Inhalation by design: novel ultra-long-acting β(2)-adrenoreceptor agonists for inhaled once-daily treatment of asthma and chronic obstructive pulmonary disease that utilize a sulfonamide agonist headgroup

Exploration of newly synthesized amantadine-thiourea conjugates for their DNA binding, anti-elastase, and anti-glioma potentials

Three newly synthesized amantadine thiourea conjugates namely MS-1 N-(((3 s,5 s,7 s)-adamantan-1-yl)carbamothioyl)benzamide, MS-2 N-(((3 s,5 s,7 s)-adamantan-1-yl)carbamothioyl)-4-methylbenzamide and MS-3 N-((3 s,5 s,7 s)-adamantan-1-ylcarbamothioyl)-4-chlorobenzamide were investigated for their structures, bindings (DNA/ elastase), and for their impact on healthy and cancerous cells. Theoretical (DFT/docking) and experimental {UV-visible (UV-), fluorescence (Flu-), and cyclic voltammetry (CV)} studies indicated binding interactions of each conjugate with DNA and elastase enzyme. Theoretically and experimentally calculated binding parameters for conjugate - DNA interaction revealed MS-3 - DNA to have most significant binding with comparatively greater values of binding parameters {(Kb/M-1: docking, 3.8 × 105; UV-, 5.95 × 103; Flu-,1.55 × 105; CV, 1.52 × 104), (∆G/ kJmol-1: docking, -32.09; UV-, -22.40; Flu-,-30.81; CV, -24.82)}. The docked structures, greater bindings site size values (n), and the trend in DNA viscosity changes in the presence of each conjugate concentration confirmed a mixed binding mode of interaction among them. Conjugate - elastase binding by docking agreed with the experimental anti-elastase findings. Cytotoxicity studies of each tested conjugate demonstrated greater cytotoxicity for cancerous (MG-U87) cells in comparison to control, while for the normal (HEK-293) cells the cytotoxicity was found comparatively low. Overall exploration suggested that MS-3 is the most effective candidate for DNA binding, anti-elastase, and for anti-glioma activities.

Discovery and Identification of Novel 5-Hydroxy-4H-benzo[1,4]oxazin-3-one Derivatives as Potent β2-Adrenoceptor Agonists through Structure-Based Design, Synthesis, and Biological Evaluation

Although β2-agonists are crucial for treatment of chronic respiratory diseases, optimizing β2-agonistic activity and selectivity remains essential for achieving favorable therapeutic outcomes. A structure-based molecular design workflow was employed to discover a novel class of β2 agonists featuring a 5-hydroxy-4H-benzo[1,4]oxazin-3-one scaffold, which potently stimulated β2 adrenoceptors (β2-ARs). Screening for the β2-agonistic activity and selectivity led to the identification of compound A19 (EC50 = 3.7 pM), which functioned as a partial β2-agonist in HEK-293 cells containing endogenous β2-ARs. Compound A19 exhibited significant relaxant effects, rapid onset time (Ot50 = 2.14 min), and long duration of action (>12 h) on isolated guinea pig tracheal strips, as well as advantageous pharmacokinetic characteristics in vivo, rendering A19 suitable for inhalation administration. Moreover, A19 suppressed the upregulation of inflammatory cytokines and leukocytes and improved lung function in a rat model of COPD, thereby indicating that A19 is a potential β2 agonist candidate for further study.

Application of an "inhalation by design" approach to the identification and in-vitro evaluation of novel purine based PI3Kδ inhibitors

PI3Kδ is a lipid kinase which plays a key role in airway inflammatory conditions. Accordingly, the inhibition of PI3Kδ can be considered a valuable strategy for the treatment of chronic respiratory diseases such as Asthma and Chronic obstructive pulmonary disease (COPD). In this work, we describe our efforts to identify new PI3Kδ inhibitors following an "inhalation by design" strategy. Starting from the identification of a purine scaffold, we carried out a preliminary SAR expansion which led to the identification of a new hit characterized by a high enzymatic potency and moderate PI3Kδ selectivity. A subsequent optimization led to novel purine based derivatives with favorable in vitro ADME profiles, which might represent promising starting points for future development of new inhaled drug candidates.

2-Phenethylamines in Medicinal Chemistry: A Review

A concise review covering updated presence and role of 2-phenethylamines in medicinal chemistry is presented. Open-chain, flexible alicyclic amine derivatives of this motif are enumerated in key therapeutic targets, listing medicinal chemistry hits and appealing screening compounds. Latest reports in discovering new bioactive 2-phenethylamines by research groups are covered too.

8-Hydroxyquinolin-2(1H)-one analogues as potential β2-agonists: Design, synthesis and activity study

β₂-Agonists that bind to plasmalemmal β₂-adrenoceptors causing cAMP accumulation are widely used as bronchodilators in chronic respiratory diseases. Here, we designed and synthesized a group of 8-hydroxyquinolin-2(1H)-one analogues and studied their β₂-agonistic activities with a cellular cAMP assay. Compounds B05 and C08 were identified as potent (EC₅₀ < 20 pM) and selective β₂-agonists among the compounds tested. They behaved as partial β₂-agonists in non-overexpressed HEK293 cells, and possessed rapid smooth muscle relaxant actions and long duration of action in isolated guinea pig tracheal strip preparations. In summary, B05 and C08 are β₂-agonists with potential applicability in chronic respiratory diseases.

Recent progress in the development of β2 adrenergic receptor agonists: a patent review (2015-2020)

INTRODUCTION

The β₂ adrenergic receptor (β₂AR) is a member of G protein-coupled receptors (GPCRs) that mediate the majority of cellular responses to external stimuli. The agonists can cause smooth muscle relaxation; therefore, many β₂AR agonists have been developed especially for the treatment of pulmonary disorders such as asthma and chronic obstructive pulmonary disease (COPD). Many new natural and synthetic compounds have been discovered and developed as novel β₂AR agonists over the past 5 years.

AREAS COVERED

This review offers an update for the development of β₂AR agonists in the patents published from 2015 to 2020, including new natural and synthetic compounds for the treatment of asthma and COPD. In particular, the latest patents about compounds possessing both muscarinic receptor antagonist and β₂ adrenergic receptor agonist activity are reviewed.

EXPERT OPINION

β₂AR agonists have been developed extensively for the treatment of asthma and COPD. In the past 5 years, novel agonists from both natural sources and synthetic methods were intensively developed. Compounds possessing both muscarinic receptor antagonist and β₂AR agonist activity represent a new trend in this area because they are possibly able to act together in a synergistic fashion, therefore, relieve the symptoms of patients through two distinct mechanisms.

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.

Structural isomers of saligenin-based β2-agonists: synthesis and insight into the reaction mechanism

Salmeterol and albuterol are well-known β2-adenoreceptor agonists widely used in the treatment of inflammatory respiratory diseases, such as bronchial asthma and chronic obstructive pulmonary disease. Here we report the preparation of structural isomers of salmeterol and albuterol, which can be obtained from the same starting material as the corresponding β2-agonists, depending on the synthetic approach employed. Using 1D and various 2D NMR measurements, we determined that the structure of prepared isomers holds the β-aryl-β-aminoethanol moiety, in contrast to the α-aryl-β-aminoethanol moiety found in salmeterol and albuterol. We investigated the reaction of β-halohydrin and amines responsible for the formation of β-aryl-β-amino alcohol - both experimentally and using computational methods. The structure of β-halohydrin with the methyl salicylate moiety imposes the course of the reaction. The solvent plays a relevant, yet ambiguous role in the direction of the reaction, while the strength of the base influences the reaction yield and isomer ratio in a more evident way. Using computational methods, we have shown that the most probable reaction intermediate responsible for the formation of the unexpected isomer is the corresponding para-quinone methide, which can be formed due to phenol present in the methyl salicylate moiety. After successful preparation of albuterol and salmeterol isomers, we tested their inhibition potency to human acetylcholinesterase (AChE) and usual and atypical butyrylcholinesterase (BChE). Kinetic studies revealed that both isomers are low-potency reversible inhibitors of human cholinesterases.

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Pulmonary delivery of a p38 α/β MAP kinase inhibitor: bioanalytical method validation and biodistribution in rat plasma and respiratory tissues

PF-03715455, an inhaled p38 α/β mitogen-activated protein (MAP) kinase inhibitor (MAPK), has being identified as an agent with potential therapeutic action on lung diseases such as COPD and severe asthma. However, little is known about this MAPKs local and systemic pharmacokinetics after pulmonary delivery. Consequently, the aim of the present work was to develop and validate a method of extraction and quantification of PF-03715455 in rat plasma and lung tissues and to determine the drug biodistribution in plasma and respiratory tissues after intratracheal administration of the drug solution in rats. The method was validated in rat plasma samples and resulted selective and linear in the concentration range of 0.08-100 ng/ml. Then a partial validation was carried out on samples obtained by the extraction and quantification of PF-03715455 from rat lung homogenate in order to ascertain method applicability on lung tissue samples. The intratracheal administration of drug in solution to rats evidenced a rapid elimination from the plasma, while on the contrary a prolonged residence time in lung tissue was evidenced. In conclusion, a linear, accurate, precise and reproducible method has been developed and validated according to FDA and EMA guidelines to quantify plasmatic and tissue-associated concentrations of PF-03715455 in order to investigate this compound in pharmacokinetics pre-clinical studies in rats. The administration of drug solution evidenced a prolonged permanence of the drug in the lungs that could be related to a slow absorption/poor permeability of the drug across airways epithelia.

Inhaled Janus Kinase (JAK) inhibitors for the treatment of asthma

Multiple asthma-relevant cytokines including IL-4, IL-5, IL-13, and TSLP depend upon JAKs for signaling. JAK inhibition may, therefore, offer a novel intervention strategy for patients with disease refractory to current standards of care. Multiple systemically delivered JAK inhibitors have been approved for human use or are under clinical evaluation in autoimmune diseases such as rheumatoid arthritis. However, the on-target side effect profiles of these agents are likely not tolerable for many asthmatic patients. Limiting JAK inhibition to the lung is expected to improve therapeutic index relative to systemic inhibition. Thus, inhaled JAK inhibitors with lung-restricted exposure are of high interest as potential treatments for asthma.

Discovery of Clinical Candidate (1R,4r)-4-((R)-2-((S)-6-Fluoro-5H-imidazo[5,1-a]isoindol-5-yl)-1-hydroxyethyl)cyclohexan-1-ol (Navoximod), a Potent and Selective Inhibitor of Indoleamine 2,3-Dioxygenase 1

A novel class of 5-substituted 5H-imidazo[5,1-a]isoindoles are described as potent inhibitors of indoleamine 2,3-dioxygenase 1 (IDO1). A structure-based drug design approach was used to elaborate the 5H-imidazo[5,1-a]isoindole core and to improve potency and pharmacological properties. Suitably placed hydrophobic and polar functional groups in the lead molecule allowed improvement of IDO1 inhibitory activity while minimizing off-target liabilities. Structure-activity relationship studies focused on optimizing IDO1 inhibition potency and a pharmacokinetic profile amenable to oral dosing while controlling CYP450 and hERG inhibitory properties.

Translation of Inhaled Drug Optimization Strategies into Clinical Pharmacokinetics and Pharmacodynamics Using GSK2292767A, a Novel Inhaled Phosphoinositide 3-Kinase δ Inhibitor

This study describes the pharmacokinetic (PK) and pharmaco-dynamic (PD) profile of N-(5-(4-(5-(((2R,6S)-2,6-dimethylmorpholino)methyl)oxazol-2-yl)-1H-indazol-6-yl)-2-methoxypyridin-3-yl)methanesulfonamide (GSK2292767A), a novel low-solubility inhaled phosphoinositide 3-kinase delta (PI3Kδ) inhibitor developed as an alternative to 2-(6-(1H-indol-4-yl)-1H-indazol-4-yl)-5-((4-isopropylpiperazin-1-yl)methyl)oxazole (nemiralisib), which is a highly soluble inhaled inhibitor of PI3Kδ with a lung profile consistent with once-daily dosing. GSK2292767A has a similar in vitro cellular profile to nemiralisib and reduces eosinophilia in a murine PD model by 63% (n = 5, P < 0.05). To explore whether a low-soluble compound results in effective PI3Kδ inhibition in humans, a first time in human study was conducted with GSK2292767A in healthy volunteers who smoke. GSK2292767A was generally well tolerated, with headache being the most common reported adverse event. PD changes in induced sputum were measured in combination with drug concentrations in plasma from single (0.05-2 mg, n = 37), and 14-day repeat (2 mg, n = 12) doses of GSK2292767A. Trough bronchoalveolar lavage (BAL) for PK was taken after 14 days of repeat dosing. GSK2292767A displayed a linear increase in plasma exposure with dose, with marginal accumulation after 14 days. Induced sputum showed a 27% (90% confidence interval 15%, 37%) reduction in phosphatidylinositol-trisphosphate (the product of phosphoinositide 3-kinase activation) 3 hours after a single dose. Reduction was not maintained 24 hours after single or repeat dosing. BAL analysis confirmed the presence of GSK2292767A in lung at 24 hours, consistent with the preclinical lung retention profile. Despite good lung retention, target engagement was only present at 3 hours. This exposure-response disconnect is an important observation for future inhaled drug design strategies considering low solubility to drive lung retention.

Design, synthesis and biological evaluation of 5-(2-amino-1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one derivatives as potent β2-adrenoceptor agonists

A series of novel β₂-adrenoceptor agonists with a 5-(2-amino-1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one moiety was designed, synthesized and evaluated for biological activity in human embryonic kidney 293 cells and isolated guinea pig trachea. Compounds 9g and (R)-18c exhibited the most excellent β₂-adrenoceptor agonistic effects and high β₂/β₁-selectivity with EC₅₀ values of 36 pM for 9g and 21 pM for (R)-18c. They produced potent airway smooth muscle relaxant effects with fast onset of action and long duration of action in an in vitro guinea pig trachea model of bronchodilation. These results support further development of the two compounds into drug candidates.

Cobalt-Catalyzed Reductive Dimethylcyclopropanation of 1,3-Dienes

Dimethylcyclopropanes are valuable synthetic targets that are challenging to access in high yield using Zn carbenoid reagents. Herein, we describe a cobalt-catalyzed variant of the Simmons-Smith reaction that enables the efficient dimethylcyclopropanation of 1,3-dienes using a Me₂ CCl₂ /Zn reagent mixture. The reactions proceed with high regioselectivity based on the substitution pattern of the 1,3-diene. The products are vinylcyclopropanes, which serve as substrates for transition-metal-catalyzed ring-opening reactions, including 1,3-rearrangement and [5+2] cycloaddition. Preliminary studies indicate that moderately activated monoalkenes are also amenable to dimethylcyclopropanation under the conditions of cobalt catalysis.

Novel Pyrrolidine Derivatives of Budesonide as Long Acting Inhaled Corticosteroids for the Treatment of Pulmonary Inflammatory Diseases

Inhaled corticosteroids (ICSs) represent the first line therapy for the treatment of asthma and are also extensively utilized in chronic obstructive pulmonary disease. Our goal was to develop a new ICS with a basic group, which can allow solid state feature modulation, achieving at the same time high local anti-inflammatory effect and low systemic exposure. Through a rational drug design approach, a new series of pyrrolidine derivatives of budesonide was identified. Within the series, several compounds showed nanomolar binding affinity ( K_i) with GR that mostly correlated with the effect in inducing GR nuclear translocation in CHO cells and anti-inflammatory effects in macrophagic cell lines. Binding and functional cell-based assays allowed identifying compound 17 as a potent ICS agonist with a PK profile showing an adequate lung retention and low systemic exposure in vivo. Finally, compound 17 proved to be more potent than budesonide in a rat model of acute pulmonary inflammation.

Synthesis, biological evaluation and molecular modeling of 2-amino-2-phenylethanol derivatives as novel β2-adrenoceptor agonists

A novel series of 2-amino-2-phenylethanol derivatives were developed as β₂-adrenoceptor agonists. Among them, 2-amino-3-fluoro-5-(2-hydroxy-1-(isopropylamino)ethyl)benzonitrile (compound 2f) exhibited the highest activity (EC₅₀ = 0.25 nM) in stimulating β₂-adrenoceptor-mediated cellular cAMP production with a 763.6-fold selectivity over the β₁-adrenoceptor. The (S)-isomer of 2f was subsequently found to be 8.5-fold more active than the (R)-isomer. Molecular docking was performed to determine the putative binding modes of this new class of β₂-adrenoceptor agonists. Taken together, these data show that compound 2f is a promising lead compound worthy of further study for the development of β₂-adrenoceptor agonists.

4-Amino-7,8-dihydro-1,6-naphthyridin-5(6 H)-ones as Inhaled Phosphodiesterase Type 4 (PDE4) Inhibitors: Structural Biology and Structure-Activity Relationships

Rational design of a novel template of naphthyridinones rapidly led to PDE4 inhibitors with subnanomolar enzymatic potencies. X-ray crystallography confirmed the binding mode of this novel template. We achieved compounds with double-digit picomolar enzymatic potencies through further structure-based design by targeting both the PDE4 enzyme metal-binding pocket and occupying the solvent-filled pocket. A strategy for lung retention and long duration of action based on low aqueous solubility was followed. In vivo efficacies were measured in a rat lung neutrophilia model by suspension microspray and dry powder administration. Suspension microspray of potent compounds showed in vivo efficacy with a clear dose-response. Despite sustained lung levels, dry powder administration performed much less well and without proper dose-response, highlighting clear differences between the two formulations. This indicates a deficiency in the low aqueous solubility strategy for long duration lung efficacy.

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.

Discovery of Narrow Spectrum Kinase Inhibitors: New Therapeutic Agents for the Treatment of COPD and Steroid-Resistant Asthma

The discovery of a novel series of therapeutic agents that has been designed and optimized for treating chronic obstructive pulmonary disease is reported. The pharmacological strategy was based on the identification of compounds that inhibit a defined subset of kinase enzymes modulating inflammatory processes that would be effective against steroid refractory disease and exhibit a sustained duration of action after inhaled delivery.

Concise asymmetric syntheses of novel phenanthroquinolizidines

The first preparation of enantioenriched phenanthroquinolizidines with a quaternary center at C14a was accomplished in seven steps from readily available starting materials. Key steps were an efficient dynamic kinetic allylation of a diastereomeric mixture of chiral tert-butylsulfinyl ketimines and the construction of a piperidine E ring by rhodium catalyzed hydroformylation. The Stevens rearrangement of the corresponding N-benzyl derivatives took place smoothly, allowing the installation of a benzyl moiety at C9 in a trans relationship with the methyl group. The cytoxicity of the prepared phenanthroquinolizidines was evaluated against different human cancer cell lines.

Update on ultra-long-acting β agonists in chronic obstructive pulmonary disease

INTRODUCTION

For the last two decades, long-acting β agonists (LABAs) have been a cornerstone in the management of chronic obstructive pulmonary disease (COPD). They relax airway smooth muscle and augment expiratory airflow, which reduces hyperinflation and improves dyspnea, functional capacity and quality of life. In recent years, Indacaterol, a LABA with an ultra-long duration of action (ultra-LABA), which only requires once-daily dosing, was approved by the FDA. The clinical efficacy of indacaterol is comparable, and, in some aspects better, than the currently available LABAs.

AREAS COVERED

This article reviews the pharmacological properties, clinical efficacy, safety and potential role of the ultra-LABAs in COPD management.

EXPERT OPINION

Ultra-LABAs are effective bronchodilators with a prolonged duration of action. By decreasing dosing frequency, ultra-LABAs potentially may improve respiratory medication adherence, which is associated with better survival and less healthcare utilization. In addition to their salubrious benefits, β agonists may produce untoward effects. Increased mortality and hospitalizations among patients with left ventricular heart failure, who were treated with β agonists, has caused concern about their use in patients with COPD and heart disease. Further experience and testing will determine the optimal role of ultra-LABAs in the management of COPD.

Discovery of TD-4306, a long-acting β2-agonist for the treatment of asthma and COPD

A multivalent approach focused on amine-based secondary binding groups was applied to the discovery of long-acting inhaled β2-agonists. Addition of amine moieties to the neutral secondary binding group of an existing β2-agonist series was found to provide improved in vivo efficacy, but also led to the formation of biologically active aldehyde metabolites which were viewed as a risk for the development of these compounds. Structural simplification of the scaffold and blocking the site of metabolism to prevent aldehyde formation afforded a potent series of dibasic β2-agonists with improved duration of action relative to their monobasic analogs. Additional optimization led to the discovery of 29 (TD-4306), a potent and selective β2-agonist with potential for once-daily dosing.

Characterizing systemic exposure of inhaled drugs: application to the long-acting β2-agonist PF-00610355

BACKGROUND AND OBJECTIVES

PF-00610355 is an orally inhaled long-acting β2-adrenoreceptor agonist that is being developed for the once-daily treatment of chronic obstructive pulmonary disease (COPD). The pharmacological effect is exerted in the lungs. However, systemic exposure of PF-00610355 is expected to be responsible for certain drug-related adverse effects. This analysis characterizes PF-00610355 using an integrated analysis of systemic exposure, across trials and patient populations.

METHODS

A total of 6,107 samples of PF-00610355 plasma concentration, collected in 264 subjects from eight studies in healthy volunteers, asthma, and COPD patients, were analyzed using non-linear mixed-effects models. Model-based mean (95 % CI) exposure profiles for a range of PF-00610355 doses in COPD patients were simulated.

RESULTS

PF-00610355 exposure profiles were described by a three-compartment disposition model with first-order absorption through a transit compartment. Patient status, inhalation device, and demographic factors were found to influence systemic drug exposure. Relative fine particle dose had a minor effect, whereas no effect of baseline lung function on the systemic exposure was found. An implicit method to address pharmacokinetic variability between occasions of drug intake yielded similar results as the established explicit method, yet in a much more efficient way.

CONCLUSION

The estimated systemic pre-dose and maximum PF-00610355 plasma concentration was 23 and 38 % in COPD patients compared to healthy volunteers, respectively. The analysis illustrated the value of an integrated pharmacokinetic analysis to address specific challenges in the clinical development of long-/ultra-long-acting β2-agonists and inhaled compounds in general, both in relation to selecting a safe starting dose in patients, but also in understanding exposure and systemic safety information across different patient populations and different inhalation devices/formulations.

Predicted heart rate effect of inhaled PF-00610355, a long acting β-adrenoceptor agonist, in volunteers and patients with chronic obstructive pulmonary disease

AIM

To assess the cardiovascular effects of a new inhaled long-acting β-adrenoceptor agonist PF-00610355 in COPD patients.

METHODS

Thirteen thousand and sixty-two heart rate measurements collected in 10 clinical studies from 579 healthy volunteers, asthma and COPD patients were analyzed. The relationship between heart rate profiles and predicted plasma concentration profiles, patient status, demographics and concomitant medication was evaluated using non-linear mixed-effects models. The median heart rate increase in COPD patients for doses of PF-00610355 up to 280 μg once daily was simulated with the final pharmacokinetic/pharmacodynamic (PKPD) model.

RESULTS

An Emax model accounting for delayed on-and off-set of the PF-00610355-induced change in heart rate was developed. The predicted potency in COPD patients was three-fold lower compared with healthy volunteers, while no difference in maximum drug effect was identified. Simulations suggested a maximum placebo-corrected increase of 2.7 (0.90-4.82) beats min(-1) in COPD patients for a PF-00610355 dose of 280 μg once daily, with 19% subjects experiencing a heart rate increase of more than 20 beats min(-1) compared with 8% in the placebo group.

CONCLUSIONS

This PKPD analysis supports the clinical observation that no relevant effects of PF-00610355 on heart rate in COPD patients should be expected for doses up to 280 μg once daily.

Sports doping: emerging designer and therapeutic β2-agonists

Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future.

Longitudinal FEV1 dose-response model for inhaled PF-00610355 and salmeterol in patients with chronic obstructive pulmonary disease

The objective of this work was to characterize the dose-response relationship between two inhaled long-acting beta agonists (PF-00610355 and salmeterol) and the forced expiratory volume in one second (FEV1) in order to inform dosing recommendations for future clinical trials in patients with chronic obstructive pulmonary disease (COPD). This meta-analysis of four studies included 8,513 FEV1 measurements from 690 patients with moderate COPD. A longitudinal kinetic-pharmacodynamic (K-PD) model was developed and adequately described changes in FEV1 measurements over time, including circadian patterns within a day, as well as changes in FEV1 measurements elicited from administration of PF-00610355 or salmeterol. The fine-particle dose, the amount of drug present in particles small enough for lung delivery, was used as the exposure measure for PF-00610355. Greater reversibility following administration of a short-acting beta agonist during run-in was associated with increased FEV1 response to long-acting beta agonists (through an increased maximal response, E(max)). Simulations were conducted to better understand the response to PF-00610355 relative to placebo and salmeterol. The results of the simulations show that once daily fine-particle doses of 28.1 μg versus placebo have a moderate probability of providing an average improvement above 100 mL at trough. The 50 μg fine-particle dose, on the other hand, has a greater than 0.78 probability of achieving a 120 mL improvement versus placebo at trough. From an efficacy perspective and assuming a fine-particle fraction of 25 % for the Phase 3 formulation; 100 and 200 μg once daily nominal doses would be of interest to investigate in future Phase 3 trials.

Emerging drugs for asthma

INTRODUCTION

Current drug treatments for asthma relieve bronchospasm and airway inflammation but do not offer a cure, and symptoms return when treatment is stopped. Asthma management guidelines emphasize the importance of effective asthma treatment to achieve and maintain asthma control. However, despite widely available and effective treatments, achieving asthma control is still an unmet need for many patients.

AREAS COVERED

Remarkable efforts have been made to identify the characteristic features of difficult-to-control (usually severe) asthma that are different from those described for mild-to-moderate asthma, setting the stage for the development of new and even individualized therapies. The most fascinating options of the new asthma treatments are biologic therapies, in particular monoclonal antibodies. In addition, some novel once-daily combinations of long-acting β(2)-agonist and inhaled corticosteroids are under development.

EXPERT OPINION

Asthma is a complex syndrome made up of a number of disease variants or asthma phenotypes, with different underlying pathophysiology. As different drugs target different pathways, it is necessary to determine the individual profile of pathophysiological abnormalities for each patient. Several cytokines have been implicated in the inflammatory cascades leading to the different asthma phenotypes, and the most relevant ones are discussed. The challenge in treating asthma resides precisely in its heterogeneity.

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.

G-protein coupled receptor and kinase targets: advances in drug discovery from molecular to clinical

The conference was organized by Visiongain and focused on a number of industrially relevant advances in G-protein coupled receptor and kinase research. Commercial stands were provided by Genscript (Bioassays), Merck Millipore (profiling services), Schrödinger (modeling) and Corning (assay development). The overall attendance was approximately 40 delegates taking part in four sessions over the two days.

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

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death in the world today. Bronchodilators, particularly muscarinic antagonists and β(2) agonists, are recommended for patients with moderate to severe COPD. Dual-pharmacology muscarinic antagonist- β(2) agonist (MABA) molecules present an exciting new approach to the treatment of COPD by combining muscarinic antagonism and β(2) agonism in a single entity. They have the potential to demonstrate additive or synergistic bronchodilation over either pharmacology alone. Due to this enticing prospect, several companies have now reported MABA discovery efforts through a conjugated/linked strategy with one candidate (GSK-961081) demonstrating clinical proof of concept. Several MABA crystal forms have been identified, satisfying the requirements for inhaled dosing devices. There are significant challenges in designing MABAs, but the potential to achieve enhanced bronchoprotection in patients and facilitate 'triple therapy' makes this an extremely important and exciting area of pharmaceutical research.

Third-generation long-acting β₂-adrenoceptor agonists: medicinal chemistry strategies employed in the identification of once-daily inhaled β₂-adrenoceptor agonists

Inhaled long-acting β(2)-adrenoceptor agonists (LABAs) are highly effective bronchodilators in the treatment of asthma and chronic obstructive pulmonary disease. There is significant interest in the development of third-generation compounds that improve upon the marketed twice-daily LABAs salmeterol and formoterol. A principal advantage sought from the next generation is duration of action that supports once-daily dosing, although improved efficacy, faster onset, and increased therapeutic index are also frequently cited as objectives. Recent publications detailing medicinal chemistry programs directed at the discovery of third-generation LABAs illustrate a wide variety of strategies that have been successfully employed towards these goals. Some recent scientific advances in the understanding of inhaled bronchodilators are discussed and the reported medicinal chemistry strategies are reviewed in the context of these advances.

A multivalent approach to the discovery of long-acting β(2)-adrenoceptor agonists for the treatment of asthma and COPD

A multivalent approach was applied to the design of long-acting inhaled β(2)-adrenoceptor agonists. A series of dimeric arylethanolamines based on the short acting β(2)-adrenoceptor agonist albuterol were prepared, varying the nature and length of the linker between the basic nitrogens. None of the C(2)-symmetric dimers demonstrated increased potency, however dimer 5j, derived from 4-phenethylamine, was found to have increased binding potency in vitro relative to the parent monomer. Optimization of this structure led to the identification of 22 (milveterol) which demonstrates high potency in vitro and long duration of action in a guinea pig model of bronchoprotection.