STEPPED-EDGE BLISTER PACK AND USE OF STEPS

Abstract: A blister pack for containing and dispensing unit doses of medication comprises a base sheet (12) and a substantially planar lidding sheet (14). The base sheet has a plurality of blister compartments (16) and a plurality of stepped edges, one stepped edge being adjacent each blister compartment. The lidding sheet (14) is peelably sealed to the base sheet (12) except at extended edge regions forming edge peel tabs (24), and the lidding sheet (14) is scored with lines of weakening (26) about each blister compartment (16). The stepped edges underlay the unsealed extended edge regions of the lidding sheet, thus providing a finger access to thereby ease the process of grasping a given edge peel tab (24) and ultimately opening a given blister compartment (16). The invention facilitates exposure of a blister compartment (16). Further, the stepped edges of the present invention reduce undesired undulation in the base sheet (12).

Description: STEPPED-EDGE BLISTER PACK AMD USE OF STEPS The present invention relates to blister packaging, such as for the containment and dispensing of fast-dissolving dosage form (FDDF) drug formulations or other forms of medication. More particularly, the present invention relates to a stepped edge blister pack having an enlarged unsealed stepped tab at an edge adjacent to each blister pocket, thus allowing for ease of opening and for reinforcement and accordingly the prevention of undesired undulation. Medication in forms such as tablets, capsules or caplets has been typically packaged in blister packages or sheets of multiple blister compartments. A base sheet of transparent or opaque plastic, for instance polyvinyl chloride (PVC or PVC type laminates) , has a plurality of blister compartments projecting from one face thereof, for containing the unit dosages of medication. Solid units of medication may be deposited into the blister compartments of the base sheet. Alternatively, as explained by Gregory et al., U.S. Patent No. 4,305,502, the medication may be closed and frozen within the plastic sheet and then dried using a freeze-drying process. Preferably, a liquid suspension is dosed into the pre-formed blister compartments of the base sheet. The base sheet containing the suspension is then cooled by a medium such as liquid nitrogen or carbon dioxide, thereby freezing the contents of the blister compartments. The frozen contents may then be subjected to reduce pressure to complete the freeze drying process. Finally, a lidding or cover sheet typically comprised at least in part of aluminum foil, is SUBSTITUTE SHEET peelably sealed, preferably by a heat sealing process, to the top of the base sheet and perforated about each blister compartment, thus removably enclosing the medication. To permit the cover sheet over an individual blister compartment to be peeled from the respective portion of the base sheet, a small portion of the edge of the cover sheet may be left unsealed to the base sheet, adjacent to each blister compartment. A patient may thus grasp the unsealed edge and accordingly peel the cover sheet from the base sheet to reveal a unit of medication. For instance, the above-mentioned Gregory et al. patent discloses a pharmaceutical dosage form package comprised of a filmic base sheet having depressions, and a covering sheet adhered to the base sheet except at side portions adjacent to each depression. The Gregory specification states that in those portions, "the covering sheet is not adhered to the filmic material so that the user may start peeling away the covering sheet at these locations." (Col. 4, lines 64-66.) Recently, developments in the medical field have necessitated an increase in the size of the edge peel tab to allow patients with dexterity difficulties a larger tab to grip and peel. Extending the size of the edge peel tab, however, has been seen to result in blister packs that have severe edge undulation due to uneven shrinkage after the heat sealing process and that are difficult to peel in part due to the tendency of the cover sheet to stick to the plastic base sheet as a result of heat transfer. Prior art blister packs have never before combined the advantages present in the present invention. This invention presents a blister pack SUBSTITUTE SHEET comprised of a base sheet having a plurality of blister compartments formed therein, and also a plurality of extended stepped edges formed therein, each stepped edge being adjacent to one of the blister compartments. A substantially planar lidding foil preferably coterminous with the base sheet is peelably sealed to the base sheet, thus enclosing the blister compartments and providing an edge tab at the stepped edge adjacent to each blister compartment. The stepped edge of the base sheet provides a useful finger access through which the edge tab may be grasped. By grasping the edge tab of the lidding foil at the finger access formed by the stepped edge and by peeling the lidding foil from a given blister compartment, a patient may dispense the contents of the given compartment. An extended edge peel tab with a stepped-base feature will thus ease the mechanism by which the package is opened and will accordingly assist in patient compliance. There is shown in the existing art various forms of blister packs, none of which embodies all of the features and advantages of the present invention. The Moser et al. reference, U.S. Pat. No. 3,941,248, for instance, discloses a tear-open package for tablets comprised of a lower base foil, a cover foil and "grasping recesses" for grasping and removal of the cover foil. Moser does not disclose a stepped-edge configuration like that of the present invention. Rather, the "grasping recesses" of Moser are concealed interiorly beneath the cover foil and cannot be easily reached until an individual tablet package is severed from the overall package or until a centrally positioned strip is severed from the overall package. SUBSTITUTESHEET Mullen, U.S. Pat No. 3,933,245, discloses an article holding and dispensing container comprised of a tray of blister compartments and a closure means heat-sealed to the tray. The tray and closure means are each scored with horizontal and vertical score lines, thus allowing each individual blister to be severed from an adjacent blister. At each intersection of score lines is a preferably circular depressed area, at which point there is an absence of heat-sealing. Thus, the sheet covering an individual blister can be peeled off either (i) by grasping the sheet at the intersection of the adjacent horizontal and vertical score lines or (ii) by detaching the blister from adjacent blisters and then grasping the sheet at the area of depression. In contrast, the cover sheet in the present invention can be peeled from an individual blister by simply grasping the edge-tab at the finger access and pulling the cover sheet away from the base sheet. Hellstrom, U.S. Pat. No. 3,472,367, discloses a quick-opening package comprised of a relatively stiff supporting layer, at least one pocket formed in the supporting layer, and a backing layer adhered to the supporting layer. In order to open the enclosed pocket, the package is bent along a line crossing the pocket, thereby rupturing the backing layer over the pocket. The supporting layer is preferably reinforced with a series of flutes or ridges to ensure that the bending occurs in the proper position relative to the pocket. Further, Hellstrom discloses a process of manufacturing this quick-opening package, wherein pockets and flutes are simultaneously stamped onto a continuous strip of blister material, a backing layer is applied, and SUBSTITUTE SHEET the resulting strip can be severed or fed from a strip dispenser. The present invention differs from Hellstrom in that the blister compartments of the present invention are not opened by bending the package and rupturing a given blister; rather, a blister compartment made in accordance with the present invention would be opened by peeling the cover sheet from the base sheet, after accessing the cover sheet from the stepped peel tab at the edge of the pack. Finally, as mentioned above, Gregory et al. , U.S. Patent No. 4,305,502, discloses a pharmaceutical dosage form package comprised of a plastic film blister sheet with depressions for receiving dosage forms, and a laminate cover sheet adhered to it except at edge peel tab areas. The surface of the cover sheet is scored to allow access to the enclosed dosage forms, which are formed in place by freeze-drying. Importantly, the Gregory package does not disclose the stepped edges and associated ease of peeling and reduced edge undulation that is achieved by the present invention. The present invention relates to an edge peel blister pack having improved ease of opening and reduced undulation. It is therefore an object of the present invention to provide a means for easing the peelability of the edge peel tabs on a blister pack by providing a stepped edge to the blister pack. A further object of the present invention is to reduce undulation at the unsealed edge of the blister pack by strengthening the edge with one or more steps or recesses, thereby reducing machine feeding problems and significantly improving pack SUBSTITUTESHEET appearance. Another object of the present invention is to prevent the cover sheet from sticking to edge of the base sheet during sealing, and accordingly to provide adequate finger access, by including an extended stepped edge adjacent to each blister compartment. Further objects and advantages of the present invention will become apparent in the following description. The invention will now be described by way of example and with reference to the accompanying drawings wherein: Figure 1 is a plan view of a stepped edge blister pack made in accordance with the present invention; Figure 2 is a sectional view taken on line 2-2 of Figure 1; Figure 3 is a perspective view of a blister sheet for use in a blister pack according to the invention; Figure 4 is a perspective view of the stepped edge blister pack shown in Figure 1; Figures 5 and 6 are partial perspective views of the stepped edge blister pack, illustrating the grasping of an edge tab and the peeling of the lidding foil from the blister sheet; and Figures 7 and 8 are partial perspective views of the stepped edge blister pack, illustrating the dispensing of a unit of medication from the blister pocket. Referring first to Figures 1 and 2, in the preferred embodiment, blister pack 10 comprises a blister sheet 12 and a lidding sheet 14. At least one but preferably a plurality of depressions or SUBSTITUTESHEET blister compartments 16 extend from the plane of the blister sheet, and a same number of stepped recesses 18 are positioned at the edge of the blister sheet, one stepped recess being adjacent to each blister compartment. The blister sheet may be made of any of a variety of translucent or opaque plastics such as polyvinyl chloride (PVC) , PVC and PVdC (polyvinyl dichloride) , polythylene PVC/PVdC/polyethylene, PVC/Aclar and cold formed aluminum materials. Within each blister compartment is a unit dosage form 20. The dosage form may be a preselected quantity of a pharmaceutical prepared by lyophilization (freeze-drying) , resulting in a fast- dissolving dosage form (FDDF) . Conventional dosage forms such as tablets, capsules, caplets or the like, may also easily be contained within the blister compartments. The unit dosage forms are retained within the blister compartments 16 by the lidding sheet 14. The lidding sheet may be comprised of any of a variety of materials such as polyester laminates, aluminum foil, aluminum/ester laminates, paper, paper/aluminum laminates, and other related materials. The lidding sheet is substantially planar and preferably coterminous with the blister sheet. As illustrated by the shaded areas in Figure 1, the lidding sheet is preferably sealed to the blister sheet by heat sealing, but remains unsealed at an extended edge area 22 adjacent to each blister compartment. This unsealed edge area 22 serves as a peel tab 24 to facilitate the ultimate removal of the lidding sheet from a given blister compartment as shown in Figure 4. As is shown in Figures 1 and 4, the lidding sheet is scored with preferably horizontal and SUBSTITUTE SHEET vertical perforated lines or other lines of weakening 26 about each blister compartment, thereby allowing the lidding sheet to be removed from an individual blister compartment while retaining the sealed cover over the remaining compartments. As shown in Figure 3, it is possible, in addition, to score the blister sheet along identical lines 28, thus permitting an entire individual blister compartment pack to be severed from the overall pack. As noted above, access to a given blister compartment on a typical edge peel blister pack may be made feasible by leaving a small portion of the edge of the cover sheet unsealed to the edge of the blister sheet, thus creating an edge peel tab 24. This tab may be marked with an appropriate label as illustrated in Figure 4. A patient grips the unsealed tab and pulls back and upwardly on the cover sheet, thereby removing the cover sheet from the blister compartment. The present invention significantly eases access to the edge peel tab 24, by providing the stepped edge 30 and finger access 32 illustrated in Figure 2. In particular, a step is formed in and at the edge of the base sheet adjacent to each blister compartment. Thus, where the lidding sheet covers a given stepped recess, a finger access 32 is formed for grasping the edge peel tab 24. Further, in order to additionally ease access to a given blister compartment, the present invention includes an extended edge peel tab. This feature is particularly aimed at users whose dexterity skills are reduced, such as the elderly, the infirm, or people suffering from chronic conditions such as arthritis. In so extending the SUBSTITUTESHEET unsealed edge 22 of the blister pack, however, it has been seen that severe edge undulation results in the blister sheet, causing unsightly pack appearance and difficulties in machine feeding and coding. The stepped edges 30 of the present invention significantly reduce this undesirable edge undulation and thereby reduce processing difficulties. Figures 5-7 illustrate the process by which a unit dosage is accessed in the preferred embodiment of the present invention. The patient inserts a finger at the finger access 32 beneath the edge-peel tab 24. The patient then grasps the edge-peel tab and pulls back and upwardly on the lidding sheet, tearing along the lines of weakening 26 and thereby removing the lidding sheet from the individual blister compartment. The patient may then dispense the unit dosage 20 by inverting the pack or by depressing the underside of the blister compartment. While a preferred embodiment of the present invention has been depicted and described, in which a plurality of blister compartments 16 are found in the base sheet 12 , it will be understood that single compartment packages can be manufactured separately. Where a plurality of blister compartments 16 are provided adjacent an edge of the base sheet 12, a single stepped recess 18 along the edge can be sufficient to facilitate removal of the lidding sheet 14 from each respective blister. However, the illustrated arrangement is preferred. SUBSTITUTESHEET

Claims: CLAIMS 1. A package for containing and dispensing at least one article, said package comprising: (a) a substantially planar base sheet having at least one depression formed therein for containing an article, the depression having a top opening; (b) a step formed in and at an edge of the base sheet; and (c) a substantially planar lidding sheet sealed to the base sheet to cover the top opening of the depression and thereby enclose the article in the depression, and provide a peel tab positioned over the step, whereby the lidding sheet is removable from the base sheet by peeling the tab and lidding sheet away from the base sheet. 2. A package according to Claim 1 wherein the lidding sheet is essentially coterminous with the base sheet. 3. A package according to Claim 1 or Claim 2 wherein the step is disposed adjacent to the depression. 4. A package according to any preceding Claim wherein the lidding sheet is heat sealed to the base sheet. 5. A package according to any preceding Claim wherein the lidding sheet is sealed to the base sheet except for a portion at the edge of the base sheet. 6. A package according to any preceding Claim wherein the base sheet comprises a plastics material or a plastics laminate. 7. A package according to any preceding Claim SUBSTITUTESHEET wherein the lidding sheet comprises aluminum foil or an aluminum laminate. 8. A blister pack for containing and dispensing at least one unit of medication, comprising: (a) a base sheet having an upper surface, a lower surface and an edge; (b) a plurality of blisters formed in and depending downwardly from the base sheet, with a substantially planar portion of the base sheet surrounding each blister, thereby defining a top opening thereof, each blister being spaced from the edge; (c) a plurality of steps formed in and depending downwardly from the base sheet, the substantially planar portion of the base sheet extending around each step, thereby defining a top opening therefor; (d) a lidding sheet essentially coterminous with the base sheet and peelably sealed to the substantially planar portion thereof, the lidding sheet traversing the top openings of the blisters and steps thereby (i) covering said blisters and (ii) providing for finger access to an unsealed tab adjacent each blister; and (e) an array of lines of weakness in the lidding sheet disposed around the top openings of the blisters, whereby a given blister is opened by peeling a portion of the lidding sheet including a tab and defined by the lines of weakness away from the base sheet to expose the respective top opening. 9. A blister pack according to Claim 8 wherein each step is disposed at the edge of the SUBSTITUTE SHEET base sheet. 10. A blister pack according to Claim 8 or Claim 9 wherein the base sheet comprises a plastics material or a plastics laminate. 11. A blister pack according to any of Claims 8 to 10 wherein the lidding sheet comprises aluminum foil or an aluminum laminate. 12. A blister pack according to any of Claims 8 to 11 wherein the lidding sheet is heat sealed to the base sheet. 13. A blister pack according to any of Claims 8 to 12 wherein the base sheet includes an array of lines of weakening disposed around the top openings of the blisters in alignment with the lines of weakening in the lidding sheet, whereby individual blister packs may be removed by severing the base sheet and the lidding sheet along the lines of weakening. 14. A method of manufacturing a blister pack comprising a base sheet having a plurality of blister pockets and a substantially planar portion surrounding each blister pocket thereby defining top openings thereof, and a substantially planar lidding sheet covering the top openings of the pockets and being peelably secured to the substantially planar portion of the base sheet, in which method recessed steps are formed in the substantially planar portion of the base sheet in order to reinforce the base sheet and prevent undulation of the said base sheet and the lidding sheet during the manufacturing process. 15. A method according to Claim 14 wherein the steps are formed at edges of the base sheet. 16. A method according to Claim 14 or Claim 15 wherein the steps are formed in the base sheet prior SUBSTITUTE SHEET to machine feeding, in order to prevent buckling of the base sheet during machine feeding. SUBSTITUTE SHEET

Inventors: MARSHALL RAY WILLIAM, THOMPSON ANDREW ROY, MARSHALL, RAY, WILLIAM, THOMPSON, ANDREW, ROY
Applicants: MARSHALL RAY WILLIAM, SCHERER CORP R P, THOMPSON ANDREW ROY, R.P. SCHERER CORPORATION
Application year: 1993
Main classification: B65D75
IPC codes: A61J1, B32B15, B32B27, B65D75