Effects of the inhalation of the m3 receptor antagonist bencycloquidium bromide in a mouse cigarette smoke-induced airway inflammation model

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.

The Impact of Muscarinic Receptor Antagonists on Airway Inflammation: A Systematic Review

Long-acting muscarinic receptor antagonists (LAMAs) are the cornerstone for the treatment of chronic obstructive pulmonary disease (COPD); furthermore, tiotropium is approved as add-on therapy in severe asthmatic patients. Accumulating evidence suggests that LAMAs may modulate airway contractility and airway hyperresponsiveness not only by blocking muscarinic acetylcholine receptors (mAchRs) expressed on airway smooth muscle but also via anti-inflammatory mechanisms by blocking mAchRs expressed on inflammatory cells, submucosal glands, and epithelial cells. The aim of this systematic review, performed according to the PRISMA-P guidelines, was to provide a synthesis of the literature on the anti-inflammatory impact of muscarinic receptor antagonists in the airways. Most of the current evidence originates from studies on tiotropium, that demonstrated a reduction in synthesis and release of cytokines and chemokines, as well as the number of total and differential inflammatory cells, induced by different pro-inflammatory stimuli. Conversely, few data are currently available for aclidinium and glycopyrronium, whereas no studies on the potential anti-inflammatory effect of umeclidinium have been reported. Overall, a large body of evidence supports the beneficial impact of tiotropium against airway inflammation. Further well-designed randomized controlled trials are needed to better elucidate the anti-inflammatory mechanisms leading to the protective effect of LAMAs against exacerbations via identifying suitable biomarkers.

Safety, Tolerability and Pharmacokinetics of Bencycloquidium Bromide, a Novel Inhaled Anticholinergic Bronchodilator, in Healthy Subjects: Results from Phase I Studies

BACKGROUND

Bencycloquidium bromide (BCQB) is a novel inhaled anticholinergic bronchodilator with high selectivity for muscarinic M3 receptor. BCQB's potential utility of for therapy in Chronic obstructive pulmonary disease (COPD) has been indicated in pre-clinical studies.

PURPOSE

To investigate the initial safety, tolerability and pharmacokinetics of BCQB delivered via pressurised Metered Dose Inhaler (pMDI) in healthy subjects.

METHODS

This study consisted of single-ascending-dose (SAD), multiple-ascending-dose (MAD) tolerability study periods, and single- plus multiple-dose pharmacokinetic study periods. Randomized, double-blind, placebo-controlled, dose-escalating tolerability and pharmacokinetic studies were conducted. Seventy-two healthy subjects were assigned 3:1 (BCQB: placebo) to 7 single-dose cohorts (125, 250, 500, 750, 1125, 1500 and 2000 μg) and 2 multiple-dose cohorts (1500 μg/d and 2000 μg/d). In the pharmacokinetic periods, 12 subjects were allocated three-way crossover to receive single dose of 250, 750 or 2000 μg BCQB, respectively. Subsequently, the same 12 subjects received multiple dose of 750 μg/d and 1000 μg/d for 7 days. Pharmacokinetic, safety and tolerability assessments were performed.

RESULTS

BCQB administered by inhalation was well tolerated, especially with favorable cardiovascular safety profile. BCQB was rapidly absorbed into plasma after inhalation through pMDI, with peak concentrations achieved within 5 to 10 minutes. Repeated inhalation caused certain degree of accumulation with the accumulation ratio R_Cmax 2.50, R_AUC 3.49 for 3 times-a-day and R_Cmax 2.23, R_AUC 3.44 for 4 times-a-day, respectively. Twice-a-day or even once-a-day dosage could be suggested in phase II study. Sex didn't affect the pharmacokinetics of BCQB and dose adjustments based on sex is not anticipated in clinical use. Approximately 4% of the BCQB dose excreted unchanged in urine and liver metabolism is the main biotransformation route of BCQB in human.

CONCLUSIONS

The results of our study provided the initial safety, tolerability and pharmacokinetic profiles of BCQB inhalation, and could enable further clinical development in COPD patients.

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.