title: The effect of salbutamol controlled release on airways responsiveness to inhaled methacholine in mild asthmatic subjects.
abstract: Single doses of inhaled bronchodilating agents have been shown to reduce airways responsiveness (AR) in both normal and asthmatic individuals. The longer term effects of these treatments on airways responsiveness are less clear. We have studied the effects of 4 weeks of treatment with oral salbutamol controlled release (SCR) (8 mg b.d.) on airways responsiveness in mild asthmatics in a double-blind, placebo-controlled study. Airways responsiveness to inhaled methacholine, baseline FEV1 and plasma salbutamol levels was assessed 6 h, 48 h and 4 weeks after commencing treatment and again 24 h and 72 h after cessation of medication. When compared to placebo, SCR significantly attenuated AR at the 48-h time point only. There were no increases in AR recorded at any of the post-treatment time points. In addition, there were no significant differences in baseline FEV1 at any of the time-points studied, when compared to placebo. The change in AR at 48 h after starting treatment was probably due to functional antagonism of smooth muscle contraction. Importantly, there were no increases in AR recorded at either of the post-treatment time points.
authors.affiliation: Department of Respiratory Medicine and Allergy, St. Bartholomew's Hospital, London, U.K.
authors.forename: M J
authors.initials: MJ
authors.lastname: Herdman
authors.forename: H
authors.initials: H
authors.lastname: Ferguson
authors.forename: K
authors.initials: K
authors.lastname: Thomas
authors.forename: C J
authors.initials: CJ
authors.lastname: Trigg
authors.forename: R J
authors.initials: RJ
authors.lastname: Davies
mesh_terms: D000328:Adult; D000420:Albuterol / Q000008:administration & dosage*; D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000188:drug therapy*; D001985:Bronchial Provocation Tests; D003692:Delayed-Action Preparations; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage*
chemical_list: D003692:Delayed-Action Preparations; D016210:Methacholine Chloride; D000420:Albuterol