Day/night variations of airway reactivity after drug premedication.

Seventeen asthmatic, non-atopic patients (aged 15-48 years) were studied at different hours of the day. On 3 different days, they were submitted to a fog-test at 03:00 p.m. and at 03:00 a.m. On 2 different days, they were given fenoterol (200 micrograms) or Duovent (fenoterol 200 micrograms plus ipratropium bromide 80 micrograms). We were able to demonstrate significant inter-hour differences of the basal values of all parameters, except FVC, in all patients at 03:00 p.m. and at 03:00 a.m. We did not observe any inter-hour difference after the fog-test. Both fenoterol and Duovent improved challenge-induced bronchoconstriction. After the fog-test, both drugs showed an inter-hour variability of ventilatory parameters, which was not significant without drugs because it was masked by the magnitude of the obstructive response to challenge.