title: Tolerance to methacholine inhalation challenge in nonasthmatic subjects.
abstract: Airway responses to inhalation challenge with methacholine in healthy nonasthmatic subjects were examined to determine whether attenuation of response occurred upon repeated challenge. In one experiment, progressively increasing tolerance to multiple-dose challenges was seen with 4 challenges at 4-h intervals. In another study, a smaller degree of tolerance was also seen when a single-dose challenge was conducted 3 times at 24-h intervals. In these studies, the doses of methacholine used to obtain responses in nonasthmatic subjects were higher than are required under conditions of clinical methacholine challenge as a diagnostic test for asthma. Consequently, these findings may be relevant only to investigations or epidemiologic studies in which serial methacholine challenges are performed at intervals of 24 h or less in nonasthmatic subjects requiring higher cumulative doses of methacholine than do asthmatics.
authors.affiliation: John B. Pierce Foundation Laboratories, Yale University School of Medicine, New Haven, Connecticut 06510.
authors.forename: W S
authors.initials: WS
authors.lastname: Beckett
authors.forename: W F
authors.initials: WF
authors.lastname: McDonnell
authors.forename: N D
authors.initials: ND
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000328:Adult; D000403:Airway Resistance; D001985:Bronchial Provocation Tests; D002940:Circadian Rhythm; D004361:Drug Tolerance; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008688:Methacholine Compounds / Q000494:pharmacology; D012016:Reference Values; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000187:drug effects*
chemical_list: D008688:Methacholine Compounds; D016210:Methacholine Chloride