Combined bronchodilator protection against histamine-induced bronchoconstriction in man.
Sixteen stable asthmatics had the protective effects of inhaled fenoterol (200 micrograms) and inhaled ipratropium bromide (60 micrograms) against standardized histamine inhalation tests at 1 h examined in a randomized double blind fashion. There was no significant difference in the baseline forced expired volume in 1 s (FEV1) for the two study days (P greater than 0.05). There was an increase in FEV1 at 1 h on the fenoterol and ipratropium day compared with the fenoterol day (0.26 versus 0.17 l; P less than 0.05). The geometric mean provocative concentration of histamine to cause a 20% fall in FEV1 (PC20) was 6.31 mg/ml after fenoterol and 8.51 mg/ml after fenoterol and ipratropium (P = 0.038). There was no significant relationship between bronchodilator effect of the bronchodilators and the increase in PC20 from pre-study values, r = 0.307 (P = 0.25) for fenoterol alone and r = 0.195 (P = 0.47) for fenoterol and ipratropium. The relationship between pre-study histamine responsiveness and the increase in PC20 caused by the bronchodilators just failed to reach statistical significance, r = -0.441 (P = 0.09) for fenoterol alone and r = -0.47 (P = 0.06) for fenoterol and ipratropium. The study has shown a greater right shift of histamine responsiveness for combined inhaled fenoterol and ipratropium compared with inhaled fenoterol alone in this group of asthmatics.
D000328:Adult; D001249:Asthma / Q000503:physiopathology / Q000517:prevention & control*; D001286:Atropine Derivatives / Q000627:therapeutic use*; D001985:Bronchial Provocation Tests; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D005280:Fenoterol / Q000008:administration & dosage / Q000627:therapeutic use*; D006633:Histamine Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D009241:Ipratropium / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011897:Random Allocation
D001286:Atropine Derivatives; D004338:Drug Combinations; D006633:Histamine Antagonists; D005280:Fenoterol; D009241:Ipratropium