[Comparison of bronchodilator effects and site of action of fenoterol and ipratropium in chronic obstructive bronchitis].

There is no lack of data in the literature reporting on the efficacy of different bronchodilators. However, the discussion concerning the superiority of one bronchodilator over another in patients with chronic bronchitis and airflow obstruction is, and remains, a controversial subject. This has been particularly so since the perfection of synthetic anticholinergics delivered by inhalation without any side-effects. The aim of the present work is to compare the bronchodilator effects of a sympathomimetic, fenoterol (Berotec), and of an anticholinergic, ipratropium bromide (Atrovent), compared to a placebo in twelve unselected chronic bronchitics who had airflow obstruction and were in a stable clinical state. The bronchodilator effect of the two drugs was judged at the same time by variations on forced expired volume (FEV1) which was taken as a reference value, and of the maximum mid-expiratory flow (MEF) measured by spirography and also the variations of pulmonary resistance (delta Rrs) measured by the forced oscillatory method. The comparison of these indices enables the site of action of these agents to be specified. The dose response curve and the duration of action over six hours was assessed for each of the three agents. These were administered in succession and at random over three days by inhalation using an inhalation chamber. All the patients who were included were capable of producing a bronchodilator response but two of them responded only to one agent. The change in the FEV1 was comparable with the two active products. The change in MEF (an index of peripheral airways) was significantly greater following ipratropium.(ABSTRACT TRUNCATED AT 250 WORDS)