A method of introducing a physiologically-active agent into the circulatory system of a mammal is disclosed herein. The method utilizes a rapid drug delivery system which prevents deactivation or degradation of the active agent being administered to a patient in need of treatment. In particular, the drug delivery system is designed for pulmonary drug delivery such as by inhalation, for delivery of the active agents such as proteins and peptides to the pulmonary circulation in a therapeutically effective manner avoiding degradation of the active agents in peripheral and vascular tissue before reaching the target site.