Serial Lung Function Measurements in Healthy and Mild Asthmatic Adults After Oral Inhalation of Ethanolic Solutions Containing Two Concentrations of the Excipient Butylated Hydroxytoluene (BHT) Administered With the Respimat® B (RMT-B)

Primary objective: To investigate the safety and local tolerability of increasing cumulative doses (2, 4, 6 actuations) of a low (0.1%) and a high (0.5%) concentration of BHT administered via oral inhalation with the Respimat® inhaler B (RMT-B) vs. 2 inhalation solutions without BHT (placebo to BHT given by RMT B and placebo given by hydroxylfluoralkane metered dose inhaler (HFA MDI)). In a first step, the trial was performed in healthy subjects and - if no safety concerns arose - in a second step in patients with mild asthma who were sensitive to metacholine in a respective challenge test. Secondary objective: To explore the pharmacokinetics (PK) of BHT.