Salmeterol, formoterol, and salbutamol in the isolated guinea pig trachea: differences in maximum relaxant effect and potency but not in functional antagonism

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

State-of-the-art beta-adrenoreceptor agonists for the treatment of asthma

INTRODUCTION

Asthma, a heterogeneous disease, is characterized by chronic airway inflammation and hyperreactivity. β₂-adrenoreceptor agonists (β₂-agonists) remain pivotal for asthma management. Short-acting β₂-agonists (SABAs) result in rapid symptomatic alleviation and bronchospasm prevention. Patients experience significant clinical benefits from therapy with long-acting β₂-agonists (LABAs) with efficacy to bronchodilate, and prolonged lung function betterment. Recently discovered β₂-agonists with longer half-lives offer once-daily dosing.

AREAS COVERED

The authors provide a thorough review of the pharmacokinetics, pharmacodynamics, efficacy, tolerability, classification, and safety of β₂-agonists through an in-depth review of current literature using these databases: U.S. National Institutes of Health's National Library of Medicine (NIH/NLM), PubMed Central, and NLM clinical trials.

EXPERT OPINION

β₂- agonists act primarily on airway smooth muscle cells and are quintessential for adequate asthma management. Given their pharmacodynamic and pharmacokinetic properties, SABAs are used as rescue medication. Notably, the current Global Initiative for Asthma (GINA) strategy document recommends using LABA/inhaled corticosteroid combinations both as a daily controller and as a rescue medication. Clinicians should assess this new treatment plan on a per-case basis, making sure to evaluate inhaler adherence and treat modifiable risk factors. The development of next-generation β₂- agonists is an exciting research area that could significantly improve patients' adherence to treatment regimens and, consequently, asthma control and quality of life.

Relaxant Effect of Urginea maritima on Tracheal Smooth Muscle Mediated by the Effect on Beta-2 Adrenergic, Muscarinic Receptors and Calcium and Potassium Channels

Urginea maritima (U. maritima) showed anti-inflammatory, antioxidant, antibacterial, diuretic, vasodilatation, and wound-healing effects on fungal infections, cardiac disorders, digestive disorders, rheumatoid disease, and respiratory disorders such as bronchitis, bronchial nosocomial infections, and severe cough. To examine the bronchodilatory effect of U. maritima, the relaxant effect of its extract on rat tracheal smooth muscle (TSM) and its possible mechanism was examined in this study. Male Wistar rats' TSM were divided into eight groups (n = 8 in each group). Four of these groups were TSM tissues, contracted with KCl (60 mM) incubated with atropine, glibenclamide, and indomethacin and nonincubated TSM, while the other four groups were TSM tissues contracted with methacholine (10 μM) for 5 min, incubated with propranolol, chlorpheniramine, and diltiazem and nonincubated TSM. Cumulative concentrations of U. maritima extract (12.5, 25, 50, 100, 20, and 400 μg/ml) were then added to organ bath every 5 min. Theophylline (0.2, 0.4, 0.6, and 0.8 mM) as positive control and saline (1 ml) as negative control were also examined in nonincubated tissues. A concentration-dependent relaxant effect of U. maritima on nonincubated TSM contracted with KCl (60 mM) or methacholine (10 μM) (p < 0.01 and p < 0.001) was observed. The relaxant effects of U. maritima extract in the incubated tissues with glibenclamide, propranolol, diltiazem, atropine, and chlorpheniramine were significantly lower than those in the nonincubated tissues (p < 0.05 to p < 0.001). EC₅₀ values of U. maritima extract in the incubated TSM with glibenclamide, propranolol, diltiazem, and atropine were significantly higher than those in the nonincubated tissues (p < 0.05 for diltiazem-incubated tissues and p < 0.001 for other cases). U. maritima extract displayed considerable relaxant effect on TSM comparable to the effect of theophylline. Beta-2 adrenoceptor stimulation and muscarinic receptor inhibition as well as potassium opening and calcium channels blocking effects are the possible mechanisms for the relaxant effects of the plant.

Calcium and potassium channels are involved in curcumin relaxant effect on tracheal smooth muscles

Context: Curcumin, the active component of Curcuma longa L. (Zingiberaceae), exhibits a wide variety of biological activities including vasodilation and anti-inflammation.Objective: The relaxant effect of curcumin in tracheal smooth muscle (TSM) was not examined so far, thus, this study was designed to assess the relaxant effect of curcumin on rat TSM and examine the underlying mechanism(s) responsible for this effect.Materials and methods: TSM was contracted by KCl (60 mM) or methacholine (10 μM), and cumulative concentrations of curcumin (12.5, 25, 50, and 100 mg/mL) or theophylline (0.2, 0.4, 0.6, and 0.8 mM, as positive control) were added to organ bath. The relaxant effect of curcumin was examined in non-incubated or incubated tissues with atropine (1 μM), chlorpheniramine (1 μM), indomethacin (1 μM), and papaverine (100 μM).Results: In non-incubated TSM, curcumin showed significant relaxant effects on KCl-induced contraction in a concentration-dependent manner (p < 0.001 for all concentrations). The relaxant effects of curcumin 12.5, 25, and 50 mg/mL were significantly lower in atropine-incubated tissue compared to non-incubated TSM (p < 0.05 to p < 0.001). A significant difference was observed in EC₅₀ between atropine-incubated (48.10 ± 2.55) and non-incubated (41.65 ± 1.81) tissues (p < 0.05). Theophylline showed a significant relaxant effect on both KCl and methacholine-induced contraction in a concentration-dependent manner (p < 0.001 for all cases).Conclusions: The results indicated a relatively potent relaxant effect of curcumin on TSM, which was less marked than the effect of theophylline. Calcium channel blocking and/or potassium channel opening properties of curcumin may be responsible for TSM relaxation.

Identification and Characterization of Novel Bronchodilator Agonists Acting at Human Airway Smooth Muscle Cell TAS2R5

Bitter taste receptors (TAS2Rs) are recognized as being expressed on multiple cell types and organs, including human airway smooth muscle (HASM) cells, where agonists promote significant relaxation to constrictive stimuli. Thus, the HASM TAS2Rs have been targeted as novel bronchodilators for the treatment of asthma and other obstructive lung diseases. The TAS2R5 subtype, a dominant receptor on HASM, has few known agonists, all with reported low potency and efficacy. We screened multiple compounds by measuring [Ca²⁺]_i release in HASM (a consequence of receptor-G protein coupling) to establish structure-activity relationships and arrive at a potent agonist for TAS2R5. HASM physiological studies using magnetic twisting cytometry confirmed the relaxation effects of lead compounds. 1,10-Phenanthroline-5,6-dione had the greatest potency (EC₅₀ ≈ 120 nM), amounting to a >1000-fold improvement over the other compounds, and displayed maximal efficacy. These studies revealed critical structural requirements for favorable potencies and efficacies for a potential first-in-class bronchodilator targeting TAS2R5 of the airway.

The contribution of beta-2 adrenergic, muscarinic and histamine (H1) receptors, calcium and potassium channels and cyclooxygenase pathway in the relaxant effect of Allium cepa L. on the tracheal smooth muscle

ETHNOPHARMACOLOGICAL RELEVANCE

There are report regarding therapeutic effects for Allium cepa L. (A. cepa) in Iranian traditional medicine and the plant has showed anti-inflammatory, anti-allergic, anti-hyperglycemic, antioxidant, anti-cancer, anti-hypertension, anti-hypercholesterolemia and anti-asthmatic activities in previous studies.

AIM OF THE STUDY

In this study, the contribution of β2 adrenergic, muscarinic and histamine (H1) receptors, calcium and potassium channels, and cyclooxygenase pathway in the relaxant effect of A. cepa extract on tracheal smooth muscle (TSM) was assessed.

MATERIALS AND METHODS

TSM was contracted by KCl (60 mM) or methacholine (10 μM) for 5 min and cumulative concentrations of A. cepa extract (2, 4, 8, 16, 32 and 64 mg/ml) were added to organ bath every 5 min. Theophylline (0.2, 0.4, 0.6 and 0.8 mM) as positive control, and saline (1 ml) as negative control were also examined in non-incubated tissues. The relaxant effect of A. cepa extract was examined on non-incubated and incubated TSM with propranolol, chlorpheniramine, diltiazem, atropine, glibenclamide and indomethacin.

RESULTS

A. cepa showed concentration-dependent relaxant effects on non-incubated TSM contracted by KCl (60 mM) or methacholine (10 μM), (P < 0.01 to p < 0.001). There was no significant difference in the relaxant effects of A. cepa between non-incubated and incubated tissues with glibenclamide, atropine, chlorpheniramine and indomethacin. The plant extract showed significant lower relaxant effects in incubated TSM with propranolol and diltiazem compared to non-incubated tissues. EC50 values of A. cepa extract in incubated TSM with propranolol and diltiazem were significantly lower than non-incubated tissues (p < 0.001 and p < 0.05, respectively). The relaxant effects of different concentrations of the extract of A. cepa were not significantly different with those of theophylline. The concentrations of A. cepa extract and theophylline were significant correlated with their relaxant effects (p < 0.05 to p < 0.001). In incubated TSM with propranolol and diltiazem, concentration ratio minus one (CR-1) values was positive (2.65 ± 0.63 and 1.28 ± 0.43 respectively).

CONCLUSION

The A. cepa extract showed relatively potent relaxant effect on TSM which was comparable to the effect of theophylline. The results showed that β2-adrenergic stimulatory and/or calcium channel blockade are the possible mechanisms for the relaxant effects of the plant.

Management of severe COPD exacerbations: focus on beclomethasone dipropionate/formoterol/glycopyrronium bromide

The major determinant of the decline in lung function, quality of life, and the increased mortality risk in patients with COPD is represented by severe acute exacerbations of the disease, that is, those requiring patients’ hospitalization, constituting a substantial social and health care burden in terms of morbidity and medical resource utilization. Different long-term therapeutic strategies have been proposed so far in order to prevent and/or reduce the clinical and social impact of these events, the majority of which were extrapolated from trials initially focused on the effect of long-acting muscarinic antagonist and subsequently on the efficacy of long-acting β2-agonists in combination or not with inhaled corticosteroids. The option to employ all three classes of molecules combined, despite the limited amount of evidence in our possession, represents a choice currently proposed by international guidelines; however, current recommendations are often based mainly on observational studies or on the results of secondary outcomes in randomized controlled trials. The present narrative review evaluates the available trials that investigated the efficacy of inhaled therapy to prevent COPD exacerbations and especially severe ones, with a particular focus on beclomethasone dipropionate/formoterol/glycopyrronium bromide fixed dose combination, which is the first treatment that comprises all the three drug classes, specifically tested for the prevention of moderate and severe COPD exacerbations.

Translational model to predict pulmonary pharmacokinetics and efficacy in man for inhaled bronchodilators

Translational pharmacokinetic (PK) models are needed to describe and predict drug concentration‐time profiles in lung tissue at the site of action to enable animal‐to‐man translation and prediction of efficacy in humans for inhaled medicines. Current pulmonary PK models are generally descriptive rather than predictive, drug/compound specific, and fail to show successful cross‐species translation. The objective of this work was to develop a robust compartmental modeling approach that captures key features of lung and systemic PK after pulmonary administration of a set of 12 soluble drugs containing single basic, dibasic, or cationic functional groups. The model is shown to allow translation between animal species and predicts drug concentrations in human lungs that correlate with the forced expiratory volume for different classes of bronchodilators. Thus, the pulmonary modeling approach has potential to be a key component in the prediction of human PK, efficacy, and safety for future inhaled medicines.

Relaxant effect of Curcuma longa on rat tracheal smooth muscle and its possible mechanisms

CONTEXT

Turmeric is a spice obtained from the root of Curcuma longa L. (Zingiberaceae) with anti-aging, anticancer, anti-Alzheimer's disease, antioxidant and other medicinal properties.

OBJECTIVE

The relaxant effect of C. longa on rat tracheal smooth muscle and its possible mechanisms were investigated in this study.

MATERIALS AND METHODS

The relaxant effects of four cumulative concentrations of hydro-ethanol extract of C. longa (6.25, 12.5, 25, 50 mg/mL) were studied on tracheal smooth muscle precontracted by methacholine or KCl in non-incubated or incubated with different substances including propranolol, diltiazem, L-NAME, glibenclamide, atropine, chlorpheniramine, indomethacin and papaverine. The duration of the study was 84 days.

RESULTS

In non-incubated tracheal smooth muscle, the extract of C. longa showed significant concentration-dependent relaxant effects (p < 0.001 for all concentrations on both KCl and methacholine-induced contraction). There was no significant difference in the relaxant effects between C. longa and theophylline in both methacholine and KCl-induced contraction conditions. In tissues incubated with propranolol, diltiazem, L-NAME and glibenclamide on methacholine-induced contraction and in tissues incubated with atropine, chlorpheniramine, indomethacin and papaverine on KCl-induced contraction, the extract also showed significant concentration-dependent relaxant effects (p < 0.001). EC₅₀ values of C. longa between non-incubated (16.22 ± 0.62) and incubated tissues (atropine: 13.03 ± 0.55, chlorpheniramine: 12.94 ± 0.68, indomethacin: 14.80 ± 0.57 and papaverine: 16.16 ± 1.42) were not significantly different.

CONCLUSIONS

Tracheal smooth muscle relaxant effects of C. longa, were comparable to those of theophylline, which could be due to the presence of methylxanthines or its possible interaction with non-adrenergic non-cholinergic nervous system.

Hydro-ethanolic Extract of Portulaca oleracea Affects Beta-adrenoceptors of Guinea Pig Tracheal Smooth Muscle

Thestimulatory effect of the extract of Portulaca oleracea (P. olerace) on β-adrenoceptor of tracheal smooth muscle was examined.To examine β-adrenoceptor stimulatory effect, concentration response curve to isoprenaline was obtained in pre-contracted tracheal smooth muscle in the presence of three concentrations of aqueous-ethanolic extract, propranolol, and saline. Values of EC₅₀ (the effective concentration of isoprenaline, causing 50% of maximum response) and dose ratio-1(CR-1) were measured. This effect was tested innon-incubated tracheal smooth muscle (group 1) and incubated tissues with chlorpheniramine (group 2). Concentration-response curves to isoprenaline in the presence of two higher concentrations of the extract in group 1 and all three concentrations in group 2 showed leftward shifts compared to isoprenaline curves produced in the presence of saline in both groups. EC₅₀ obtained in the presence of propranolol was significantly higher than that of saline in both groups of experiments (p<0.05 for both cases). However, the EC₅₀ obtained in the presence of two higher concentrations of the extract in group 1 and lower concentration in group 2 were non-significantly but those obtained of medium and high extract concentrations in the group 2 were significantly (p<0.05 for both cases)lower than those of saline. The values of (CR-1) obtained in the presence of all concentrations of the extract in groups1 and 2 were significantly lower than that of propranolol (p<0.05 to p<0.001).The results indicated a stimulatory effect of the P. olerace extract on ß ₂-adrenoceptors of tracheal smooth muscle.

Pharmacological evaluation of Apium leptophyllum (Pers.) on bronchial asthma

Objective:

The present study was to investigate the antiasthmatic potential from the flavonoid fraction of Apium leptophyllum fruit (FFALF) to validate its traditional claim.

Materials and Methods:

The antiasthmatic activity of FFALF was evaluated by histamine or acetylcholine-induced bronchospasm model in guinea pigs, compound 48/80 induced mast cell degranulation in albino rats and histamine-induced tracheal contraction in guinea pig. The preconvulsion dyspnea time at 0^th and 7^th day at the dose of 100 and 200 mg/kg in guinea pig's bronchospasm model, the percentage of granulated and degranulated mast cell at the dose of 500, 750, and 1000 μg/ml in rats and tracheal contraction at the dose of 500, 750, and 1000 μg/ml in guinea pig were measured and compared with respective control groups.

Results:

The treatments of FFALF were significantly (P < 0.001) decreased the histamine/acetylcholine-induced bronchospasm, mast cell degranulation, and histamine-induced tracheal contraction as compared to inducer group. In addition, FFALF showed dose-dependent antiasthmatic activity in all the animals.

Conclusion:

Hence, this study suggested that the FFALF showed antiasthmatic activity probably by membrane stabilizing property as well as suppressing antibody production and inhibiting of antigen induced by histamine and acetylcholine.

Possible Mechanisms for Functional Antagonistic Effect of Ferula assafoetida on Muscarinic Receptors in Tracheal Smooth Muscle

BACKGROUND

The contribution of histamine (H1) receptors inhibitory and/or β-adrenoceptors stimulatory mechanisms in the relaxant property of Ferula assa-foetida. (F. asafoetida) was examined in the present study.

METHODS

We evaluated the effect of three concentrations of F. asafoetida extract (2.5, 5, and 10 mg/mL), a muscarinic receptors antagonist, and saline on methacholine concentration-response curve in tracheal smooth muscles incubated with β-adrenergic and histamine (H1) (group 1), and only β-adrenergic (group 2) receptors antagonists.

RESULTS

EC50 values in the presence of atropine, extract (5 and 10 mg/mL) and maximum responses to methacholine due to the 10 mg/mL extract in both groups and 5 mg/mL extract in group 1 were higher than saline (P < 0.0001, P = 0.0477, and P = 0.0008 in group 1 and P < 0.0001, P = 0.0438, and P = 0.0107 in group 2 for atropine, 5 and 10 mg/mL extract, respectively). Values of concentration ratio minus one (CR-1), in the presence of extracts were lower than atropine in both groups (P = 0.0339 for high extract concentration in group 1 and P < 0.0001 for other extract concentrations in both groups).

CONCLUSION

Histamine (H1) receptor blockade affects muscarinic receptors inhibitory property of F. asafoetida in tracheal smooth muscle.

A review of the relaxant effect of various medicinal plants on tracheal smooth muscle, their possible mechanism(s) and potency

ETHNOPHARMACOLOGICAL RELEVANCE

The therapeutic effects of the medicinal plants described in the current review on obstructive pulmonary diseases have found mention in ancient Iranian medical texts and in traditional folk medicine. These effects are attributed to their bronchodilatory activity, which relaxes the smooth muscles of the airway. Therefore, in the present review, the relaxant effects of various extracts, fractions and constituents of medicinal plants on tracheal smooth muscle are reviewed in light of their therapeutic effects on obstructive pulmonary diseases.

MATERIALS AND METHODS

The online literature was searched using Medline, PubMed, ScienceDirect, Scopus, Google Scholar, Web of Science and SID (for articles written in Persian). Moreover, local books on ethnopharmacology from 1918 to 2014 were searched with keywords such as tracheal smooth muscle, airway smooth muscle, relaxant effect, bronchodilatory effect and related mechanisms to identify studies on the relaxant effects of medicinal plants on tracheal smooth muscle and the possible mechanism(s) of these effects.

RESULTS

All studied plants showed significant relaxant effects on tracheal smooth muscle, which were similar or superior to the effect of theophylline at the used concentrations. According to the results, most of these plants also showed an inhibitory effect on muscarinic and histamine (H1) receptors, whereas some plants showed more pronounced stimulatory effects on the beta-adrenergic receptor. Some of the studied plants also showed inhibitory effects on calcium and potassium channels.

CONCLUSION

The present article reviewed the relaxant effects of several medicinal plants on tracheal smooth muscle, which were comparable or superior to the effect of theophylline at the studied concentration. The possible mechanisms of the relaxant effects of the studied medicinal plants and a comparison of these effects were also reviewed. This review presents the fractions and constituents of plants with potent relaxant effects on tracheal smooth muscle, which can be used to treat obstructive pulmonary disease.

Rosiglitazone elicits in vitro relaxation in airways and precision cut lung slices from a mouse model of chronic allergic airways disease

Rosiglitazone (RGZ), a peroxisome proliferator-activated receptor-γ (PPARγ) ligand, is a novel dilator of small airways in mouse precision cut lung slices (PCLS). In this study, relaxation to RGZ and β-adrenoceptor agonists were compared in trachea from naïve mice and guinea pigs and trachea and PCLS from a mouse model of chronic allergic airways disease (AAD). Airways were precontracted with methacholine before addition of PPARγ ligands [RGZ, ciglitazone (CGZ), or 15-deoxy-(Δ12,14)-prostaglandin J2 (15-deoxy-PGJ2)] or β-adrenoceptor agonists (isoprenaline and salbutamol). The effects of T0070907 and GW9662 (PPARγ antagonists) or epithelial removal on relaxation were assessed. Changes in force of trachea and lumen area in PCLS were measured using preparations from saline-challenged mice and mice sensitized (days 0 and 14) and challenged with ovalbumin (3 times/wk, 6 wk). RGZ and CGZ elicited complete relaxation with greater efficacy than β-adrenoceptor agonists in mouse airways but not guinea pig trachea, while 15-deoxy-PGJ2 did not mediate bronchodilation. Relaxation to RGZ was not prevented by T0070907 or GW9662 or by epithelial removal. RGZ-induced relaxation was preserved in the trachea and increased in PCLS after ovalbumin-challenge. Although RGZ was less potent than β-adrenoceptor agonists, its effects were additive with salbutamol and isoprenaline and only RGZ maintained potency and full efficacy in maximally contracted airways or after allergen challenge. Acute PPARγ-independent, epithelial-independent airway relaxation to RGZ is resistant to functional antagonism and maintained in both trachea and PCLS from a model of chronic AAD. These novel efficacious actions of RGZ support its therapeutic potential in asthma when responsiveness to β-adrenoceptor agonists is limited.

Why use long acting bronchodilators in chronic obstructive lung diseases? An extensive review on formoterol and salmeterol

Long-acting β2-adrenoceptor agonists, formoterol and salmeterol, represent a milestone in the treatments of chronic obstructive lung diseases. Although no specific indications concerning the choice of one molecule rather than another are provided by asthma and COPD guidelines, they present different pharmacological properties resulting in distinct clinical employment possibilities. In particular, salmeterol has a low intrinsic efficacy working as a partial receptor agonist, while formoterol is a full agonist with high intrinsic efficacy. From a clinical perspective, in the presence of low β2-adrenoceptors availability, like in inflamed airways, a full agonist can maintain its bronchodilatory and non-smooth muscle activities while a partial agonist may be less effective. Furthermore, formoterol presents a faster onset of action than salmeterol. This phenomenon, combined with the molecule safety profile, leads to a prompt amelioration of the symptoms, and allows using this drug in asthma as an "as needed" treatment in patients already on regular treatment. The fast onset of action and the full agonism of formoterol need to be considered in order to select the best pharmacological treatment of asthma and COPD.

The Effect of Hydroethanol Extract of Achillea Millefolium on β-adrenoceptors of Guinea Pig Tracheal Smooth Muscle

Different pharmacological effects of Achillea millefolium including its relaxant effect on smooth muscle have been shown previously. In the present study the stimulatory effect of the plant extract on β-adrenoceptor of tracheal muscle was examined in order to investigate one possible mechanism for its observed relaxant effect. Effect of three concentrations of hydroethanol extract, 10 nM propranolol, and saline on β-adrenoceptor was tested in two experimental groups including; nonincubated tracheal smooth muscles (group 1) and incubated tracheal smooth muscle with chlorpheniramine (group 2). Concentration response curves to isoprenaline were performed in precontracted tracheal smooth muscle in the presence of the extract, propranolol and saline. Values of EC₅₀ and CR-1 were measured. Leftward shifts in isoprenaline curves were observed in the presence of medium and high concentrations of the extract compared with saline in both groups. The values of EC₅₀ obtained in the presence of medium and high concentrations of the extract only in group 1 were nonsignificantly lower than that of saline. The values of CR-1 obtained in the presence of all concentrations of the extract in both groups were negative and significantly different with that of propranolol. The results indicated a small stimulatory effect of the extract on ß₂-adrenoceptors.

Evaluation of the Bronchorelaxant, Genotoxic, and Antigenotoxic Effects of Cassia alata L

Aqueous-ethanolic extract of Cassia alata (AECal) and its derived fractions obtained through liquid-liquid fractionation were evaluated for their bronchorelaxant, genotoxic, and antigenotoxic effects. Contractile activity of rats' tracheas in the presence of tested materials, as well as its modifications with different inhibitors and blockers, was isometrically recorded. The antigenotoxic potential of AECal was evaluated on cyclophosphamide- (CP-) induced genotoxicity in the rat. Animals were pretreated with the extract, then liver comet assay was performed. AECal and its chloroformic fractions (CF-AECal) relaxed the contraction induced by Ach, but both were significantly less potent in inhibiting contraction induced by KCl (30 mM; 80 mM). Propranolol, indomethacin, L-NAME, methylene blue, and glibenclamide did not modify the relaxant effect of CF-AECal. TEA altered the response of trachea to CF-AECal. CF-AECal caused a rightward shift without affecting the E max in cumulative concentration-response curves of Ach only at low concentrations. In animals pretreated with the extract, the percentage of CP-induced DNA damage decreased. Our results suggest that (1) muscarinic receptors contribute at least in part to the relaxant effects of CF-AECal; (2) CF-AECal interferes with membrane polarization; and (3) AECal is not genotoxic in vivo and contains chemopreventive phytoconstituents offering protection against CP-induced genotoxicity.

Possible Mechanism(s) of the Relaxant Effects of Achillea wilhelmsii on Guinea-Pig Tracheal Chains

Achillea wilhelmsii have been used in folk remedies. The relaxant effects of the extract of A. wilhelmsii on tracheal chains of guinea pigs were examined. The relaxant effects of four cumulative concentrations of the extract, theophylline and saline were examined by their relaxant effects on precontracted tracheal chains of guinea pig by KCl (group 1), 10 μM methacholine (group 2), incubated tissues by atropine, propranolol and chlorpheniramine and contracted by KCl (group 3) and incubated tissues by propranolol and chlorpheniramine and contracted by methacholine (group 4). In group 1 and 2, all concentrations of theophylline and three higher concentrations (4, 6 and 8 mg/mL) of the extract showed significant relaxant effects compared to that of saline. In groups 3 and 4 experiments also all concentrations of the extract showed significant relaxant effects compared to that of saline. The relaxant effect of three higher concentrations (4, 6 and 8 mg/mL) of the extract in group 1 were significantly greater than those of group 2 and in group 3 were significantly lower than those of group 1. There were significant positive correlations between the relaxant effects and concentrations for theophylline in groups 1 and 2 and the extract in all four groups of experiments. These results showed a potent relaxant effect for the extract from A. wilhelmsii on tracheal chains of guinea pigs. A muscarinc receptor blockade was also suggested for the extract.

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.

Evaluation of antiasthmatic activity of ethanolic extract of Elephantopus scaber L. leaves

AIMS

The aim of study was to evaluate the scientific basis for the traditional use of Elephantopus scaber leaves.

MATERIALS AND METHODS

In the present study, ethanol extract of Elephantopus scaber leaves was evaluated for preliminary phytochemical screening and antiasthmatic activity using histamine and acetylcholine-induced bronchospasm, mast cell degranulation and histamine induced constriction on isolated guinea pig tracheal chain at different dose levels. Student's t-Test and Dunett's test were used for statistical analysis.

RESULTS

The result of present investigation showed that the ethanolic extract of E. scaber significantly (P<0.001) decreased the bronchospasm induced by histamine, acetylcholine and protected mast cell degranulation as compared to control groups. It also decreased the histamine induce constriction on isolated guinea pig trachea in dose-dependent manner. Phytochemical studies revealed the presence of steroids, saponin, flavonoids, and phenolic compounds in the extract.

CONCLUSIONS

The present study concludes that the antiasthmatic activity of ethanolic extract of E. scaber leaves may be due to the presence of flavonoids or steroids. Antiasthmatic action of the E. scaber could be due to its antihistaminic, anticholinergic and mast-cell-stabilizing property.

Controversies regarding long-acting β2-agonists

PURPOSE OF REVIEW

This review examines the literature regarding the efficacy and safety of long-acting β2-agonists as add-on therapy to inhaled corticosteroids.

RECENT FINDINGS

The Global Initiative for Asthma (GINA) 2009 guidelines and the National Heart, Lung, and Blood Institute (NHLBI) 2007 asthma guidelines recommend adding long-acting β2-agonists to patients inadequately controlled on inhaled corticosteroids. These recommendations must be balanced against published data which demonstrate a signal of increased morbidity and mortality with use of long-acting β2-agonists. These conflicting data raise the question of whether or not there may be genotypic or phenotypic discriminators leading to disparate responses to long-acting β2-agonists.

SUMMARY

The combination of long-acting β2-agonists and inhaled corticosteroids demonstrates improvement in asthma control and exacerbation rates; however, long-acting β2-agonists are not recommended for use as monotherapy or without optimization of inhaled corticosteroid dose. Although the majority of asthmatic patients appear to benefit from the addition of long-acting β2-agonists, there are concerns that a small proportion of patients, including steroid-naïve patients and African Americans, may not obtain such benefits. Thus far, studies have not clearly demonstrated genotypic or phenotypic differences explaining the variability in response.

Dichrostachys cinerea (L.) Wight et Arn (Mimosaceae) hydro-alcoholic extract action on the contractility of tracheal smooth muscle isolated from guinea-pig

BACKGROUND

Dichrostachys cinerea (L.) Wight et Arn. (Mimosaceae) is largely used in ethno-medically across Africa, and mainly employed for the treatment of asthma in Ivory Coast and Gabon. The paper analyses the relaxation induced by the methanolic extract of D. cinerea (Edici) in the guinea-pig trachea preparations (GPTPs).

PURPOSE

This study aimed to bring out the scientific basis to the use of this plant leading to the validation of this phytomedicine.

METHOD

The aorta obtained from guinea-pigs was immediately placed in a Mac Ewen solution. Experiments were performed in preparations suspended between two L-shaped stainless steel hooks in a 10 ml organ bath containing Mac Ewen solution. The isometric contractile force of the aorta strips of guinea-pig were recorded by using a strain gauge. The different drugs were directly administered into the organ bath and the magnitude of GPTPs was evaluated.

RESULTS

Phytochemical analysis of the methanolic extract of Dichrostachys cinerea (Edici) using chemical methods revealed the presence of flavenoids, tannins, sterols, triterpenes and polyphenols. Pharmacological studies performed in GPTPs show that of Dichrostachys cinerea (0.1 mg/ml - 2 mg/ml) evoked a broncho-constriction in GPTPs. Whereas, at concentration up to 2 mg/ml, Edici induced a significant dose-dependent relaxation in the GPTPs. KCl-, ACh- or histamine-evoked contractions of isolated trachea was significantly inhibited by increasing concentrations of Edici (3.5-10 mg/ml). Edici (10 mg/ml) as well as promethazine (0.25 mg/ml) significantly inhibited contractions induced by increasing concentrations of histamine (1×10-7-1×10-4mg/ml). In the presence of atropine at a concentration of 10-6mg/ml, contractile response curve (CRC) evoked by ACh (1×10-5-1×10-2 mg/ml) was significantly abolished in concentration-dependent manner. Edici did not significantly reduced ACh evoked contraction (10-5-10-2mg/ml).

CONCLUSION

These observations suggest that Edici could act through two mechanisms: firstly by activation of β-adrenergic or histaminergic receptors; and secondly muscarinic receptors may not be greatly involved, that justifying the use of the extract in traditional Medicine in Africa.

Effects of formoterol on protein metabolism in myotubes during hyperthermia

Proteolysis in skeletal muscle is mainly carried out by the activity of the ubiquitin-dependent proteolytic system. For the study of protein degradation through the ubiquitin-proteasome pathway, we used a model of hyperthermia in murine myotubes. In C2C12 cells, hyperthermia (41°C) induced a significant increase in both the rate of protein synthesis (18%) and degradation (51%). Interestingly, the addition of the β(2) -adrenoceptor agonist formoterol resulted in a significant decrease in protein degradation (21%) without affecting protein synthesis. The decrease in proteolytic rate was associated with decreases in gene expression of the different components of the ubiquitin-dependent proteolytic system. The effects of the β(2) -agonist on protein degradation were dependent exclusively on cAMP formation, because inhibition of adenylyl cyclase completely abolished the effects of formoterol on protein degradation. It can be concluded that hyperthermia is a suitable model for studying the anti-proteolytic potential of drugs used in the treatment of muscle wasting.

Zataria multiflora Boiss and Carvacrol Affect β(2)-Adrenoceptors of Guinea Pig Trachea

The stimulatory effect of Zataria multiflora Boiss (Labiatae) and carvacrol on β-adrenoceptors was examined on guinea pig trachea. The effects of three concentrations of aqueous-ethanolic extract, carvacrol, and propranolol (β-receptor antagonist) on β-adrenoceptors were tested in nonincubated (group 1, n = 8) and incubated tracheal chains with 1 μM chlorpheniramine (histamine H1 receptor antagonist) (group 2, n = 5). Isoprenaline (β-receptor agonist) curves obtained in the presence of all concentrations of the extract and carvacrol showed leftward shifts compared with that of saline in both groups. In both groups, the EC50 (the effective concentration of isoprenaline, causing 50% of maximum response) obtained in the presence of all concentrations of the extract and carvacrol was significantly lower compared to that of saline (P < .01 to P < .001). All values of (CR-1: (EC50 in the presence of active substances/EC50 obtained in the presence of saline)-1) obtained in the presence of concentrations of the extract and carvacrol in both groups were negative and significantly different from that of propranolol (P < .001 for all cases). The results indicated a stimulatory effect of Zataria multiflora Boiss extract on β(2)-adrenoceptors which is perhaps due to its constituent, carvacrol.

Optimising treatment for COPD--new strategies for combination therapy

Chronic obstructive pulmonary disease (COPD) is a multi-component disease characterised by airflow limitation and airway inflammation. Exacerbations of COPD have a considerable impact on the quality of life, daily activities and general well-being of patients and are a great burden on the health system. Thus, the aims of COPD management include not only relieving symptoms and preventing disease progression but also preventing and treating exacerbations. Attention towards the day-to-day burden of the disease is also required in light of evidence that suggests COPD may be variable throughout the day with morning being the time when symptoms are most severe and patients' ability to perform regular morning activities the most problematic. While available therapies improve clinical symptoms and decrease airway inflammation, they do not unequivocally slow long-term progression or address all disease components. With the burden of COPD continuing to increase, research into new and improved treatment strategies to optimise pharmacotherapy is ongoing - in particular, combination therapies, with a view to their complementary modes of action enabling multiple components of the disease to be addressed. Evidence from recent clinical trials indicates that triple therapy, combining an anticholinergic with an inhaled corticosteroid and a long-acting beta(2)-agonist, may provide clinical benefits additional to those associated with each treatment alone in patients with more severe COPD. This article reviews the evidence for treatment strategies used in COPD with a focus on combination therapies and introduces the 3-month CLIMB study (Evaluation of Efficacy and Safety of Symbicort as an Add-on Treatment to Spiriva in Patients With Severe COPD) which investigated the potential treatment benefits of combining tiotropium with budesonide/formoterol in patients with COPD with regard to lung function, exacerbations, symptoms and morning activities.

Stimulatory effect of Crocus sativus (saffron) on beta2-adrenoceptors of guinea pig tracheal chains

To study the mechanism(s) of the relaxant effects of Crocus sativus (Iridaceae), the stimulatory effect of aqueous-ethanolic extracts of this plant and one of its constituent, safranal was examined on beta-adrenoceptors in tracheal chains of guinea pigs. The beta(2)-adrenergic stimulatory was tested by performing the cumulative concentration-response curves of isoprenaline-induced relaxation of pre-contracted isolated guinea pig tracheal chains. The studied solutions were included two concentrations of aqueous-ethanolic extract from Crocus sativus (0.1 and 0.2g%), safranal (1.25 and 2.5 microg), 10nM propranolol, and saline. The study was done in two different conditions including: non-incubated (group 1, n=9) and incubated tissues with 1 microM chlorpheniramine (group 2, n=6). The results showed clear leftward shifts in isoprenaline curves obtained in the presence of only higher concentration of the extract in group 1 and its both concentrations in group 2 compared with that of saline. The EC(50) (the effective concentration of isoprenaline, causing 50% of maximum response) obtained in the presence of both concentrations of the extract (0.17+/-0.06 and 0.12+/-0.02) and safranal (0.22+/-0.05 and 0.22+/-0.05) in group 1 and only in the presence of two concentrations of the extract (1.16+/-0.31 and 0.68+/-0.21) in group 2 was significantly lower compared to saline (1.00+/-0.22 and 4.06+/-1.04 for groups 1 and 2, respectively) (p<0.05-0.001). The maximum responses obtained in the presence of both concentrations of the extract and safranal in group 1 were significantly lower than that of saline (p<0.005 for all cases). All values (CR-1=(EC(50) obtained in the presence of active substances/EC(50), obtained in the presence of saline)-1) obtained in the presence of higher concentrations of extract in group 1, its both concentrations and higher concentration of safranal in group 2 were negative and there were significant differences in this value between propranolol and those obtained in the presence of extract and safranal (p<0.05 to p<0.001). The results indicated a relatively potent stimulatory effect of the extract from Crocus sativus on beta(2)-adrenoceptors which is partially due to its constituent, safranal. A possible inhibitory effect of the plant on histamine (H(1)) receptors was also suggested.

Relaxations to beta-adrenoceptor subtype selective agonists in wild-type and NOS-3-KO mouse mesenteric arteries

We have investigated the role of nitric oxide (NO) in relaxations to beta-adrenoceptor agonists in mesenteric artery from wild-type (WT) and NO synthase-3 knockout (NOS-3-KO) mice. Isoprenaline, formoterol and BRL 37344 ((R(),R())-(+/-)-4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl)amino]propyl]phenoxyacetic acid) were chosen as non-selective and beta(2)- and beta(3)-adrenoceptor agonists, respectively. Atenolol, ICI 118,551 ((+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride) and SR59230A (1-(2-ethylphenoxy)-3-[[(1S)-1,2,3,4-tetrahydro-1-naphthalenyl]amino]-(2S)-2-propanol hydrochloride) were chosen as selective beta(1)-, beta(2)- and beta(3)-adrenoceptor antagonists, respectively. Experiments employing isoprenaline were carried out in the presence of prazosin (0.1 microM). Isoprenaline produced relaxations with a potency of 5.68+/-0.36 (-log M, n=6) in WT mice. Relaxations to isoprenaline were blocked by atenolol (10 microM) and were absent in vessels from NOS-3-KO animals. Formoterol produced relaxations with two components. ICI 118,551 (1 microM) abolished relaxations to low concentrations of formoterol (0.1-10 microM), but failed to affect relaxations to formoterol (100 microM). In NOS-3-KO mice only the highest concentration of formoterol (100 microM) produced relaxations: the relaxation was resistant to all of the beta-adrenoceptor antagonists employed. BRL 37344 (5.75+/-0.28, n=9) was approximately equipotent with isoprenaline but produced a smaller degree of relaxation, in WT mice. SR59230A (1 microM) abolished relaxations to BRL 37344 in WT mice. In NOS-3-KO mice, BRL 37344 produced concentration-dependent relaxations which were abolished by SR59230A. It is concluded that the predominant beta-adrenoceptor mediating relaxations in mouse mesenteric artery is beta(1), and relaxations involve NOS-3. In addition, beta(3)-adrenoceptors mediate smaller relaxations at least partly independent of NOS-3, and beta(2)-adrenoceptors may mediate smaller relaxations dependent on NOS-3.

Long duration of airway but not systemic effects of inhaled formoterol in asthmatic patients

RATIONALE

Formoterol is approved as asthma rescue medication in many countries. The exact duration of the airway vs. systemic effects of formoterol compared with another rescue medication, salbutamol, has not been evaluated.

OBJECTIVE

To assess the duration of airway bronchodilatory effects vs. systemic effects of inhaled formoterol and salbutamol in asthmatic patients.

METHODS

Twenty-six patients with stable and reversible asthma were given single doses of formoterol dry-powder inhaler (OxisTurbuhaler) 2x9 microg (lower dose; LD) and 6x9 microg (higher dose; HD), salbutamol (VentolinDiskhaler) 3x400 microg (LD) and 9x400 microg (HD), and placebo in a randomized, double-blind, crossover trial. Airway and systemic effects were assessed by forced expiratory volume in 1s (FEV1), serum potassium, blood pressure, corrected QT-interval (QTc), and palpitation and tremor scores. Time with clinically relevant bronchodilation (FEV1 increase 12%) without clinically relevant markers of systemic effects (serum potassium suppression 0.2 mmol/L, QTc-prolongation 20 ms, or heart rate increase 8 beats per minute) was evaluated.

RESULTS

Bronchodilation was maintained for 24h with both formoterol doses and for 7-11h with salbutamol. Maximum bronchodilation and systemic effects were similar after formoterol and salbutamol, except for statistically significantly larger maximum heart rate and palpitation and tremor scores after salbutamol. Systemic responses were similarly brief for formoterol and salbutamol (7 h).

CONCLUSIONS

The airway effects of inhaled formoterol are of long duration, whereas the systemic effects are of a similarly short duration as salbutamol. Thus, the time with clinically relevant bronchodilation without systemic effects is substantially longer after formoterol than after salbutamol.

Relaxant effect of Crocus sativus (saffron) on guinea-pig tracheal chains and its possible mechanisms

As indicated in ancient Iranian medical books, Crocus sativus has therapeutic effects on respiratory diseases. The relaxant effect of this plant has been observed also on smooth muscles in previous studies. Therefore, in this study the relaxant effects of aqueous-ethanolic extracts of C. sativus and one of its main constituents, safranal, were examined on guinea-pig tracheal chains. The relaxant effects of four cumulative concentrations of aqueous-ethanolic extract (0.15, 0.3, 0.45, and 0.60 g %) and safranal (0.15, 0.30, 0.45, and 0.60 mL 0.2 mg mL(-1) solution) in comparison with saline, as negative control, and four cumulative concentrations of theophylline (0.15, 0.30, 0.45, and 0.60 mM), as positive control, were examined using guinea-pig precontracted tracheal chains. The tracheal chains had been precontracted by three different methods. Group 1 had been precontracted using 10 microM methacholine. The other two groups had been precontracted using 60 mM KCl at two different conditions: non-incubated tissues (group 2) and tissues incubated with 1 microM propranolol, 1 microM chlorpheniramine and 1 microM atropine (group 3) (for each group, n = 6). In group 1 all concentrations of theophylline, extract and safranal showed significant relaxant effects compared with saline (P < 0.05 to P < 0.001). In group 2 theophylline, extract and safranal showed concentration-dependent relaxant effects also compared with saline (P < 0.05 to P < 0.001 for different concentrations except two low concentrations of safranal). However, in group 3 the extracts of C. sativus showed a weak relaxant effect (P < 0.05 only for the highest concentration). The effects of the last concentration of safranal (0.60 mL 0.2 mg mL(-1) solution) in group 1, and all its concentrations in group 2 were significantly lower than those of theophylline (P < 0.05 to P < 0.001). In addition, the effects of safranal 0.45 and 0.60 mL 0.2 mg mL(-1) solution in groups 1 and 2 were significantly lower than that of C. sativus extract. There were significant correlations between the relaxant effects and concentrations for extract, safranal and theophylline in all experimental groups (P < 0.001 for all cases). These results showed a potent relaxant effect of C. sativus on tracheal chains of guinea-pigs that was comparable to or even higher than that of theophylline at the concentrations used. The results indicated that safranal was, at least in part, responsible for the relaxant effect of C. sativus.

Systemic administration of beta2-adrenoceptor agonists, formoterol and salmeterol, elicit skeletal muscle hypertrophy in rats at micromolar doses

beta(2)-Adrenoceptor agonists provide a potential therapy for muscle wasting and weakness, but their use may be limited by adverse effects on the heart, mediated in part, by beta(1)-adrenoceptor activation. Two beta(2)-agonists, formoterol and salmeterol, are approved for treating asthma and have an extended duration of action and increased safety, associated with greater beta(2)-adrenoceptor selectivity. The pharmacological profiles of formoterol and salmeterol and their effects on skeletal and cardiac muscle mass were investigated in 12-week-old, male F344 rats. Formoterol and salmeterol were each administered via daily i.p. injection at one of seven doses (ranging from 1 to 2,000 microg kg(-1) day(-1)), for 4 weeks. Rats were anaesthetised and the EDL and soleus muscles and the heart were excised and weighed. Dose-response curves were constructed based on skeletal and cardiac muscle hypertrophy. Formoterol was more potent than salmeterol, with a significantly lower ED(50) in EDL muscles (1 and 130 microg kg(-1) day(-1), P <0.05), whereas salmeterol had greater intrinsic activity than formoterol in both EDL and soleus muscles (12% greater hypertrophy than formoterol). The drugs had similar potency and intrinsic activity in the heart, with a smaller leftward shift for formoterol than seen in skeletal muscle. A dose of 25 microg kg(-1) day(-1) of formoterol elicited greater EDL and soleus hypertrophy than salmeterol, but resulted in similar beta-adrenoceptor downregulation. These results show that doses as low as 1 microg kg(-1) day(-1) of formoterol can elicit significant muscle hypertrophy with minimal cardiac hypertrophy and provide important information regarding the potential therapeutic use of formoterol and salmeterol for muscle wasting.

The use of inhaled formoterol in the treatment of asthma

OBJECTIVE

To discuss the clinical efficacy and safety of formoterol when used to relieve symptoms of asthma and prevent exercise-induced bronchoconstriction (EIB).

DATA SOURCES

A PubMed search was performed for articles published between 1997 and 2005 with the keywords formoterol, asthma, and long-acting beta2-adrenergic agonist, with cross-referencing to identify peer-reviewed journal articles.

STUDY SELECTION

Published articles on the clinical use of formoterol for asthma or EIB were included as well as articles detailing the pharmacologic properties of the drug. To present a thorough review of the literature, published studies based on patient number, study design, or other measures of study quality were not excluded.

RESULTS

Formoterol is the only long-acting beta2-adrenergic agonist that combines a rapid onset of action (within 3 minutes) with a long duration of effect (approximately 12 hours). Clinically, as recommended by asthma treatment guidelines, formoterol in conjunction with inhaled corticosteroids (ICSs) is a preferred treatment for moderate to severe persistent asthma. Significant clinical data support the use of formoterol in combination with ICSs for the treatment of asthma, with studies demonstrating improved pulmonary function and symptom scores and decreased need for maintenance ICSs and short-acting beta2-adrenergic agonists (SABAs) as relief medication. Recent studies also demonstrate that use of formoterol as needed as relief medication is associated with a prolonged time to exacerbation, improved pulmonary function, and decreased asthma symptoms. When used as monotherapy, formoterol provides protection against EIB. Clinical data also demonstrate that formoterol is safe and well tolerated even in high doses, with an adverse event profile similar to that of SABAs.

CONCLUSION

Overall, formoterol is safe and effective as adjunct controller therapy for moderate and severe persistent asthma and as monotherapy for EIB.

Relaxant effects of Rosa damascena on guinea pig tracheal chains and its possible mechanism(s)

Several therapeutic effects including hypnotic, antispasmodic, treatment of abdominal and chest pain and strengthening the heart have been described for the flowers of Rosa damascena. Therefore in the present study, the relaxant effects of ethanolic extract and essential oils of Rosa damascena on tracheal chains of guinea pigs were examined. The relaxant effects of four cumulative concentrations of ethanolic extract (0.25, 0.5, 0.75, and 1.0g%) and essential oils (0.25, 0.5, 0.75, and 1.0vol.%) in comparison with saline as negative control and four cumulative concentrations of theophylline (0.25, 0.5, 0.75, and 1.0mM) were examined by their relaxant effects on precontracted tracheal chains of guinea pig by 60mM KCl (group 1, n=5) and 10microM methacholine in two different conditions including: non-incubated tissues (group 2, n=8) and incubated tissues with 1microM propranolol and 1microM chlorpheniramine (group 3, n=5). In group 1 experiments two final concentrations of essential oil and theophylline and only final concentration of ethanolic extract showed relaxant effects compared to that of saline (p<0.01-0.001). In group 2 three higher concentrations of ethanolic extract and theophylline and all concentrations of essential oil showed concentration dependent relaxant effects compared to that of saline (p<0.05-0.001). In addition, the effect of 0.25 and 0.5g% of essential oils in group 2 was significantly higher than those of theophylline and ethanolic extract (p<0.01 for all cases). However, in group 3 experiments the extract and essential oil of Rosa damascena did not show any significant relaxant effect. There were significant correlations between the relaxant effects and concentrations for ethanolic extract and essential oil and theophylline in groups 1 and 2. These results showed a potent relaxant effect of Rosa damascena on tracheal chains of guinea pigs that was comparable to that of theophylline at concentrations used.

Effects of tiotropium and other long acting bronchodilators in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) accounts for a major workload in both primary and secondary care. It is characterised by progressive airflow obstruction which does not fully reverse to inhaled or oral pharmacotherapy. The diagnosis should be considered in any current or former smoker who has symptoms of breathlessness, wheeze, cough, sputum production and impaired exercise tolerance. From a pharmacological perspective, short-acting bronchodilators (anti-cholinergics and beta(2)-agonists) play a vital role in immediate relief of symptoms. However, in patients with persistent symptoms and exacerbations, long-acting bronchodilator therapy is advocated for regular use. Tiotropium is a newly introduced long-acting anti-cholinergic which facilitates once daily administration. This evidence based review article discusses the use of long acting bronchodilators in COPD with a particular emphasis on the putative benefits of tiotropium.

Relaxant effect ofThymus vulgaris on guinea-pig tracheal chains and its possible mechanism(s)

Thymus vulgaris for the treatment of respiratory diseases is indicated widely, and relaxant effects on smooth muscle have been shown previously. In the present study, the relaxant effects of macerated and aqueous extracts of Thymus vulgaris on tracheal chains of guinea-pigs were examined using cumulative concentrations of macerated and aqueous extracts in comparison with saline (as the negative control) and theophylline (as the positive control). The relaxant effects of four cumulative concentrations of macerated and aqueous extracts (0.25, 0.5, 0.75 and 1.0 g %) in comparison with saline (as the negative control) and four cumulative concentrations of theophylline (0.25, 0.5, 0.75 and 1.0 mm; as the positive control) were examined for their relaxant effects on precontracted tracheal chains of guinea-pig by 60 mm KCl and 10 microm methacholine in two different conditions: non-incubated tissues and incubated tissues with 1 microm propranolol and 1 microm chlorphenamine. There were significant correlations between the relaxant effects and the concentrations for both extracts and theophylline in all experimental groups (p < 0.01 to p < 0.001). These results demonstrated a potent relaxant effect of Thymus vulgaris on guinea-pig tracheal chains that was comparable to theophylline at the concentrations used.

Past, present and future--beta2-adrenoceptor agonists in asthma management

The beta-adrenoceptor agonists (beta-agonists) have been used to relieve bronchoconstriction for at least 5000 years. beta-agonists are based on adrenaline and early forms, such as isoprenaline, Lacked bronchial selectivity and had unpleasant side effects. Modern beta-agonists are more selective for the beta2-adrenoceptors (beta2-receptors) located in bronchial smooth muscle and have less cardiotoxicity. Traditional beta2-adrenoceptor agonists (beta2-agonists), such as salbutamol, terbutaline and fenoterol, were characterised by a rapid onset but relatively short duration of action. While valuable as reliever medication, their short duration gave inadequate night-time relief and limited protection from exercise-induced bronchoconstriction. beta2-agonists with longer durations of action, formoterol and salmeterol, were subsequently discovered or developed. When combined with inhaled corticosteroids they improved lung function, and reduced symptoms and exacerbations more than an increased dose of corticosteroids. However, tolerance to the bronchprotective effects of long-acting beta2-agonists and cross-tolerance to the bronchodilator effects of short-acting beta2-agonists is apparent despite use of inhaled corticosteroids. The role of beta2-receptor polymorphisms in the development of tolerance has yet to be fully determined. Formoterol is unique in having both a long-lasting bronchodilator effect (> 12 h) and a fast onset of action (1-3min from inhalation), making it effective both as maintenance and reliever medication. The recent change in classification from short- and long-acting beta2-agonists to rapid-acting and/or long-acting agents reflects the ongoing evolution of beta2-agonist therapy.

Long-acting beta2-agonists: comparative pharmacology and clinical outcomes

Salmeterol and formoterol are both long-acting beta(2)-adrenoceptor agonists (beta(2)-agonists). They both provide excellent bronchodilating and bronchoprotective effects in patients with asthma but their are some differences between these two long-acting beta(2)-agonists in vitro and in vivo. Formoterol has a greater potency and intrinsic activity than salmeterol, which can become especially apparent at higher doses than that clinically recommended, and in contracted bronchi. Long-term use of long-acting beta(2)-agonists can induce tolerance, which can be partially reversed with corticosteroids. Long-acting beta(2)-agonists have some anti-inflammatory effects in vitro, but data in vivo are less convincing. Compared with doubling the dose of inhaled corticosteroids, the addition of inhaled long-acting beta(2)-agonists to inhaled corticosteroids improves symptom control in patients with asthma and reduces both the exacerbation rate of asthma and hospital admission rate. No enhanced airway responsiveness or loss of perception of dyspnea has been observed with the use of inhaled long-acting beta(2)-agonists. Monotherapy with long-acting beta(2)-agonists is not recommended.

Long-lasting smooth-muscle relaxation by a novel PACAP analogue in human bronchi

We compared the relaxant effect of original pituitary adenylate cyclase-activating peptide (PACAP)1-27 with that of a newly developed, synthetic PACAP1-27 analogue, [Arg15,20,21 Leu17]-PACAP-Gly-Lys-Arg-NH2, in human bronchi in vitro (n=4-5 in each group). Using precontraction by carbachol (0.1 microM), cumulative administration of PACAP1-27 and salbutamol caused concentration-dependent smooth muscle relaxation with similar potencies and maximum relaxant effects. Non-cumulative administration of the PACAP1-27 analogue and the original PACAP1-27 caused concentration-dependent relaxation with a similar maximum relaxant effect and potency as well. However, the onset and offset of action was markedly slower for the PACAP1-27 analogue than for the original PACAP1-27 (>90% versus <10% of peak relaxation remaining 5 h after administration). Peptidase inhibition by captopril (10 microM) and phosphoramidon (1 microM) significantly increased the maximum relaxant effect and duration of action of PACAP1-27 but not of the PACAP1-27 analogue, during the 3 h of observation in the human bronchi. We conclude that [Arg15,20,21 Leu17]-PACAP-Gly-Lys-Arg-NH2 produces significant concentration-dependent and sustained bronchial smooth muscle relaxation in vitro. The sustained relaxant effect is due, at least in part, to the synthetic PACAP1-27 analogue being less susceptible to cleavage by peptidases than the original peptide PACAP1-27.

Anticachectic effects of formoterol: a drug for potential treatment of muscle wasting

In cancer cachexia both cardiac and skeletal muscle suffer an important protein mobilization as a result of increased proteolysis. Administration of the beta2-agonist formoterol to both rats and mice bearing highly cachectic tumors resulted in an important reversal of the muscle-wasting process. The anti-wasting effects of the drug were based on both an activation of the rate of protein synthesis and an inhibition of the rate of muscle proteolysis. Northern blot analysis revealed that formoterol treatment resulted in a decrease in the mRNA content of ubiquitin and proteasome subunits in gastrocnemius muscles; this, together with the decreased proteasome activity observed, suggest that the main anti-proteolytic action of the drug may be based on an inhibition of the ATP-ubiquitin-dependent proteolytic system. Interestingly, the beta2-agonist was also able to diminish the increased rate of muscle apoptosis (measured as DNA laddering as well as caspase-3 activity) present in tumor-bearing animals. The present results indicate that formoterol exerted a selective, powerful protective action on heart and skeletal muscle by antagonizing the enhanced protein degradation that characterizes cancer cachexia, and it could be revealed as a potential therapeutic tool in pathologic states wherein muscle protein hypercatabolism is a critical feature such as cancer cachexia or other wasting diseases.

Budesonide and formoterol in a single inhaler controls asthma in adolescents

Despite the availability of effective treatments and national guidelines, morbidity from asthma remains high among adolescents. Adolescents need to be considered as a distinct group of individuals with different requirements to those of children and adults. In particular, their non-adherence to prescribed treatment regimens is of concern and is a significant factor contributing to the high rate of morbidity in adolescents. Studies in children aged 4 to 17 years suggest that the combination of an inhaled corticosteroid (ICS) and a long-acting beta2-agonist effectively controls asthma symptoms in patients who remain symptomatic on ICS alone. In order to improve adherence to therapy, the use of combined therapy with an ICS and a long-acting beta2-agonist in a single inhaler should be considered and the dosing frequency should be adjusted according to the severity of asthma symptoms. This should empower patients with a greater degree of self-management and may be important in helping adolescents feel responsible for the management of their asthma. Results from a recent subanalysis demonstrate that the combination of budesonide and formoterol administered twice daily via a single inhaler (Symbicort Turbuhaler) rapidly gains and maintains control of asthma in adolescents whose asthma is not controlled on ICS alone. It is anticipated that this will lead to improved adherence to therapy in this difficult-to-treat population.

Cross tolerance to salbutamol occurs independently of beta2 adrenoceptor genotype-16 in asthmatic patients receiving regular formoterol or salmeterol

BACKGROUND

The development of tolerance following the use of long acting beta(2) agonists in asthmatic patients with either the homozygous arginine (Arg-16) or glycine (Gly-16) genotypes is poorly documented, especially in relation to the acute reliever response to salbutamol in constricted airways. A study was undertaken to evaluate the Arg-16 and Gly-16 genotypes for the acute salbutamol response following methacholine bronchial challenge between the first and last doses of formoterol (FM) and salmeterol (SM) combination inhalers.

METHODS

Parallel groups of 10 matched homozygous Arg-16 and 10 homozygous Gly-16 patients completed a randomised, double blind, double dummy, crossover study. Following a 1 week washout period, patients received treatment for 2 weeks with either inhaled budesonide (BUD) 200 micro g + FM 6 micro g (two puffs twice daily) or inhaled fluticasone propionate (FP) 250 micro g + SM 50 micro g (one puff twice daily). After washouts and randomised treatments (1 hour after the first and last inhalation) a methacholine challenge was performed followed by salbutamol 200 micro g, with recovery over 30 minutes (the primary outcome).

RESULTS

Washout values for forced expiratory volume in 1 second (FEV(1)), methacholine hyperreactivity, and salbutamol recovery were similar for both treatments and genotypes. Pre-challenge FEV(1) values for both genotypes did not differ significantly between the first and last doses of each treatment. Salbutamol recovery as mean (SE) area under the 30 minute time-response curve was significantly delayed (p<0.05) equally in both genotype and treatment groups. There were no differences in salbutamol recovery in either genotype or treatment group.

CONCLUSION

Acute salbutamol recovery in methacholine constricted airways was significantly delayed to a similar degree in both genotypes due to cross tolerance induced by FM or SM.

Inhibitory effect of Bunium persicum on histamine (H1) receptors of guinea pig tracheal chains

The antihistaminic effects of aqueous and macerated extracts, essential oil, 20 nM chlorpheniramine, and saline were tested by performing the cumulative log concentration-response curves of histamine-induced contraction of isolated guinea pig tracheal chains incubated with three different conditions including: (1) 1.4 microM indomethacin, (2) indomethacin, 1 microM propranolol, and 10 nM atropine, and (3) indomethacin and propranolol (for each group n = 8). The results showed clear parallel rightward shifts in histamine-response curves obtained in the presence of macerated extract in group 2, aqueous extract in group 3, and essential oil in groups 2 and 3 experiments compared with the curves obtained in the presence of saline. The EC50 (effective concentration of histamine causing 50% of maximum response) obtained in the presence of essential oil, extracts, and chlorpheniramine in all three sets of experiments were significantly higher than that of saline (P<0.05 to p<0.001). The maximum response obtained in the presence of aqueous extract in group 3 compared to group I and that of macerated extract in group 2 compared to the other two sets of experiments were improved. These results indicated a competitive antagonistic effect of Bunium persicum at histamine H1 receptors.

Bronchodilatory effect of Portulaca oleracea in airways of asthmatic patients

Therapeutic effects of Portulaca oleracea for respiratory diseases are indicated in ancient Iranian medical books. The relaxant effect of this plant have also been observed on smooth muscle tissue in previous studies. Therefore, in the present study, the bronchodilatory effect of the boiled extract of Portulaca oleracea in the airway of asthmatic patients was examined. The relaxant effect of the orally administered 0.25 ml/kg of 5% boiled extract in comparison with 3 mg/kg oral theophylline and 200 microg inhaled salbutamol was studied by measuring forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal mid-expiratory flow (MEF(25-75)), and specific airway conductance (sGaw). The FEV1, PEF, MEF(25-75), and sGaw were measured before, administration and repeated 15, 30, 60, 90, and 120 min after administration of the oral extract and theopylline. For inhaled salbutamol measurements were performed 5, 15, 30, and 60 min post-inhalation. Results showed that the boiled extract of Portulaca oleracea caused significant increases in all measured pulmonary function tests (PFTs), (P < 0.05 to P < 0.01). There was no significant difference between the maximum increase in measured PFTs due to the boiled extract and theophylline. However, maximum increase in PEF and MEF(25-75) due to the boiled extract were significantly lower than those of salbutamol (P < 0.05 for both cases). The onset of brochodilatory effect of extract was similar to that of theophylline beginning 60 min, but the effect of extract decline after 120 min after administration. In conclusion, the results of the present study showed that Portulaca oleracea has a relatively potent but transient bronchodilatory effect on asthmatic airways.

Benefit-risk assessment of long-acting beta2-agonists in asthma

The use of a regular long-acting beta2-adrenoceptor agonists (beta2-agonists; LABA) is now established in asthma guidelines as the preferred option for second-line controller therapy in addition to inhaled corticosteroids. This has been driven by data showing beneficial effects of LABAs on exacerbation rates, in turn suggesting a putative corticosteroid-sparing effect. As LABAs are devoid of any clinically meaningful anti-inflammatory activity in vivo, their effects on exacerbations are presumably due to a diurnal stabilising effect on airway smooth muscle. LABAs have marked effects on symptoms and lung function, and this may make it difficult to assess anti-inflammatory control with inhaled corticosteroids when used in a combination inhaler such as fluticasone propionate/salmeterol or budesonide/formoterol. The use of fixed-dose combination inhalers is in many respects counter-intuitive to conventional teaching regarding flexible dosage titration with inhaled corticosteroids. It would therefore seem prudent first to gain optimal control of inflammation with inhaled corticosteroids before considering adding a LABA. Increasing the dosage of inhaled corticosteroids will have a relatively greater effect on exacerbations than on symptoms and lung function, whereas the converse applies when adding a LABA. Another option is to add a leukotriene receptor antagonist, which confers additional anti-inflammatory activity and is as effective on exacerbations as adding a LABA. Despite in vitro and ex vivo data showing a ligand-independent effect of LABAs on glucocorticoid receptor activation, clinical data do not indicate any relevant synergy between LABAs and inhaled corticosteroids when used together in the same inhaler. In particular, there is no evidence of potentiation by LABAs of the in vivo anti-inflammatory activity of inhaled corticosteroids that would suggest any genuine corticosteroid-sparing activity. Nonetheless, the data support the additive effects of inhaled corticosteroids and LABAs when used together due to their separate effects on inflammation and smooth muscle, respectively. Tolerance with LABAs is a predictable pharmacological phenomenon that occurs despite concomitant therapy with inhaled corticosteroids. Moreover, cross-tolerance also develops to short-acting beta2-agonists used for protection against bronchoconstrictor stimuli as a result of LABA-induced down-regulation, desensitisation and prolonged occupancy of beta2-adrenoceptors. The exact role of beta2-adrenoceptor polymorphism in determining tolerance with LABAs requires further prospective clinical studies evaluating long-term effects on outcomes such as exacerbations in patients with relevant genotypes and haplotypes. The next decade will provide challenging issues for clinicians with respect to defining further the role of LABAs as add-on controller therapy, particularly in evaluating the long-term effects of combination inhalers on inflammatory outcomes and airway remodelling.

Possible mechanism(s) for relaxant effect of aqueous and macerated extracts from Nigella sativa on tracheal chains of guinea pig

BACKGROUND

In previous studies, the relaxant, anticholinergic (functional antagonism) and antihistaminic effects of Nigella sativa have been demonstrated on guinea pig tracheal chains. To elucidate the other mechanisms responsible for the relaxant effect of this plant, its inhibitory effect on the calcium channel was examined in this study.

RESULTS

The inhibitory effects of both concentrations of diltiazem in all three groups of experiments were significantly greater than those of saline (p < 0.01 to P < 0.001). The inhibitory of two larger concentrations of aqueous extracts in group 1 and 2 were significantly greater than those of saline (p < 0.01 to P < 0.001). The effect of two larger concentrations of macerated extract in group 1 and all concentrations of this extract in group 2 were also significantly greater than those of saline (p < 0.01 to P < 0.001). However, the extract of Nigella sativa did not show any inhibitory effect in group 3. There was a significant correlation between inhibitory effect and increasing concentrations for both extracts and diltiazem in groups 1 and 2 (p < 0.05 to p < 0.005).

CONCLUSION

Although the extracts of Nigella sativa showed inhibitory effects on pre-contracted tracheal chains in the presence of both ordinary and calcium free Krebs solution, the absence of inhibitory effects of the extracts on KCl induced contraction of tracheal chains suggest that the calcium channel blocking effect of this plant dose not contribute to the relaxant effect of this plant on the tracheal chains of guinea pigs.

The arginine-16 beta2-adrenoceptor polymorphism predisposes to bronchoprotective subsensitivity in patients treated with formoterol and salmeterol

AIMS

The relationship between beta2-adrenoceptor polymorphisms and bronchoprotective response with long-acting beta2-adrenoceptor agonists is unknown.

METHODS

We retrospectively analysed data from six placebo-controlled randomized studies in corticosteroid treated asthmatics where formoterol or salmeterol were administered over a 1-2-week period, with prior 1-2 week washout, assessing the primary end point of methacholine PD20 and adenosine monophosphate PC20, following first and last dose, expressed as doubling dose difference from placebo.

RESULTS

There was no significant heterogeneity between the different studies. Patients who had homozygous or heterozygous genotypes containing the arginine-16 polymorphism (Arg16-Arg16 or Arg16-Gly16) had greater bronchoprotective subsensitivity compared with the homozygous glycine-16 genotype (Gly16-Gly16), amounting to a mean doubling dose difference of 1.49 (95% CI 0.50, 2.48), after the last dose. Subsensitivity of response was greater with formoterol than salmeterol after the last dose in all genotypes, especially with the arginine-16 polymorphism, amounting to a doubling dose difference of 3.00 (95% CI 1.01, 4.99) between formoterol and salmeterol.

CONCLUSIONS

Our retrospective analysis showed that the arginine-16 polymorphism was associated with subsensitivity of response for bronchoprotection, which was greater for formoterol than salmeterol. A prospective study will be required in order to further evaluate these findings, particularly to assess whether these differences are mirrored by exacerbations.