EP1942876A1

EP1942876A1 - Sealed tablet

Info

Publication number: EP1942876A1
Application number: EP06808372A
Authority: EP
Inventors: Jason Teckoe
Original assignee: Bioprogress Technology Ltd
Current assignee: Bioprogress Technology Ltd
Priority date: 2005-10-31
Filing date: 2006-10-31
Publication date: 2008-07-16
Also published as: WO2007052003A1; CA2627504A1; CN101365429A; WO2007052003A9; JP2009513693A; GB0522186D0

Abstract

The present invention relates to a coated tablet and a method for making a coated tablet and in particular the present invention provides a tablet having a coating formed from at least 2 separate film layers, wherein the film layers overlap and the overlapping film layers are sealed so that there is at least one non-sealed region.

Description

Sealed Tablet

The present invention relates to a coated tablet and a method for making a coated tablet.

Ingestible tablets, for example, of a medicament, vitamin, dietary supplement, etc., are usually coated with an ingestible material so that the tablets are more stable during storage and easier to swallow. The coating also acts as a safeguard against tampering. It is known to enrobe tablets in gelatin for this purpose by dipping tablets into a gelatin solution and allowing the solution to dry to form a coating. Suitable gelatin solutions may be coloured, and it is known to produce dual colour gelatin coatings by coating the entire tablet with a first coloured coating and then, after drying, coating half of the tablet with a differently coloured gelatin. This produces a tamper-evident tablet.

A further method for enrobing tablets has been described in US Patent Application US 2004/0161527. In this application, a method of enrobing tablets comprising vacuum forming a film of material onto the surface of a tablet is described. In the method a film is vacuum formed around a first surface of the tablet, excess film is removed, the tablet is turned over and a second film is vacuum formed on the now exposed surface of the tablet so that the tablet is entirely enrobed. Any overlapping layers of film produced by this method are then sealed together with glue applied to at least one of the overlapping surfaces.

A problem with many tablets is that the rate of disintegration and/or dissolution cannot be easily altered. In particular, when a tablet is ingested, the rate of disintegration and/or dissolution will depend at least in part on the material used to coat the tablet. Accordingly, in order to alter the disintegration and/or dissolution rate of a tablet, the thickness or composition of the coating can be altered. Making such alterations can be time consuming and the rate of disintegration and/or dissolution only varied to a relatively small degree depending on the type of coating material used. iy of altering the rate of disintegration and/or dissolution of tablets is to laser etch part of the coating away to thereby allow direct access of media to the tablet. Such etching procedures require the use of expensive laser equipment and can only be used with certain types of coated tablets.

The present invention provides a coated tablet that can be easily produced and wherein the disintegration and/or dissolution rate of the tablet can be changed easily.

The present invention provides a tablet having a coating formed from at least 2 separate film layers, wherein the film layers overlap and the overlapping film layers are sealed so that there is at least one non-sealed region.

It has been found that by not fully sealing the overlapping edges the rate of disintegration and/or dissolution of the tablet is increased. Furthermore, it has been found that the rate of disintegration and/or dissolution of the tablet can be varied by varying how much of the overlapping layers are sealed. The more the overlapping layers are sealed the slower the rate of dissolution.

The term "tablet" as used herein means any solid form of medicament, etc., including tablets, caplets, capsules, etc. For simplicity, all such forms are referred to herein as tablets. The tablets can be any suitable shape, including tablets of a circular symmetrical form with a circular cylindrical side wall, capsule shaped, oblong shaped, lozenge shaped and oval shaped.

The tablet of the present invention is coated with at least 2 films. Preferably the films are thermoforming films that are thermoformed onto the tablets. Thermoforming a film onto a tablet involves heating the film to a desired temperature so that the film becomes deformable so as to be conformable to the external surface of a tablet. Preferably the films are water soluble and ingestible. Suitable thermoforming films are described in US Patent Application US 2004/0161527. Suitable thermoforming film materials include cellulosics such as hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC)₅ hydroxyethyl cellulose (HEC), ethyl cellulose (EC), methyl cellulose arboxy methyl cellulose (CMC) etc., enteric polymers such as HPMC-AS (HPMC-acetate succinate), HPMC-P (HPMC-phthalate) and others such as pectin, polyvinyl alcohol (PVOH) polyethylene oxide (PEO), PEO-PEG graft copolymers, alginates, pullulan or derivatives of any of these. Preferably the thermoforming film is a hydroxypropyl methyl cellulose (HPMC) film material. Methods for thermoforming films onto tablets are known to those skilled in the art. See in particular US Patent Application US 2004/0161527.

Generally, a first film is formed on just over 50% of the tablet, so that on turning over the tablet and forming a second film on the other side of the tablet, the tablet is fully coated and the first and second films overlap.

Surface modifying material, such as adhesive material may be applied to the surface of the tablets prior to coating with the film. Any appropriate surface modifying material may be used, in particular one that dissolves the film's surface, such as water or alcohol, hi some instances, it is preferable to apply surface modifying material to the whole of the tablet surface, in order to partially bond the film to the tablet. This can help with identifying tampering with the tablets. The application of an adhesive to the surface of the tablet is described in US patent application US 2004/0161527.

The overlapping film layers are sealed by providing a surface modifying material, such as an adhesive between the overlapping films. If necessary, heat and/or pressure can be applied to the overlapping film layers to assist with forming the seal. The surface modifying material may be any suitable material, as discussed above. In particular, the surface modifying material may be an alcohol, or may conveniently have the same composition as the firm layers but with a greater proportion of plasticiser, e.g., 93% to 98% plasticiser, so as to provide a less viscous material. The surface modifying material such as the adhesive, may be a different colour to the film layers so as to provide a pattern where the film layers overlap.

In order to ensure that there is at least one non-sealed region, surface modifying material is not applied to at least one zone of the overlapping region of the films. The egion allows media to have direct access to the tablet. Suitable media include fluids such as water, saline solutions, the stomach content of an individual, etc. The presence of the non-sealed regions means that the overlapping layers of film do not form a complete seal but instead ensure that the overlapping film layers do not form a watertight or airtight seal. The non sealed regions can be varied in size or proximity to each other, for example to change the size of the sealed regions, or to change the degree of capillarity or wicking of fluids.

The specific application of surface modifying material, particularly adhesive, can be achieved in a variety of ways. Preferably the surface modifying material is applied to the film by only applying the surface modifying material onto the film in areas that are to become sealed. Such accurate application can be achieved using any suitable apparatus, such as by ink jet printing, offset gravure with a pattern, pad printing, mark spray, and blanket coating methods such as using a doctor blade or extrusion die in combination with a suitable mask to enable coating of the required pattern. Preferably ink jet printing is used to apply the adhesive to the film.

As will be appreciated by those skilled in the art, the size of the sealed regions and non-sealed regions can be varied to affect the disintegration and/or dissolution rate of the tablet. For example, if the tablet is to have a low dissolution rate only a small part of the overlapping films will not be sealed (e.g., 5%). If the tablet is to have a high dissolution rate a substantial part of the overlapping films are not sealed (e.g., about 40%, preferably about 60%). It is particularly preferred that the sealed regions are evenly spaced around the overlapping film region of the tablet so that the at least 2 layers or film are still held together on the tablet.

The present invention also provides a method of coating a tablet with a film comprising

i. thermoforming at least 2 layers of film around the tablet so that the layers of film overlap; and ii. sealing the overlapping film layers together so that there is at least one non-sealed region. A suitable method for thermoforaiing a film around a tablet is disclosed in US patent application US 2004/0161527. As indicated above, the at least one non-sealed region is formed by not applying surface modifying material, such as adhesive, to at least one region of the overlapping films thereby preventing the films from forming a seal. The surface modifying material is preferably applied to the film before the film is thermoformed around the tablet. The surface modifying material is preferably only applied to regions of film which will form an overlap with another film layer and which are to form a seal. The surface modifying material can be applied to each layer of film that forms an overlap or to just one layer of the film. If the surface modifying material is applied to the film prior to thermoforming the film around the tablet, the position of the surface modifying material must be co-ordinated with the subsequent position of the tablet.

According to a second aspect of the present invention there is provided a method of coating a tablet with a film comprising: i. thermoforming at least 2 layers of film around the tablet so that- the layers of film overlap; and ii. sealing the overlapping film layers together with a surface modifying material that has only been applied between the overlapping film layers.

By applying the surface modifying material, such as an adhesive, between the film layers in the region of overlap only, the amount of surface modifying material used is considerably reduced. This will result in a significant reduction in production costs.

As indicated above, a suitable method for thermoforming a film around a tablet is disclosed in US patent application US 2004/0161527. The surface modifying material is preferably applied to the film before the film is thermoformed around the tablet. The surface modifying material can be applied to each layer of film that forms an overlap or just one layer. If the surface modifying material is applied to the film prior to thermoforming the film around the tablet, the position of the surface modifying material must be co-ordinated with the subsequent position of the tablet. The surface modifying be applied using any suitable technique, such as those mentioned above.

As indicated above, preferably surface modifying material is applied to the film by accurately spraying the surface modifying material onto those areas of the film that will form an overlap with another layer of film. Preferably ink jet printing is used to apply the surface modifying material to the film.

The present invention also relates to a tablet produced by the method according to the second aspect of the present invention.

Also provided by the invention is a layer of film to which surface modifying material, such as adhesive, has been applied in a discontinuous manner, the film being suitable for use in the methods of the invention. Preferably the surface modifying material and film are as defined above.

The term "discontinuous manner" is used to describe the way the surface modifying material is applied to the film. It means that the surface modifying material is not applied to the whole of the film surface. In fact, the surface modifying material is only applied to areas of the surface. As described above, the film is used to cover a tablet. When the layer of film is wrapped around the tablet, it overlaps with a second layer. The surface modifying material is applied to form a seal between the two layers, but some areas are left without any surface modifying material, so the seal formed is not complete. The surface modifying material is applied to the film discontinuously so that some areas will be left unsealed.

The present invention is now described by way of example only with reference to the following Figures.

Figure 1 shows a tablet half enrobed with a film.

Figure 2 shows a film on which is deposited an adhesive.

Figure 3 shows a sectional view of a tablet coated with 2 film layers. Figure 4 shows a film on which is deposited an adhesive in defined areas.

EXAMPLE 1 A tablet (1) is half-coated with a first thermoforming film (3) according to the method disclosed in US patent application US 2004/0161527 and held on a support (5) (see Figure 1). A second thermoforming film (7) having a ring of surface modifying material (adhesive) (9) formed thereon (see Figure 2) is then thermoformed over the non-coated surface of the tablet (1), wherein the part of the second film (7) comprising the surface modifying material (9) overlaps the first film (3) so that the surface modifying material (9) is positioned between overlapping first (3) and second film layers (7). A tablet (1) having overlapping films (3, 7) with the surface modifying material (9) positioned in-between is shown in Figure 3. The second film (7) is thermoformed onto the partially coated tablet (1) according to the method disclosed in US patent application US 2004/0161527.

The ring of surface modifying material (9) is applied to the second film (7) using a printing jet.

It will be appreciated by those skilled in the art that a ring of surface modifying material (9) may have been positioned on the first layer of film (3) at a position that is overlapped by the second film (7), which may or may not also have a corresponding ring of surface modifying material (9) formed thereon.

EXAMPLE 2

A tablet (1) is half-coated with a first thermoforming film (3) according to the method disclosed in US patent application US 2004/0161527 (see Figure 1). A second film (7) having sections of surface modifying material (9) formed thereon (see Figure 4) is then thermoformed over the non-coated surface of the tablet (1), wherein the part of the second film (7) comprising the surface modifying material (9) overlaps the first film (3) so that the surface modifying material (9) is positioned between overlapping first (3) and second (7) film layers. The coated tablet (1) has overlapping sections that are iced by the presence of the surface modifying material (9)) and overlapping sections that are not sealed, i.e. non-sealed sections (produced by the absence of the surface modifying material (9)). The non-sealed sections allow direct fluid access to the tablet (1) resulting in a quicker disintegration and/or dissolution rate compared to the coated tablet (1) described in Example 1. The second film (7) is thermoformed onto the partially coated tablet (1) according to the method disclosed in US patent application US 2004/0161527.

The sections of surface modifying material (9) are applied to the second film (7) using a printing jet.

It will be appreciated by those skilled in the art that sections of surface modifying material (9) may have been positioned on the first layer of film (3) at a position that is overlapped by the second film (7), which may or may not also have corresponding sections of surface modifying material (9) formed thereon.

The present invention provides tablets and method of making tablets that have different disintegration and/or dissolution rates.

As will be apparent to those skilled in the art numerous modification can be made to the tablet described above. Such modifications are considered to be part of the scope of the present invention which is defined in the appended claims.

All documents cited above are incorporated herein by reference.

Claims

1. A tablet having a coating formed from at least 2 separate film layers, wherein the film layers overlap and the overlapping film layers are sealed so that there is at least one non-sealed region.

2. The tablet according to claim 1, wherein the film layers are thermoforming films that are thermoformed around the tablet.

3. The tablet according to any one of the preceding claims, wherein the at least one non-sealed region allows direct fluid access to the tablet.

4. The tablet according to any one of the preceding claims, wherein the overlapping layers are sealed together using an surface modifying material positioned between the overlapping layers.

5. The tablet according to any one of the preceding claims, wherein there are 2 layers of film.

6. The tablet according to any one of the preceding claims, wherein there are a plurality of non-sealed regions.

7. A method of coating a tablet with a film comprising i. thermoforming at least 2 layers of film around the tablet so that the layers of film overlap; and ii. sealing the overlapping film layers together so that there is at least one non-sealed region.

8. The method according to claim 7, wherein the overlapping film layers are sealed together by applying a surface modifying material between the overlapping layers and wherein the at least one non-sealed region is formed by not applying surface modifying it least one region of the overlapping films thereby preventing the films from forming a seal.

9. The method according to claim 7 or claim 8, wherein the surface modifying material is applied to the film before the film is thermoformed around the tablet.

10. The method according to any one of claims 7 to 9, wherein surface modifying material is applied to each layer of film that forms an overlap.

11. The method according to any one of claims 7 to 10, wherein the surface modifying material is applied to the film by accurately applying the surface modifying material to those areas of the film that will form a seal.

12. A method of coating a tablet with a film comprising: i. thermoforming at least 2 layers of film around the tablet so that the layers of film overlap; and ii. sealing the overlapping film layers together with an surface modifying material that has only been applied between the overlapping film layers.

13. The method according to claim 12, wherein the surface modifying material is applied to the film before the film is thermoformed around the tablet.

14. The method according to claim 12 or claim 13, wherein the surface modifying material is applied to each layer of film that forms an overlap

15. The method according to any one of claims 12 to 14, wherein the surface modifying material is applied to the film by accurately spraying the surface modifying material to those areas of the film that will form an overlap with another layer of film.

16. A method according to any one of claims 7 to 15, wherein the surface modifying material is also applied to the tablet prior to thermoforming the film around the tablet.

. produced by the method according to any one of claims 7 to 16.

18. A layer of film to which surface modifying material has been applied in a discontinuous manner and which is suitable for use in the method of any one of claims 7 to 16.