Package making – Methods – With contents treating
Patent
1995-11-15
1998-03-24
Moon, Daniel
Package making
Methods
With contents treating
53453, B65B 5514
Patent
active
057299587
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates generally to the field of manufacturing and dispensing pharmaceuticals, and more particularly to an improved method for manufacturing freeze dried pharmaceutical tablets in disposable single dose aluminum blister packs. In recent years, pharmaceutical producers have turned to the use of blister packs for use in both the forming and dispensing of pharmaceutical tablets. These blister packs generally consist of a blister sheet or a blister film and a lidding sheet. The blister sheet contains depressions for containing individual dosages. In a standard process for manufacturing freeze dried tablets, a single dosage, in liquid form, is introduced into each depression of the blister sheet. The blister sheet, along with the liquid dosages, is then placed into a refrigerated environment where the dosages are subjected to low temperatures to freeze them. The blister sheets are then transferred to a freeze drier, where the ice is removed by sublimation. When freeze drying is completed, the sheets are removed from the drying chamber and covered with an adhesive lidding sheet, which seals the solid dosages into their individual depressions. U.S. Pat. No. 4,305,502 is incorporated herein by reference as teaching, inter alia, a known process for manufacturing freeze dried tablets.
However, blister sheets that have heretofore been used in freezing and freeze drying processes have suffered from several deficiencies. First, the blister sheets have typically been made of a polymeric substance, which, over time, can allow moisture to permeate the blister pack and reach the dosages stored inside. To solve this problem, blister sheets have been developed in which a layer of aluminum is laminated between layers of polymer. While the presence of the aluminum layer prevents moisture from permeating the blister pack, it leads to a second problem. Namely, when subjected to temperature changes during the freezing process, conventional aluminum/polymer laminates tend to curl up, due to the differences in the degree of thermal expansion or contraction of the opposing layers of the laminate. This makes their use in freezing processes difficult, since liquid product can easily spill from the formed depressions or can lie unevenly in the depressions during filling and freezing operations. Furthermore, the curling of the blister sheet can cause dosages to freeze or sublimate unevenly, since some depressions may not be in physical contact with the cold surfaces of the refrigerator or freeze drier. The only solution has been to use weights on the edges of the laminate strips to hold them sufficiently flat. Such measures are not practical in large scale manufacturing operations, and can interfere with the freezing process.
A need therefore exists for a method of utilizing a high barrier aluminum laminate in the manufacture of freeze dried dosage forms that avoids the problem of curling of the blister sheet.
SUMMARY OF THE INVENTION
In a basic aspect, the invention is an improved method for manufacturing freeze dried dosage forms in aluminum blister packs. The dosages are introduced as a liquid into the depressions of a blister sheet. The blister sheet comprises an impermeable intermediate layer positioned between first and second outer layers, with each of the outer layers having substantially the same overall coefficient of thermal expansion, as that term is defined herein. The properties of the outer layers of the laminate are such that there are no inter-layer stresses that will cause curvature of the laminate when it is subjected to temperature changes during the freeze drying process. The symmetrical response of the outer layers to such temperature changes can be achieved by using the same film material for both outer layers, or by using different materials which, by virtue of their intrinsic properties or thickness, exhibit similar degrees of thermal expansion or contraction. The outer layers can each consist of separate sublayers, as long as the sublayers in one outer layer are s
REFERENCES:
patent: 4305502 (1981-12-01), Gregory et al.
patent: 4371080 (1983-02-01), Haines
patent: 4754597 (1988-07-01), Buxton et al.
patent: 5310060 (1994-05-01), Bitner et al.
patent: 5343672 (1994-09-01), Kearney et al.
patent: 5469968 (1995-11-01), Matthews et al.
Kearney Patrick
Thompson Andrew Roy
Yarwood Richard John
Moon Daniel
R. P. Scherer Corporation
Tolan Ed
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