The utility of methacholine airway responsiveness measurements in evaluating anti-asthma drugs

J Allergy Clin Immunol. 1998 Mar;101(3):342-8. doi: 10.1016/S0091-6749(98)70246-5.


Background: Measurements of airway responsiveness are frequently used to evaluate anti-asthma drugs.

Objective: This study investigated the utility of methacholine airway responsiveness measurements in evaluating anti-asthma medications, both in terms of a bronchoprotective effect and the ability to attenuate allergen-induced methacholine airway hyperresponsiveness.

Methods: Methacholine airway responsiveness was measured as PC20 on two occasions (separated by 35+/-17 days, mean +/- SD) in 40 subjects with mild, stable asthma. Additional subjects had PC20 measurements made before and after administration of either inhaled salbutamol (200 microg) (n = 20) or allergen inhalation challenge (n = 31).

Results: The reproducibility of the methacholine PC20 with this method was high (intraclass correlation coefficient = 0.94). The average shift in PC20 after salbutamol was 4.11 doubling concentrations (SD = 1.08). On the basis of these results, a sample size of 12 subjects would be required to demonstrate a 1 doubling concentration difference in the bronchoprotective effect of two drugs with a 90% power. The average shift in PC20 after allergen was 1.29 doubling concentrations. On the basis of these results and an estimated SD of 0.96, a sample size of 24 subjects would be required to demonstrate that a drug is effective in attenuating 50% of allergen-induced airway hyperresponsiveness with a 90% power.

Conclusion: These results confirm the high reproducibility of methacholine PC20 measurements in subjects with mild, stable asthma and demonstrate its utility in evaluating the effects of anti-asthma drugs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Adrenergic beta-Agonists / administration & dosage
  • Adrenergic beta-Agonists / pharmacology
  • Albuterol / administration & dosage
  • Albuterol / pharmacology
  • Allergens / administration & dosage
  • Allergens / immunology
  • Anti-Asthmatic Agents / therapeutic use*
  • Asthma / drug therapy*
  • Bronchial Hyperreactivity / chemically induced
  • Bronchial Hyperreactivity / drug therapy*
  • Bronchial Hyperreactivity / immunology
  • Bronchial Provocation Tests*
  • Bronchoconstrictor Agents / pharmacology
  • Drug Monitoring / methods*
  • Forced Expiratory Volume
  • Humans
  • Methacholine Chloride / pharmacology
  • Reproducibility of Results


  • Adrenergic beta-Agonists
  • Allergens
  • Anti-Asthmatic Agents
  • Bronchoconstrictor Agents
  • Methacholine Chloride
  • Albuterol