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 µ g ipratropium bromide + 200 µ g fenoterol), fenoterol (400 µ g), salbutamol (200 µ g), 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). When comparison was made between the tests, it was observed that the level of protection remained constantly similar for fenoterol and Duovent and that there was no statistically significant difference between the two treatments after the respective challenges. Salbutamol offers poorer protection than fenoterol or Duovent since the duration of action is shorter. This difference in protection between salbutamol on the one hand and Dosberotec and Duovent on the other becomes statistically significant at the 4th stimulus (p < 0.01). DSCG does not offer a significant degree of protection against bronchospasm induced by CAIH with the exception of the first test. Effect of Duovent on Bronchospasm Induced by CAIH 197 Our study results confirm that after the CAIH test there is no refractory period, that the test can be easily reproduced, that Duovent and fenoterol offer effective protection against bronchospasm induced by CAIH which lasts up to 6 h in most cases, and show that the combination with ipratropium bromide allows the dose of fenoterol to be reduced to only 200 µ g without any signs of a loss in the antibronchoconstrictive effect.

Keywords:
Cold air, Hyperventilation, Bronchospasm, Asthmatics, Antiasthmatic drugs
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© 1986 S. Karger AG, Basel
1986
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