Long-Acting Muscarinic Antagonists Under Investigational to Treat Chronic Obstructive Pulmonary Disease

Introduction

Bronchodilators are the cornerstone of chronic obstructive pulmonary disease (COPD) therapy and long-acting muscarinic antagonists (LAMAs) as a mono or combination treatment play a pivotal role. Several LAMAs are already available on the market in different formulations, but developing a new compound with a higher M3 receptor selectivity and a lower affinity to M2 receptors to increase the therapeutic effect and minimize the adverse effects is still a goal. Moreover, new formulations could improve adherence to therapy.

Areas Covered

This systematic review assesses investigational long-acting muscarinic antagonist in Phase I and II clinical trials over the last decade. It offers insights on whether LAMAs and/or their new formulations in clinical development can become effective treatments for COPD in the future.

Expert Opinion

Research on LAMA seems to have come to a standstill, the few new molecules under study do not show distinctive characteristics compared to the previous ones. Muscarinic antagonist/β2-agonist (MABAs) appear to be the major innovation currently under investigation, and they could theoretically open new research frontiers on the effect between adrenergic and muscarinic interaction in the same cell.

Emerging muscarinic receptor antagonists for the treatment of asthma

INTRODUCTION

The increased acetylcholine signaling in asthma pathophysiology offers the rationale for the use of LAMAs in the treatment of asthmatic patients. Tiotropium is still the only LAMA approved for use in asthma but there is a real interest in developing novel LAMAs for the treatment of asthma, or at least to extend this indication to other LAMAs already on the market.

AREAS COVERED

We examined and discussed trials and research that have studied or are evaluating the role of LAMAs already on the market in asthma and possible novel muscarinic acetylcholine receptor antagonists.

EXPERT OPINION

Glycopyrronium and umeclidinium will soon be included in the GINA strategy with the same current indications of tiotropium. It is likely that the choice of the LAMA will be influenced not so much by its pharmacological profile as by the type of triple therapy chosen. It is extremely difficult to identify a new LAMA that is more effective than tiotropium, but is it plausible that new technologies that will allow delivering the drug in a more targeted way and with a lower risk of adverse effects may represent the real progress in the use of LAMAs in asthma in the coming years.

LABA/LAMA fixed-dose combinations in patients with COPD: a systematic review

OBJECTIVES

The aim of this study was to assess the current evidence for long-acting β2-agonist (LABA)/long-acting muscarinic antagonist (LAMA) fixed-dose combinations (FDCs) in the treatment of COPD.

MATERIALS AND METHODS

A systematic literature search of randomized controlled trials published in English up to September 2017 of LABA/LAMA FDCs vs LABA or LAMA or LABA/inhaled corticosteroid (ICS) FDCs in COPD patients was performed using PubMed, Embase, Scopus, and Google Scholar. Outcomes including forced expiratory volume in 1 second (FEV1), Transition Dyspnea Index (TDI) scores, St George's Respiratory Questionnaire (SGRQ) scores, exacerbations, exercise tolerance (endurance time [ET]), inspiratory capacity (IC), and rescue medication use were evaluated.

RESULTS

In total, 27 studies were included in the review. LABA/LAMA FDCs significantly improved lung function (FEV1) at 12 weeks compared with LABA or LAMA or LABA/ICS. These effects were maintained over time. Significant improvements with LABA/LAMA FDCs vs each evaluated comparator were also observed in TDI and SGRQ scores, even if significant differences between different LABA/LAMA FDCs were detected. Only the LABA/LAMA FDC indacaterol/glycopyrronium has shown superiority vs LAMA and LABA/ICS for reducing exacerbation rates, while olodaterol/tiotropium and indacaterol/glycopyrronium have been shown to improve ET and IC vs the active comparators. Rescue medication use was significantly reduced by LABA/LAMA FDCs vs the evaluated comparators. LABA/LAMA FDCs were safe, with no increase in the risk of adverse events with LABA/LAMA FDCs vs the monocomponents.

CONCLUSION

Evidence supporting the efficacy of LABA/LAMA FDCs for COPD is heterogeneous, particularly for TDI and SGRQ scores, exacerbation rates, ET, and IC. So far, indacaterol/glycopyrronium is the LABA/LAMA FDC that has the strongest evidence for superiority vs LABA, LAMA, and LABA/ICS FDCs across the evaluated outcomes. LABA/LAMA FDCs were safe; however, more data should be collected in a real-world setting to confirm their safety.

The discovery and development of aclidinium bromide for the treatment of chronic obstructive pulmonary disease

INTRODUCTION

Bronchodilators, including long-acting muscarinic receptor antagonists (LAMAs), are a mainstay of the pharmacological treatment of chronic obstructive pulmonary disease (COPD). LAMAs act as bronchodilators principally by antagonizing airway smooth muscle cells M₃ muscarinic receptors. Aclidinium bromide is a twice-daily LAMA which was developed to improve on the efficacy and/or safety of previous LAMAs. Area covered: Herein, the authors present the pharmacotherapeutic role of aclidinium in COPD and point out unmet need in this research area. The following aspects are covered: a) the discovery and medicinal chemistry of aclidinium bromide; b) an overview of the market; c) its mechanism of action; d) its pharmacokinetic/pharmacodynamic profile derived from pre-clinical studies; e) the clinical studies which led to its licensing; f) the evidence from meta-analyses; g) the aclidinium/formoterol fixed dose combination for COPD and h) priorities in this area of research. Expert opinion: Aclidinium bromide has the pharmacological properties, safety and efficacy profile and inhaler characteristics which makes it a valuable therapeutic option for pharmacological management of patients with COPD. Due to its rapid biotransformation into inactive metabolites, aclidinium is potentially one of the safest LAMAs. Further head-to-head randomized clinical trials are required to define efficacy and safety of aclidinium when compared to once-daily LAMAs. The clinical relevance of airway anti-remodeling effects of aclidinium has to be defined.

Comparison of the in vitro pharmacological profiles of long-acting muscarinic antagonists in human bronchus

BACKGROUND AND PURPOSE

Long-acting muscarinic antagonists (LAMAs) have been recommended for the treatment of chronic obstructive pulmonary disease and (more recently) asthma. However, the in vitro pharmacological profiles of the four LAMAs currently marketed (tiotropium, umeclidinium, aclidinium and glycopyrronium) have not yet been compared (relative to ipratropium) by using the same experimental approach.

EXPERIMENTAL APPROACH

With a total of 560 human bronchial rings, we investigated the antagonists' potency, onset and duration of action for inhibition of the contractile response evoked by electrical field stimulation. We also evaluated the antagonists' potency for inhibiting cumulative concentration-contraction curves for acetylcholine and carbachol.

KEY RESULTS

The onset and duration of action were concentration-dependent. At submaximal, equipotent concentrations, the antagonists' onsets of action were within the same order of magnitude. However, the durations of action differed markedly. After washout, ipratropium's inhibitory activity decreased rapidly (within 30-90 min) but those of tiotropium and umeclidinium remained stable (at above 70%) for at least 9 h. Aclidinium and glycopyrronium displayed less stable inhibitory effects, with a progressive loss of inhibition at submaximal concentrations. In contrast to ipratropium, all the LAMAs behaved as insurmountable antagonists by decreasing the maximum responses to both acetylcholine and carbachol.

CONCLUSIONS AND IMPLICATIONS

The observed differences in the LAMAs' in vitro pharmacological profiles in the human bronchus provide a compelling pharmacological rationale for the differences in the drugs' respective recommended daily doses and frequencies of administration.

Umeclidinium in chronic obstructive pulmonary disease: latest evidence and place in therapy

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity, mortality and health care expenditure throughout the world. COPD guidelines recommend the use of long-acting muscarinic antagonist (LAMA) either alone or in combination with a long-acting β2 agonist (LABA). For over 10 years, tiotropium was the only LAMA that was used in the management of COPD. Over the past few years, various new drugs have been identified that act on the muscarinic receptors and β2 receptors. Umeclidinium (Umec) is a new LAMA currently approved for use in patients with COPD either as monotherapy or in combination with vilanterol (Vil). Both Umec alone and in combination with Vil delivered through a multi-dose dry powder Ellipta™ device have shown improvement in lung function, health-related quality of life and exacerbation frequency in patients with COPD. This review provides an overview of the pharmacology, pharmacodynamics and pharmacokinetics of Umec, and evaluates the clinical efficacy and safety studies in patients with COPD.

Ozone-Induced Hypertussive Responses in Rabbits and Guinea Pigs

Cough remains a major unmet clinical need, and preclinical animal models are not predictive for new antitussive agents. We have investigated the mechanisms and pharmacological sensitivity of ozone-induced hypertussive responses in rabbits and guinea pigs. Ozone induced a significant increase in cough frequency and a decrease in time to first cough to inhaled citric acid in both conscious guinea pigs and rabbits. This response was inhibited by the established antitussive drugs codeine and levodropropizine. In contrast to the guinea pig, hypertussive responses in the rabbit were not inhibited by bronchodilator drugs (β2 agonists or muscarinic receptor antagonists), suggesting that the observed hypertussive state was not secondary to bronchoconstriction in this species. The ozone-induced hypertussive response in the rabbit was inhibited by chronic pretreatment with capsaicin, suggestive of a sensitization of airway sensory nerve fibers. However, we could find no evidence for a role of TRPA1 in this response, suggesting that ozone was not sensitizing airway sensory nerves via activation of this receptor. Whereas the ozone-induced hypertussive response was accompanied by a significant influx of neutrophils into the airway, the hypertussive response was not inhibited by the anti-inflammatory phosphodiesterase 4 inhibitor roflumilast at a dose that clearly exhibited anti-inflammatory activity. In summary, our results suggest that ozone-induced hypertussive responses to citric acid may provide a useful model for the investigation of novel drugs for the treatment of cough, but some important differences were noted between the two species with respect to sensitivity to bronchodilator drugs.

Long-acting muscarinic antagonists

Chronic obstructive pulmonary disease (COPD) is a major cause of death and disability worldwide. Inhaled bronchodilators are the mainstay of COPD pharmacological treatment. Long-acting muscarinic antagonists (LAMAs) are a major class of inhaled bronchodilators. Some LAMA/device systems with different characteristics and dosing schedules are currently approved for maintenance therapy of COPD and a range of other products are being developed. They improve lung function and patient-reported outcomes and reduce acute bronchial exacerbations with good safety. LAMAs are used either alone or associated with long-acting β₂-agonists, eventually in fixed dose combinations. Long-acting β₂-agonist/LAMA combinations assure additional benefits over the individual components alone. The reader will obtain a view of the safety and efficacy of the different LAMA/device systems in COPD patients.

Impact of drug administration route on drug delivery and distribution into the lung: an imaging mass spectrometry approach

During the last decade, significant technological improvements in mass spectrometry have had a great impact on drug discovery. The development of matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) has set a new frontier for the study of the distribution of endogenous and exogenous molecules present within a tissue. MALDI-IMS is a surface sampling technique that allows not only the detection of multiple analytes but also gives the spatial distribution of those analytes. Active compounds for pulmonary disease need an optimal and well-studied delivery into the lungs, in order to assure distribution with greater penetration into the peripheral or the alveolar region of the lung to maximize the therapeutic effects. IMS is very useful in the field of drug discovery, showing drug delivery and distribution in the body and organs. In this study, we present a comparison between two different ways of carrying out pulmonary drug administration: inhalation of a nebulized aerosol of aqueous drug solutions and intratracheal administration, which is much simpler, not expensive and commonly used during in vivo screening. Tiotropium bromide is a long-acting anticholinergic medicine used for maintenance treatment of chronic obstructive pulmonary disease. In the present work, tiotropium was administered by nebulization and by intratracheal instillation to guinea pigs at doses able to induce significant anti-bronchoconstrictive activity. Lung samples were dissected, frozen, cryosectioned and coated with matrix (α-hydroxy-cinnamic acid). IMS analyses were performed using a MALDI-LTQ-Orbitrap XL. Using this technique we were able to compare different distributions of the drug depending on the method of administration.

Long-acting muscarinic receptor antagonists for the treatment of respiratory disease

The use of muscarinic receptor antagonists in the treatment of chronic obstructive pulmonary disease (COPD) is well established. More recently, the potential for long-acting muscarinic receptor antagonists (LAMAs) in the treatment of asthma has also been investigated. While LAMAs offer advantages over short-acting muscarinic receptor antagonists, in terms of a reduced dosing frequency, there remains a need for therapies that improve symptom control throughout both the day and night, provide better management of exacerbations and deliver improved health-related quality of life. Furthermore, the potential for unwanted anticholinergic side effects, particularly cardiovascular effects, remains a concern for this class of compounds. Novel LAMAs in clinical development for the treatment of respiratory disease include: aclidinium bromide, NVA237 (glycopyrronium bromide), GP-MDI, EP-101, CHF-5259, umeclidinium bromide, CHF-5407, TD-4208, AZD8683 and V-0162. These compounds offer potential advantages in terms of onset of action, symptom control and safety. In addition, a number of LAMAs are also being developed as combination treatments with long-acting β2-agonists (LABAs) or inhaled glucocorticosteroids, potentially important treatment options for patients who require combination therapy to achieve an optimal therapeutic response as their disease progresses. More recently, compounds such as GSK961081 and THRX-198321 have been identified that combine LAMA and LABA activity in the same molecule, and have the potential to offer the benefits of combination therapy in a single compound. Here, we review novel LAMAs and dual action compounds in clinical development, with a particular focus on how they may address the current unmet clinical needs in the treatment of respiratory disease, particularly COPD.

Muscarinic receptors and their antagonists in COPD: anti-inflammatory and antiremodeling effects

Muscarinic receptors are expressed by most cell types and mediate cellular signaling of their natural ligand acetylcholine. Thereby, they control numerous central and peripheral physiological organ responses to neuronal activity. In the human lung, muscarinic receptors are predominantly expressed by smooth muscle cells, epithelial cells, and fibroblasts. Antimuscarinic agents are used for the treatment of chronic obstructive pulmonary disease and to a lesser extent for asthma. They are primarily used as bronchodilators, but it is now accepted that they are also associated with anti-inflammatory, antiproliferative, and antiremodeling effects. Remodeling of the small airways is a major pathology in COPD and impairs lung function through changes of the extracellular matrix. Glycosaminoglycans, particularly hyaluronic acid, and matrix metalloproteases are among extracellular matrix molecules that have been associated with tissue inflammation and remodeling in lung diseases, including chronic obstructive pulmonary disease and asthma. Since muscarinic receptors have been shown to influence the homeostasis of glycosaminoglycans and matrix metalloproteases, these molecules may be proved valuable endpoint targets in clinical studies for the pharmacological exploitation of the anti-inflammatory and antiremodeling effects of muscarinic inhibitors in the treatment of chronic obstructive pulmonary disease and asthma.

Pharmacology and therapeutics of bronchodilators

Bronchodilators are central in the treatment of of airways disorders. They are the mainstay of the current management of chronic obstructive pulmonary disease (COPD) and are critical in the symptomatic management of asthma, although controversies around the use of these drugs remain. Bronchodilators work through their direct relaxation effect on airway smooth muscle cells. at present, three major classes of bronchodilators, β(2)-adrenoceptor (AR) agonists, muscarinic receptor antagonists, and xanthines are available and can be used individually or in combination. The use of the inhaled route is currently preferred to minimize systemic effects. Fast- and short-acting agents are best used for rescue of symptoms, whereas long-acting agents are best used for maintenance therapy. It has proven difficult to discover novel classes of bronchodilator drugs, although potential new targets are emerging. Consequently, the logical approach has been to improve the existing bronchodilators, although several novel broncholytic classes are under development. An important step in simplifying asthma and COPD management and improving adherence with prescribed therapy is to reduce the dose frequency to the minimum necessary to maintain disease control. Therefore, the incorporation of once-daily dose administration is an important strategy to improve adherence. Several once-daily β(2)-AR agonists or ultra-long-acting β(2)-AR-agonists (LABAs), such as indacaterol, olodaterol, and vilanterol, are already in the market or under development for the treatment of COPD and asthma, but current recommendations suggest the use of LABAs only in combination with an inhaled corticosteroid. In addition, some new potentially long-acting antimuscarinic agents, such as glycopyrronium bromide (NVA-237), aclidinium bromide, and umeclidinium bromide (GSK573719), are under development, as well as combinations of several classes of long-acting bronchodilator drugs, in an attempt to simplify treatment regimens as much as possible. This review will describe the pharmacology and therapeutics of old, new, and emerging classes of bronchodilator.

New bronchodilators

Bronchodilators are central in the treatment of airway diseases including chronic obstructive pulmonary disease (COPD). Bronchodilators in COPD aim to improve lung function, reduce symptoms, prevent exacerbation, and enhance quality of life. The majority of programs in development for novel bronchodilators are focused on enhancing existing targets to once daily dosing and improving their safety profiles. However, just as important are other programs that aim to discover novel pharmacologic targets such as EP4 receptor agonists, bitter taste receptors, and selective PDE inhibitors. Furthermore, existing and novel bronchodilators have become vital components of multiple combination therapies targeting COPD. This review will discuss emerging bronchodilators highlighting preclinical data and available clinical trials.

Inhaled long-acting muscarinic antagonists in chronic obstructive pulmonary disease

In 2002, the first long-acting muscarinic antagonist, tiotropium bromide (Spiriva®), was launched as a once-daily bronchodilating agent for the treatment of chronic obstructive pulmonary disease. Since then, there has been intense discovery research activity in this area and, currently, several alternative inhaled long-acting muscarinic antagonists are reported under clinical development by several pharmaceutical companies. This article will review the current inhaled development candidates, as well as literature reports of the most significant preclinical chemical series specifically designed as inhaled antimuscarinic agents.