Beta-2-agonists of third generation

Beta-adrenergic agents have been used for a long time in the treatment of asthma. For the purpose of bronchodilation the better results would be attained with the increase in Beta-2-selectivity. From the newer Beta-agonists the mot currently used are TERBUTALINE, FENOTEROL, SALBUTAMOL, CLEMBUTEROL, TOLBUTEROL, CARBUTEROL, PROCATEROL, RIMITEROL and REPROTEROL, this last combining in its molecule the structure of a beta-agonist with a Xanthine group. These agents could be used in different ways, by mouth, injection and inhalation (with a exception of Clembuterol which is effective only by oral route). The authors have, some years ago, comparatively studied the bronchodilating effect of Salbutamol and Fenoterol including 18 patients. The main increase of PFR was slightly higher after FENOTEROL but this difference was not significant. The authors have studied REPROTEROL by inhalation and oral routes in 11 asthmatic patients. After inhalation of 400 mcg of REPROTEROL the bronchodilator effect was comparable to others inhaled bronchodilators. However they could not confirm that REPROTEROL acts also as a Xanthine and only traces of Theophylline have been detected in blood of subjects taking it. These data seem to indicate that REPROTEROL do not release Theophylline in the body or only release a Xanthine like compound not detected by "EMIT" of high pressure liquid chromatography.