The invention relates to a method and a device for lyophilizing, reconstituting, and administering a reconstituted agent. Said device comprises an elongate housing (3) with a forward housing end (6) located on the discharge side and a rear housing end (7) which lies opposite the forward housing end (6). A first chamber (1) containing a lyophilisate is disposed in the area of the forward housing end (6) inside the housing. Said first chamber (1) is tightly sealed at the end that faces the forward housing end (6) by means of a removable closure (9) while being tightly sealed in the direction of the rear housing end (7) with the aid of a plunger (11). A second chamber (2) that is connected to the ambient atmosphere via at least one opening (13...
