Patent Application
20090036862
The present disclosure relates to a multilayer plastic container for storing lyophilized products and to a method of using such a container.
Lyophilized or freeze-dried products such as medical products typically are stored in Type 1 glass containers or vials, which have very low moisture vapor transmission rates that keep the lyophilized cake intact. Plastic containers, although less expensive and more rugged than glass containers, typically have not been employed for storing lyophilized products because of the higher moisture vapor transmission rates of typical plastic containers. A general object of the present disclosure is to provide a plastic container suitable for long-term storage of lyophilized products, and to provide a method of storing lyophilized products in such a container.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A multilayer plastic container for storing lyophilized products, in accordance with one aspect of the present disclosure, includes at least three layers consisting of inner and outer layers having a moisture vapor transmission rate of not more than 0.1 gm mil/100 sq. in.—day at 73° F. and 95% rh, and an intermediate layer of hygroscopic resin construction having a moisture content less than 1000 ppm. The hygroscopic intermediate layer preferably comprises at least 30% of the total thickness of the three layers. The inner and outer layers preferably are of cyclic olefin polymer or cyclic olefin copolymer construction, and the hygroscopic intermediate layer preferably is of amorphous nylon construction. The container preferably is empty and sealed within a secondary container, such as a metallized bag, that is impervious to moisture.
A method of storing a lyophilized product, in accordance with a second aspect of the present disclosure, includes providing a multilayer plastic container having first and second layers with moisture vapor transmission rates of not more than 0.1 gm mil/100 sq. in.—day at 73° F. and 95% rh, and a third layer between the first and second layers of hygroscopic plastic construction having a moisture content of less than 1000 ppm. The multilayer plastic container is stored in a low humidity environment, such as within a sealed metallized bag. At the time of use, the container is removed from the low humidity environment, a product is placed within the container and the product is lyophilized. The hygroscopic third layer of the container functions as a desiccant to absorb any moisture transmitted through the first and second layers.
The disclosure, together with additional objects, features, advantages and aspects thereof, will best be understood from the following description, the appended claims and the accompanying drawings in which:
In an exemplary embodiment of the present disclosure, inner and outer layers 12,14 of container 10 are of cyclic olefin polymer construction such as Zeon COP or cyclic olefin copolymer construction such as Ticona COC. Intermediate layer 16 preferably comprises at least 30% of the total thickness of layers 12,14,16, and most preferably is of amorphous nylon construction such as EMS G-21. Amorphous nylon is hygroscopic and provides a barrier to oxygen transmission. As purchased, amorphous nylon typically has a moisture content less than 200 ppm. Further processing prior to container manufacture can reduce this moisture content to less than 50 ppm.
After manufacture, empty container 10 preferably is stored in a low-humidity environment, such as sealed within a secondary container 20 that is impervious to moisture. Secondary container 20 preferably comprises a metallized bag having a metal layer 22 of aluminum for example sandwiched within layers 24,26,28 of plastic construction. A presently preferred secondary container 20 is marketed by Ludlow Coated Products, product FR-2175-B having an outer layer 28 of oriented polypropylene, a layer 26 of polyethylene, a metal foil layer 22 and an inner layer 24 of low density polyethylene. Other metallized bags and secondary containers can be employed.
When ready for use, container 10 is removed from secondary container 20 and the product is placed within the container. The product is lyophilized and the container is sealed. Container layers 12,14 resist transmission of moisture vapor into the container. Hygroscopic intermediate layer 16 resists transmission of oxygen and other gases into the container. Furthermore, the hygroscopic intermediate layer acts as a desiccant to absorb any moisture that is transmitted through layer 14, and indeed draws any moisture remaining within container 10 through layer 12 and absorbs this moisture. Hygroscopic layer 16 thus acts as a scavenger of any moisture that permeates through layer 14, and maintains a low relative humidity across layer 12 reducing the amount of moisture that enters the product and extending the shelf life of the product.
There thus has been disclosed a multilayer plastic container and a method of use for storing lyophilized products that fully achieve all of the objects and aims previously set forth. The disclosure has been presented in conjunction with an exemplary embodiment, and modifications and variations have been discussed. Other modifications and variations readily will suggest themselves to persons of ordinary skill in the art in view of the foregoing discussion. The disclosure is intended to encompass all such modifications and variations as fall within the spirit and broad scope of the appended claims.
