[Equivalence of methacholine and carbachol in a nonspecific provocation test (dose-response relationship)]

Within the framework of unspecific inhalation provocation tests with pharmacological substances for the purpose of diagnosing bronchial hyperreactivity, the cholinergics methacholine and carbachol are often used besides histamine. We examined 21 patients with known bronchial hyperreactivity in the symptom-free interval using the methacholine inhalation provocation test and 15 hyperreactive patients using the carbachol inhalation provocation test with the purpose of determining the extent to which methacholine and carbachol differ from each other in respect of their effect. Standard reference values were the provocation doses PD100/0.5Rt and PD20FEV1. It was found that methacholine and carbachol exercise an equivalent effect in the inhalation provocation test. No statistically significant difference for the provocation doses PD100/0.5Rt and PD20FEB1 was seen in group comparisons.