title: Interaction of inhaled beta 2 agonist and inhaled corticosteroid on airway responsiveness to allergen and methacholine.
abstract: Regular treatment with salbutamol increases airway responsiveness to allergen but not to methacholine and produces tolerance to the bronchoprotective effect of salbutamol. The current study addresses the effect of inhaled corticosteroid on these aspects of regular beta 2 agonist use. A group of 13 atopic asthmatic subjects free from all asthma medications and remote from allergen exposure were studied. We used a double-blind, random-order, crossover study to compare four 1-wk treatment periods with > or = 1 wk washout: placebo, salbutamol, 200 micrograms four times per day, budesonide, 400 micrograms four times per day, and the combination of salbutamol and budesonide. We measured the methacholine PC20 and the methacholine dose shift produced acutely by 200 micrograms salbutamol after 7 d and the allergen PC15 after 8 d treatment. Blinded medications were withheld for 8 to 10 h before measurements. The methacholine PC20 was not affected by regular salbutamol but increased significantly (p < 0.014) after both budesonide-containing regimens. Neither the dose shift nor its significant reduction by regularly used beta 2 agonist were influenced by the inhaled corticosteroid. The four allergen PC15 values were significantly different from each other. Compared with placebo, the allergen PC15 was 0.6 doubling doses lower after salbutamol (p = 0.021) and 1.3 doubling doses higher after budesonide (p < 0.001); the allergen PC15 was reduced by 0.53 doubling doses from this new baseline (p = 0.039) when salbutamol and budesonide were used together.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, Royal University Hospital, University of Saskatchewan, Saskatoon, Canada.
authors.forename: D W
authors.initials: DW
authors.lastname: Cockcroft
authors.forename: V A
authors.initials: VA
authors.lastname: Swystun
authors.forename: R
authors.initials: R
authors.lastname: Bhagat
mesh_terms: D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage*; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage*; D000485:Allergens; D000704:Analysis of Variance; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology; D001980:Bronchi / Q000187:drug effects* / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods / Q000706:statistics & numerical data; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D019819:Budesonide; D004311:Double-Blind Method; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D011282:Pregnenediones / Q000008:administration & dosage*
chemical_list: D000318:Adrenergic beta-Agonists; D000485:Allergens; D001993:Bronchodilator Agents; D011282:Pregnenediones; D016210:Methacholine Chloride; D019819:Budesonide; D000420:Albuterol