Resolution of Rac-Bambuterol via Diastereoisomeric Salt Formation with o-Chloromandelic Acid and Differences in the Enantiomers' Pharmacodynamical Effects in Guinea Pigs and Beagles

In this study an enantioseparation method for rac-bambuterol (5-(2-(tert-butylamino)-1-hydroxyethyl)-1,3-phenylene bis(dimethylcarbamate)) via diastereoisomeric salt formation with o-chloromandelic acid was developed. The enantiomeric excess (ee) values and chemical purities of the desired products were confirmed by high-performance liquid chromatography (HPLC) using chiral stationary phase and reverse-phase HPLC analyses, respectively. The ee values and the chemical purities both exceeded 99%. Animal experiments showed that (R)-bambuterol was a potent inhibitor for histamine-induced asthma reactions. (S)-bambuterol was ineffective in relaxing the airways. Both enantiomers increased heart rates in beagles. Therefore, replacing rac-bambuterol with (R)-bambuterol could be beneficial for asthma patients.

Study on the determination and chiral inversion of R-salbutamol in human plasma and urine by liquid chromatography-tandem mass spectrometry

The chiral inversion has been a concerned issue during the research and development of a chiral drug. In this study, a sensitive chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for determination of salbutamol enantiomers in human plasma and urine. The chiral inversion mechanism of R-salbutamol was fully investigated for the first time by studying the effects of physicochemical factors, including pH, temperature and time. A fitted model to predict the chiral inversion ratio of R-salbutamol was proposed using a Box-Behnken design. All the samples were separated on an Astec Chirobiotic T column and detected by a tandem mass spectrometer in multiple reaction monitoring mode. Lower limit of quantification of 0.100ng/mL was achieved under the optimized conditions. The method was fully validated and successfully applied to the clinical pharmacokinetic study of R-salbutamol in healthy volunteers. Chiral inversion of R-salbutamol to S-salbutamol has been detected in urine samples. The results indicated that pH and temperature were two dominant factors that caused the chiral inversion of R-salbutamol, which should be taken into consideration during the analysis of chiral drugs. The chiral inversion of R-salbutamol determined in this study was confirmed resulted from the gastric acid in stomach rather than caused by the analysis conditions. Moreover, the calculated results of the fitted model matched very well with the enantioselective pharmacokinetic study of R-salbutamol, and the individual difference of the chiral inversion ratio of R-salbutamol was related to the individual gastric environment. On the basis of the results, this study provides important and concrete information not only for the chiral analysis but also for the metabolism research of chiral drugs.

Turning a molecule into a medicine: the development of indacaterol as a novel once-daily bronchodilator treatment for patients with COPD

Indacaterol is the first once-daily, long-acting β2-adrenergic agonist (LABA) approved for the treatment of chronic obstructive pulmonary disease (COPD). Indacaterol was developed using a combination of informed drug design and molecular chemistry to generate a β2-adrenergic agonist with a fast onset and long duration of action, enabling once-daily dosing with an acceptable safety profile. Early preclinical studies with indacaterol demonstrated these characteristics, and this promising molecule was taken into clinical development, originally for asthma treatment. Subsequent safety concerns over LABA monotherapy in patients with asthma redirected indacaterol's development to centre on COPD, where a good evidence base and guideline recommendations for bronchodilator monotherapy existed. Clinical development was initially complicated by different inhaler devices and differing doses of indacaterol. Using a phase III innovative adaptive-design clinical trial (INHANCE), indacaterol 150 and 300 μg once-daily doses were selected to be taken forward into the phase III INERGIZE programme. This programme delivered placebo-controlled and active-comparator data, including comparisons with formoterol, tiotropium and salmeterol/fluticasone, as well as the use of indacaterol in combination with tiotropium. Together, these studies provided a comprehensive assessment of the benefit-risk profile of indacaterol, allowing for regulatory submission. Indacaterol was first approved at once-daily doses of 150 and 300 μg in the European Union in 2009, followed by 150 µg in Japan (2011) and China (2012), and 75 μg in the United States (2011). To date, indacaterol is approved and marketed in more than 100 countries worldwide for once-daily maintenance treatment of COPD.

Pharmacological interaction between LABAs and LAMAs in the airways: optimizing synergy

Nowadays there is solid clinical information for combining β2-agonists and anti-muscarinic agents, although the nature (additive or synergistic) of the net clinical result obtained by co-administration of these two classes of bronchodilators is not completely elucidated from a pharmacological point of view. Recent preclinical studies demonstrated that combining a long-acting β2-agonist (LABA) with a long-acting anti-muscarinic agent (LAMA) provides synergistic benefit on airway smooth muscle relaxation, which may have major implications for the use of LABA/LAMA combinations in the treatment COPD. Indeed, the LABA/LAMA synergism has been proved also in patients with moderate-to-severe COPD. Nevertheless, there is still a strong medical need for dose-finding clinical trials designed to identify the most favourable doses of LABA/LAMA combinations able to induce a real synergism. We strongly believe that the Bliss Independence theory represents an effective model for investigating the cross-talk between β2-adrenoreceptor and the muscarinic pathways leading to the synergistic interaction between β2-agonists and anti-muscarinic agents. In any case, the possibility of eliciting a synergistic bronchodilator effect when combining a LABA and a LAMA suggests that the therapeutic approach proposed by GOLD recommendations to only use LABA/LAMA combination in more severe COPD patients who are not controlled by a single bronchodilator should be reconsidered. We support the possibility of an early intervention with low doses of LABA/LAMA combination to optimize bronchodilation and reduce the risk of adverse events that characterize both LABAs and LAMAs, especially when administered at the full doses currently approved for the treatment of COPD.

Contribution of sensory nerves to LPS-induced hyperresponsiveness of human isolated bronchi

AIMS

Bacterial lipopolysaccharide (LPS) can induce bronchial hyperresponsiveness (BHR), but the underlying mechanisms remain to be determined. Here, the possible contribution of sensory nerves to LPS-induced BHR was examined in human isolated bronchi to pharmacologically identify the mechanisms underlying this phenomenon.

MAIN METHODS

Human isolated bronchial tone was induced by electrical field stimulation (EFS). The responses of airways to LPS, with or without capsaicin desensitization or thiorphan treatment were studied and the transient receptor potential vanilloid type 1 (TRPV1) expression was assessed. We performed similar experiments in the presence of a TRPV1 or a neurokinin (NK) 2 receptor antagonist using SB366791 and GR159897, respectively.

KEY FINDINGS

LPS increased (≃2.3-fold, P<0.001) the contraction induced by EFS, compared to control tissues. Acute administration of capsaicin enhanced (≃2.3-fold, P<0.001) the EFS-mediated contraction, but did not potentiate the effect of LPS. Thiorphan increased (≃1.3-fold, P<0.05) the contractile response of LPS treated tissues and, at lower frequencies, it enhanced (≃1.7-fold, P<0.001) the capsaicin-induced contraction. In capsaicin-desensitized bronchi, LPS did not modify (P>0.05) the EFS contractile response, nor after treatment with thiorphan. Capsaicin desensitization reduced (≃0.4-fold, P<0.001) the LPS-induced BHR. SB366791 and GR159897 prevented the LPS-induced BHR and the release of NKA. LPS increased (+85.3±9.5%, P<0.01) the surface membrane expression of TRPV1 in parasympathetic ganglia.

SIGNIFICANCE

Our results demonstrate the involvement of capsaicin-sensitive sensory nerves and neutral endopeptidases in LPS-induced BHR of the human bronchi, associated with an upregulation of TRPV1 and release of NKA.

Detection and pharmacokinetics of salbutamol in thoroughbred racehorses following inhaled administration

Salbutamol sulphate (Ventolin Evohaler) was administrated via the inhalation route to six horses at a dose of 0.5 mg every 4 h during the day for 2 days (total dose 4 mg). Urine and blood samples were taken up to 92 h postadministration. Hydrolyzed plasma and urine were extracted using solid phase extraction (SPE). A sensitive tandem mass spectrometric method was developed in this study, achieving a lower limit of quantification (LLOQ) for salbutamol of 10 pg/mL in plasma and urine. The parent drug was identified using UPLC-MS/MS. Most of the determined salbutamol plasma concentrations, post last administration, lie below the LLOQ of the method and so cannot be used for plasma PK analysis. Urine PK analysis suggests a half-life consistent with the pharmacological effect duration. An estimate of the urine average concentration at steady-state was collected by averaging the concentration measurements in the dosing period from -12 to 0 h relative to the last administered dose. The value was averaged across the six horses and used to estimate an effective urine concentration as a marker of effective lung concentration. The value estimated was 9.6 ng/mL and from this a number of detection times were calculated using a range of safety factors.

Anesthesia of the geriatric equine

Advancements in veterinary medicine have resulted in an increased number of geriatric horses being presented for medical or surgical procedures that require general anesthesia. Due to the physiological changes associated with aging and the likelihood of concurrent disease conditions, the geriatric equine is at an increased risk during anesthesia. The main physiological changes associated with aging, and their impact on anesthesia, are discussed in this review.

Levosalbutamol for chronic obstructive pulmonary disease: a treatment evaluation

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder associated with considerable morbidity and mortality. β2-adrenoceptor agonists (β2-agonists) act by stimulating the β2-adrenoceptor present on smooth muscle and other cells in the airways, resulting in bronchodilatation. β2-agonists play a central role in the treatment of breathlessness in patients with COPD. Salbutamol is a chiral drug with (R)- and (S)- isomers. Almost all β2-agonists that are currently used are racemic mixtures of (R)- and (S)-salbutamol.

AREAS COVERED

(R)-salbutamol alone (Xenopex®, generically known as levosalbutamol) is now indicated for the treatment or prevention of bronchospasm with reversible obstructive airway disease. This evaluation demonstrates that (R)-salbutamol provides a beneficial β2-agonist effect at a cellular level and in experimental models of airways disease. Furthermore, we demonstrate that (S)-salbutamol opposes the desirable effects of (R)-salbutamol and can actually cause features of asthma and COPD in vitro and in experimental asthma.

EXPERT OPINION

Despite this strong body of preclinical experimental evidence, (R)-salbutamol has not shown consistent superiority over (S)- or racemic salbutamol in the treatment of patients with COPD.

Heaves, an asthma-like disease of horses

Animal models have been developed to investigate specific components of asthmatic airway inflammation, hyper-responsiveness or remodelling. However, all of these aspects are rarely observed in the same animal. Heaves is a naturally occurring disease of horses that combines these features. It is characterized by stable dust-induced inflammation, bronchospasm and remodelling. The evaluation of horses during well-controlled natural antigen exposure and avoidance in experimental settings allows the study of disease mechanisms in the asymptomatic and symptomatic stages, an approach rarely feasible in humans. Also, the disease can be followed over several years to observe the cumulative effect of repeated episodes of clinical exacerbation or to evaluate long-term treatment, contrasting most murine asthma models. This model has shown complex gene and environment interactions, the involvement of both innate and adaptive responses to inflammation, and the contribution of bronchospasm and tissue remodelling to airway obstruction, all occurring in a natural setting. Similarities with the human asthmatic airways are well described and the model is currently being used to evaluate airway remodelling and its reversibility in ways that are not possible in people for ethical reasons. Tools including antibodies, recombinant proteins or gene arrays, as well as methods for sampling tissues and assessing lung function in the horse are constantly evolving to facilitate the study of this animal model. Research perspectives that can be relevant to asthma include the role of neutrophils in airway inflammation and their response to corticosteroids, systemic response to pulmonary inflammation, and maintaining athletic capacities with early intervention.