Analysing the effect caused by increasing the molecular volume in M1-AChR receptor agonists and antagonists: a structural and computational study

M1 muscarinic acetylcholine receptor (M1-AChR), a member of the G protein-coupled receptors (GPCR) family, plays a crucial role in learning and memory, making it an important drug target for Alzheimer's disease (AD) and schizophrenia. M1-AChR activation and deactivation have shown modifying effects in AD and PD preclinical models, respectively. However, understanding the pharmacology associated with M1-AChR activation or deactivation is complex, because of the low selectivity among muscarinic subtypes, hampering their therapeutic applications. In this regard, we constructed two quantitative structure-activity relationship (QSAR) models, one for M1-AChR agonists (total and partial), and the other for the antagonists. The binding mode of 59 structurally different compounds, including agonists and antagonists with experimental binding affinity values (pKi), were analyzed employing computational molecular docking over different structures of M1-AChR. Furthermore, we considered the interaction energy (Einter), the number of rotatable bonds (NRB), and lipophilicity (ilogP) for the construction of the QSAR model for agonists (R2 = 89.64, QLMO2 = 78, and Qext2 = 79.1). For the QSAR model of antagonists (R2 = 88.44, QLMO2 = 82, and Qext2 = 78.1) we considered the Einter, the fraction of sp3 carbons fCsp3, and lipophilicity (MlogP). Our results suggest that the ligand volume is a determinant to establish its biological activity (agonist or antagonist), causing changes in binding energy, and determining the affinity for M1-AChR.

Ultra Long-Acting β-Agonists in Chronic Obstructive Pulmonary Disease

INTRODUCTION

Inhaled β-agonists have been foundational medications for maintenance COPD management for decades. Through activation of cyclic adenosine monophosphate pathways, these agents relax airway smooth muscle and improve expiratory airflow by relieving bronchospasm and alleviating air trapping and dynamic hyperinflation improving breathlessness, exertional capabilities, and quality of life. β-agonist drug development has discovered drugs with increasing longer durations of action: short acting (SABA) (4-6 h), long acting (LABA) (6-12 h), and ultra-long acting (ULABA) (24 h). Three ULABAs, indacaterol, olodaterol, and vilanterol, are approved for clinical treatment of COPD.

PURPOSE

This article reviews both clinically approved ULABAs and ULABAs in development.

CONCLUSION

Indacaterol and olodaterol were originally approved for clinical use as monotherapies for COPD. Vilanterol is the first ULABA to be approved only in combination with other respiratory medications. Although there are many other ULABA's in various stages of development, most clinical testing of these novel agents is suspended or proceeding slowly. The three approved ULABAs are being combined with antimuscarinic agents and corticosteroids as dual and triple agent treatments that are being tested for clinical use and efficacy. Increasingly, these clinical trials are using specific COPD clinical characteristics to define study populations and to begin to develop therapies that are trait-specific.

Evidence-based review of data on the combination inhaler umeclidinium/vilanterol in patients with COPD

The use of inhaled, fixed-dose, long-acting muscarinic antagonists (LAMA) combined with long-acting, beta2-adrenergic receptor agonists (LABA) has become a mainstay in the maintenance treatment of chronic obstructive pulmonary disease (COPD). One of the fixed-dose LAMA/LABA combinations is the dry powder inhaler (DPI) of umeclidinium bromide (UMEC) and vilanterol trifenatate (VI) (62.5 µg/25 µg) approved for once-a-day maintenance treatment of COPD. This paper reviews the use of fixed-dose combination LAMA/LABA agents focusing on the UMEC/VI DPI inhaler in the maintenance treatment of COPD. The fixed-dose combination LAMA/LABA inhaler offers a step beyond a single inhaled maintenance agent but is still a single device for the COPD patient having frequent COPD exacerbations and persistent symptoms not well controlled on one agent. Currently available clinical trials suggest that the once-a-day DPI of UMEC/VI is well-tolerated, safe and non-inferior or better than other currently available inhaled fixed-dose LAMA/LABA combinations for COPD.

Abediterol (LAS100977), an inhaled long-acting β2-adrenoceptor agonist, has a fast association rate and long residence time at receptor

This study describes the association rate and residence time of abediterol, a novel long-acting β₂-adrenoceptor agonist (LABA) in Phase II development for treatment of asthma and COPD, in comparison with indacaterol, olodaterol, vilanterol and salmeterol, for both human β₁- and β₂-adrenoceptors. Abediterol association and dissociation rates were monitored directly by using its tritiated form. Moreover, association was determined indirectly using experimental K_i and k_off obtained from assays performed with unlabelled compound. Dissociation was also studied indirectly by measuring the association rate of ³H-CGP12177 to beta adrenoceptors previously occupied by unlabelled compounds. Abediterol shows a fast association for the β₂-adrenoceptor (k_on 1.4 × 10⁷ ± 1.8 × 10⁶M^-1min^-1) while its dissociation rate is between 30 and 64 times slower than that of the reference LABA compounds tested, with a residence time of 91.3 ± 13.3min (measured directly) and 185.5 ± 7.5min (measured indirectly). Abediterol shows kinetic selectivity for the β₂- over the β₁-adrenoceptor, with a dissociation rate from the β₁-adrenoceptor similar to the other LABA compounds tested. In conclusion, abediterol is a potent LABA with a fast association rate and a long residence time at β₂-adrenoceptors. These data are in agreement with the onset and duration of action of abediterol shown in humans.

Umeclidinium/vilanterol: a review of its use as maintenance therapy in adults with chronic obstructive pulmonary disease

Umeclidinium/vilanterol (Anoro(®) Ellipta™; Laventair™) is an inhaled fixed-dose combination of a long-acting muscarinic receptor antagonist and a long-acting β2-adrenoceptor agonist. It is available in several countries, including Japan, the USA, Canada and those of the EU, where it is indicated for oral inhalation in adults with chronic obstructive pulmonary disease (COPD). Umeclidinium/vilanterol is administered once daily using the Ellipta™ multi-dose dry powder inhaler, which is regarded as easy to use. Umeclidinium/vilanterol (62.5/25 µg once daily, equivalent to a delivered dose of 55/22 µg once daily) was effective and well tolerated in adult patients with COPD participating in large, multicentre trials of up to 24 weeks' duration. Umeclidinium/vilanterol improved pulmonary function to a significantly greater extent than placebo and each of the individual components. Moreover, umeclidinium/vilanterol was significantly more effective than once-daily tiotropium bromide monotherapy and a twice-daily fixed combination of salmeterol/fluticasone propionate at improving pulmonary function. Umeclidinium/vilanterol also had beneficial effects on dyspnoea, use of rescue medication, exacerbations, health-related quality of life and, in one study, exercise endurance. Umeclidinium/vilanterol is generally well tolerated in patients with COPD, with the most common adverse events in clinical trials being headache and nasopharyngitis. Umeclidinium/vilanterol was not associated with a clinically relevant increased risk of cardiovascular adverse events in patients with COPD, when data from several clinical trials were pooled. Thus, inhaled umeclidinium/vilanterol extends the treatment options currently available for the maintenance treatment of adults with COPD and has the convenience of once-daily administration.

Pharmacokinetics of aclidinium bromide/formoterol fumarate fixed-dose combination compared with individual components: A phase 1, open-label, single-dose study

Inhaled, long-acting bronchodilators represent a cornerstone of maintenance treatment for chronic obstructive pulmonary disease (COPD). Aclidinium bromide/formoterol fumarate 400/12 μg fixed-dose combination (FDC) has recently been licensed for use in adults with COPD in the European Union. This phase 1, randomized, open-label, 3-way, complete crossover, single-dose study assessed the pharmacokinetics, safety, and tolerability of an FDC, aclidinium bromide 400 μg, and formoterol fumarate 12 μg, all administered via Genuair™ to 30 healthy subjects. The rate and extent of absorption were comparable for aclidinium/formoterol FDC and individual monotherapies; aclidinium/formoterol FDC and aclidinium alone: Cmax , 270 and 215 pg/mL, respectively; AUC0-t , 229 and 222 pg · h/mL, respectively; aclidinium/formoterol FDC and formoterol alone: Cmax , 11 and 9.3 pg/mL, respectively; AUC, 36 and 32.4 pg · h/mL, respectively. There were no major differences in relative bioavailability between the combination and monotherapies: the aclidinium Cmax and AUC0-t were 26% and 3% higher, respectively, with aclidinium/formoterol FDC compared with aclidinium alone, and 18% and 11% higher, respectively, compared with formoterol alone. Aclidinium/formoterol FDC was well tolerated; the incidence of adverse events was low and similar to the monotherapies. Aclidinium/formoterol FDC was not associated with any major differences in rate and extent of absorption or relative bioavailability compared with monotherapies.

Bronchodilators, receptors and cross-talk: Together is better?

The most widely used maintenance therapies in chronic obstructive pulmonary disease (COPD) are long-acting muscarinic antagonists (LAMAs), and a number of these drugs are now available in combination with long-acting β2-agonists (LABAs). LAMAs inhibit the parasympathetic muscarinic pathway, while LABAs, as sympathomimetics, reduce airway smooth muscle (ASM) tone. As well as directly controlling the constriction and relaxation of ASM, muscarinic and adrenergic receptors are found on inflammatory cells, and drugs that target these receptors may also reduce inflammation in COPD. Evidence suggests that the muscarinic and adrenergic pathways cross-talk at the level of neuronal input to the ASM via second-messenger pathways within ASM cells. Although the cross-talk is not completely understood, pharmacologically targeting both pathways in COPD can maximize bronchodilation. Combining LAMAs and LABAs demonstrated improved efficacy compared with the individual therapies and so, for greater convenience, several fixed-dose combinations for once-daily use have been developed. These fixed-dose combinations demonstrate improvements in both lung-function and patient-reported outcomes compared with well-established monotherapies, with similar tolerability profiles to the individual agents.

Pharmacological treatment of chronic obstructive pulmonary disease: from evidence-based medicine to phenotyping

Chronic obstructive pulmonary disease (COPD) is characterized by large phenotype variability, reflected by a highly variable response to pharmacological treatment. Nevertheless, current guidelines suggest that patients with COPD of similar severity should be treated in the same way. The phenotype-based pharmacotherapeutic approach proposes bronchodilators alone in the nonfrequent exacerbator phenotype and a combination of bronchodilators and inhaled corticosteroids in patients with asthma-COPD overlap syndrome (ACOS) and moderate-to-severe exacerbator phenotype. The clinical importance of phenotypes is changing the paradigm of COPD management from evidence-based to personalized medicine. However, the personalized pharmacological strategy of COPD has to be validated in future clinical studies.

Tailoring of corticosteroids in COPD management

This literature review updates the reader on the new studies regarding steroid therapy over the last year in stable COPD and in exacerbations. In stable COPD, we critique the 2011 update and 2013 revision of the GOLD guidelines, discuss why combining inhaled corticosteroids (ICS) with long-acting beta-agonists (LABA) (ICS/LABA) is preferable over LABA alone and review the literature for intraclass differences, finding that the evidence does not clearly support superiority of any particular ICS/LABA. We also address other comparisons against ICS/LABA, including triple therapy. We briefly review which type of inhaler should be chosen. For exacerbations, we report the REDUCE trial findings favouring a 5-day course of systemic steroids, and other trials addressing which steroid and route to use, including in an intensive care setting. Lastly, the future lies in new anti-inflammatories and re-phenotyping the heterogeneous amalgamation of COPD. A Spanish guideline recommends distinguishing steroid-responsive eosinophilic exacerbators from other phenotypes.

Differential pharmacology and clinical utility of emerging combination treatments in the management of COPD--role of umeclidinium/vilanterol

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease characterized by airflow limitation that is not fully reversible. Bronchodilator therapy is the cornerstone in COPD treatment. Bronchodilation in COPD is mainly achieved via administration of long- and ultralong-acting β₂-agonists and with long-acting muscarinic antagonists. New combinations of bronchodilators with dual-acting muscarinic antagonist and β₂-agonist properties have been licensed, and others are currently being developed with the aim of achieving once-daily dosing, and therefore may improve the likelihood of treatment compliance. These combination bronchodilators include glycopyrronium bromide/indacaterol maleate, umeclidinium (UMEC) bromide/vilanterol trifenatate (VI), aclidinium bromide/formoterol and tiotropium bromide/olodaterol (Boehringer Ingelheim, Germany). This review will focus mainly on studies and clinical trials involving the novel fixed-dose combination of UMEC/VI at doses of 125/25 μg and 62.5/25 μg in patients with COPD. Data from large clinical trials involving more than 4,500 COPD patients indicate that UMEC/VI is an effective once-daily treatment in COPD with improved pulmonary function. Future studies assessing the impact of this combination on exacerbations, delay in disease progression, and health status in patients with COPD are warranted.

Considerations for new dual-acting bronchodilator treatments for chronic obstructive pulmonary disease

Current guidelines recommend treatment with one or more bronchodilators for chronic obstructive pulmonary disease (COPD) patients. Combination therapy with long-acting muscarinic antagonists (LAMA) and long-acting β2-agonists (LABA) should be recommended in patients who are not fully controlled with one of them. In this article, two closely related approaches to provide long-acting treatments are compared: the LABA/LAMA fixed-dose combination therapy, and the dual-acting muscarinic receptor antagonist and β2-adrenoceptor agonist (MABA). The author in that study concludes that both approaches have been shown to provide clinically enhanced bronchodilator activity that is superior to that offered by current standard treatment. LAMA/LABA fixed-dose combinations are expected to become a new standard in the treatment of COPD. It is important to know the characteristics of the different LAMA or LABA, the inhalation device and the duration of action, because diversity can help to personalize the treatment. Dose-finding studies are required. It is also required to investigate the existence of pharmacodynamics or pharmacokinetic interactions between the components as well as the safety profile. MABA represent an alternative to these combinations, but there is little clinical data yet reported. They have the potential to act as a useful platform for the development of triple therapy in one inhaler.