Biological actions of formoterol isomers

Deep Eutectic Solvents: An Eco-friendly Design for Drug Engineering

In the spirit of circular economy and sustainable chemistry, the use of environmentally friendly chemical products in pharmacy has become a hot topic. In recent years, organic solvents have been the subject of a great range of restriction policies due to their harmful effects on the environment and toxicity to human health. In parallel, deep eutectic solvents (DESs) have emerged as suitable greener solvents with beneficial environmental impacts and a rich palette of physicochemical advantages related to their low cost and biocompatibility. Additionally, DESs can enable remarkable solubilizing effect for several active pharmaceutical ingredients (APIs), thus forming therapeutic DESs (TheDESs). In this work, special attention is paid to DESs, presenting a precise definition, classification, methods of preparation, and characterization. A description of natural DESs (NaDESs), i. e., eutectic solvents present in natural sources, is also reported. Moreover, the present review article is the first one to detail the different approaches for judiciously selecting the constituents of DESs in order to minimize the number of experiments. The role of DESs in the biomedical and pharmaceutical sectors and their impact on the development of successful therapies are also discussed.

Advances in deep eutectic solvents and water: applications in metal- and biocatalyzed processes, in the synthesis of APIs, and other biologically active compounds

This review highlights recent advances in metal- and biocatalyzed transformations, in the synthesis of APIs and other biologically active compounds, when employing deep eutectic solvents and water as environmentally responsible solvents.

Separation of a diastereomeric diol pair using the mechanical properties of crystals

The visually indistinguishable acicular crystals of a (2S,3R/S)-3-ethyl-1-phenylhex-5-ene-2,3-diol (ephd) diastereomeric pair are separated via the mechanical response based on elastic (2S,3R, right) and brittle (2S,3S, left) crystals.

Addition of Highly Polarized Organometallic Compounds to N-tert-Butanesulfinyl Imines in Deep Eutectic Solvents under Air: Preparation of Chiral Amines of Pharmaceutical Interest

Highly polarized organometallic compounds of s-block elements are added smoothly to chiral N-tert-butanesulfinyl imines in the biodegradable d-sorbitol/choline chloride eutectic mixture, thereby granting access to enantioenriched primary amines after quantitatively removing the sulfinyl group. The practicality of the method is further highlighted by proceeding at ambient temperature and under air, with very short reaction times (2 min), enabling the preparation of diastereoisomeric sulfinamides in very good yields (74-98 %) and with a broad substrate scope, and the possibility of scaling up the process. The method is demonstrated in the asymmetric syntheses of both the chiral amine side-chain of (R,R)-Formoterol (96 % ee) and the pharmaceutically relevant (R)-Cinacalcet (98 % ee).

Enantioselective disposition of (R,R)-formoterol, (S,S)-formoterol and their respective glucuronides in urine following single inhaled dosing and application to doping control

Formoterol is a long-acting beta2-adrenoceptor agonist (LABA) used for the treatment of asthma and exercise-induced bronchoconstriction. Formoterol is usually administered as a racemic (rac-) mixture of (R,R)- and (S,S)-enantiomers. While formoterol is restricted by the World Anti-Doping Agency (WADA), inhalation of formoterol is permitted to a predetermined dose (54 μg/24 hours) and a urine threshold of 40 ng/mL. However, chiral switch enantiopure (R,R)-formoterol is available, effectively doubling the therapeutic advantage for the same threshold. The aim of this study was to investigate whether formoterol exhibits enantioselective urinary pharmacokinetics following inhalation. Six healthy volunteers were administered a 12 μg inhaled dose of rac-formoterol. Urine was collected over 24 hours and analyzed by enantioselective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay. Total (free drug plus conjugated metabolite) median (min-max) rac-formoterol urine levels following inhalation were 1.96 (1.05-13.4) ng/mL, 1.67 (0.16-9.67) ng/mL, 0.45 (0.16-1.51) ng/mL, 0.61 (0.33-0.78) ng/mL, and 0.17 (0.08-1.06) ng/mL at 2, 4, 8, 12, and 24 hours, respectively, well below the 2019 urine threshold. The proportion of conjugation differed between enantiomers with glucuronide conjugation much greater for (R,R)-formoterol (around 30%-60% of total) compared to (S,S)-formoterol (0%-30%). There was clear evidence of inter-individual enantioselectivity observed in the ratios of (R,R):(S,S)-formoterol, where (S,S)- was predominant in free formoterol, and (R,R)- predominant in the conjugated metabolite. In conclusion, rac-formoterol delivered by inhalation exhibits enantioselective elimination in urine following single-dose administration. Enantioselective assays should be employed in doping control to screen for banned beta2-agonist chiral switch products such as (R,R)-formoterol, and total hydrolyzed rac-formoterol is warranted to account for inter-individual differences in enantioselective glucuronidation.

Long-Acting β2-Agonists in Asthma: Enantioselective Safety Studies are Needed

Long-acting β2-agonists (LABAs) such as formoterol and salmeterol are used for prolonged bronchodilatation in asthma, usually in combination with inhaled corticosteroids (ICSs). Unexplained paradoxical asthma exacerbations and deaths have been associated with LABAs, particularly when used without ICS. LABAs clearly demonstrate effective bronchodilatation and steroid-sparing activity, but long-term treatment can lead to tolerance of their bronchodilator effects. There are also concerns with regard to the effects of LABAs on bronchial hyperresponsiveness (BHR), where long-term use is associated with increased BHR and loss of bronchoprotection. A complicating factor is that formoterol and salmeterol are both chiral compounds, usually administered as 50:50 racemic (rac-) mixtures of two enantiomers. The chiral nature of these compounds has been largely forgotten in the debate regarding LABA safety and effects on BHR, particularly that (S)-enantiomers of β2-agonists may be deleterious to asthma control. LABAs display enantioselective pharmacokinetics and pharmacodynamics. Biological plausibility of the deleterious effects of β2-agonists (S)-enantiomers is provided by in vitro and in vivo studies from the short-acting β2-agonist (SABA) salbutamol. Supportive clinical findings include the fact that patients in emergency departments who demonstrate a blunted response to salbutamol are more likely to benefit from (R)-salbutamol than rac-salbutamol, and resistance to salbutamol appears to be a contributory mechanism in rapid asthma deaths. More effort should therefore be applied to investigating potential enantiospecific effects of LABAs on safety, specifically bronchoprotection. Safety studies directly assessing the effects of LABA (S)-enantiomers on BHR are long overdue.

Beta2-Agonist Doping Control and Optical Isomer Challenges

The World Anti-Doping Agency (WADA) currently allows therapeutic use of the beta2-agonists salbutamol, formoterol and salmeterol when delivered via inhalation despite some evidence suggesting these anti-asthma drugs may be performance enhancing. Beta2-agonists are usually administered as 50:50 racemic mixtures of two enantiomers (non-superimposable mirror images), one of which demonstrates significant beta2-adrenoceptor-mediated bronchodilation while the other appears to have little or no pharmacological activity. For salbutamol and formoterol, urine thresholds have been adopted to limit supratherapeutic dosing and to discriminate between inhaled (permitted) and oral (prohibited) use. However, chiral switches have led to the availability of enantiopure (active enantiomer only) preparations of salbutamol and formoterol, which effectively doubles their urine thresholds and provides a means for athletes to take supratherapeutic doses for doping purposes. Given the availability of these enantiopure beta2-agonists, the analysis of these drugs using enantioselective assays should now become routine. For salmeterol, there is currently only a therapeutic dose threshold and adoption of a urinary threshold should be a high priority for doping control.

Health resource utilization for inpatients with COPD treated with nebulized arformoterol or nebulized formoterol

OBJECTIVE

Arformoterol is the (R,R)-enantiomer of formoterol. Preclinical studies suggest that it is a stronger bronchodilator than the racemic (R,R/S,S)-formoterol; however, its potential clinical advantages have not been demonstrated. This study compared the length of stay (LOS), 30-day readmission rates, and doses of rescue medication administered in hospitalized patients with COPD who were treated with nebulized arformoterol or nebulized formoterol.

METHODS

This retrospective analysis utilized data from Premier, Inc. (Charlotte, NC, USA), the largest nationwide hospital-based administrative database. COPD patients ≥40 years of age were included if they were hospitalized between January 2011 and July 2014, had no asthma diagnoses, and were treated with nebulized arformoterol or nebulized formoterol. LOS was measured from the day the patients initiated the study medication (index day). Rescue medications were defined as short-acting bronchodilators used from the index day onward. Multivariate statistical models included a random effect for hospital and controlled for patient demographics, hospital characteristics, admission characteristics, prior hospitalizations, comorbidities, pre-index service use, and pre-index medication use.

RESULTS

A total of 7,876 patients received arformoterol, and 3,612 patients received nebulized formoterol. There was no significant difference in 30-day all-cause (arformoterol =11.9%, formoterol =12.1%, odds ratio [OR] =0.981, P=0.82) or COPD-related hospital readmission rates (arformoterol =8.0%, formoterol =8.0%, OR =1.002, P=0.98) after adjusting for covariates. The adjusted mean LOS was significantly shorter for arformoterol-treated vs formoterol-treated patients (4.6 vs 4.9 days, P=0.039), and arformoterol-treated patients used significantly fewer doses of rescue medications vs formoterol-treated patients (5.9 vs 6.6 doses, P=0.006).

CONCLUSION

During inpatient stays, treating with arformoterol instead of nebulized formoterol may lead to shorter LOS and lower rescue medication use.

Bronchopulmonary pharmacokinetics of (R)-salbutamol and (S)-salbutamol enantiomers in pulmonary epithelial lining fluid and lung tissue of horses

AIMS

Salbutamol is usually administered as a racemic mixture but little is known about the enantioselectivity of salbutamol pharmacokinetics in the lung. This study was designed to investigate enantiomer concentrations in lung tissue after inhaled dosing.

METHODS

Horses (n = 12) received racemic salbutamol 1000 μg via inhalation. Enantioselective ultra performance liquid chromatography-tandem mass spectrometry was used to determine salbutamol concentrations in pulmonary epithelial lining fluid (PELF) sampled 2, 5, 10 and 15 min after administration, in central lung (endoscopic bronchial biopsy) and peripheral lung (percutaneous pulmonary biopsy) tissues (at 20 and 25 min respectively), and in plasma samples.

RESULTS

Mean ± 95% confidence interval (CI) yield of PELF was 57 ± 10 mg. Initial mean ± 95%CI (R)- and (S)-salbutamol PELF concentrations were 389 ± 189 ng g^-1 and 378 ± 177 ng g^-1 respectively, and both reduced approximately 50% by 15 min. Mean ± 95%CI central lung levels of drug were higher than peripheral lung tissue for both (R)-salbutamol (875 ± 945 vs. 49.5 ± 12 ng g^-1 ) and (S)-salbutamol (877 ± 955 vs. 50.9 ± 12 ng g^-1 ) respectively. There was no evidence of enantioselectivity in PELF or central lung but minor (~2%) enantioselectivity was observed in the peripheral lung. Enantioselectivity was clearly evident in plasma with (S):(R) ratio of 1.25 and 1.14 for both area under the concentration-time curve (0-25 min) and C_max respectively.

CONCLUSIONS

PELF sampling in horses offers sufficient yield allowing direct detection of drug and, combined with tissue sampling, is a valuable model to investigate bronchopulmonary pharmacokinetics. Salbutamol did not demonstrate enantioselectivity in PELF or central lung tissue uptake following acute dosing, however, enantioselective plasma concentrations were demonstrated, with minor enantioselectivity in the peripheral lung.

Exacerbations, health services utilization, and costs in commercially-insured COPD patients treated with nebulized long-acting β2-agonists

OBJECTIVE

This retrospective cohort study compared exacerbations, health services utilization, and costs among chronic obstructive pulmonary disease (COPD) patients who received nebulized arformoterol or nebulized formoterol therapy.

METHODS

Using PharMetrics Plus health plan claims, 417 nebulized long-acting β2-agonist (LABA) users meeting the study inclusion criteria were identified: had ≥2 fills of nebulized arformoterol or nebulized formoterol from January 1, 2009, to December 31, 2011, adhered to using their index drug ≥60% of the days during 1 year post-index, were ≥35 years old and continuously enrolled 180 days pre- and 1 year post-index, and did not use a nebulized LABA or have an asthma diagnosis during the pre-index period. Descriptive and multivariate analyses were performed.

RESULTS

A total of 274 nebulized arformoterol users and 143 nebulized formoterol users were identified with comparable demographic characteristics. However, significant differences were observed between the two groups in some clinical characteristics at index including comorbidities and use of antibiotics. At 1 year post-index, a lower proportion of nebulized arformoterol users had ≥1 exacerbation compared to nebulized formoterol users (70.4% vs 80.4%; p = 0.028). Among patients with ≥1 hospital admission, COPD-related costs per inpatient stay were significantly lower for nebulized arformoterol users than nebulized formoterol users (median = $9542 vs $14,025; p = 0.009). After controlling for confounders, nebulized arformoterol users had 19% marginally lower risk of exacerbations than nebulized formoterol users (hazard ratio = 0.81, 95% confidence interval = 0.64-1.03; p < 0.084) and 14.4% marginally lower COPD-related total costs at 1 year post-index (p = 0.062), primarily related to fewer hospital readmissions (7.6% vs 12.2%) and lower average costs per readmission stay (median = $7392 vs $18 081; p = 0.006).

CONCLUSIONS

This study suggests that the choice of nebulized LABA may influence COPD-related exacerbation occurrence and costs. Future studies with larger and more closely matched nebulized arformoterol and nebulized formoterol users are needed to confirm these findings.

Recruitment of β-arrestin 1 and 2 to the β2-adrenoceptor: analysis of 65 ligands

Beyond canonical signaling via Gαs and cAMP, the concept of functional selectivity at β2-adrenoceptors (β2ARs) describes the ability of adrenergic drugs to stabilize ligand-specific receptor conformations to initiate further signaling cascades comprising additional G-protein classes or β-arrestins (βarr). A set of 65 adrenergic ligands including 40 agonists and 25 antagonists in either racemic or enantiopure forms was used for βarr recruitment experiments based on a split-luciferase assay in a cellular system expressing β2AR. Many agonists showed only (weak) partial agonism regarding βarr recruitment. Potencies and/or efficacies increased depending on the number of chirality centers in (R) configuration; no (S)-configured distomer was more effective at inducing βarr recruitment other than the eutomer. βarr2 was recruited more effectively than βarr1. The analysis of antagonists revealed no significant effects on βarr recruitment. Several agonists showed preference for activation of Gαs GTPase relative to βarr recruitment, and no βarr-biased ligand was identified.

IN CONCLUSION

1) agonists show strong bias for Gαs activation relative to βarr recruitment; 2) agonists recruit βarr1 and βarr2 with subtle differences; and 3) there is no evidence for βarr recruitment by antagonists.

Review of drug safety and efficacy of arformoterol in chronic obstructive pulmonary disease

INTRODUCTION

The global initiative for chronic obstructive lung disease guidelines recommend maintenance therapy using long-acting bronchodilators for patients with chronic obstructive pulmonary disease (COPD) who have daily symptoms. Arformoterol is the (R, R) - enantiomer of the racemic formoterol and is more potent than (R, R/ S, S) - formoterol.

AREAS COVERED

Currently, arformoterol is one of two nebulized long-acting β-agonists on the market. It has a low incidence of cardiovascular side effects with incidence of arrhythmia and ischemia similar to placebo. β-adrenergic adverse effects are infrequent, numerically lower than formoterol, but have a quicker onset of action than salmeterol. There was no observed clinical tolerance over 12 months. arformoterol is safe in combination therapy with inhaled corticosteroids, tiotropium and rescue inhalers. A 12-month Phase IV trial found no increased risk of respiratory death or COPD exacerbation-related hospitalizations. arformoterol can potentially benefit patients with hyperinflation and low inspiratory flow rates.

EXPERT OPINION

The introduction of the centers for medicare and medicaid services penalization for COPD readmissions may boost the appeal of long-acting bronchodilators as new discharge medications. With the advent of ultra long-acting bronchodilators, its potential as a once daily agent in isolation or combination with these new therapies needs further study.

Effects of (r,r)- and (r,r/s,s)-formoterol on airway relaxation and contraction in an experimental rat model

BACKGROUND

Racemic (R,R/S,S)-formoterol is a long-acting β-agonist composed of a 50:50 mixture of (R,R)- and (S,S)-enantiomers.

OBJECTIVE

The aim of this study was to determine whether (R,R)-formoterol and (R,R/S,S)-formoterol have differing effects on airway contraction and relaxation in vitro.

METHODS

Cylindrical airway segments 3-mm long were isolated from the mid-trachea of healthy Sprague-Dawley rats and placed in a modified Krebs-Henseleit solution. Dose-response curves of bethanechol-induced contraction (measured as milligrams of tension) and the concentration of bethanechol that elicited 50% to 75% of maximal contraction (EC50-75) were determined. The air-way cylinders were then precontracted with bethanechol at the EC50-75 and exposed to different concentrations of (R,R)-formoterol (0.0001-1.0 μM) or (R,R/S,S)-formoterol (0.0002-2.0 μM). Each concentration of the 2 formoterol formulations contained the same amount of (R,R)-enantiomer (eg, [R,R]-formoterol 0.0001 μM and [R,R/S,S]-formoterol 0.0002 1JM contained the same amount of [R,R]-enantiomer). The relaxation percentage in response to formoterol was calculated as a reduction in tension (in milligrams) in relation to baseline tension in the precontracted state, with each tracheal cylinder serving as its own control. To determine the effect of (R,R)-formoterol on airway contraction, tracheal cylinders were incubated with (R,R)- or (R,R/S,S)-formoterol before electrical field stimulation (EFS).

RESULTS

Tracheae from 56 three-week-old Sprague-Dawley rats were used in the study. The relaxation percentage of precontracted trachea was significantly greater after exposure to (R,R)-formoterol than to (R,R/S,S)-formoterol at a 2-fold higher concentration (P = 0.03; general linear model with repeated measures analysis comparing the 2 groups of animals). However, in a post hoc analysis, the mean (SE) relaxation percentage of precontracted trachea was significantly greater only after exposure to (R,R)-formoterol 0.01 μM than to (R,R/S,S)-formoterol 0.02 μM (15.6% [5.8%] vs 39.0% [5.6%]; P < 0.05, unpaired t test). EFS-induced airway contraction was significantly less in tracheal cylinders incubated in (R,R)-formoterol compared with those incubated in (R,R/S,S)-formoterol at a 2-fold higher concentration (P = 0.05; general linear model with repeated measures analysis comparing the 2 groups of animals). However, in the post hoc analysis, mean (SE) EFS-induced tracheal contraction was significantly less only in (R,R)-formoterol 0.01 μM compared with (R,R/S,S)-formoterol 0.02 μM at 10 V (1070 [55] mgvs 1225 [28] mg; P < 0.05, unpaired t test).

CONCLUSION

We found that (R,R)-formoterol may induce greater relaxation of precontracted airway smooth muscle cells than (R,R/S,S)-formoterol and that (R,R)-formoterol may have a greater inhibitory effect on the endogenous cholinergic and excitatory nonadrenergic, noncholinergic contractile airway responses than (R,R/S,S)-formoterol. We speculate that the presence of the (S,S)-enantiomer in (R,R/S,S)-formoterol may impair airway relaxation of pre-contracted trachea in rats.

Design, synthesis and evaluation of dual pharmacology β2-adrenoceptor agonists and PDE4 inhibitors

A novel series of formoterol-phthalazinone hybrids were synthesised and evaluated as dual pharmacology β2-adrenoceptor agonists and PDE4 inhibitors. Most of the hybrids displayed high β2-adrenoceptor agonist and moderate PDE4 inhibitory activities. The most potent compound, (R,R)-11c, exhibited agonist (EC50=1.05nM, pEC50=9.0) and potent PDE4B2 inhibitory activities (IC50=0.092μM).

Nebulized arformoterol: what is its place in the management of COPD?

Chronic obstructive pulmonary disease (COPD) is a serious global health burden. Comprehensive management of COPD includes both pharmacologic and non-pharmacologic interventions aimed at improving disease-related functional capacity, health-related quality of life, and survival. The primary medications used for treatment of COPD are inhaled bronchodilator drugs which are delivered directly to the patient's airways through a number of different mechanisms. Arformoterol, the (R,R) enantiomer of racemic formoterol, was the first long-acting beta agonist approved by the U.S. Food and Drug Administration (FDA) for nebulized delivery. We discuss the pharmacology, clinical efficacy, and safety of arformoterol, and provide recommendations for its use during longitudinal management of patients with COPD.

Chronic obstructive pulmonary disease: an update on diagnosis and management issues in older adults

Chronic obstructive pulmonary disease (COPD) is a debilitating disease of the elderly that causes significant morbidity and mortality. Despite being a treatable and preventable disease, the prevalence continues to rise because of the worldwide epidemic of smoking. COPD is associated with enormous healthcare costs. It has systemic effects, and common co-morbid conditions such as cardiovascular disease, muscle wasting and osteoporosis may all be linked through a common systemic inflammatory cascade. Depression, anxiety and malnutrition are also common in elderly COPD patients. These factors not only affect quality of life (QOL) but also compliance with therapy. Malnutrition is an independent predictor of mortality and poor outcome. Spirometry is essential for the diagnosis of COPD, but the criteria defining airflow limitation are not clear cut for elderly patients and could result in over-diagnosis. However, older patients perceive their symptoms differently, and COPD could also be under-diagnosed in this population. Acute exacerbations result in worsening symptoms that necessitate additional treatment, and may cause a more rapid decline in lung function and QOL. The management of elderly patients with COPD should encompass a multidisciplinary approach. An evaluation of patients' nutritional status and mental health should be undertaken, in addition to assessing their lung function and functional impairment. Significant underlying co-morbidities should be evaluated and treated to derive the maximal benefit of therapy. Specific therapy for COPD should start with cessation of exposure to the most important risk factor, tobacco smoke. Smoking cessation rates in the elderly have not declined, and this may reflect an underlying reluctance by physicians to counsel and offer smoking cessation therapies to the elderly. Unlike oxygen therapy in hypoxaemic patients, bronchodilators and corticosteroids do not decrease mortality in COPD patients and they are primarily directed towards symptom relief. However, they do have a positive effect on QOL and exacerbation rates. The choice of delivery devices for inhaled medications is important in the elderly, and patients' inhaler technique and manual dexterity should be frequently assessed. Pulmonary rehabilitation and nutritional supplementation are other important components of care. End-of-life issues should be adequately addressed in the elderly with COPD, and an approach integrating curative and palliative interventions is recommended.

Effects of formoterol on contraction and Ca2+ signaling of mouse airway smooth muscle cells

Formoterol, a long-acting beta(2)-receptor agonist, is used to relieve bronchial constriction. However, formoterol is often a racemic formulation, and contains both (R,R)- and (S,S)-enantiomers. Because the activity of each isomer is poorly defined, the mechanisms by which formoterol relaxes smooth muscle cells (SMCs) of intrapulmonary airways are not well understood. Consequently, we compared the effects of (S,S)-, (R,R)-, and racemic formoterol, as well as (R)-albuterol, on the contraction and Ca(2+) signaling of airway SMCs in mouse lung slices with phase-contrast and confocal microscopy. Small airways were contracted with methacholine and the associated SMCs displayed sustained Ca(2+) oscillations and an increase in Ca(2+) sensitivity. These contracted airways displayed a substantial, concentration-dependent relaxation in response to (R,R)-formoterol. Racemic formoterol had a similar potency as (R,R)-formoterol for relaxing airways. By contrast, (S,S)-formoterol only induced a small relaxation. In conjunction with relaxation, (R,R)- and racemic formoterol stopped and decreased the methacholine-induced Ca(2+) oscillations and Ca(2+) sensitivity of the SMCs, respectively, whereas (S,S)-formoterol only decreased the Ca(2+) sensitivity. In these studies, (R,R)- and racemic formoterol had a similar, but much greater, potency than (R)-albuterol for relaxing mice airways. This action was quickly initiated at high concentrations by decreasing the frequency of Ca(2+) oscillations, but was more usually mediated at lower concentrations by decreasing the Ca(2+) sensitivity of the SMCs.

Arformoterol and salmeterol in the treatment of chronic obstructive pulmonary disease: a one year evaluation of safety and tolerance

INTRODUCTION

Concerns have been raised regarding the safety of extended use of long-acting beta2-agonists (LABAs). The safety of arformoterol (50 microg QD), and salmeterol (42 microg BID), was assessed over 12 months in subjects with COPD. The study also examined the occurrence of tolerance with these agents, i.e. whether improvement in airway function diminished or frequency of exacerbations increased with 12-months of use.

METHODS

Subjects with COPD (mean FEV1 1.2 L, ~41% predicted) were enrolled in the study and randomized to receive nebulized arformoterol 50 microg QD (n = 528) or salmeterol 42 microg BID (MDI; n = 265) in a prospective, multicenter, open-label, 12-month trial. The frequency of adverse events, COPD exacerbations, and use of short-acting bronchodilator agents were assessed throughout the study period. Pulmonary function was also examined.

RESULTS

Among treated subjects, the frequency of adverse events was similar for those taking arformoterol (90.5%) and salmeterol (88.3%). Tremor was more frequent among subjects treated with arformoterol (13.4%) than those treated with salmeterol (1.1%). The frequency of COPD exacerbations did not increase over 12 months for arformoterol and salmeterol (weeks 0-13: 15.7% and 11.7%, respectively; weeks 39-52: 10.0% and 9.4%, respectively). Supplemental ipratropium bromide and rescue racemic albuterol use decreased for both groups by 0.8 to 1.5 actuations/day, decreases that remained stable throughout the 52-week study. Mean predose (trough) FEV1 improved for arformoterol and salmeterol at week 13 (7.1% +/- 17.0 and 7.6% +/- 17.8, respectively) and the improvement continued at week 52 (5.9% and 6.2%, respectively). Mean peak percent predicted postdose FEV1 over the course of the 52-week study declined by about 2% for both treatments, but throughout was higher for arformoterol than for salmeterol.

CONCLUSION

In this trial, both arformoterol 50 microg QD and salmeterol 42 microg BID were well tolerated in patients with COPD. Both LABAs produced effective bronchodilation and their use was not associated with the development of clinically meaningful tolerance over a 1-year treatment period.

Chiral HPLC analysis of formoterol stereoisomers and thermodynamic study of their interconversion in aqueous pharmaceutical formulations

A chiral HPLC method was validated and successfully applied for the determination of formoterol stereoisomers and their inversion products in an aqueous matrix stored at 5-70 degrees C up to 3 weeks. Analysis was performed on a Chiral-AGP column (100 x 4-mm, 5-microm) using a variable mixture of mobile phase A (50-mM sodium phosphate buffer, pH 7.0) and B (10% v/v IPA) at a flow rate of 1.3 ml min(-1), and UV detection at 242 nm. All four formoterol stereoisomers were adequately resolved with acceptable detection and quantitation limits varying from 0.01-0.04 microg/ml and 0.04-0.1 microg/ml, respectively. The method showed acceptable accuracy (> or = 88%), precision (RSD < or = 8.5%) and good linearity (r(2) > or = 0.9999) over the concentration range investigated. While interconversion at 5+/-3 degrees C and 25+/-2 degrees C/60% RH +/-5% RH was too low to be determined accurately within the study period, chiral inversion of formoterol stereoisomers measured at high temperatures followed the first order rate kinetics and occurred at a single chiral center, resulting in the reversible formation of diastereoisomers, (R,R)<-->(S,R) and (S,S)<-->(R,S). No enantiomerization or diastereomerization occurred. There was no significant difference in inversion of the active components in racemic (R,R/S,S)-formoterol fumarate and the single isomer (R,R)-arformoterol tartrate drug formulations, and both drugs are expected to maintain their stereochemical integrity throughout the proposed shelf-life at the recommended storage condition (5+/-3 degrees C).

Comparison of enantiomers of SPFF, a novel beta2-Adrenoceptor agonist, in bronchodilating effect in guinea pigs

Previous study on racemic SPFF [2-(4-amino-3-chloro-5-trifluomethyl-phenyl)-2-tert-butylamino-ethanol hydrochloride], a novel beta2-adrenoceptor agonist, has validated that it is a potent, long-acting bronchodilator with relative higher beta2-adrenoceptor selectivity. On the basis of this study, we compared the pharmacological properties of SPFF and its enantiomers ((-)-SPFF and (+)-SPFF) in guinea pigs taking isoprenaline or salbutamol (SAB) as referenced drugs. For the relaxation of both normal and precontracted trachea strips in vitro, (-)-SPFF was found more potent than (+/-)-SPFF or (+)-SPFF. Moreover, we confirmed that the bronchodilator effect of (-)- and (+)-enantiomers were due to activation of the beta2-adrenoceptor because this effect was antagonized by a specific beta2-adrenoceptor antagonist, ICI-118551, with similar pA2 values to those of (+/-)-SPFF. Radioligand binding assay revealed that affinity of (-)-enantiomer to beta2-adrenoceptor was 6 and 164 fold greater than that of (+/-)- and (+)-SPFF, respectively. In addition, isomeric difference of overall selectivity between (-)-SPFF and (+)-SPFF was 10.7 fold for lung versus atria. (-)-SPFF displayed almost the same protective effect against bronchospasm induced by histamine-acetylcholine aerosol in conscious guinea pigs as (+/-)-SPFF did. However, the latent time of (+)-SPFF (1 mg.kg(-1)) was significantly shorter than that of (+/-)- and (-)-SPFF at the same doses. Finally, in the inhibition of histamine-induced increase of pulmonary resistance (RL) in anesthetized guinea pigs, (-)-SPFF was 1.3 and 3.5 times more potent than (+/-)- and (+)-SPFF. Correspondingly, in inhibiting the decrease of pulmonary compliance (CL) , the potencies of (-)- and (+)-enantiomers were approximately equivalent to that of (+/-)-SPFF. Furthermore, a study on the long-lasting action of the test drugs had shown that the effects of (-)-SPFF (30 microg.kg(-1)), (+/-)-SPFF (30 microg.kg(-1)) and (+)-SPFF (100 microg.kg(-1)) in inhibiting the increase of RL all lasted for 4 h. Nevertheless, the effects of (-)- and (+)-enantiomers were slightly lower 4 h after intraduodenal administration in inhibiting the decrease of CL. In conclusion, (-)-SPFF may be beneficial for the treatment of asthma because of its more potent efficacy and higher adrenoceptor affinity than (+/-)- or (+)-SPFF.

A pharmacokinetic/pharmacodynamic study comparing arformoterol tartrate inhalation solution and racemic formoterol dry powder inhaler in subjects with chronic obstructive pulmonary disease

BACKGROUND

Arformoterol is a single-isomer (R,R-formoterol) nebulized long-acting beta(2)-agonist approved for use in patients with chronic obstructive pulmonary disease (COPD). Exposure (plasma concentrations of (R,R)-formoterol) and forced expiratory volume in 1s (FEV(1)) were compared for 15 microg nebulized arformoterol and 12 and 24 microg racemic formoterol (containing 6 and 12 microg (R,R)-formoterol, respectively) delivered by dry powder inhaler (DPI).

METHODS

An open-label, randomized, three-way crossover study in 39 subjects with COPD (FEV(1) 1.4L, 44.4% predicted). Twice-daily treatments included nebulized arformoterol (15 microg) and racemic formoterol DPI (12 and 24 microg) for 14 days. Plasma concentrations of (R,R)- and (S,S)-formoterol were determined on days 1 and 14 of each treatment period. Airway function efficacy endpoints included the percent change in trough FEV(1) from baseline on day 14 of each treatment period.

RESULTS

At steady state, exposure to (R,R)-formoterol was similar following nebulized 15 microg arformoterol (C(max): 6.5 pg/mL; AUC(0-tau): 56.5 pgh/mL) and 12 microg racemic formoterol DPI (C(max): 6.2 pg/mL; AUC((0-)(tau)()): 46.3 pgh/mL). The geometric mean ratios between these two treatments (90% confidence intervals) for C(max) and AUC((0-)(tau)()) were 0.91 (0.76, 1.09) and 1.16 (1.00, 1.35), respectively. Treatment with 24 microg racemic formoterol DPI resulted in dose proportionally higher (R,R)-formoterol: C(max) (10.8 pg/mL) and AUC((0-)(tau)()) (83.6 pgh/mL). Detectable (S,S)-formoterol was consistently measured only after treatment with racemic formoterol. The mean percent increase in trough FEV(1) was 19.1% in the arformoterol group, and 16.0% and 18.2% in the 12 and 24 microg racemic formoterol groups, respectively. Changes in (R,R)-formoterol concentrations over time paralleled changes in FEV(1).

CONCLUSIONS

In this study, plasma exposure to (R,R)-formoterol was similar for nebulized 15 microg arformoterol and 12 microg racemic formoterol DPI, and 40% lower than 24 microg racemic formoterol DPI. There was no evidence of chiral interconversion following treatment with arformoterol. Finally, temporal changes in airway function in all treatment groups corresponded to changes in (R,R)-formoterol plasma concentrations.

Effect of nebulized arformoterol on airway function in COPD: results from two randomized trials

RATIONALE

Arformoterol, a single isomer long-acting beta(2)-agonist, was developed as an inhalation solution for the maintenance treatment of bronchoconstriction in COPD.

METHODS

The pulmonary function efficacy of nebulized arformoterol (15 micro g BID, 25 micro g BID, 50 micro g QD) and salmeterol MDI (42 micro g BID) versus placebo was assessed in 1456 subjects (mean FEV(1) 1.2L, mean predicted 41%). Data were pooled from 2 identical, 12-week, double-blind, randomized trials. The percent change in trough FEV(1), percent change in FEV(1) average AUC((0 - 12 hrs)) and peak percent change FEV(1) from predose were analyzed.

RESULTS

Improvement in trough FEV(1) averaged over 12 weeks was greater for arformoterol and salmeterol versus placebo (mean differences from placebo [95% CI] arformoterol-15 micro g BID: 11.4% [8.4, 14.3]; 25 micro g BID: 15.4% [12.2, 18.6]; 50 micro g QD: 10.9% [7.9, 13.9]); salmeterol: (11.6% [8.8, 14.4]). Greater improvements versus placebo occurred after the first dose (mean differences between arformoterol and placebo for trough FEV(1): 13-19%; FEV(1) AUC((0 - 12 hrs)): 19-24%; peak percent change: 20-25%) and at week 12 (trough FEV(1): 10-13%; FEV(1) AUC((0 - 12 hrs)): 6-13%; peak percent change: 7-14%); all 95% CIs excluded zero. Increases in FEV(1) AUC((0 - 12 hrs)) and peak percent change were greater for arformoterol than for salmeterol (95% CIs excluded zero). After 12 weeks, 78-87% of arformoterol subjects had > or = 10% increases in FEV(1) from pre-dose (56% salmeterol, 44% placebo); the median time to response was 3-13 minutes (142 minutes salmeterol).

CONCLUSIONS

In these trials, COPD subjects administered nebulized arformoterol demonstrated significant and sustained improvement in lung function over 12 weeks.

Stereoconfiguration of antiallergic and immunologic drugs

OBJECTIVE

To review the concept of chirality and its current role in the pharmacology of antiallergic, antiasthmatic, and immunologic agents.

DATA SOURCES

Ovid MEDLINE and PubMed databases from 1950 to the present time were searched.

STUDY SELECTION

Articles that described the pharmacology of chiral antiallergic, antiasthmatic, and immunologic medications were used for this review.

RESULTS

Stereoselectivity affects the pharmacologic profiles of medications in different ways from class to class and within the classes. This summary illustrates that enantiomers differ not only in potency in receptor binding and physiologic effects but also in pharmacokinetic parameters such as volume of distribution, plasma protein binding, metabolism, and clearance. Different enantiomers may produce unrelated pharmacologic effects as well. This review summarizes the variety of possible effects that different stereoisomers may produce and further underlines the importance of the purification and in-depth analysis of chiral compounds.

CONCLUSION

Chirality plays an important role in pharmacokinetics and pharmacodynamics of various pharmaceutical agents. The importance of stereoisomeric purity in the pharmacologic industry has increased during the past decade as demonstrated by the increased number of studies that examined the in vivo and in vitro effects produced by changes in stereoconfiguration of pharmaceutical agents. This review highlights such effects in certain frequently used medications used in the treatment of asthma and various allergic and immunologic disorders.

Role of arformoterol in the management of COPD

Formoterol is a beta2-agonist that has both short and long acting bronchodilator effects. Beta2-agonists used as bronchodilators have been synthesized as racemates that comprise (R,R) and (S,S)-enantiomers. Compounds that are beta2-selective derive their bronchodilator effect from an interaction between the (R,R)-enantiomer and the beta2-adrenoceptor. Arformoterol is the (R,R)-enantiomer and is distinguished from the more commonly used racemic (RR/S,S)-diasteriomer of formoterol. Overall literature on the use of arformoterol in COPD is very preliminary. There is some in vitro data that demonstrate significant bronchodilation and inhibition of inflammation with arformoterol, and these effects may be more pronounced than those caused by racemic formoterol. There are limited clinical trial data that demonstrate that arformoterol produces significant improvement in lung function in COPD; however, many of the subjects involved had marked baseline airway reversibility. Arformoterol has been very well tolerated in clinical trials and could potentially be used only once every 24 hours (due to its prolonged effect). It can only be given in nebulized form. Arformoterol can potentially be given with other inhaled medications.

Nebulized arformoterol in patients with COPD: a 12-week, multicenter, randomized, double-blind, double-dummy, placebo- and active-controlled trial

OBJECTIVE

The aim of this study was to assess the efficacy and tolerability of nebulized arformoterol tartrate (a selective, long-acting beta(2)-adrenergic agonist that is the [R,R] isomer of formoterol) and salmeterol xinafoate versus placebo in patients with chronic obstructive pulmonary disease (COPD).

METHODS

This 12-week, multicenter, randomized, double-blind, double-dummy, placebo- and active-controlled trial was conducted at 60 centers across the United States. Male and female patients aged >or=35 years with physician-diagnosed COPD received arformoterol (15 microg BID, 25 microg BID, or 50 microg QD via nebulizer), salmeterol (42 microg BID via metered dose inhaler), or placebo. Pulmonary function was assessed by spirometry; dyspnea, by the Transitional Dyspnea Index (TDI); and health status, by the St. George's Respiratory Questionnaire (SGRQ). Adverse events (AEs) were assessed by site personnel at all clinic visits (screening, first dose at week 0, and at weeks 3, 6, 9, 12, and follow-up). COPD exacerbations were defined as worsening respiratory status requiring a change in medication or an unscheduled provider visit.

RESULTS

A total of 717 patients received study medication. The demographic composition of all treatment arms was similar. The mean age was 62.9 years, 58% were men, and mean baseline forced expiratory volume in 1 second (FEV(1)) was 1.2 L (41% predicted). Mean improvement in trough FEV(1) over 12 weeks was significantly greater with all 3 arformoterol doses (15 microg BID, +16.9%; 25 microg BID, +18.9%; 50 microg QD, +14.9%) and for salmeterol (+17.4%) relative to placebo (+6.0%; P < 0.001). There were significantly greater improvements in the mean percentage change in FEV(1) AUC(0-12h) from the predose value over 12 weeks (15 microg BID, 12.7%, 25 microg BID, 13.9%, 50 microg QD, 18.9%; salmeterol, 9.8%) versus placebo (2.7%; P <or= 0.001); all doses of arformoterol were statistically different from salmeterol for this end point (P <or= 0.024). At week 12, TDI focal scores were significantly greater with all arformoterol doses compared with placebo (mean [95% CI]: 15 microg BID, 0.97 [0.25-1.69]; 25 microg BID, 1.08 [0.3-1.86]; 50 microg QD, 1.04 [0.32-1.771), suggesting treatment-associated improvement in dyspnea, however, the difference between salmeterol and placebo was not statistically significant (0.36 [-0.40 to 1.12]). Improvements in health status, as measured using SGRQ total scores, were -2.6 to -3.6 U in the arformoterol groups, -4.4 U for salmeterol, and -1.2 U for placebo; 95% CI of differences versus placebo suggested significant improvement for the arformoterol 25 microg BID and salmeterol groups. There was a similar frequency of AEs and COPD exacerbations across all groups, including placebo.

CONCLUSIONS

In this trial, patients with moderate to severe COPD administered nebulized arformoterol over 12 weeks were observed to have significant and sustained improvements in airway function and dyspnea compared with placebo. The results also suggest that all doses of arformoterol, including the lowest dose (15 microg BID), were effective. Overall, nebulized arformoterol was well tolerated.

ultra-long-acting beta2-adrenoceptor agonists: an emerging therapeutic option for asthma and COPD?

There has been a real interest recently in developing once-daily beta(2)-adrenoceptor agonists (ultra-long-acting beta(2)-adrenoceptor agonists [ultra-LABAs]) for treating asthma and chronic obstructive pulmonary disease (COPD) in an attempt to simplify their management, although an increasing amount of convincing data show an association of LABAs with a rise in asthma-related deaths and life-threatening experiences. This paper reviews the effects of different ultra-LABAs that are at varying stages of development. Arformoterol, carmoterol, indacaterol and GSK-159797 are ultra-LABAs that are likely to be introduced into the market before 2010. It is plausible that once-daily dose administration of an LABA will lead to increased convenience for patients, which may also lead to enhancement of adherence, and may have advantages leading to improved overall clinical outcomes in patients with asthma and COPD.

The effect of formoterol over 24 h in patients with asthma: the role of enantiomers

The single-dose effect of formoterol racemate and enantiomers on bronchodilatation up to 24 h was determined. Forty-six reversible asthmatic patients were randomised to this double blind, crossover study. Formoterol was inhaled by nebulizer (HaloLite); 4.5 and 36 microg of the racemate (rac-formoterol), 2.25 and 18 microg of (R;R)-formoterol, 18 mirog of (S;S)-formoterol, or placebo. Airway and systemic effects were assessed by serial measurements of forced expiratory volume during the first second, FEV1 (24 h), and heart rate (4 h). Rac- and (R;R)-formoterol significantly and dose-dependently increased FEV1 with similar mean maximal effect. (S;S)-formoterol was without significant effects on FEV1 and heart rate. (R;R)- and rac-formoterol were still effective 22-24 h after single high doses, but this was associated with some systemic side effect (increased heart rate) initially. Average 22-24 h FEV1 was 8% (rac-formoterol 36 microg) and 11% ((R;R)-formoterol 18 microg) over placebo, respectively. No significant differences in effects were observed between rac- and (R;R)-formoterol. Thus, the single dose bronchodilatating effect of formoterol resides in (R;R)-formoterol. This study does not indicate a clinically important advantage of (R;R)-formoterol as acute bronchodilator compared to the racemate.

Three-dimensional pharmacology, a subject ranging from ignorance to overstatements

Stereoselectivity has been known to play a role in drug action for 100 years or more. Nevertheless, chiral drugs have been developed and used as racemates, neglecting the fact that they comprise mixtures of two or more compounds which may have quite different pharmacological properties. A very limited access to pure enantiomers in the past has been responsible for this unsatisfactory state of affairs. During the last 20 years, significant achievements have made it possible to perform stereoselective synthesis and analysis. Today, novel chiral drugs are as a rule developed as single enantiomers. Yet, studies of old racaemic drugs are still designed, performed and published without mention of the fact that two or more compounds are involved. In recent years, a number of old racaemic drugs have been re-evaluated and re-introduced into the clinical area as the pure, active enantiomer (the eutomer). While in principle correct, the clinical benefit of this shift from a well established racaemate to a pure enantiomer often seems to be limited and sometimes exaggerated. Racaemic drugs with a deleterious enantiomer that does not contribute to the therapeutic effect (the distomer), may have been sorted out in the safety evaluation process. However, in the future any pharmacological study of racaemic drugs must include the pure enantiomers. This will generate new, valuable information on stereoselectivity in drug action and interaction.

(S,S)-formoterol increases the production of IL-4 in mast cells and the airways of a murine asthma model

BACKGROUND

Racemic formoterol is an equimolar mixture of (R,R)- and (S,S)-formoterol. Several studies have shown (S,S)-formoterol to have proinflammatory effects. We previously reported that (S)-albuterol increased the secretion of histamine and interleukin (IL)-4 in murine mast cells. We thus hypothesized that (S,S)-formoterol promotes asthma by enhancing IL-4 production in mast cells of the asthmatic airway.

METHODS

Murine and human mast cells were stimulated by high affinity IgE receptor (Fc epsilon RI) cross-linking or with phorbol myristate acetate/calcium ionophore A23187 (PMA/A23187). Jurkat T cells were stimulated with PMA. Cells were pretreated with either (R,R)- or (S,S)-formoterol. Ovalbumin (OVA)-sensitized BALB/c mice were pretreated with (R,R)- or (S,S)-formoterol before each intranasal OVA challenge for 10 days. Bronchoalveolar lavage fluid was obtained from the mice. The levels of IL-4, histamine and PGD(2) were measured. Early and late allergic responses (EAR and LAR, respectively) to OVA challenge and airway hyperresponsiveness (AHR) were measured.

RESULTS

(S,S)-formoterol enhanced the production of IL-4, histamine, and PGD(2) in mast cells, whereas (R,R)-formoterol had no effect. Neither (S,S)- nor (R,R)-formoterol had effect on IL-4 production in Jurkat T cells. In OVA-challenged mice, (S,S)-formoterol increased IL-4 secretion, whereas (R,R)-formoterol had no effect. Finally, (S,S)-formoterol enhanced the inflammatory changes in the peribronchial and perivascular areas without affecting EAR, LAR or AHR, whereas (R,R)-formoterol reduced EAR, LAR and AHR as well as cellular infiltration in the lung tissue of these mice.

CONCLUSION

(S,S)-formoterol may exert adverse effects in asthma control by activating mast cells to produce proinflammatory mediators such as IL-4.