Lung mechanics after aerosol and intravenous SCH 1000 in normal humans

A functional study was carried out in six normal subjects before and after 0.5 mg of an intravenous atropine congener (SCH 1000) by evaluating the following parameters: static pulmonary volumes, resistance of the airways (Raw), N2 closing volume/vital capacity ratio, maximal expiratory flow volume, and the pressure-volume curves. From these curves we calculated the maximum flow-static recoil curves and the resistance of the airways upstream from the equal pressure point (Rus). On the following day four of six subjects inhaled 6 puffs (240 micrograms) of aerosolized SCH 1000 and the same parameters were evaluated. Both procedures caused a significant increase in maximum expiratory flow and a decrease in Raw. However, only intravenous SCH 1000 caused an increase in lung compliance and a decrease in Rus. When compared with previous data, our results show no dose-response effect on the atropine-induced modifications of pulmonary mechanics, and thus confirm the exclusive central bronchodilator effect of the aerosolized SCH 1000.