Adhesive composition for ostomy bag

Abstract

A composition for an adhesive for fixing an ostomy bag to the skin of a user, comprising oatmeal, silica, hydrocolloid, and polyolefin. The composition may comprise no gelatine. The composition may co

Description

FIELD OF THE INVENTION This invention relates to an adhesive composition comprising oatmeal, silica, hydrocolloid and polyolefin. The composition is useful for fixing an ostomy bag to the skin of a user. BACKGROUND OF THE INVENTION Ostomy bags generally comprise a pouch for receiving waste and an annular flange for attachment of the bag to skin around a stoma of an ostomy patient. Typically, the flange has a hydrocolloid adhesive applied thereto so that it can be fixed in position on the skin. When ostomy patients wear an adhesive against their skin for extended periods of time it causes moisture to build up and presents the skin with an abnormal environment. The accumulation of moisture can lead to the proliferation of bacteria. The removal of the adhesive also causes damage in the form of skin cell stripping. These effects cause patients skin to be sore and in some cases leads to further complications with skin health. The skin can become inflamed and sore especially after adhesive removal. Skin cells have to be grown to replace the thickness of the stratum corneum. In view of these drawbacks, there is a need for an alternative or improved composition that acts effectively as an adhesive and which helps with long term health of the skin or the ability to grow skin cells and maintain barrier function. The present invention seeks to provide an alternative or improvement which preferably addresses one or more of the problems presented by prior art arrangements. SUMMARY OF THE INVENTION The present invention is directed to providing a composition for use as an adhesive useful for fixing an ostomy bag to the skin of a user, wherein the composition comprises substantially no gelatine. In this regard, the present invention employs a hydrocolloid as well as oatmeal and silica to provide an adhesive composition whilst avoiding gelatine. Remarkably, this allows production of a composition with technical advantages as will be detailed below. Accordingly, in a first aspect, the present invention provides a composition for use as an adhesive useful for fixing an ostomy bag to the skin of a user, wherein the composition comprises oatmeal, silica, hydrocolloid and polyolefin. Preferably, the composition comprises substantially no gelatine. Most preferably, it comprises no gelatine. Preferably, the composition comprises about 5% to about 25% oatmeal by weight. More preferably, it comprises about 15% to about 22% oatmeal by weight. Most preferably, it comprises about 19% oatmeal by weight. Preferably, the composition comprises about 1% to about 8% silica by weight. More preferably, it comprises about 3% to about 5% silica by weight. Most preferably, it comprises about 4% silica by weight. Preferably, the composition comprises about 30% to about 60% hydrocolloid by weight. More preferably, the composition comprises about 40% to about 50% hydrocolloid by weight. Most preferably, the composition comprises about 45% hydrocolloid by weight. Preferably, the hydrocolloid comprises one or more of carboxymethylcellulose, pectin, alginate carrageenan, xanthan gum, gum karaya, hydroxyethyl cellulose, polyacrylamide, polyvinyl alcohol, and polyvinyl pyrrolidone. Most preferably, the hydrocolloid comprises one or more of carboxymethylcellulose and pectin. Preferably, the polyolefin is selected from one or more of polyethylene, polypropylene, polyisobutylene, propylene-ethylene, propylene-butylene, propylene-hexylene, propylene-ethylene-butylene. Most preferably, the polyolefin is polyisobutylene. Such an adhesive composition has surprisingly been found to produce a particularly good adhesive, which provides sufficient tack, but can be peeled from the skin of a user with minimal damage to the skin. In accordance with a second aspect, the present invention provides a method for producing an adhesive composition according to the invention, which comprises the step of mixing oatmeal and silica together with hydrocolloid and polyolefin to a substantially homogeneous blend. In an embodiment of the method, the step of mixing includes blending in a z-blade mixer. Preferably, mixing is carried out at about 75°C to about 80°C. Preferably, mixing is carried out at a pressure of about 101.325 kPa. In a further aspect, the invention provides an ostomy bag comprising an adhesive composition according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described with reference to the accompanying drawings in which: Figures 1 to 3 show the results of comparative tack tests; Figure 4 shows the results of comparative tests of peel strength from skin at 10, 60 and 240 minutes; Figure 5 shows the results of comparative tests of 180 degree peel strength results; Figure 6 shows the results of comparative tests of ISO water absorbency tests Figure 7 shows the results of comparative tests of moisture vapour transmission rates (MVTR); and Figure 8 shows the results of comparative tests of sample thickness. DETAILED DESCRIPTION OF THE INVENTION It will be appreciated that aspects, embodiments and preferred features of the invention have been described herein in a way that allows the specification to be written in a clear and concise way. However, unless circumstances clearly dictate otherwise, aspects, embodiments and preferred features can be variously combined or separated in accordance with the invention. Thus, preferably, the invention provides a composition having features of a combination of two or more, three or more, or four or more of the aspects described herein. In a preferred embodiment, a composition in accordance with the invention comprises all aspects of the invention. The following definitions shall apply throughout the specification and the appended claims. Within the context of this specification, the word "comprises" means "includes, among other things" and should not be construed to mean "consists of only". Within the context of this specification, the word "about" means preferably plus or minus 20%, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2%. Within the context of this specification, the word "substantially" means preferably at least 90%, more preferably 95%, even more preferably 98%, most preferably 99%. Within the context of this specification, the term "oatmeal" is taken to mean kernels of oats ground into a fine powder. The finely ground oat Kernels have a particle size distribution defined by sieving to be 2g per 100g greater than about 150pm and 11g per 100g greater than about 75pm. Preferably, the oatmeal is in the form of colloidal oatmeal. It has surprisingly been found that combining hydrocolloid as well as oatmeal and silica results in a high quality and particularly effective adhesive composition for use in fixing an ostomy bag to the skin of a user. By contrast, the use of other substrates, such as pectin fibres and cellulose fibres resulted in unusable mixtures. In this regard, pectin fibres and cellulose fibres were found to affect the composition by increasing the strength and cohesion properties, but they had a negative effect on adhesive properties. Accordingly, the present invention provides a composition for use as an adhesive useful for fixing an ostomy bag to the skin of a user, wherein the composition comprises oatmeal, silica, hydrocolloid and polyolefin. Therefore, the invention also provides an ostomy bag comprising an adhesive composition of the invention. In an embodiment, the composition comprises no gelatine. Advantageously, it makes the adhesive composition more acceptable to all religions and to those who do not like to use animal products. One embodiment of the composition comprises about 19% oatmeal and about 4% silica by weight. Such an adhesive composition has surprisingly been found to produce a particularly good adhesive, which provides sufficient tack, but can be peeled from the skin of a user. Comparative test results showing this care described below. The present invention also provides a method for producing an adhesive composition according to the invention, which comprises the step of mixing oatmeal and silica with hydrocolloid and polyolefin to a substantially homogeneous blend. In one particularly preferred embodiment of the invention, a pyrogenic silica is added to the mixture in order to promote cohesive strength. This allows for a suitable balance of properties. In this regard, it has been found that pyrogenic silica improves cohesion with less effect on the rheology needed for adhesion. The silica forms percolating networks with the formation of loosely connected chains. These chains increase viscosity at low shear rates but have less influence when sheared at high shear rates. EXAMPLES Example 1 Introduction An adhesive composition according to the invention was prepared as described below. For comparison, a known hydrocolloid adhesive referred to as'original' herein was also nronaroH pi cpdl cU. Aims The aim of this trial is to compare an adhesive composition according to the invention with a known hydrocolloid adhesive. It is the intention to demonstrate that adhesion of a composition according to the invention is not compromised compared to a known adhesive. The composition must demonstrate its viability at production scale during processing as well as having desirable properties following production. The moisture handling properties are expected to reduce, this is considered acceptable since the water absorption properties of the known hydrocolloid adhesive is considered to be excessive. The reason for this assertion is due to comparisons between the known hydrocolloid adhesive used in the trial compared to other known hydrocolloid adhesives. In this regard, the known hydrocolloid adhesive used in the trial was originally intended for exuding wounds and not intact skin. Method Tack Test A tack test was carried out using a PT-1000 Probe tack tester fitted with a 21b load cell. The PT-1000 tack test involves attaching a sample of hydrocolloid to a ring. The probe is then lifted at a fixed rate to the sample with a dwell time of one second. As the probe comes down the sample and ring is detached, the force required to remove the probe is recorded. A 19.51g weight is used in conjunction with a custom made 5mm domed probe. The adhesive sample was 1mm deep and 25mm in diameter. The sample number was between 10 and 15 samples. The probe end was cleaned with a wet cloth and dried with a paper towel. Measurements are made every 30 seconds to allow the probe tip to return to room temperature. Peel Test A test was carried out using an Instron machine (a tensile testing machine what can be used for peel testing in the laboratory) to determine how well an adhesive composition of the invention can be peeled from a surface compared to a known hydrocolloid adhesive composition. Adhere the hydrocolloid strips (15mm x 40-90mm) (Non-woven face) were adhered to a stainless steel plate using twin sided adhesive. Release liner was removed from each hydrocolloid strip and polyester strips were placed onto the adhesive using light finger pressure. The strips were rolled twice in each direction with a standard test roller at a speed of approximately 10 mm per second to obtain intimate contact between the hydrocolloid and the Polyester surface. The test was repeated five times. After applying the polyester strips to the hydrocolloid, the strips were left for a period of 10 minutes before testing as follows. A test plate and strip were fixed in the machine so that the angle of peel was 180°. (Note for these sets of tests, strips of Polyester having a surface of 15mm x 200mm were used). The machine was set at 300mm per minute jaw separation rate. Peel test from skin A 90 degree Peel Test was carried out at 300mm / min. A force gauge was connected via a thin metal cable and crocodile clip to each test specimen in turn. The samples measured 4cm by 7 cm and they were attached to the inside forearm. Three different adhesion times were used, 10, 60 and 240 minutes. Four samples are attached to the upper forearm. Integrity test An Integrity test was performed by sticking a disc of hydrocolloid (4cm diameter) to a sheet of glass in triplicate. The sheet of glass is placed in phosphate buffered saline solution so the hydrocolloid discs are submerged. The phosphate buffered saline (PBS) solution was prepared by adding 2 tablets to 400mL di-ionized water. This gives 0.01 M phosphate buffer, 0.0027 M potassium chloride and 0.137 M sodium chloride. The resultant solution has a pH 7.4 at 25°C. The PBS was poured into the plastic tray. The diameter of the hydrocolloid discs were measured through the transparent glass with Vernier callipers before the PBS solution is added. The disc was measured after 24 hours and the percentage reduction in diameter recorded. This provides a measure of how fast the hydrocolloid brakes up in biological fluid. Materials Oat COM USP - Colloidal Oatmeal, Avena sativa (oat) Kernel Flour CAS-No. 134134-86-4 EC No. 310-127-6 HDK®N20 PHARMA Hydrophilic Pyrogenic Silica. CAS-No. 112945-52-5 EC No. 1272 / 2008 GENU®Pectin (citrus) type USP / 100 CAS 9000-69-5 405-12 Porcine Gelatine PS-225 Bloom Cekol® 30000 P. Sodium Carboxymethyl cellulose CAS-No 9004-32-4 Oppanol® B12- Polyisobutylene SFN CAS 9003-27-4 Clear Loperex (Formerly Infiana) release liner RRA-REL-R11 Wovern backing material RRA-REL-R05 Trial Details Z blade mixing chamber temperatures: Start 52C° Finish 79C° Extruder speed 40rpm and belt speed 12 meters / min Mixture details Component % Component by weight Mass(Kg) Polyisobutylene 44 40 Amorphous Silica 4 3.64 Carboxymethyl Cellulose 19 17.27 Pectin 14 12.73 Oatmeal 19 17.27 Total 100 90.91 Notes on trial: The trial date of the extrusion involved the use of MIX-EXT-100 to create roll P36. This roll was created immediately prior to the extrusion of test adhesive referred to as HB195. The oatmeal and silica were mixed separately in a drum by rolling and shaking. They were introduced halfway between the loadings of other hydrocolloids by pouring through the hatch located at the top of the mixer. Small streaks of unmixed silica could be seen on the logs extruded directly from the mixer. This was not considered a problem due to the large volume that this material occupies. Results Comparative test results are shown in the Figures as described below. Discussion In figure 1 it can be seen that the tack test results for the three sections of each roll. The sections were taken 20 meters apart and are 1 meter long. These sections were split into a left, middle and right channels. Each channel is 8cm wide. The tack samples were taken from these channels. Each section has 15 samples cut from each channel for a total of 45 measurements per section reported as a box for each section on the box plot. In figure 2, the 135 measurements made on each roll have been combined to make a roll to roll comparison in the form of a box plot. A 2-sample t test was carried out on two adhesives - a known hydrocolloid adhesive compared to an adhesive according to the invention. For this large number of measurements it was found that there is no significant difference between the two adhesives. The tack is not a measure of how secure a product is. The peel measurements are a more important measure of how a product will resist the worst mode of product failure. The final section of the HB195 roll appears to be 'out of control' in terms of individual and moving range charts (Not featured). In figure 3 we can see the sample sets for each channel in each section. The difference between channels is quite large suggesting that there is quite a large 'across roll' variation. Peel testing from skin was conducted for three different time periods (Figure 4). The 10 minute test observes the adhesive when it has had very little time to flow into the recesses of the skin. After 60 minutes the B.M Squibb type adhesives have usually maximised their peel strength. Peel testing at 4 hours is chosen as a practical time for when the adhesive has stabilized in its peel strength. The individual data points show two different groups of data. This is believed to be the case due to the two positions on the volar forearm being different in the strength of their bond. The position closest to the wrist is observed to be the higher peel strength group. Although the sample number was only 12 there are three sets of data indicating no sign of a problem. At least the mean values do not give a suggestion that peel strength from skin has been compromised. In figure 5 the results of 180 degree FINAT peel test can be seen for each channel for one sheet only. There is some 'across roll variation' but it is less than that shown for tack. This might be due to the fact that an increase in surface molecular weight effects tack more than peel adhesion. This particular collection of data is not statistically significant. A single sample set from one section was used for the moisture handling tests. These tests are much more precise than the adhesion related tests so only one set of samples was tested. The ISO 12505 water-absorbency test results are shown in figure 6. There is a statistically significant reduction of about 10% for the new HB195 oatmeal adhesive. This is not considered a problem since the B.M Squibb formula is more absorbent than what the market place requires. This is based on previous studies of competitor products. The MVTR results show a significant difference for the three days tested (Figure 7). This is to be expected since the gelatine is the hydrocolloid most responsible for absorbing water vapour from air. In a Paddington cup the adhesive is attached to the lid of the chamber and is exposed to water vapour not liquid. The saline absorbency test correlates with skin hydration via permittivity more than the MVTR. The graph shows that when the hydrocolloids become hydrated the difference between the variants becomes much less. The wafer construction does ultimately result in the backing being occluded in some places with pouch film. The thickness of the rolls was tested for the same sheets used in the tack testing. In figure 8 it can be seen that there was very little variation and the 'across roll variation' demonstrated previously cannot be attributed to differences in thickness across the roll. It seems more likely that the variation is due to a process issue where the surface of the hydrocolloid ends up with different molecular weights. The wear test results are shown below. This wear testing is conducted after the formulation has demonstrated an acceptable peel strength and tensile strength. The adhesive rolls are used to create a prototype that can be worn by test volunteers. The adhesive can now experience realistic movements and forces that represent real product use. The appendix includes a description of what the test involves. The wear test did not give an indication of a potential problem in terms of security or other unacceptable observations. The question answers and comments did not indicate a problem. It has been noticed that during a patient evaluation for example identical components are reported as different. The wear test results roughly balance each other out in terms of marginal preference. Conclusion The physical properties of the adhesive have been found to be comparable to the original Welland formulation derived from the B.M Squibb formula. It is acceptable for the marketplace and the next stage of testing can begin. The biophysical testing for the effects of oatmeal can be followed by a patient evaluation. It might be the case that any subtle drawback of the new formulation might need a clear indication of benefits to using oatmeal. Wear Test Results for Adhesives According to the Invention The following is a wear-test procedure for new adhesives. It is a test of the products performance. The test is used to assess the products ability to maintain a seal and strong bond with a patient's skin. The movements or exercises challenge the security of the product. The movement during the exercise presents the adhesive bond with a moving adherend. This is unlike peel testing. The wear test enables the participants to judge the success of the prototype before the next stage of development. In order to make this judgement the prototypes have to experience the same test conditions that are considered representative of the movement's patients would make for the duration of the products use. The exercises only take about 30 to 40 minutes which is a practical time for testing. The comments and judgements shall be recorded after the test group has finished the exercises. The test group can continue wearing the prototype for longer and record observations. Place the product onto the appropriate location of the body. The new adhesive will be compared with the current adhesive so both products are worn at the same time. 1. Fill the product with 100g of smooth plastic pellets. 2. Attach products to abdomen. 3. Wait 10 minutes before moving. 4. Climb up and down six floors of a building. (This means that you can walk up and down one flight of stairs six times) 5. Sit down and up again on a chair 20 times. 6. Do 20 sit-ups. The type of sit-up is the one where the hands are placed onto the knees as recommended for ostomates for hernia prevention. 7. 20 torso twists with a 180 degree turn. The person wearing the product must now assess the performance after completing the described exercises. Test Results Did the prototype leak? Did the prototype remain mostly attached? Is there any evidence of peeling? Is there any evidence of creasing? Yes / No Yes / No Yes / No Yes / No Person Adhesive A(HB195) Adhesive B(P36) Adhesive A(HB195) Adhesive B(P36) Adhesive A(HB195) Adhesive B(P36) Adhesive A(HB195) Adhesive B(P36) 1. NO No Yes Yes Yes Yes Yes Yes 2. No No Yes Yes Yes No Yes Yes 3. No No Yes Yes Yes Yes No No 4. No No Yes Yes Yes Yes No No 5. No No Yes No Yes Yes No Yes 6. No No Yes Yes Yes No No No 7. No Yes Yes Yes Yes No Yes Yes 8. No No Yes Yes Yes Yes No No 9. No No Yes Yes Yes Yes No Yes 10. No No Yes Yes Yes Yes Yes No 11. No No Yes Yes Yes Yes No No 12. No No Yes Yes Yes No No No Embodiments have been described herein in a concise way. It should be appreciated that features of these embodiments may be variously separated or combined within the invention. It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.

Claims

1. A composition for use as an adhesive useful for fixing an ostomy bag to the skin of a user, wherein the composition comprises oatmeal, silica, hydrocolloid and polyolefin; and wherein the composition comprises no gelatine.

2. The composition according to claim 1, wherein the composition comprises 5%to 25% oatmeal by weight.

3. The composition according to any one of the preceding claims, wherein the composition comprises 1% to 8% silica by weight.4.5.The composition according to any one of the preceding claims, wherein the composition comprises 30% to 60% hydrocolloid by weight.The composition according to any one of the preceding claims, wherein the hydrocolloid comprises one or more of carboxymethylcellulose, pectin, alginate carrageenan, xanthan gum, gum karaya, hydroxyethyl cellulose, polyacrylamide, polyvinyl alcohol, and polyvinyl pyrrolidone.

6. The composition according to any one of the preceding claims, wherein the polyolefin is selected from one or more of polyethylene, polypropylene, polyisobutylene, propylene-ethylene, propylene-butylene, propylenehexylene, propylene-ethylene-butylene.

7. A method for producing an adhesive composition according to any one of claims 1 to 6, wherein the method comprises the step of mixing oatmeal and silica together with hydrocolloid and polyolefin to a substantially homogeneous blend.

8. The method according to claim 7, wherein the step of mixing includes blending in a z-blade mixer.

9. The method of claim 7 or claim 8, wherein mixing is carried out at 75°C to 80°C.

10. The method of any one of claims 7 to 9, wherein mixing is carried out at a pressure of 101.325 kPa.

11. An ostomy bag comprising an adhesive composition according to any one of claims 1 to 6.LDCM

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