methacholine challenge /meth′əkō″lēn/ , a method of measuring airway activity by an inhalation challenge test. The patient inhales a saline aerosol as a control, followed by increasing concentrations of methacholine chloride, a cholinergic drug. The test is used to confirm the diagnosis of asthma when symptoms are not present. This is a potentially dangerous test and should be performed only by qualified personnel, with resuscitation equipment readily available.
