Mechanism of Action of Long-Acting Bronchodilators:

The β2 -adrenoceptor agonist terbutaline recovers rat pharyngeal dilator muscle force decline during severe hypoxia

RATIONALE

Obstructive sleep apnoea syndrome (OSAS) is a debilitating condition characterized by recurrent occlusions of the pharyngeal airway during sleep accompanied by arterial hypoxaemia. Upper airway muscle dysfunction is implicated in the pathophysiology of OSAS. Pharmacological agents that improve muscle contractile and endurance properties may have therapeutic value.

AIM

We tested the hypothesis that the β(2) -adrenoceptor agonist terbutaline improves rat sternohyoid muscle performance especially during hypoxic stress.

METHODS

Isometric contractile and endurance properties were examined ex vivo in Krebs solution at 35°C. Muscles were incubated in tissue baths under hyperoxic (95% O(2) /5% CO(2)) conditions in the absence (control) or presence of the β(2) -adrenoceptor agonist terbutaline (1 μM). In additional experiments under hypoxic (95% N(2) /5% CO(2)) conditions, the effects of terbutaline were examined in the presence of the β-adrenoceptor antagonist propranolol (1 μM).

RESULTS

Hypoxia significantly impaired sternohyoid force production. Terbutaline completely recovered hypoxic depression of force, an effect that was blocked by co-application with propranolol.

CONCLUSION

The β(2) -adrenoceptor agonist terbutaline completely recovers hypoxic depression of upper airway muscle force. β(2) -adrenoceptor agonists warrant investigation in animal models of OSAS reporting upper airway and diaphragm muscle dysfunction.

Sports doping: emerging designer and therapeutic β2-agonists

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

Prevalence and risk factors for depressive symptoms in persons with chronic obstructive pulmonary disease

BACKGROUND

Although depression is a risk factor for adverse outcomes in chronic illness, little is known about the prevalence or risk factors for depressive symptoms in chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To determine the prevalence of depressive symptoms in COPD as compared to other chronic illnesses and to identify risk factors for depressive symptoms in COPD.

DESIGN AND PATIENTS

Cross-sectional study of 18,588 persons (1,736 subjects with self-reported COPD), representing a sample of the US population aged > or =50 years who participated in the 2004 Health and Retirement Survey.

MEASUREMENTS

Presence of COPD and other chronic conditions was defined by self-report. Presence of depressive symptoms was assessed using the CES-D8 scale. Participants with a score > or =3 on CES-D8 were classified as having clinically significant depressive symptoms.

MAIN RESULTS

Of 1,736 participants with COPD, 40% had > or =3 depressive symptoms. Depressive symptoms were more common in COPD than in coronary heart disease, stroke, diabetes, arthritis, hypertension, and cancer. Risk factors for > or =3 depressive symptoms in COPD: younger age (OR 1.02/per year younger, 95% CI [1.02-1.03]), female gender (1.2 [1.1-1.3]), current smoking (1.5 [1.3-1.7]), marital status [divorced/separated (1.8 [1.6-2.1]), widowed (1.8 [1.6-2]), never married (1.4 [1.1-1.8]), < or =high school degree (1.6 [1.5-1.8]), dyspnea (2.3 [2.1-2.6]), difficulty walking (2.8 [2.5-3.2]), and co-morbid diabetes (1.2 [1.1-1.4]), arthritis (1.3 [1.2-1.5]) or cancer (1.2 [1.1-1.4]).

CONCLUSIONS

Depressive symptoms are common in COPD and are more likely to occur in COPD than in other common chronic illnesses. The risk factors identified may be used for targeted depression screening in COPD patients.