Time course of methacholine induced bronchoconstriction during drugs and spontaneous resolution

We examined the resolution of the bronchial spasm induced by methacholine after administration of a dose sufficient to provoke PD20 to study, in patients with bronchial asthma, how spontaneous resolution (as opposed to bronchodilator-induced resolution) takes place. According to a randomization criterion, the patients were divided into four groups: 1) resolution induced by salbutamol (S), 2) by ipratropium bromide (I), 3) after placebo (P) and 4) spontaneous resolution (R). In brief, we observed that variations in FEV1 after methacholine PD20, reach statistically significant levels after 15 minutes in patients from groups (S) and (I), after 30 minutes in patients from groups (P) and (R) (p < 0.05). Comparing the phenomenon at various intervals in the four experimental situation, we found a pairing trend: groups (S) and (I) on the one hand, and groups (P) and (R) on the other. On the whole, this phenomenon shows that pharmacological treatment accelerates the process of spontaneous resolution of the bronchial spasm induced by methacholine which, in our experience, beings to show after 15 minutes, and that after 60 minutes, there are no statistically significant differences in the four groups. It is our opinion that closer examination of this phenomenon may provide greater knowledge of the mechanisms that come into play during the phase after stimulation of the muscarinic receptors and that reasonably involve the system to eliminate the muscarinic drug.