This invention relates to the lyophilization art and more particularly to an improved apparatus and method for maintaining communication with the interior of a container during lyophilization and providing for the sealing of the container thereafter.
Certain kinds of drugs must be lyophilized to avoid deterioration during moderate or long-term storage. Lyophilization, also known as freeze drying, involves removing the water from a substance by sublimation to produce a crystalline solid. When a substance is lyophilized in a vial or other container, provision must be made for water vapor to escape from the container. When aseptic substances are involved, it is also important that the container be promptly sealed to prevent contamination of the lyophilized product. To accomplish these purposes, lyophilization is often conducted in a closed environment wherein a plurality of vials containing the substance to be dried rest atop a cooling plate. Each vial is provided with a stopper partially received within an upwardly directed open end, the stoppers being provided with cross-holes or passages extending between openings on the side and base of the stopper, respectively. The openings on the side of the stopper are positioned to be exposed when the stoppers are in the initial partially inserted condition. Communication is thus initially provided between the interiors of the containers and the atmosphere within the lyophilizer. In this condition, the process of lyophilization takes place with the water vapor escaping from the vials through the cross-holes. After lyophilization, a horizontal top plate or ram is actuated downwardly against the stoppers to drive them into the vial to a second sealing condition.
The use of stoppers having cross-holes carries with it a number of disadvantages. Initially, the holes are relatively expensive to produce, adding to the total cost of the medication or other substance packaged in the vial. The holes also reduce the sealing capability of the stoppers, raising questions as to the adequacy of the assembled package to keep out contamination. Therefore, in many applications, it is desirable to provide an improved apparatus and method for maintaining communication with the interior of a vial during lyophilization of a substance within the vial and positively sealing the vial when lyophilization is complete.