Cold-air isocapnic hyperventilation test in the study of the effects and duration of action of Duovent. Comparison with fenoterol, salbutamol, disodium cromoglycate and placebo.

The cold-air isocapnic hyperventilation (CAIH) test is a challenge test for non-specific bronchitis which was recently incorporated into the study of bronchial hyperreactivity. As it is easy to perform and to reproduce, the CAIH test is regarded as a valuable examination in clinical pharmacology. We carried out a study using this test in 12 atopic asthmatics in intercritical phase. The patients were treated for a few days before, under double-blind conditions and random order, with Duovent (80 micrograms ipratropium bromide + 200 micrograms fenoterol), fenoterol (400 micrograms), salbutamol (200 micrograms), disodium cromoglycate (DSCG) (10 mg) and placebo. All the drugs were administered by aerosol 30 min before the test which was repeated at intervals of 120, 240 and 360 min after intake of the drug. Certain parameters of respiratory function were measured by dry spirometry (Vicatest 2 C) before administration of the drug as well as before and 0, 3, 5, 15, 30 and 60 min after each test. For the sake of brevity only the FEV1 values are shown in the figures since the other parameters all revealed a similar pattern. After placebo, all the patients reacted to the CAIH test with significant falls after each of the 4 tests, but there was no statistically significant difference between the 4 tests; there were no statistically significant differences between the pretreatment values in FEV1 recorded before each treatment (verum or placebo).(ABSTRACT TRUNCATED AT 250 WORDS)