Interaction of corticosteroids and catecholamines in the treatment of asthma.

Twelve patients with airways obstruction (due to asthma and/or chronic bronchitis) were given a trial of prednisone therapy to assess reversibility. Six asthmatic patients responded well but no predictive criteria were found. In three patients improvement in forced expiratory volume in 1 second (FEV1) was detectable at 6 hours but not at 3 hours. One patient took 36 hours to show any sign of improvement. None of the patients who improved reached their peak FEV1 before six days treatment with prednisone, which suggests that a 'trial of steroids' should last for at least one week. Potentiation, as measured by either a greater peak rise or a more sustained increase in FEV1 after isoprenaline, was observed in five of the six asthmatic patients responding to steroids. It is concluded that potentiation of catecholmines is one of the mechanisms by which corticosteroids may act in asthma.