Dual-pharmacology muscarinic antagonist and β₂ agonist molecules for the treatment of chronic obstructive pulmonary disease

Advances in adrenergic receptors for the treatment of chronic obstructive pulmonary disease: 2023 update

INTRODUCTION

Strong scientific evidence and large experience support the use of β2-agonists for the symptomatic alleviation of COPD. Therefore, there is considerable effort in discovering highly potent and selective β2-agonists.

AREAS COVERED

Recent research on novel β2-agonists for the treatment of COPD. A detailed literature search was performed in two major databases (PubMed/MEDLINE and Scopus) up to September 2023."

EXPERT OPINION

Compounds that preferentially activate a Gs- or β-arrestin-mediated signaling pathway via β- adrenoceptors (ARs) are more innovative. Pepducins, which target the intracellular region of β2-AR to modulate receptor signaling output, have the most interesting profile from a pharmacological point of view. They stabilize the conformation of the β2-AR and influence its signaling by interacting with the intracellular receptor-G protein interface. New bifunctional drugs called muscarinic antagonist-β2 agonist (MABA), which have both muscarinic receptor (mAChR) antagonism and β2-agonist activity in the same molecule, are a new opportunity. However, all tested compounds have been shown to act predominantly as mAChR antagonists or β2-agonists. An intriguing idea is to utilize allosteric modulators that bind to β2-ARs at sites different than those bound by orthosteric ligands to augment or reduce the signaling transduced by the orthosteric ligand.

Identification of core therapeutic targets for Monkeypox virus and repurposing potential of drugs against them: An in silico approach

Monkeypox virus (mpox virus) outbreak has rapidly spread to 82 non-endemic countries. Although it primarily causes skin lesions, secondary complications and high mortality (1-10%) in vulnerable populations have made it an emerging threat. Since there is no specific vaccine/antiviral, it is desirable to repurpose existing drugs against mpox virus. With little knowledge about the lifecycle of mpox virus, identifying potential inhibitors is a challenge. Nevertheless, the available genomes of mpox virus in public databases represent a goldmine of untapped possibilities to identify druggable targets for the structure-based identification of inhibitors. Leveraging this resource, we combined genomics and subtractive proteomics to identify highly druggable core proteins of mpox virus. This was followed by virtual screening to identify inhibitors with affinities for multiple targets. 125 publicly available genomes of mpox virus were mined to identify 69 highly conserved proteins. These proteins were then curated manually. These curated proteins were funnelled through a subtractive proteomics pipeline to identify 4 highly druggable, non-host homologous targets namely; A20R, I7L, Top1B and VETFS. High-throughput virtual screening of 5893 highly curated approved/investigational drugs led to the identification of common as well as unique potential inhibitors with high binding affinities. The common inhibitors, i.e., batefenterol, burixafor and eluxadoline were further validated by molecular dynamics simulation to identify their best potential binding modes. The affinity of these inhibitors suggests their repurposing potential. This work can encourage further experimental validation for possible therapeutic management of mpox.

Discovery of Clinical Candidate CHF-6366: A Novel Super-soft Dual Pharmacology Muscarinic Antagonist and β2 Agonist (MABA) for the Inhaled Treatment of Respiratory Diseases

The development of molecules embedding two distinct pharmacophores acting as muscarinic antagonists and β₂ agonists (MABAs) promises to be an excellent opportunity to reduce formulation issues and boost efficacy through cross-talk and allosteric interactions. Herein, we report the results of our drug discovery campaign aimed at improving the therapeutic index of a previous MABA series by exploiting the super soft-drug concept. The incorporation of a metabolic liability, stable at the site of administration but undergoing rapid systemic metabolism, to generate poorly active and quickly eliminated fragments was pursued. Our SAR studies yielded MABA 29, which demonstrated a balanced in vivo profile up to 24 h, high instability in plasma and the liver, as well as sustained exposure in the lung. In vitro safety and non-GLP toxicity studies supported the nomination of 29 (CHF-6366) as a clinical candidate, attesting to the successful development of a novel super-soft MABA compound.

The future of inhalation therapy in chronic obstructive pulmonary disease

The inhaled route is critical for the administration of drugs to treat patients suffering from COPD, but there is still an unmet need for new and innovative inhalers to address some limitations of existing products that do not make them suitable for many COPD patients. The treatment of COPD, currently limited to the use of bronchodilators, corticosteroids, and antibiotics, requires a significant expansion of the therapeutic armamentarium that is closely linked to the widening of knowledge on the pathogenesis and evolution of COPD. The great interest in the development of new drugs that may be able to interfere in the natural history of the disease is leading to the synthesis of numerous new molecules, of which however only a few have entered the stages of clinical development. On the other hand, further improvement of inhaled drug delivery could be an interesting possibility because it targets the organ of interest directly, requires significantly less drug to exert the pharmacological effect and, by lowering the amount of drug needed, reduces the cost of therapy. Unfortunately, however, the development of new inhaled drugs for use in COPD is currently too slow.

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Inhalation therapy is central when treating patients with COPD.

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There has been and still there is a substantial evolution in inhaler devices.

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New targets possibly useful for the development of new drugs have been identified.

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Only very few of new drugs are being evaluated for inhaled administration.

Navafenterol (AZD8871) in patients with mild asthma: a randomised placebo-controlled phase I study evaluating the safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending doses of this novel inhaled long-acting dual-pharmacology bronchodilator

Background

Navafenterol (AZD8871) is an inhaled long-acting dual-pharmacology muscarinic antagonist/β₂-adrenoceptor agonist (MABA) in development for the treatment of obstructive airways diseases. The safety, tolerability, pharmacodynamics, and pharmacokinetics of navafenterol were investigated in patients with mild asthma.

Methods

This was a randomised, single-blind, placebo-controlled, single-ascending-dose study. Patients were randomly assigned to one of two cohorts which evaluated escalating doses of navafenterol (50–2100 μg) in an alternating manner over three treatment periods. The primary pharmacodynamic endpoint was the change from pre-dose baseline in trough forced expiratory volume in 1 s (FEV₁) for each treatment period.

Results

Sixteen patients were randomised; 15 completed treatment. Data from all 16 patients were analysed. The maximum tolerated dose was not identified, and all doses of navafenterol were well tolerated. The most frequently reported treatment-emergent adverse events (TEAEs) were headache (n = 10, 62.5%) and nasopharyngitis (n = 7, 43.8%). No TEAEs were serious, fatal, or led to discontinuation, and no dose dependency was identified. Navafenterol demonstrated a dose-ordered bronchodilatory response with a rapid onset of action (within 5 min post-dose). Doses ≥200 μg resulted in improvements in trough FEV₁ (mean change from baseline range 0.186–0.463 L) with sustained bronchodilation for 24–36 h. Plasma concentrations increased in a dose-proportional manner, peaking ~ 1 h post-dose, with a derived terminal elimination half-life of 15.96–23.10 h.

Conclusions

In this study navafenterol was generally well tolerated with a rapid onset of action which was sustained over 36 h.

Trial registration

ClinicalTrials.gov; No.: NCT02573155

Navafenterol (AZD8871) in patients with COPD: a randomized, double-blind, phase I study evaluating safety and pharmacodynamics of single doses of this novel, inhaled, long-acting, dual-pharmacology bronchodilator

BACKGROUND

Navafenterol (AZD8871) is a dual-pharmacology muscarinic antagonist β2-agonist (MABA) molecule in development for the treatment of chronic obstructive pulmonary disease (COPD). The pharmacodynamics, safety and tolerability of single doses of navafenterol were investigated in patients with moderate to severe COPD.

METHODS

This was a randomized, five-way complete cross-over study. Patients received single doses of navafenterol 400 μg, navafenterol 1800 μg and placebo (all double-blind) and indacaterol 150 μg and tiotropium 18 μg (both open-label active comparators). The primary pharmacodynamic endpoint was change from baseline in trough forced expiratory volume in 1 s (FEV1) on day 2. Safety and tolerability were monitored throughout.

RESULTS

Thirty-eight patients were randomized and 28 (73.7%) completed the study. Navafenterol 400 μg and 1800 μg demonstrated statistically significant improvements vs placebo in change from baseline in trough FEV1 (least squares mean [95% confidence interval]: 0.111 [0.059, 0.163] L and 0.210 [0.156, 0.264] L, respectively, both P < .0001). The changes were significantly greater with navafenterol 1800 μg vs the active comparators (least squares mean treatment difference: 0.065-0.069 L, both P < .05). The frequency of treatment-emergent adverse events was similar for placebo and the active comparators (range 34.4-37.5%), slightly higher for navafenterol 400 μg (52.9%), and lowest for navafenterol 1800 μg (22.6%).

CONCLUSIONS

Both doses of navafenterol demonstrated sustained bronchodilation over 24 h. Navafenterol was well tolerated and no safety concerns were raised.

TRIAL REGISTRY

ClinicalTrials.gov ; No.: NCT02573155 ; URL: www.clinicaltrials.gov . Registered 9th October, 2015.

Navafenterol (AZD8871) in healthy volunteers: safety, tolerability and pharmacokinetics of multiple ascending doses of this novel inhaled, long-acting, dual-pharmacology bronchodilator, in two phase I, randomised, single-blind, placebo-controlled studies

BACKGROUND

Navafenterol (AZD8871) is a novel, long-acting, dual-pharmacology (muscarinic receptor antagonist and β2-adrenoceptor agonist) molecule in development for chronic obstructive pulmonary disease and asthma.

METHODS

These two phase I, randomised, single-blind, multiple-ascending-dose studies evaluated inhaled navafenterol and placebo (3:1 ratio) in healthy, male, non-Japanese (study A; NCT02814656) and Japanese (study B; NCT03159442) volunteers. In each study, volunteers were dosed in three cohorts, allowing gradual dose escalation from 300 μg to 600 μg to 900 μg. The primary objective was to investigate the safety and tolerability of navafenterol at steady state. Pharmacokinetics were also assessed.

RESULTS

Twenty-four volunteers completed each study (navafenterol, n = 6; placebo, n = 2 in each cohort). There were no deaths, serious adverse events (AEs) or treatment-emergent AEs (TEAEs) leading to discontinuation of navafenterol. The most frequent TEAEs were vessel puncture-site bruise (placebo, n = 2; navafenterol 900 μg; n = 3) in study A and diarrhoea (placebo, n = 1; navafenterol 300 μg, n = 2; navafenterol 900 μg, n = 3) in study B. No dose-response relationship was observed for TEAEs. There was a dose-dependent increase in mean heart rate on day 16 in both studies. The pharmacokinetics of navafenterol were similar between non-Japanese and Japanese volunteers.

CONCLUSIONS

Multiple ascending doses of navafenterol were well-tolerated and the safety and pharmacokinetics of navafenterol were similar in non-Japanese and Japanese volunteers. The findings support navafenterol clinical development.

TRIAL REGISTRATION

ClinicalTrials.gov ; Nos.: NCT02814656 and NCT03159442; URL: www.clinicaltrials.gov .

A randomized, controlled, repeat-dose study of batefenterol/fluticasone furoate compared with placebo in the treatment of COPD

Background

Batefenterol (BAT) is a bi-functional molecule with both muscarinic antagonist and β₂-adrenoceptor agonist pharmacology. This Phase II, randomized, placebo-controlled, double-blind study evaluated the safety and tolerability of BAT 300 μg with fluticasone furoate (FF) 100 μg administered via the ELLIPTA inhaler (BAT/FF 300/100).

Methods

Subjects with stable chronic obstructive pulmonary disease were randomized 2:1 to receive BAT/FF 300/100 or placebo once daily for 6 weeks. The primary endpoint was change from baseline in 0–4-h weighted mean (WM) heart rate (HR, measured by electrocardiogram [ECG]) on Day 42. Other endpoints included WM and maximum 0–4-h corrected QT interval (ECG on Days 1, 28, and 42), HR measured by Holter monitoring (Day 42), and standard safety assessments. Study protocol was approved by an Investigational Review Board.

Results

Sixty-two patients were randomized and received ≥1 dose of study medication (BAT/FF 300/100 n = 42; placebo n = 20). Mean age was 62.5 years (standard deviation [SD] 8.17). Study completion rates were 83% (BAT/FF 300/100) and 100% (placebo). Screening mean (SD) post-bronchodilator percentage-predicted forced expiratory volume in 1 s was 57.57 (11.42) in the BAT/FF 300/100 group and 55.68 (14.03) in the placebo group. BAT/FF 300/100 was non-inferior to placebo for the primary endpoint, treatment difference: − 2.2 beats per minute (bpm), 95% confidence interval [CI]: − 6.2, 1.7). There were no clinically relevant differences between treatment groups in WM or maximum 0–4-h corrected QT interval, or mean HR based on Holter monitoring on Day 42 (BAT/FF 300/100: 76.3 bpm [SD 11.38]; placebo: 84.8 bpm [SD 9.87]). Adverse events (AEs) occurred in 38% (BAT/FF 300/100) and 35% (placebo) of patients. AEs in ≥2 subjects with BAT/FF 300/100 were dysgeusia (10%), diarrhea (7%), nasopharyngitis (7%), and cough (5%). AEs leading to discontinuation occurred in two subjects who received BAT/FF 300/100: post-treatment severe pneumonia (serious AE) and non-serious AEs of moderate vomiting and severe gastroenteritis; both were not considered drug-related. No deaths occurred.

Conclusions

Six weeks of BAT/FF 300/100 treatment was non-inferior to placebo for change from baseline in HR, with no new clinically relevant general or cardiovascular safety signals.

Trial registration

Clinicaltrials.gov: NCT02573870 (submitted October 12, 2015).

Pharmacological Profile of AZD8871 (LAS191351), a Novel Inhaled Dual M3 Receptor Antagonist/β 2-Adrenoceptor Agonist Molecule with Long-Lasting Effects and Favorable Safety Profile

AZD8871 is a novel muscarinic antagonist and β ₂-adrenoceptor agonist in development for chronic obstructive pulmonary disease. This study describes the pharmacological profile of AZD8871 in in vitro and in vivo assays. AZD8871 is potent at the human M₃ receptor (pIC₅₀ in binding assays: 9.5) and shows kinetic selectivity for the M₃ (half-life: 4.97 hours) over the M₂ receptor (half-life: 0.46 hour). It is selective for the β ₂-adrenoceptor over the β ₁ and β ₃ subtypes (3- and 6-fold, respectively) and shows dual antimuscarinic and β ₂-adrenoceptor functional activity in isolated guinea pig tissue (pIC₅₀ in electrically stimulated trachea: 8.6; pEC₅₀ in spontaneous tone isolated trachea: 8.8, respectively), which are sustained over time. AZD8871 exhibits a higher muscarinic component than batefenterol in human bronchi, with a shift in potency under propranolol blockade of 2- and 6-fold, respectively, together with a persisting relaxation (5.3% recovery at 8 hours). Nebulized AZD8871 prevents acetylcholine-induced bronchoconstriction in both guinea pig and dog with minimal effects on salivation and heart rate at doses with bronchoprotective activity. Moreover, AZD8871 shows long-lasting effects in dog, with a bronchoprotective half-life longer than 24 hours. In conclusion, these studies demonstrate that AZD8871 is a dual-acting molecule with a high muscarinic component and a long residence time at the M₃ receptor; moreover, its preclinical profile in animal models suggests a once-daily dosing in humans and a favorable safety profile. Thus, AZD8871 has the potential to be a next generation of inhaled bronchodilators in respiratory diseases.

Randomized dose-finding study of batefenterol via dry powder inhaler in patients with COPD

Background

Batefenterol is a novel bifunctional muscarinic antagonist β₂-agonist in development for COPD. The primary objective of this randomized, double-blind, placebo-controlled, active comparator, Phase IIb study was to model the dose–response of batefenterol and select a dose for Phase III development.

Patients and methods

Patients aged ≥40 years with COPD and FEV₁ ≥30% and ≤70% predicted normal were randomized equally to batefenterol 37.5, 75, 150, 300, or 600 µg, placebo, or umeclidinium/vilanterol (UMEC/VI) 62.5/25 µg once daily. The primary and secondary endpoints were weighted-mean FEV₁ over 0–6 hours post-dose and trough FEV₁, analyzed by Bayesian and maximum likelihood estimation E_max of dose–response modeling, respectively, on day 42.

Results

In the intent-to-treat population (N=323), all batefenterol doses demonstrated statistically and clinically significant improvements from baseline vs placebo in the primary and secondary endpoints (191.1–292.8 and 182.2–244.8 mL, respectively), with a relatively flat dose–response. In the subgroup reversible to salbutamol, there were greater differences between batefenterol doses. Lung function improvements with batefenterol ≥150 µg were comparable with those with UMEC/VI. Batefenterol was well tolerated and no new safety signals were observed.

Conclusion

Batefenterol 300 µg may represent the optimal dose for Phase III studies.

Pharmacokinetics, Excretion, and Mass Balance of [14 C]-Batefenterol Following a Single Microtracer Intravenous Dose (Concomitant to an Inhaled Dose) or Oral Dose of Batefenterol in Healthy Men

Inhaled batefenterol is an investigational bifunctional molecule for the treatment of chronic obstructive pulmonary disease. The excretion balance and pharmacokinetics of batefenterol using [¹⁴C]‐radiolabeled drug administered orally and as intravenous (IV) infusion were assessed. In this 2‐period, open‐label study, 6 healthy male subjects received a single IV microtracer 1‐hour infusion of 4 μg [¹⁴C]‐batefenterol concomitant with inhaled nonradiolabeled batefenterol (1200 μg) followed by oral [¹⁴C]‐batefenterol (200 μg) in period 2 after a 14‐day washout. The primary end points included: the area under the concentration‐time curve from time zero to last time of quantifiable concentration (AUC_0‐t); maximum observed concentration (C_max); and time of occurrence of maximum observed concentration. Following IV administration, the geometric mean AUC_0‐t of [¹⁴C]‐batefenterol was 121.9 pgEq • h/mL; maximum observed concentration and time of occurrence of maximum observed concentration were 92.7 pgEq/mL and 0.8 hours, respectively; absolute oral bioavailability was 0.012%. The mean AUC_0‐t ratio indicated that [¹⁴C]‐batefenterol accounted for 85% of total circulating radioactivity in the plasma initially and declined rapidly following IV administration, but only ∼0.2% of total circulating radioactivity following oral administration. Cumulative mean recovery of total radioactive [¹⁴C]‐batefenterol in urine and feces was 6.31% and 77.6%, respectively. Overall, batefenterol exhibited low systemic bioavailability after inhaled and oral administration, and high fecal excretion and low urinary excretion following IV and oral administration.

Open-Label, Crossover Study to Determine the Pharmacokinetics of Fluticasone Furoate and Batefenterol When Administered Alone, in Combination, or Concurrently

The study aim was to investigate the pharmacokinetics of single high doses and repeated therapeutic doses of fluticasone furoate (FF) and batefenterol (BAT; a bifunctional muscarinic antagonist and β₂ -agonist) administered in combination (BAT/FF) or as monotherapy. In this open-label, 6-period, crossover study of 48 subjects, the treatment sequences were (1) single high-dose BAT/FF 900/300 μg followed by repeated therapeutic doses of BAT/FF 300/100 μg (once daily for 7 days); (2) single high-dose BAT 900 μg administered concurrently with FF 300 μg; (3) single high-dose BAT 900 μg followed by repeated therapeutic-dose BAT 300 μg; (4) single high-dose FF 300 μg followed by repeated therapeutic-dose FF 100 μg; (5) single high-dose FF 300 μg (magnesium stearate); and (6) single high-dose FF/vilanterol 300/75 μg. Plasma FF area under the plasma drug concentration-time curve (AUC) was reduced after single high-dose BAT/FF versus FF alone (ratio of geometric least squares means: 0.79; 90% confidence interval: 0.75-0.83). After repeat dosing, FF AUC at the lower therapeutic dosage was similar for BAT/FF and FF (primary endpoint; AUC geometric least squares means: 1.03). Adverse events were minor, the most common being cough. These data support the feasibility of developing BAT/inhaled corticosteroid triple therapy in a single inhaler.

Bifunctional Drugs for the Treatment of Respiratory Diseases

Over the last decade, there has been a steady increase in the use of fixed dose combinations for the treatment of a range of diseases, including cancer, AIDS, tuberculosis and other infectious diseases. It is now evident that patients with asthma or chronic obstructive pulmonary disease (COPD) can also benefit from the use of fixed dose combinations, including combinations of a long-acting β₂-agonist (LABA) and an inhaled corticosteroid (ICS), and combinations of LABAs and long-acting muscarinic receptor antagonists (LAMAs). There are now also "triple inhaler" fixed dose combinations (containing a LABA, LAMA and ICS) under development and already being made available in clinical practice, with the first such triple combination having been approved in India. The use of combinations containing drugs with complementary pharmacological actions in the treatment of patients with asthma or COPD has led to the discovery and development of drugs having two different primary pharmacological actions in the same molecule that we have called "bifunctional drugs". In this review we have discussed the state of the art of bifunctional drugs that can be categorized as bifunctional bronchodilators, bifunctional bronchodilator/anti-inflammatory drugs, bifunctional anti-inflammatory drugs and bifunctional mucolytic and anti-inflammatory drugs.

Safety of inhaled long-acting anti-muscarinic agents in COPD

Evidence-based guidelines recommend inhaled long-acting anti-muscarinic agents (LAMAs) as first-line maintenance therapy for symptomatic patients with COPD. Several LAMAs are now available for use either as monotherapy or in combination with other COPD medications, including long-acting β₂-agonists (LABAs) or inhaled corticosteroids (ICS). The efficacy and long-term safety of these medications have been evaluated in multiple clinical trials and real-life studies. This review evaluates the evidence available on the safety of existing LAMAs alone or in combination with LABAs and ICS in patients with COPD.

Investigational beta-2 adrenergic agonists for the treatment of chronic obstructive pulmonary disease

INTRODUCTION

Long-acting bronchodilators are pivotal in the therapeutic management of COPD patients with moderate-to-severe airflow obstruction. New ultra-long-acting β2-agnoists (ultra-LABAs) have been developed, some of which have been licensed for use as monotherapy and/or in combination with other bronchodilators or inhaled corticosteroids, for use in COPD patients with persistent symptoms and worsening airflow limitation. These new agents are faster in onset and have a prolonged duration of action, with a similar safety profile to the traditional twice-daily bronchodilators which may have an impact on patient concordance. Areas covered: A number of these ultra-LABAs are still under development and bi-functional hybrid molecules containing regions functioning as β2-agonists, and as muscarinic agonists (MABAs) has been developed. This review summarizes these (excluding the licensed ultra-LABAs) with attention on phase II studies data available to-date on their pharmacological profiles, clinical efficacy and safety, and future perspectives. Expert opinion: Despite all the new agents' available, the challenges that persist include any differences in efficacy and safety between the various possible LAMA/LABA combinations, relative advantages of MABAs over fixed-dose LAMA/LABAs, and the impact of these new molecules in terms of long term safety, especially in certain populations in co-morbidities frequently associated with COPD.

Optimal treatment sequence in COPD: Can a consensus be found?

There is currently no consensus on the treatment sequence in chronic obstructive pulmonary disease (COPD), although it is recognized that early diagnosis is of paramount importance to start treatment in the early stages of the disease. Although it is fairly consensual that initial treatment should be with an inhaled short-acting beta agonist, a short-acting muscarinic antagonist, a long-acting beta-agonist or a long-acting muscarinic antagonist. As the disease progresses, several therapeutic options are available, and which to choose at each disease stage remains controversial. When and in which patients to use dual bronchodilation? When to use inhaled corticosteroids? And triple therapy? Are the existing non-inhaled therapies, such as mucolytic agents, antibiotics, phosphodiesterase-4 inhibitors, methylxanthines and immunostimulating agents, useful? If so, which patients would benefit? Should co-morbidities be taken into account when choosing COPD therapy for a patient? This paper reviews current guidelines and available evidence and proposes a therapeutic scheme for COPD patients. We also propose a treatment algorithm in the hope that it will help physicians to decide the best approach for their patients. The authors conclude that, at present, a full consensus on optimal treatment sequence in COPD cannot be found, mainly due to disease heterogeneity and lack of biomarkers to guide treatment. For the time being, and although some therapeutic approaches are consensual, treatment of COPD should be patient-oriented.

Positioning new pharmacotherapies for COPD

COPD imposes considerable worldwide burden in terms of morbidity and mortality. In recognition of this, there is now extensive focus on early diagnosis, secondary prevention, and optimizing medical management of the disease. While established guidelines recognize different grades of disease severity and offer a structured basis for disease management based on symptoms and risk, it is becoming increasingly evident that COPD is a condition characterized by many phenotypes and its control in a single patient may require clinicians to have access to a broader spectrum of pharmacotherapies. This review summarizes recent developments in COPD management and compares established pharmacotherapy with new and emerging pharmacotherapies including long-acting muscarinic antagonists, long-acting β-2 sympathomimetic agonists, and fixed-dose combinations of long-acting muscarinic antagonists and long-acting β-2 sympathomimetic agonists as well as inhaled cortiocosteroids, phosphodiesterase inhibitors, and targeted anti-inflammatory drugs. We also review the available oral medications and new agents with novel mechanisms of action in early stages of development. With several new pharmacological agents intended for the management of COPD, it is our goal to familiarize potential prescribers with evidence relating to the efficacy and safety of new medications and to suggest circumstances in which these therapies could be most useful.

Cyclic nucleotide-based therapeutics for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) defines a group of chronic inflammatory disorders of the airways that are characterised by a progressive and largely irreversible decline in expiratory airflow. Drugs used to treat COPD through actions mediated by cyclic AMP (cAMP) are restricted to long-acting and short-acting β2-adrenoceptor agonists and, in a subset of patients with chronic bronchitis, a phosphodiesterase 4 inhibitor, roflumilast. These agents relax airway smooth muscle and suppress inflammation. At the molecular level, these effects in the airways are mediated by two cAMP effectors, cAMP-dependent protein kinase and exchange proteins activated by cAMP. The pharmacology of newer agents, acting through these systems, is discussed here with an emphasis on their potential to interact and increase therapeutic effectiveness.

Dualsteric GPCR targeting and functional selectivity: the paradigmatic M(2) muscarinic acetylcholine receptor

Muscarinic acetylcholine receptors belong to Class Aseven transmembrane helical receptors and serve as important drug targets in the treatment of various diseases such as chronic obstructive pulmonary disease, overactive bladder, bronchial asthma and glaucoma. Despite intensive research the discovery of experimental ligands which activate or block specific muscarinic receptor subtypes has only been successful for the M1 and M4 subtypes but remains a challenging task at the other subtypes. In recent years, ligands have been introduced which bind simultaneously to the acetylcholine binding site, that is, the orthosteric site, and to an allosteric binding site. These so-called dualsteric ligands display M2 subtype preference due to the addressing of the allosteric binding site. As proven recently, dualsteric receptor activation goes along with a pronounced signaling bias which follows clear structure–bias-relationships. Dualsteric receptor targeting might represent a common strategy to generate functional selectivity.

Nonhuman targets in allergic lung conditions

Existing therapies for allergic asthma are far from perfect: the global prevalence of disease increases despite them and they are poorly effective in dealing with the exacerbations that account for hospitalization and asthma deaths. Commercially, there are pressures on these existing medicines too--a growing threat from generics and reluctance by payers to reimburse for increasingly marginal improvements in medicines with precedented mechanisms. Experience shows that attempts to devise selective small-molecule interventions directed at the myriad of downstream effector pathways has not been a fertile ground for the development of effective new medicines. An alternative strategy, exploiting breakthroughs in understanding the molecular basis of allergenicity and the key role of innate immune mechanisms in asthma, is to direct new approaches to the disease triggers themselves: allergens. This raises interesting possibilities for anti-Lipinski drug design (extracellular nonhuman targets, inhaled delivery) and creates unprecedented pharmacological opportunities in the therapeutic area.

Combination bronchodilator therapy in the management of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) represents a significant cause of global morbidity and mortality, with a substantial economic impact. Recent changes in the Global initiative for chronic Obstructive Lung Disease (GOLD) guidance refined the classification of patients for treatment using a combination of spirometry, assessment of symptoms, and/or frequency of exacerbations. The aim of treatment remains to reduce existing symptoms while decreasing the risk of future adverse health events. Long-acting bronchodilators are the mainstay of therapy due to their proven efficacy. GOLD guidelines recommend combining long-acting bronchodilators with differing mechanisms of action if the control of COPD is insufficient with monotherapy, and recent years have seen growing interest in the additional benefits that combination of long-acting muscarinic antagonists (LAMAs), typified by tiotropium, with long-acting β(2)-agonists (LABAs), such as formoterol and salmeterol. Most studies have examined free combinations of currently available LAMAs and LABAs, broadly showing a benefit in terms of lung function and other patient-reported outcomes, although evidence is limited at present. Several once- or twice-daily fixed-dose LAMA/LABA combinations are under development, most involving newly developed monotherapy components. This review outlines the existing data for LAMA/LABA combinations in the treatment of COPD, summarizes the ongoing trials, and considers the evidence required to inform the role of LAMA/LABA combinations in treatment of this disease.

The future of combining inhaled drugs for COPD

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality globally, and its prevalence is projected to continue to increase owing to trends in smoking. Treatment of COPD has evolved from the initial adaptations of drugs and treatment strategies successfully used in asthma into more specific pharmacological strategies following global guidelines. Bronchodilating anticholinergic and beta-2-stimulating agents and anti-inflammatory corticosteroid drugs delivered by inhalators are the mainstay of COPD treatment. Despite significant progress, current pharmacotherapies neither fully alleviate the airway obstruction in COPD, nor reverse the progressive nature of the disease. This review discusses inhalation therapies which have recently become clinically available or are being developed, with focus on combination therapies. There is accumulating evidence that the combination of two or all three drug classes, triple therapy, is superior to single drug therapy. Several fixed combinations of both currently available and novel molecules will be launched for clinical use within the next few years. Also, improved understanding of subgroups within the clinical spectrum of COPD, is likely to offer new potentials to improve COPD care.