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

Expanding the Role of Chiral Drugs and Chiral Nanomaterials as a Potential Therapeutic Tool

Chirality, the property of molecules having mirror-image forms, plays a crucial role in pharmaceutical and biomedical research. This review highlights its growing importance, emphasizing how chiral drugs and nanomaterials impact drug effectiveness, safety, and diagnostics. Chiral molecules serve as precise diagnostic tools, aiding in accurate disease detection through unique biomolecule interactions. The article extensively covers chiral drug applications in treating cardiovascular diseases, CNS disorders, local anesthesia, anti-inflammatories, antimicrobials, and anticancer drugs. Additionally, it explores the emerging field of chiral nanomaterials, highlighting their suitability for biomedical applications in diagnostics and therapeutics, enhancing medical treatments.

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.

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.

Chiral Switch Drugs for Asthma and Allergies: True Benefit or Marketing Hype

Enantiomers are one of several possible molecular configurations present in a drug that has at least 1 chiral center. A drug containing 2 or more enatiomers is called a racemic mixture. Enatiomers are being developed from racemic mixtures as drugs in their own right often to extend patent protection of highly popular drugs. However, the therapeutic advantages of single enantiomer drugs developed for respiratory use such as levalbuterol, arformoterol, and levocetirizine over their racemate has been disappointing. In addition, single enantiomer drugs may be several fold more expensive than the racemic drug. New single enantiomer drugs, which are stable (no interconversion back to the racemate) and have fewer adverse effects and a more predictable pharmacodynamic or pharmacokinetic profile would confer a therapeutic advantage and thus would be beneficial for clinical use.

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.

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.