Acute Airway Vascular Smooth Muscle Effects of Inhaled Budesonide

Glucocorticosteroids recently have been shown to have non-genomic actions that are plasma membrane-mediated and do not require gene transcription and translation. One of these non-genomic effects is the inhibition of adrenergic agonist transport into airway vascular smooth muscle cells with an increase of adrenergic agonist concentrations at adrenergic receptor sites and enhance the physiological effects of endogenous adrenergic agonists (e.g. locally released norepinephrine from noradrenergic neurons) or exogenous adrenergic agonists (e.g. inhaled beta-adrenergic agonists).

Inhaled glucocorticosteroids typically are not recommended for the treatment of acute asthma attacks. This practice is based on the fact that glucocorticosteroids by themselves do not cause rapid bronchodilation. However, the acute inhibition of adrenergic agonist disposal by the non-genomic action of glucocorticosteroids could lead to bronchial vasoconstriction by locally released norepinephrine thereby decongesting the airway wall, and potentiate the bronchodilator effect of a concomitantly administered beta-adrenergic agonist through the same mechanism. The purpose of this study is to assess the vasoconstrictive effects of single and repetitive high-dose budesonide inhalations in moderate to severe asthmatics who use inhaled glucocorticosteroids regularly. As a secondary endpoint, airway inflammation and airway function will also be measured with the expectation that acute improvements in airflow might be detectable as a result of airway decongestion, notably in subjects with moderately severe asthma who have lower baseline lung function.

Qaw will be measured before and up to 6 hours after a single inhaled dose of 360ug, 720ug, and 1440ug budesonide or placebo from a DPI, using a double-blinded randomized design on different days.

FEV1 will be measured before and up to 6 hours after a single inhaled dose of 360ug, 720ug, and 1440ug budesonide or placebo from a DPI, using a double-blinded randomized design on different days.

Inclusion Criteria: Twenty lifetime nonsmokers moderate or severe asthmatics; FEV1≥50 of predicted on the screening day Exclusion Criteria: Women of childbearing potential who do not use accepted birth control measures; pregnant and breast feeding women; Cardiovascular disease and/or use of cardiovascular medication; Subjects with known beta-adrenergic agonist or glucocorticosteroid intolerance; Acute respiratory infection and or acute exacerbation of asthma within four weeks prior to the study; Use of systemic glucocorticosteroids within 4 weeks prior to the study; Daily ICS dose (fluticasone or budesonide) > 500ug; Diabetes mellitus

Horvath G, Sutto Z, Torbati A, Conner GE, Salathe M, Wanner A. Norepinephrine transport by the extraneuronal monoamine transporter in human bronchial arterial smooth muscle cells. Am J Physiol Lung Cell Mol Physiol. 2003 Oct;285(4):L829-37. doi: 10.1152/ajplung.00054.2003. Epub 2003 Jun 13.

Horvath G, Lieb T, Conner GE, Salathe M, Wanner A. Steroid sensitivity of norepinephrine uptake by human bronchial arterial and rabbit aortic smooth muscle cells. Am J Respir Cell Mol Biol. 2001 Oct;25(4):500-6. doi: 10.1165/ajrcmb.25.4.4559.

Mendes ES, Pereira A, Danta I, Duncan RC, Wanner A. Comparative bronchial vasoconstrictive efficacy of inhaled glucocorticosteroids. Eur Respir J. 2003 Jun;21(6):989-93. doi: 10.1183/09031936.03.00072402.

Brieva JL, Danta I, Wanner A. Effect of an inhaled glucocorticosteroid on airway mucosal blood flow in mild asthma. Am J Respir Crit Care Med. 2000 Jan;161(1):293-6. doi: 10.1164/ajrccm.161.1.9905068.

Mendes ES, Rebolledo P, Campos M, Wanner A. Immediate antiinflammatory effects of inhaled budesonide in patients with asthma. Ann Am Thorac Soc. 2014 Jun;11(5):706-11. doi: 10.1513/AnnalsATS.201307-220OC.