WO2001002265A1

WO2001002265A1 - Blister packs

Info

Publication number: WO2001002265A1
Application number: PCT/GB2000/002420
Authority: WO
Inventors: Michael John Cooper; James Lake Robertson
Original assignee: Pago Limited
Priority date: 1999-07-06
Filing date: 2000-07-06
Publication date: 2001-01-11
Also published as: GB9915643D0

Abstract

A blister pack (10) comprises a blister sheet having at least one row of blisters (12) and a cover sheet (11) laid over and bonded to the area of the blister sheet which surrounds the blisters. The cover sheet is burstable by pressure applied through a blister to a product therein, so freeing the product. A label (13) is applied to the cover sheet (11), which label provides a security strip (14, 15, 24) extending over each blister (12), the strip having sufficient strength to resist bursting of the cover sheet unless at least one end of the strip is mostly freed from the surrounding areas of the cover sheet. That one end may be mostly freed by cutting away the strip at one end of the pack or by using a peel-tab (31) to lift up the strip (24) adjacent the end blister (17) of a row.

Description

BLISTER PACKS

This invention concerns blister packs. In particular, the invention relates to blister packs primarily (but not exclusively) intended for containing pills, tablets or capsules and having at least one row of blisters formed by a blister sheet together with a cover sheet laid over and bonded to the blister sheet, and also to a method of constraining the freeing of products sequentially from each blister of a row thereof in a blister pack. The invention further relates to a label for use in the manufacture of a blister pack.

Blister packs having a plurality of blisters, usually arranged in one or more rows, are widely used in the pharmaceutical industry, for the packaging of individual tablets, pills and capsules (all of which are hereinafter referred to simply as "tablets"). Such packs maintain each tablet in its own environment until the blister is opened by pushing a tablet through the cover sheet by pressing on the blister. In this way, the tablets are hygienically protected until required for use and it can immediately be seen if a pack has been tampered with since the removal of a tablet ruptures the cover sheet. Moreover, the dispensing of a particular number of tablets is much facilitated, without the need for a pharmacist to count individual tablets.

Though the pack may be marked to show that the tablets should be taken in a particular order or at particular times, a patient may release a tablet from any chosen blister of the pack and markings on the pack are frequently ignored. In addition, tablets may easily be removed from blister packs by children, since a relatively small force is required to free a tablet from its blister, through the cover sheet. If child-resistance is important, then it is necessary to keep a blister pack in a child-proof outer container.

In an attempt to address the above problems, it is known to provide an unburstable security strip which extends along and over each blister of a row thereof in a blister pack, as disclosed in GB-2312421-A. However, the techniques described in this specification are very difficult to implement in a production environment, in view of the problem of positioning and attaching the security strip over a row of blisters. As a consequence, those techniques have not yet been taken up commercially, to impart a measure of child-resistance to a blister pack. It is a principal aim of the present invention further to address the problems mentioned above. This is achieved by improving the blister pack configurations disclosed in GB-2312421-A, so making the product commercially viable, for use principally in the pharmaceutical industry. According to one aspect of the present invention, there is provided a blister pack comprising a blister sheet having at least one row of blisters formed therein, a cover sheet laid over and bonded to the area of the blister sheet surrounding the blisters and burstable in the region of each blister, and a label adhered to the external surface of the cover sheet, the label providing a burst- resistant security strip which when the label is adhered to the cover sheet is aligned with the row of blisters in the blister sheet to extend over each blister.

The blister pack of the present invention differs from a conventional blister pack in that a special label is applied to the cover sheet so as thereby to furnish the cover sheet with a security strip overlying the blisters, which strip has sufficient strength to resist bursting of the cover sheet by pressing on a blister from the other side, to urge a contained product - such as a pharmaceutical tablet - out of the blister. However, by defining the security strip in such a way that it may peel away from the cover sheet, a blister may be opened to free a contained product; that peeling away may be permitted either by cutting through the entire pack adjacent a blister or, preferably, by starting to free tablets from the blister at one end of the row thereof.

It would be possible to apply to the cover sheet a label carrying a security strip which imparts to the finished pack the desired properties, for example by laminating to the label a separate strip which could be of a suitable plastics material. This may be done during conversion of the label stock to form the labels, or may instead be performed at the application station, as the labels are applied to the packs. In either case, advantageously the strip is positioned between the cover sheet and the label, in which case the strip should be adhered to the cover sheet as well as the label, though the strip could be applied to the outer surface of the label.

Despite the above, the most preferred way of implementing this invention is for the label itself to define the strip, by cutting or otherwise defining (for example, perforating, scoring or partially-cutting) the required shape of the strip out of the material of the label. This has the advantage that the strip can be defined and secured to a blister pack merely by using entirely conventional labelling techniques, which are well understood and widely used, so greatly facilitating the implementation of the invention on a conventional blister- packaging line.

The label may be of a conventional material as is commonly employed for labelling. Thus the label could be of paper or a paper-like plastics material. Preferably, each label is cut from a web of self-adhesive label stock by a die- cutting operation, in which case the strip is formed by die-cutting the required strip profile in the material of the label at the same time.

The strip could be specially profiled to ensure it has the required strength and adhesion properties to impart to the finished pack the desired characteristics, for example by adjusting the width of the strip between the blisters, the strength of the adhesive bonding the strip to the cover sheet, the strength of the material forming the label and also the spacing between adjacent blisters. Preferably, however, the strip is of simple linear form and of a width sufficient to ensure that the strip prevents bursting of a blister other than a blister immediately adjacent an already-burst blister, except for the blisters at the ends of the row thereof. As mentioned above, the blister at the end of a row may be opened either by cutting through the pack immediately adjacent the end of the blister, so permitting the strip to peel away. Alternatively, the strip may be cut during manufacture of the label to terminate part-way across that end blister, or may extend only a short way beyond that end blister towards the end of the pack, so that the strip permits the opening of the end blister. Another possibility is to provide a peel-tab which connects to the security strip and which may be lifted away from the cover sheet, then to facilitate peeling of the security strip, thereby permitting release of the tablet in the first blister of the row thereof.

In a case where the label is made from a relatively high-strength material, opening of each individual blister may be facilitated by forming cuts part-way through the thickness of the label (but not through the strip) in the region of each blister. For example, the cuts may radiate from a position substantially centrally of the blister. In a preferred embodiment, the strip has a discontinuity in the region of each blister, so as to enhance the burst-resistance offered by the provision of the label over the cover sheet. In the case of essentially circular blisters, the discontinuity may be up to about 50% of the diameter of the blister, and preferably is disposed centrally of the blister.

Further to enhance the burst-resistant properties afforded by a linear strip, that strip may have a width of up to about 50% of the diameter of a blister over which the strip passes, for the case of a row of circular blisters. For blisters of other shapes, a suitable width for a strip may be determined empirically, taking into account factors including the shape and size of both the blister and the tablet contained therein, the strength and other properties of the cover sheet and label, and the intended size of the discontinuity (if there be one) in the strip. Equally, the size of the discontinuity may also be determined empirically. Preferably, the label is printed on the face thereof opposed to that adhered to the cover sheet. The label may be printed with identifying information concerning products (tablets) in the blisters, and also with information concerning the freeing of the products from the blisters. In the case of tablets, that information may include days of the week to identify when the tablets should be taken, as well as the first tablet to be taken. The label may further carry an information leaflet adhered thereto in a manner known per se.

The blister pack of this invention may have a plurality of parallel rows of blisters, a single label being applied to the cover sheet of the pack but which label defines a plurality of security strips, one for each row respectively. This invention extends to a label for use in the manufacture of a blister pack including a blister sheet having at least one row of blisters formed therein and a cover sheet laid over and bonded to the area of the blister sheet surrounding the blisters, which label is adapted to be adhered to the external surface of the cover sheet and provides a security strip which, when the label is adhered to the cover sheet, is aligned with and extends over the row of blisters in the blister sheet.

The invention further extends to a method of constraining the freeing of products sequentially from each blister of a row thereof in a blister pack comprismg a blister sheet having at least one row of blisters formed therein and a cover sheet laid over and bonded to the area of the blister sheet surrounding the blisters and burstable in the region of each blister to free the contained product, in which method a label is adhered to the external surface of the cover sheet, the label providing a security strip which is aligned with the row of blisters in the blister sheet to extend over each blister, whereby the strip resists bursting of the cover sheet of any blister except for the end blister of the row thereof and following the freeing of the product from said end blister, the strip permits the freeing of a product only from the next adjacent blister to a previously opened blister It will be understood that the method of this invention may be used to serve either or both purposes of ensuring the freeing of products (such as pharmaceutical tablets) sequentially in order from a row thereof as well as imparting a measure of child-resistance to the pack.

By way of example only, several specific embodiments of this invention will now be described in detail, reference being made to the accompanying drawings, in which. -

Figure 1 is a plan view on a first embodiment of blister pack of this invention, also showing variations thereof;

Figure 2 is a plan view similar to that of Figure 1 but on a second embodiment of blister pack of this invention;

Figures 3A, 3B, 3C and 3D are general perspective views showing, respectively, the pack of Figure 2, cutting the end of the pack to allow removal of a tablet from the first blister, the removal of that tablet and then the removal of a tablet from the next adjacent blister; and Figures 4 and 5A-5D correspond to Figures 2 and 3A-3D but of a third embodiment

The following description of examples of this invention concerns solely the packaging of pharmaceutical tablets It is to be understood that the invention is not limited to this use and may be used for packaging a wide variety of diverse products.

Figure 1 illustrates one face of a blister pack 10 comprising a cover sheet 11 laid over and bonded to a blister sheet (not shown) so as to form a plurality of individual circular blisters (or pockets) 12, formed by appropriate shaping of the blister sheet. The blister sheet is usually made from a transparent or lightly-coloured plastics material by a suitable moulding technique to permit the formation of the individual blisters 12, whereas the cover sheet may be of a variety of materials but conventionally is of aluminium foil when the blister pack is to be used for the packaging of pharmaceutical tablets, with one tablet in each of the blisters 12 of the pack The design and manufacture of such a blister pack is very well known and understood in the art and since it forms no part of the present invention as such, it will not be discussed in further detail here. As shown in Figure 1 , the embodiment of blister pack of this invention has two rows of three blisters 12, though other numbers of blisters could be provided. A label 13 is laid over and adhered to the outer surface of the cover sheet 11 , which label is formed from a self-adhesive paper label stock such as is widely employed in the packaging industry though other materials and adhesion techniques for the label may be employed. During the conversion step on the label stock to manufacture the labels, the label is die-cut to form two strips 14 and 15 extending along the label. The width and profile of the strips 14,15 should be selected so as to resist rupture of the cover sheet when subjected to the normal forces used to release a tablet from a blister, through the cover sheet. In turn, this depends upon the label material and thickness and the strength of the adhesive bonding the label to the cover sheet.

The upper strip 14 shown in Figure 1 is of simple linear form and extends centrally over the blisters 12 of the upper row thereof. The ejection of a tablet from a blister 12 by force applied to the blister itself, in an attempt to burst the tablet through the cover sheet 11 and label 13 is resisted by the presence of the label, which greatly adds to the strength of the cover sheet 11. The precise configuration of the pack, including the spacing between blisters 12 and the area of the label 13 may be controlled to ensure that there is sufficient bonding of the label 13 to the cover sheet 11 to continue resisting the ejection of a tablet from a blister, when normal forces are applied thereto.

In order to open the pack and permit the release of tablets from the blisters of the upper row, a cut line 16 is marked on the pack. By using a pair of scissors to cut off the end portion of the pack in line with the upper row of blisters, part-way along line 16, the area of the upper strip 14 adjacent the end blister and adhered to the cover sheet is reduced; force then applied to the end blister 17 to eject a tablet through the cover sheet and label will permit the strip 14 to peel away from the cut line 16. The remainder of the label over that blister will either lift or tear, depending upon the strength of the label and the adhesive employed, whereby the cover sheet 11 may be ruptured and the tablet in the blister ejected. Thereafter, a tablet in the next adjacent blister along the row thereof may be released after pulling the freed part of the strip 14 to reduce the length of strip held down by its adhesive, between the blisters. In an alternative arrangement (not shown) the blisters may be arranged with a much closer spacing than is shown in Figure 1 ; then the area of the strip 14 between adjacent blisters will be very much reduced and so, following the release of a tablet from an end blister 17, there will be only a small area of the strip adhering to the cover sheet between adjacent blisters, to prevent the strip lifting away. Thus, once the pack has been opened by releasing a first tablet from an end blister 17, the tablets may be released sequentially along the row merely by pressing on each blister, in turn. However, should an attempt be made to release a tablet from a blister with intact blisters to each side of that blister, there still will be sufficient strip area to both sides of that blister to prevent the bursting thereof. Consequently, a patient is constrained to open the blisters in turn, from the end blister 17.

The label 13 may be provided with cuts 18 in the vicinity of each blister 12 as shown on all but the upper left-hand blisters of the pack 10 of Figure 1. These cuts 18 may facilitate bursting of the next blister to be opened, to free a contained tablet. As shown, such cuts 18 may extend generally radially of the respective blister and should extend towards - but not into - the strip 14 or 15. Depending upon the strength of the label stock, such cuts may be formed part way or wholly through the thickness of the label, using conventional die-cutting techniques. On the other hand, those cuts may be omitted, for example, if the pack has relatively small blisters.

Strip 15, overlying the lower row of blisters 12, is of a modified form as compared to strip 14. Here, the strip has enlarged portions 19,20 between each pair of blisters and these serve to increase the bonding of the strip 15 to the cover sheet 11. Thus, the security provided by the strip 15 is enhanced and the opening of a blister by rupturing the cover sheet 11 is greatly resisted, other than by opening the blisters in order from end blister 21.

A blister pack 10 would ordinarily be provided with only one type of strip over the blisters in the pack. Moreover, the enlarged portions (if provided) would all be of the same dimensions and shape, on any one pack. Thus, the pack shown in Figure 1 has these variations merely for illustrative purposes, of this invention.

It will be appreciated that the placement of a label 13 on a blister pack 10 may be achieved using existing labelling technology. Self-adhesive labelling machines typically may maintain a ± 1mm placement tolerance and thus the label 13 may be positioned on a blister pack sufficiently accurately to ensure the strips 14 and 15 extend over the blisters, even when those blisters are relatively small, for containing small tablets. Currently, blister packs are frequently marked or decorated by the use of a pre-printed foil to serve as the cover sheet, with the printing or embossing of variable data such as a lot number or a date. When printed text changes are required, for example for different markets, the foil may have to be changed which results in an interruption in the blister packing line. By contrast, a blister pack of this invention may use a standard unprinted foil but enjoy the benefit of a multi-colour self-adhesive label printing step. With the addition of readily- available text changes using proven on-line variable printing technology, increased production flexibility can be obtained.

Referring now to Figures 2 and 3, there is shown a second embodiment of blister pack of this invention, which is broadly similar to that of Figure 1 and so like reference numbers are used to indicate like parts; those parts will not be described again here.

The pack of Figures 2 and 3 differs from the arrangement shown in the upper part of Figure 1 , which uses a simple linear strip 14, in that the strip 24 is of a greater width and has discontinuities 25 in the region of the strip which overlies each blister 12. The discontinuities are provided simply by appropriately die-cutting the label 13, during the label conversion step from label stock. Typically, the discontinuity is up to a maximum of about 50% of the diameter of each blister 12 (for the case of the illustrated circular blisters) and is disposed essentially centrally over each blister. Further, the width of each strip 24 is of the order of up to 50% of the blister diameter.

Figure 3A shows, in a general perspective manner, the pack of Figure 2. When tablets are to be removed from the lower row of blisters 12, a pair of scissors 26 is used (Figure 3B) to make a cut part-way across the pack, along line 16 printed on the label 13. Then, pressure applied to the end blister 17 will peel away from the cover sheet the short length 27 of strip 24 beyond that end blister, so permitting the cover sheet to burst and free the tablet (Figure 3C). The part 28 of the strip still adhering to the cover sheet between blister 17 and the next blister 29, serves to ensure mere pressure on that blister 29 will not burst the cover sheet, so retaining a tablet in the blister 29. However, as shown in Figure 3D, the part of the strip which was overlying end blister 17 may be grasped to peel away part 28 from between the blisters, so that subsequent pressure on blister 29 will burst the cover sheet and free the tablet from that blister. This process may be continued for the entire row of blisters, of the pack.

Figures 4 and 5 show a modification of the arrangement shown in Figures 2 and 3 and again like reference numbers are used to show like parts. In the arrangement of Figures 4 and 5, there is provided for each strip 24 a peel-tab 31 which communicates with the strip but extends transversely to the length of the strip, to an edge of the label 13. During the manufacture of the label or at the time of applying the label to the cover sheet 11 , the adhesive underlying the peel-tab 31 is at least partially deadened, so that the peel-tab is not so securely bonded to the cover sheet as is the main part of each strip 24.

The arrangement of Figures 4 and 5 permits opening of the pack and removal of tablets within the blisters without the need to use scissors to effect an initial cut transversely of the pack. Rather, the end part of the peel-tab 31 may be lifted away from the cover sheet (Figure 5B) and then grasped more firmly so as to start peeling of the strip 24 up to the end blister 17, whereafter a tablet may be released from the end blister (Figure 5C) in the manner described above. Thereafter, further tablets may be removed as with the previous embodiment. The overall configuration of the strips, for all of the embodiments described above, as well as the materials to be employed in the production of a pack of this invention may be determined empirically, having regard to the characteristics to be imparted to the pack. The parameters which may be taken into account include:

• The shape and size of the blisters 12;

• The spacing between the blisters;

• The rupture strength of the cover sheet 11 ;

• The rupture strength of the label 13; • The style and depth of the cuts in the label, defining the strips; and

• The strength of the adhesive holding the label and defined strip to the cover sheet.

It will be appreciated that a conventional blister pack may be modified in accordance with the present invention essentially by the use of labelling technology. Thus, the blister packaging process for example for pharmaceutical tablets may be operated entirely conventionally, whereafter the blister packs containing the tablets are, in effect, labelled but using the special form of label described above. The labels may be manufactured on-line, including the printing thereof, or those labels may be pre-produced by a suitable conversion process from label stock with the strips die-cut therein, at that time.

A multi-folded pamphlet, such as an information leaflet may be adhered to the label 13, either during conversion of the label stock or subsequent to the application of a label to a blister pack. The production and adhering of such multi-folded pamphlets is well-known in the labelling art and already is widely used; it may usefully be employed particularly with pharmaceutical tablet blister packs and so with packs of this invention.

When completed, a blister pack of this invention has considerable child- resistant properties since a child could not release from the pack a random tablet by pressing on a chosen blister, unless the child happened to choose a pack as shown in Figures 4 and 5 and that child also initially succeeded in lifting up the peel-tab 31. Moreover, the pack serves to constrain the release of tablets in a predetermined order, from a row of blisters.

Claims

1. A blister pack comprising a blister sheet having at least one row of blisters formed therein, a cover sheet laid over and bonded to the area of the blister sheet surrounding the blisters and burstable in the region of each blister, and a label adhered to the external surface of the cover sheet, the label providing a burst-resistant security strip which when the label is adhered to the cover sheet is aligned with the row of blisters in the blister sheet to extend over each blister.

2. A blister pack as claimed in claim 1 , wherein the strip is separately formed and is provided on the side of the label which is adhered to the cover sheet.

3. A blister pack as claimed in claim 2, wherein the strip comprises a strip of a plastics material.

4. A blister pack as claimed in claim 1 , wherein the security strip is defined by the material of the label itself, by forming lines of weakness in the material.

5. A blister pack as claimed in claim 4, wherein the strip is die-cut out of the material of the label, at the time of the conversion of a web of label stock to form a plurality of the labels supported on a release backing web.

6. A blister pack as claimed in claim 4 or claim 5, wherein the strip extends only part-way across a blister located at one end of the row of blisters.

7. A blister pack as claimed in any of the preceding claims, wherein the strip is discontinuous over a portion of each blister.

8. A blister pack as claimed in any of the preceding claims, wherein the width of the strip does not exceed about 50% of a blister diameter.

9. A blister pack as claimed in any of claims 4 to 7, wherein the width of the strip is greater in the region of the area between blisters than where the strip extends over a blister.

10. A blister pack as claimed in any of the preceding claims, wherein the label is printed on the face thereof opposed to that adhered to the cover sheet.

11. A blister pack as claimed in any of the preceding claims, wherein the spacing between adjacent blisters along the row thereof is greater than the width of each blister, in the same direction.

12. A blister pack as claimed in any of the preceding claims, wherein the pack includes a separation line for the removal of a portion of the blister sheet, cover sheet and label transversely across one end of the pack to permit the subsequent ejection of a product from the blister nearest the removed portion.

13. A blister pack as claimed in any of claims 1 to 11 , wherein the label includes a peel-tab communicating with the security strip, which tab is only lightly adhered to the cover sheet whereby the tab may be lifted from that sheet.

14. A blister pack as claimed in any of the preceding claims, wherein the blister sheet has a plurality of parallel rows of blisters, each row having a multiplicity of spaced blisters, and the label provides a respective strip for each row.

15. A blister pack as claimed in any of the preceding claims, wherein each blister of the blister sheet is configured for holding a tablet for pharmaceutical use.

16. A label for use in the manufacture of a blister pack including a blister sheet having at least one row of blisters formed therein, and a cover sheet laid over and bonded to the area of the blister sheet surrounding the blisters which label is adapted to be adhered to the external surface of the cover sheet and provides a security strip which, when the label is adhered to the cover sheet, is aligned with and extends over the row of blisters in the blister sheet.

17. A method of constraining the freeing of products sequentially from each blister of a row thereof in a blister pack comprising a blister sheet having at least one row of blisters formed therein and a cover sheet laid over and bonded to the area of the blister sheet surrounding the blisters and burstable in the region of each blister to free the contained product, in which method a label is adhered to the external surface of the cover sheet, the label providing a security strip which is aligned with the row of blisters in the blister sheet to extend over each blister, whereby the strip resists bursting of the cover sheet of any blister except for the end blister of the row thereof and following the freeing of the product from said end blister, the strip permits the freeing of a product only from the next adjacent blister to a previously opened blister.