CA2093287A1

CA2093287A1 - Blister pack

Info

Publication number: CA2093287A1
Application number: CA002093287A
Authority: CA
Inventors: Heinrich Eggert; Hans Schwartz; Matthaeus Muller
Original assignee: Dr Karl Thomae GmbH
Current assignee: Boehringer Ingelheim Pharma GmbH and Co KG
Priority date: 1992-04-03
Filing date: 1993-04-02
Publication date: 1993-10-04
Also published as: EP0563934A1; HU9300981D0; KR930021511A; AU3566193A; JPH0639020A; HUT68553A

Abstract

Abstract Blister Pack The invention relates to a blister pack comprising a base with product unit retaining wells and a covering film thereon to seal said wells, each well having a side wall and a well base and containing at least two product units arranged one above the other, wherein said side wall is thinner than said well base and is deformable to create a product unit retaining means when pressure is applied to said well base to release the uppermost product unit from the well, said retaining means serving to retain the subsequent product unit in said well and being deformable under further pressure exerted on said well base whereby to permit release of said subsequent product unit. The blister pack can be produced by cold deep-drawing of polypropylene films or plastics films having similar mechanical properties.

Description

2~932~7 59315.559 Blister Pack The present invention relates to a blister pack with double or multiple dosing in a wéll, and the production thereof. The base of th~ blister pack is preferably made of plastics films, e.g. polypropylene films or plastics films having similar mechanical properties.

Conventionally, blister packs are used in pharmacy as containers for holding pharmaceutical products such as plain or coated tablets and capsules. These blister packs, which are formed with at least one well, contain units of such products sealed tight with a covering film. The blister packs have the task of protecting the product unit contained in the well from all possible environmental influences such as water, water vapour and any kind of contamination, in order to assure the consumer of the given durability and authenticity of the product packaged therein.

Commercially available blister packs for pharmaceutical products generally contain one plain or coated tablet or capsule in each well. Since each product unit requires a certain area of film material to accommodate it safely, large amounts of film material are re~uired by the packaging industry for packaging these products.
Moreover, the empty blister packs have to be disposed of by some kind of recycling.

There is thus a need for an improved packaging in order to stem the flood of this recyclable material and at the same time reduce the costs for the necessary film by at least half.

DE-A-3623331 describes packaging, e.g. blister packs with chambers which contain at least two solid dosage - . -,.;,.. .. ., ., : . .
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units, not mechanically joined together, of different pharmaceutical compositions. To avoid the risk of confusion when taking the drugs, the dosage units differ recognisably, e.g. in their shape, size or colour, and the dosage forms are separated from one another by the spatial configuration, e.g. by a bar-shaped convexity or by additional pieces of film.

DE-A-1544098 describes blister packs for tablets, having an accompanying dehydrating element, e.g. a pastille, held in a constriction or narrowing in the side wall of the well at a distance below the tablet. The diameter of the well is smaller in its lower region containing the dehydrating element than in the upper region containing the tablet, and the tablet is separated from the dehydrating element by a water-permeable piece of paper or cardboard.

DE-A-1486408 describes tear-open packages for tablets or coated tablets, consisting of a receiving portion which contains deep-drawn or pressed pouches for receiving the tablets and which is closed off on the outside by a covering film. The plain or coated tablets are secured on the covering film or in the receiving portion by adhesive bonding or by means of mechanical retaining means and the covering film can be returned to the closed position after one or more items have been removed. The side walls of the wells of the receiving portion may have elastic ties for mechanical]y securing the tablets.

An object of the present invention is to provide a double or multiple dosing, particularly of plain or coated tablets, within the same well, the product units however being adapted to be taken individually. Thus, for example, two doses may be accommodated in one well, thereby reducing by half the film required.

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2 ~ 7 Viewed from one aspect the present invention provides a blister pack comprlsing a base with product unit retaining wells and a covering film thereon to seal said wells, each well having a side wall and a well base and containing at least two product units arranged one above the other, wherein said side wall is thinner than said well base and is deformable to create a product unit retaining means when pressure is applied to said well base to release the uppermost product unit from the well, said retaining means serving to retain the subsequent product unit in said well and being deformable under further pressure exerted on said well base whereby to permit release of said subsequent product unit.

In one embodiment the wells which are formed or drawn in the blister strip have uniformly smoothly shaped side walls and well bases, the wells each having at least two product units arranged one above the other and optionally touching, the height of the side walls corresponding to at least the total height of the product units to be accommodated in one well and the wells having no preformed retaining means for any other product units located underneath the topmost product, and the part of the film which forms the side wall being thinner than the film wall of the well base, preferably three to ten times thinner. The film material which becomes superfluous by compression when the upper product is removed by pressing on the well base `
conveniently arranges itself in a bead or welt in the form of a concertina in front of the next product remaining in the blister well, so that this product is retained in the blister well, and the welt-like closure can be overcome by increased pressure in order to release the product thus retained.

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The blister pack base is preferably made of plastics film and the well side walls are preferably 3-10 times thinner than the well bases.

The thickness of the well base depends on the thickness of the strips of film used to produce the blister pack;
for practical manufacturing reasons it is generally 5 to 20% thinner than the thickness of the strip of film used.

If a well of this kind is filled with two or more product units, preferably with two similarly shaped units, e.g.
tablets, of the same drug preparation, and outwardly covered with a covering film which can be pressed out, a single unit can be removed by pressing on the base of the well because the subsequent product unit is held in position by the formation of the concertina-like product unit retaining means in the region of the well opening.
Only by increased pressure on the well base is it possible to free this next product unit. Specifically, this is carried out by exerting further pressure on the well base of the now superfluous part of the side wall, thereby pressing it towards the opening of the well and in this area forming an encircling barrier or a concertina-like accumuiàtion of material which initially prevents the next product unit from being released. If this product unit is also to be released, the pressure on the base of the well should be increased until this barrier is overcome. This thereby ensures that each individual product unit can be removed separately.

The base of the well can be adapted to the surface shape of the product; for planar contents, e.g. tablets, it is preferably planar but for contents with a convex surface it is preferably adapted to fit this curvature.

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The side wall of the depression is preferably conically shaped and may be adapted to the geometry of the contents, e.g. the side wall is preferably encircling in the case of circular tablets and in the case of oblong tablets or capsules it preferabl~ extends along the longitudinal axis of the contents. For cubic contents the side walls are advantageously adapted to fit the cube.

The covering film may consist of a sheet metal film (e.g. of aluminium) or of plastics or corresponding paper films which can be burst open b~ pressing out.

The blister packs according to the invention can be produced by cold-forming plastics films, particularly by cold deep-drawing polypropylene films or plastics films having equivalent mechanical properties.

Thus viewed from a further aspect the invention provides a process for the cold deep-drawing of plastics films without preheating comprising securing a plastics film -between a perforated die and a holding means, and urging the secured film and a forming punch together whereby to deform said film over the rim and into the bore of a forming aperture in said die, said rim providing a smooth shoulder merging either directly or via a step into said bore.

Following base formation, the product units are loaded onto the wells in the base and a closure film is disposed over the wells and secured to the base to seal the wells.

The apparatus used in base formation is novel and forms a further aspect of the invention. Viewed from this aspect the invention provides apparatus for the cold deep drawing of plastics films without preheating " .. : :. : . : : ::: ., i: ~ ' ,: ::
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2~2~7 comprising a forming punch, holding means and a perforated die, wherein the rim of a forming aperture in said perforated die (10) provides a smooth shoulder merging either directly or via a step with the bore of said aperture.

In the conventional manufacture of blister packs by deep-drawing the film material with thermoforming, well forms are produced which have a thin well base compared with the thickness of the side walls. A film fi~ed between a forming punch and a perforated die corresponding in diameter to the forming punch is heated and forming is carried out by pressing the perforated die towards the forming punch or vice versa. The film material which forms the side walls of the well in this forming process comes almost exclusively from that part of the film which subsequently produces the well base, since the entire projection area of the blister well opening onto the original strip of film is available for forming. The side walls of the blister wells thermally formed in this way are thus necessarily thicker and less flexible than the side walls of the blister wells according to the invention, with the result that pressure on the base of a thermally formed blister well does not produce a product unit retaining means in the form of a concertina, as described above.

In contrast, when the blister strip according to the invention is produced by cold deep-drawing of plastics films, the part of the film predominantly deformed is that part of the original film which constitutes the projection area of the gap between the outer edge of the shoulder of the perforated die used and the forming punch arranged centrally to engage with the perforated die (see Figures IV and V). By varying the diameter of the die bore in relation to the diameter of the forming punch, blister wells with side walls of different ', , `, ~ , . : .
, , ,',~ ~.: ;., 2~3~7 thickness can be produced, the side walls being thinner than the walls of the base of the well, preferably three to ten times thinner, and the thickness of the base of the well is only slightly reduced, preferably by 5 to 20%, compared with the thickness of the original strip of film. Such blister wells are capable of forming a product unit retaining means in the form of a concertina as described above by applying pressure to the well base.

The blister packs according to the invention may expediently be produced using plastics films of polypropylene or plastics films having equivalent mechanical properties. ~owever, it is preferable to use polypropylene films having a thickness of 150 to 350 ~m, a tear strength in the longitudinal and transverse directions of at least 20 N/mm2 in each case and an ~;
elongation at break in the longitudinal and transverse directions of at least 800% in each case. It is particularly preferred to use polypropylerle deep-drawn films with a thickness of 200 to 300 ~m, a tear strength in the longitudinal and transverse directions of 25 to 40 N/mm2 in each case and an elongation at break in the longitudinal and transverse directions of 900 to 1400%
in each case.

The blister packs according to the invention may be produced from plastics films using a cold deep-drawing process, in which the plastics films are deformed by pressure at ambient temperature, i.e. without previously heating the material, and without using a counter-punch.
It is expedient to use a punch with a central bore, the inner cavity of which is connected to the outside by one or more transverse bores and which engages centrally with the bore of a perforated die, the bore diameter of which is greater than the external diameter of the punch. The inner cavity in conjunction with the : . ,, ................. , - , . . : . : :

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2 ~ 7 transverse bores ensures a constant equalisation of pressure with the environment throughout the entire pressing operation. The presence of the ventilated inner cavity in the punch and the use of a perforated die ensure that there are no pressure differences in the shaped part of the film during deep-drawing. When the product is stripped away from the forming punch there is no suction to exert a deforming effect on the shaped film.

The perforated die has a smooth, optionally polished, shoulder, rounded off with a radius, the shoulder merging either directly or by means of a step into the bore of the die so that in the latter case the bore of the die underneath the shoulder has a larger diameter than in the region of the shoulder.

During the deformation process it is sufficient if one forming element (e.g. the perforated die) is moved towards the other (e.g. the forming punch). However, it is advantageous if the perforated die is moved towards the forming punch, since fixing elements for fixing the length of film can be more readily mounted on the perforated die.

Preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Figure I shows a cross-section through a conventional blister well with a single dose;

Figure II shows a cross-section through a blister well with a double dose having the same well diameter as in Figure I but with a double depth according to the invention;

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2ag3~7 Figure III shows a cross-section through a blister well with double depth according to the invention, from which one tablet has already been removed from the blister well by pressing on the base of the well; and Figures IV and V show cross-sections through the cold deep-drawing apparatus used to produce the blister wells in accordance with the invention. `

Referring to Figure I/ a conventional blister pack is shown. The blister well has a side wall ~1) and well base (5), cont.ains a product unit (tablet) (2) and is sealed by closure film (3).

In Figure II, the blister pack according to the invention has a well which is twice as deep, has side wall (1) and base (5~, contains two tablets (2 and 4) and is sealed by closure film (3). The well base (5) is thicker than the side wall (1) but 5 to 20% less thick than the strip of film used to produce the blister well.

In Figure III, is shown the blister pack of Figure II
from which the first tablet (4) has been removed, by pressure on well base (5). This pressure ruptures closure film (3) and deforms the relatively thin side wall (1) to produce a concertina-like constriction (6) at the opening of the blister well.

As can be seen from Figure III, after one tablet has been removed, the excess Eilm material of the side wall (1) of the blister well, which was originally twice as high, forms a concertina-like product unit retaining means in front of the second tablet (2) which is left behind in the blister well after the first tablet (4) is removed. Tablet (2) remaining in the blister well is thereby protected from accidentally falling out of the blister well. When further pressure is applied to the :, ; :: ~ : - : : ; ; ~ ;

2 ~ 7 base (5) of the well the resistance of the concertina-like closure (6) is overcome and in this way the second tablet (2) is released.

The sectional drawings of Figures IV and V illustrate the method of production of the blister well described.

In Figure IV is shown a flat plastics film (15) clamped between perforated die (10) and holding means (14). The holding means has an aperture (13) through which the forming punch (11) may be urged into contact with the film to press it into the forming aperture of die (10).
The forming aperture has a smooth shoulder (16) at its rim which has a stepped junction with the larger diameter bore (7). Shoulder (16) has a rounded profile in cross section, which may have a specific radius, and it preferably is polished. The forming punch (11) sits centrally on the punch holders (12). The punch preferably has a well or inner cavity (8) at its film contacting and which is outwardly connected to one or more transverse bores (9).

Figure V shows the final phase of cold deep-drawing of a blister well. The flat plastics film (15) is firmly clamped between the holding means (14) and the perforated die (10). As can be seen from Figure V, the flat plastics film (15) is pressed into the bore (7) of the die by the forming punch (11) over the shoulder (16) of the die. The shape of the blister well as shown in Figure V is characterised in that the flat film (15) is forcibly pressed into the perforated die (10) over the shoulder (16) of the die with the application of pressure. The bore (7) of the die is larger in diameter than the forming punch (11). The frustoconicity of the blister well is determined by the ratio of the diameter of the die shoulder (16) and the diameter of the forming punch (11).

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. . ~, , 2 ~ 3 7 $ 7 In the cold deep-drawing process, first of all a film (15) is inserted between the holding means (14) and perforated die (10). The holding means (14) are raised so that the film (15) is located over the forming punch (11). Forming is carried out by the pressure of the perforated die (10) on the holding means (14), both elements together with the film tl5) clamped between them sliding over the forming punch (11), preferably at reduced speed. The shaped item (1) thus formed is released by pulling back the perforated die (10) and holding means (14) from the forming punch (11), the perforated die being pulled back to a greater extent so that the shaped item lying on the holding means is freed and can thus be pulled away sideways between the holding means and the perforated die.

The blister pack according to the present invention results in a saving of at least half the deep-drawn film which is normally required for packaging in deep-drawn blisters with single dosing, by giving a multiple dose of tablets or the like, and further reduces by at least half the covering film (3) required.

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Claims

Claims l. A blister pack comprising a base with product unit retaining wells and a covering film thereon to seal said wells, each well having a side wall and a well base and containing at least two product units arranged one above the other, wherein said side wall is thinner than said well base and is deformable to create a product unit retaining means when pressure is applied to said well base to release the uppermost product unit from the well, said retaining means serving to retain the subsequent product unit in said well and being deformable under further pressure exerted on said well base whereby to permit release of said subsequent product unit.
2. A blister pack as claimed in claim 1, wherein the base comprises a plastics film.
3. A blister pack as claimed in claim l or claim 2, wherein said side wall is 3-10 times thinner than said well base.
4. A blister pack as claimed in any one of claims l to 3, wherein said base is formed from plastics film and the thickness of said well base is 5 to 20% less than the thickness of the plastics film used to produce said base.
5. A blister pack as claimed in any one of claims 1 to 4, wherein said wells are substantially frustoconical.
6. A blister pack as claimed in any one of claims l to 5 wherein said wells have a cross-sectional shape corresponding to that of the product units contained therein.
7. A blister pack as claimed in any one of claims 1 to 6, wherein the wells contain two similarly shaped product units of the same pharmaceutical preparation.
8. A blister pack as claimed in any one of claims 1 to 7, wherein said base is formed from polypropylene film.
9. A blister pack as claimed in claim 8, wherein said base is formed from polypropylene film having a thickness of 150 to 350 µm.
10. A blister pack as claimed in claim 8, wherein said base is formed from polypropylene film having a thickness of 200 to 300 µm.
11. A blister pack as claimed in any one of claims 8 to 10, wherein said polypropylene film has a tear strength in the longitudinal and transverse directions of at least 20 N/mm2 in each case and an elongation at break in the longitudinal and transverse directions of at least 800% in each case.
12. A blister pack as claimed in any one of claims 8 to 10, wherein said polypropylene fi:lm has a tear strength in the longitudinal and transverse directions of 25 to 40 N/mm2 in each case and an elongation at break in the longitudinal and transverse directions of 900 to 1400%
in each case.
13. A blister pack as claimed in any one of claims 2 to 12, wherein the wells are formed in said base by cold deep-drawing of a plastics film.
14. A process for the cold deep-drawing of plastics films without preheating comprising securing a plastics film between a perforated die and a holding means, and urging the secured fi]m and a forming punch together whereby to deform said film over the rim and into the base of a forming aperture in said die, said rim providing a smooth shoulder merging either directly or via a step into said bore.
15. A process as claimed in claim 14 wherein said shoulder is polished.
16. Apparatus for the cold deep drawing of plastics films without preheating comprising a forming punch, holding means and a perforated die, wherein the rim of a forming aperture in said perforated die provides a smooth shoulder merging either directly or via a step with the bore of said aperture.
17. Apparatus as claimed in claim 16 wherein said forming punch is provided with a well in the face which engages with the material to be formed, said well having a pressure release conduit preventing it from being closed on engagement with said material.
18. A blister pack substantially as herein described with reference to Figures II and II of the accompanying drawings.
19. A process for the cold deep-drawing of plastics films substantially as herein described with reference to Figures IV and V of the accompanying drawings.
20. Each and every novel product, process and apparatus as herein described.