ADHESIVES AND SILICONE ACRYLIC POLYMERS

BRIEF SUMMARY OF THE INVENTION

[0001] The present invention relates to novel film-forming agents formed by combining (e.g., mixing or blending) silicone pressure sensitive adhesives and silicone acrylic copolymers (the silicone acrylic copolymers also referred to herein as copolymer or copolymers) in generally desired ratio ranges. The resulting film-forming agents demonstrate unexpected properties. The film-forming agents can be used in medical and personal care applications requiring pliability, cohesiveness, non-tackiness, flexibility and low coefficients of friction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Various advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.

[0003] FIG. 1 shows flux profiles for certain drug loaded formulations.

[0004] FIG. 2 shows flux profiles for certain further drug loaded formulations.

[0005] While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0006] According to the embodiments of the invention, when (a) silicone pressure sensitive adhesives and (b) silicone acrylic copolymers are combined (e.g., mixed or blended) together within a generally desired ratio range to form film-forming agents, the resulting film-forming agents exhibit ideal characteristics of a good film former and characteristics that original components (a) and (b) individually lack. It is unexpected that by mixing or blending the silicone pressure sensitive adhesive (component (a)) and the silicone acrylic copolymer (component (b)) in a generally desired ratio range, the resulting film-forming agents are pliable, non-tacky, cohesive, substantive, water resistant, water repelling, transparent, biocompatible, oxygen (or gas) permeable, semi-occlusive, flexible and have low coefficients of friction.

[0007] The use of films for human skin contact is common in applications such as medical and personal care applications. Films for use in skin contact applications need to substantive (i.e., resist rub-off) and flexible enough to allow movement of the skin. However, film formers also need to be non-tacky after application and need to resist breaking. Effective film formers used on skin need to have gentle adhesion and be removable without causing trauma to the skin or mucous membranes.

[0008] Silicone pressure sensitive adhesives alone generally tacky. While films made from silicone pressure sensitive adhesives alone are flexible and substantive, they are undesirable as they remain tacky and may stick to the skin so well that the assistance of a solvent is needed to remove the film from the skin. The removal of films made from silicone pressure sensitive adhesives alone can be difficult due to high adhesion to the skin. Additionally, films made from silicone pressure sensitive adhesives alone may even act to bond surfaces that are not desired to be bonded together and pick up unwanted dirt and other particles.

[0009] The silicone acrylic copolymers used in this invention have a high Tg (glass transition temperature) and are generally cohesive and have a minimum level of tackiness but are typically brittle and inflexible. As a result, films made from silicone acrylic copolymers alone are undesirable as they are susceptible to various disadvantages such as cracking and flaking.

[0010] Thus, there exists a need for films which may be used in skin contact applications which are effective in such environments. The novel film-forming agents formed by mixing or blending (a) silicone pressure sensitive adhesives and (b) silicone acrylic copolymers in generally desired ratio ranges overcome the disadvantages of the individual silicone pressure sensitive adhesives and the individual silicone acrylic copolymers when used alone. Components (a) and (b) are mixed or blended by any suitable technique which results in mixing or blending of the components. The novel film-forming agents described herein have the appropriate balance of flexibility, cohesiveness, pliability, tackiness, substantive properties, water resistant properties, water repelling properties, transparent properties, biocompatibility, oxygen (or gas) permeability, semi-occlusive properties, flexibility, low coefficients of friction, and resistance to cracking and flaking to be effective in skin contact applications.

[0011] The silicone pressure sensitive adhesives (PSAs) (component (a)) for use in the embodiments detailed herein are the product of condensation between silanol functional silicone polymers and resins. Such condensation processes are known in the art. The silicone pressure sensitive adhesives used in the embodiments described herein can either be used in this state or can be further reacted by capping the residual silanol with trimethyl- silyl groups to create an adhesive that is more resistant to reaction with amine functional drugs. The silicone pressure sensitive adhesives used in the embodiments described herein can be dispersed in one or more solvents such that the silicone pressure sensitive adhesives can be delivered to end users in solvent form. Typical solvents used to deliver the silicone pressure sensitive adhesives include, but are not limited to, aliphatic hydrocarbons such as hexane, heptanes, isododecane, aromatic hydrocarbons such as toluene, xylene, esters such as ethyl acetate, volatile linear siloxanes such as hexamethyldisiloxane, and cyclic siloxanes such as decamethylpentacyclosiloxane.

[0012] A variety of polymer to resin ratios can be used for the ratio of the silanol functional silicone resin to silicone polymer to create a silicone pressure sensitive adhesive. In general, materials with higher polymer content will yield a softer & tackier adhesive while higher resin content yields a less tacky and more cohesive adhesive. The typical resin to polymer ratios of commercial silicone pressure sensitive adhesive (PSA) range from about 55:45 for very high tack silicone pressure sensitive adhesive (PSA) to 65:35 for very low tack pressure sensitive adhesive (PSA).

[0013] The silanol functional silicone polymers used to form the silicone pressure sensitive adhesives of component (a) include, but are not limited to polydiorganosiloxane comprising ARSiO units optionally terminated with endblocking TRASiOi _/2 units, wherein the polydiorganosiloxane has a viscosity of from about 100 centipoise to about 30,000,000 centipoise at 25° C. Each A radical is independently selected from R or halohydro-carbon radicals having from 1 to 6 inclusive carbon atoms, each T radical is independently selected from the group consisting of R, OH, H or OR', and each R' is independently an alkyl radical of from 1 to 4 inclusive carbon atoms.

[0014] The resins used to form the silicone pressure sensitive adhesives of component (a) include, but are not limited to, resin copolymers comprising triorganosiloxy units of the formula R ₃ SiOi _/2 and tetrafunctional siloxy units of the formula Si0 _4/2 in a ratio of about 0.6 to 0.9 triorganosiloxy units for each tetrafunctional siloxy unit.

[0015] The silicone pressure sensitive adhesives of component (a) may also be commercially available. Examples of commercially available silicone pressure sensitive adhesives include, but are not limited to, Dow Corning® BIO-PSA 7-4101 , Dow Corning® BIO-PSA 7-4201 , Dow Corning® BIO-PSA 7-4301 , Dow Corning® BIO-PSA 7-4102, Dow Corning® BIO-PSA 7-4202, Dow Corning® BIO-PSA 7-4302, Dow Corning® BIO-PSA 7- 4401 , Dow Corning® BIO-PSA 7-4501 , Dow Corning® BIO-PSA 7-4601 , Dow Corning® BIO-PSA 7-4402, Dow Corning® BIO-PSA 7-4502, Dow Corning® BIO-PSA 7-4602, Dow Corning® 7-4560 BIO-PSA, Dow Corning® 7-4408 Cosmetic Fluid, Dow Corning® 7-4405 Cosmetic Fluid, Dow Corning® 7-4408 Cosmetic Fluid, Dow Corning® 7-441 1 Cosmetic Fluid, Dow Corning® 7-4412 Cosmetic Fluid, Dow Corning® 7-4413 Cosmetic Fluid, all available from Dow Corning Corporation (Midland, Ml) and DDR-1370 available from NuSil Technologies (Carpenteria, CA). These commercially available silicone pressure sensitive adhesives are sold dispersed in one or more solvents.

[0016] The silicone acrylic copolymers (component (b)) for use in the embodiments of the invention include, but are not limited to, polydimethylsiloxymethacrylate copolymers. The silicone acrylic copolymers used in the embodiments described herein can be dispersed in one or more solvents such that the silicone acrylic copolymers can be delivered to end users in solvent form. Typical solvents used to deliver the silicone acrylic copolymers include, but are not limited to, linear or branched aliphatic hydrocarbons such as isododecane, hexane, heptane, alcohols including ethanol and isopropanol, esters such as ethyl acetate, volatile linear siloxanes such as hexamethyldisiloxane, cyclic siloxanes such as octamethyltetracyclosiloxane, decamethylpentacyclosiloxane and dodecamethylcyclohexasiloxane and aromatic hydrocarbons such as toluene or xylene. Alternatively, blends of these and other compatible solvents may be used to achieve desired properties and compatibility with the copolymer and adhesive mixture and any other ingredients added to achieve the desired final product.

[0017] According to the embodiments of the invention, when silicone pressure sensitive adhesives and silicone acrylic copolymers are mixed or blended together within a generally desired ratio range of about 30% w/w to about 80% w/w of silicone acrylate copolymer, this ratio provides a film that is essentially tack free, yet retains many of the textural characteristics of the pressure sensitive adhesive such as cohesiveness and flexibility. In some embodiments, the generally desired ratio range is about 40% w/w to about 70% w/w of silicone acrylate copolymer. In still further embodiments, the generally desired ratio range is about 50% w/w to about 60% w/w of silicone acrylate copolymer. It is not intended that the silicone pressure sensitive adhesives and silicone acrylic copolymers described herein be mixed or blended at these precise ratio levels. At these generally desired ranges, the typical blending phenomenon exemplified by incremental or linear changes in properties is not observed.

[0018] Additional optional components can be added to the blend of the silicone pressure sensitive adhesives and the silicone acrylic copolymers. These components include fillers such as talc, silica, which have a matting and de-tackifying effect when added in concentrations from about 0.5% (w/w) to about 15% (w/w). Agents such as ethylcellulose, methylcellulose, polyethylene oxide may increase the breathability of the resulting film when added in amounts from about 0.5% to about 10%. If desired, other components can be added to the blend including, but not limited to, stabilizers, absorbents, fillers, pigments, plasticizers, additives for improving adhesion, chain extenders, pharmaceutical agents, penetration enhancers, drugs, cosmetic agents, natural extracts, fluids or other materials conventionally used in gels, gelling agents, silicone fluids, silicone waxes, silicone polyethers, emollients, surfactants, perfumes, fragrances, and rheology modifiers such as thickening agents or thixotropic agents.

[0019] The film-forming agents may ultimately be used in varying forms depending on the desired end use of the film-forming agent. The film-forming agents described herein are particularly suited for skin-facing applications. The film-forming agents may, for example, be in the form of a liquid coating which may be applied to the skin, a liquid form which is suitable for spraying such as onto the skin, a semi-solid form such as a cream, lotion, gel or ointment form which may be rubbed onto or otherwise applied to the skin, a drug delivery form, etc. The drug delivery form may be a liquid or cream, lotion, gel or ointment. In the drug delivery form, a drug may be dispersed, loaded or solubilized into the film forming agent using appropriate solubilizers, co-solvents, and non-solvents and, optionally penetration enhancers as are commonly known in the art to deliver the drug or other active to the skin. The drug may be dispersed, loaded or solubilized into the film forming agent using blending and other techniques known in the art.

[0020] To form the film-forming agent into, for example, a liquid form which is suitable for spraying such as onto the skin, the film-forming agent may be diluted with one or more solvent(s) to form a spray formulation. The spray formulation may be applied via spraying by aerosol or mechanical (e.g., pump or squeeze-activated) spraying equipment.

[0021] The film-forming agent into may also be formed, for example, into a cream or lotion by combining the film-forming agent with oil and water. Both lotions and creams are combinations of oil and water. Creams are typically made of approximately 50% oil and 50% water while lotions are formulated with a lower amount of (and sometimes no) oil for a lighter consistency. The final viscosity of creams and lotions is also different. Lotions typically have a lower viscosity and can be squeezed or pumped from a bottle while a cream typically has a higher viscosity. Where the film-forming agent is formed into a cream or lotion, the amount of oil and water which is used and the viscosity which is employed will depend on the desired physical properties of the resulting cream or lotion.

[0022] To form the film-forming agent into, for example, an emulsion, the film-forming agent may be blended with water and oil to form a "water-in-oil" emulsion or an "oil-in water" emulsion as desired. The "water-in-oil" emulsion is achieved by blending an oily phase and an aqueous phase together with mixing in the presence of an emulsifier to disperse the water in the oil. The "oil-in-water" emulsion is achieved by blending an oily phase and an aqueous phase together with mixing in the presence of an emulsifier to disperse the oil in the water. The emulsifier stabilizes the emulsion by increasing its kinetic stability. Emulsifiers are known in the art and include, but are not limited to, glycols, polyethers, ceteareth compounds, cetearyl alcohol, and polysorbate 20.

[0023] The film-forming agent into may also be formed, for example, into a gel by placing the film-forming agent into a polymer swollen in a liquid to achieve a semi-solid gel. Gels can be created using a variety of different polymers including, but not limited to, cationic organic polymers, silicones, and co-polymers of methacrylamide and N-vinylimidazole. Other components can be added to the semi-solid gel formulation to achieve desired performance characteristics.

[0024] The film-forming agent into may also be formed, for example, into an ointment by combining the film-forming agent into a liquid base. Ointments are typically high viscosity, grease or wax-based topical formulations with low water content. Ointments are typically prepared by incorporating a solubilized drug and other excipients into a liquid base (here, the liquid base includes the film-forming agent) and mixing the resulting materials, while cooling, to create a semisolid ointment formulation.

[0025] When the inventive film-forming agent is applied (whether by a liquid application, a spraying application, a spreading application, etc.) and air dried on the skin or a wound to form an adherent, solid protective film, the resulting film can act as a bandage or dressing to protect the skin or the wound without significant stinging or sticking to the user's skin or mucous membranes. The film can prevent further microorganism or particulate contamination to the skin, mucous membrane wounds, or incisions. The film provides a non- tacky, transparent or translucent covering which does not attract or hold dirt and can remain colorless for wound viewing as well as cosmetic attractiveness. The film is comfortable, elastic and flexible and avoids irritating the skin or mucous membranes.

[0026] Medicants, pharmaceutical agents, or other active agents such as perfumes or fragrances may be incorporated into the film-forming agents for gradual release into targeted areas. For example, the medicants, pharmaceutical agents, or other active agents may be loaded into the film-forming agents for gradual, controlled or targeted release into targeted areas of the body. Medicament concentrations usually range from about 20 ppm to about 15% or as is necessary to achieve the desired therapeutic concentration. Pharmaceutical agent concentrations usually range from about 10 ppm to about 20% or as is necessary to achieve the desired therapeutic concentration. Additionally, to achieve the desired release of the medicant(s), pharmaceutical agent(s), or other active agent(s), other common excipients can be added to solubilize the medicament, pharmaceutical agent, or other active agent in the film forming agent or to enhance the therapeutic value of the medicament (e.g., penetration enhancers) or pharmaceutical agent. Typical excipients to solubilize and/or enhance the penetration of the medicament, pharmaceutical agent or other active agent include glycols such as propylene glycol and polyethylene glycol of various molecular weights, organic esters such as isopropyl myristate, volatile skin-friendly solvents such as ethanol, isopropanol, hexamethyldisiloxane, aliphatic alcohols such as oleyl alcohol, and aliphatic acids such as oleic acid and other solvents and excipients commonly used in delivery technology.

[0027] The film-forming agents prepared according to the embodiments of the present invention can be useful in a variety of end applications by virtue of their unique combination of properties. Compositions prepared according to the embodiments of the present invention can be used in various end applications demanding tack free, flexible, cohesive, breathable, cosmetically acceptable, water repellant, and skin adhesive films, for example, in the fields of health/medical care such as neonatal care, medical device attachment, pressure wound prevention, protective skin care such as with sedentary patients, incontinence care, wound care, blister or other friction wound treatment and prevention, skin therapy, scar management, medical dressings and medical wound dressings; pharmaceutical applications; personal care such as cosmetics, hair-care products, moisturizers, and beauty care items; other skin topical applications; drug delivery and pharmaceutics and the like.

[0028] Additives or agents commonly added to medical dressings may also be included in the film-forming agents described herein. For instance, the film-forming agent may also include agents that provide a pain-relieving effect such as through the use of pain-relieving active agents, provide an antiseptic effect, deliver hormones, help sterility, and speed healing. One suitable example of an active agent for use in the embodiments of the invention that provides a pain-relieving effect is ketoprofen. Another suitable example for hormone replacement and delivery therapies is estradiol. In one embodiment, the film- forming agent may include silver particles which can be used to impart antimicrobial properties into the resulting film.

[0029] A medical dressing, as known to those of skill in the art, is an adjunct used by a person for application to a wound to promote healing and/or prevent further harm. A medical dressing is designed to be in direct contact with the wound, although, for the purposes of this application, direct contact on all areas of the wound is not necessary. Among other purposes, a medical dressing is designed to perform one or more of the following: (a) stem bleeding and help to seal the wound to expedite the clotting process; (b) absorb exudate by soaking up blood, plasma and other fluids exuded from the wound; (c) ease pain of the wound; (d) debride the wound by removing the slough and foreign objects from the wound; (e) protect the wound from infection and mechanical damage; and (f) promote healing through granulation and epithelialization. A medical dressing comprising the film former described herein, like other medical dressings, is designed to accomplish one or more of these objectives.

[0030] Representative examples of additional skin-facing uses of the film-forming agents described herein are in athletic apparel such as biking shorts and feminine hygiene products. The film-forming agents may also be used for blister/friction protection such as for athletes. By way of example, athletes such as runners may rub the film-forming agents described herein on locations where portions of the body may rub against one another such as arms against the torso or other "hotspots" experienced by hikers, runners, and other athletes.

EXAMPLES

[0031] These examples are intended to illustrate the invention to one of ordinary skill in the art and should not be interpreted as limiting the scope of the invention set forth in the claims. All parts and percentages in the examples are on a weight basis and all measurements were indicated at about 25°C, unless indicated to the contrary. In a number of the examples, the copolymer used was Dow Corning® FA-4001 CM Silicone Acrylate available from Dow Corning Corporation. Dow Corning® FA-4001 CM Silicone Acrylate is provided as silicone acrylate polymer dissolved in cyclopentasiloxane. For the experiments below, this solvent was stripped and the solids were dissolved in ethyl acetate to match the solvent of the pressure sensitive adhesive.

[0032] The tack force in all of the following examples was measured utilizing a TA XT Plus

Texture Analyzer (commercially available from Texture Technologies Corp. of Scaresdale,

NY) and a 7 mm stainless steel (1 inch radius) probe (part no. TA-57 R) and the following test settings:

Pre-test speed: 0.5 mm/sec.

Test speed: 0.2 mm/sec.

Post-test speed: 0.2 mm/sec.

Test force: 100 grams

Dwell time: 0.5 sec.

Trigger force: 1 .0 gram

Trigger mode: Auto

Collection rate: 200 points/sec.

Five independent measurements are taken at different points on the surface of the material. The median of the five independent measurements is reported. The peak force required to remove the probe from the material after the 0.5 sec. dwell time at the 100 g test force was reported as the tack.

Examples 1-6

[0033] Examples 1 -6 demonstrate the loss of tack as a copolymer component is added to a low tack silicone pressure sensitive adhesive (PSA). The copolymer was blended with the low tack silicone pressure sensitive adhesive in the weight percentages listed in Table A below for the six samples. The copolymer used was Dow Corning® FA-4001 CM Silicone Acrylate. The low tack silicone pressure sensitive adhesive used was Dow Corning® 7-4408 Cosmetic Fluid available from Dow Corning Corporation. The average adhesion force of the resulting films was tested using the TA XT Plus Texture Analyzer using the protocol describe above to indicate the amount of force that was generated when pressure was applied to the film. Examples 1-6 demonstrate the change in tack observed when a copolymer component is added to a high resin (e.g., low tack) "standard" pressure sensitive adhesive (e.g., a silicone adhesive that has all available silanol (-OH) functionality remaining).

Table A

[0034] Examples 1 -4 display a nearly linear reduction of tack typical of a blending phenomenon. However, as the copolymer to PSA ratios exceeds 1 : 1 , a relative plateau of the tack values is observed as exemplified by Examples 4, 5, and 6, which all show nearly tack-free results (as measured using the tack test described above). In general, unexpectedly, the tackiness of the films are not determined by composition (e.g., polymer to resin ratio or the amount of silanol functionality) of the silicone pressure sensitive adhesive used. As seen in the examples, the reduction of tack was linear until approximately 50% of the film composition was copolymer. Neither high nor low tack adhesives followed the trajectory of tack loss that would be expected if this were a typical blending phenomenon, i.e., an incremental loss of tack as less tacky substance is added to the adhesive.

Examples 7-13 [0035] Examples 7-13 demonstrate the change in tack observed when a copolymer component is added to a high tack, low resin content amine compatible silicone pressure sensitive adhesive (e.g., a silicone adhesive that has little available silanol functionality remaining). The copolymer was blended with the high tack, low resin content amine compatible silicone pressure sensitive adhesive in the weight percentages listed in Table B below for the seven samples. The copolymer used was Dow Corning® FA-4001 CM Silicone Acrylate available from Dow Corning Corporation. The high tack, low resin content amine compatible silicone pressure sensitive adhesive used was Dow Corning® BIO-PSA 7- 4302 Silicone Pressure Sensitive Adhesive available from Dow Corning Corporation. The average tack force of the resulting films was tested using the TA XT Plus Texture Analyzer using the protocol describe above to indicate the amount of force that was generated when pressure was applied to the film.

Table B

[0036] Examples 7-13 demonstrate that tack increased and then precipitously diminished between 40 and 50% copolymer. Neither high nor low tack adhesives followed the trajectory of tack loss that would be expected if this were a typical blending phenomenon, i.e., an incremental loss of tack as less tacky substance is added to the adhesive.

Examples 14-19

[0037] Examples 14-19 demonstrate the change in tack observed when a copolymer component is added to a high tack, low resin content silanol functional silicone pressure sensitive adhesive. The copolymer was blended with the high tack, low resin content silanol functional silicone pressure sensitive adhesive in the weight percentages listed in Table C below for the six samples. The copolymer used was the solids obtained from Dow Corning® FA-4001 CM Silicone Acrylate after stripping the solvent. These solids were dispersed in ethyl acetate. The high tack, low resin content silanol functional silicone pressure sensitive adhesive used was Dow Corning® BIO-PSA 7-4602 Silicone Pressure Sensitive Adhesive available from Dow Corning Corporation. The average adhesion force of the resulting films was tested using the TA XT Plus Texture Analyzer using the protocol describe above to indicate the amount of force that was generated when pressure was applied to the film.

Table C

[0038] Examples 14-19 demonstrate that the tack was fairly constant in the range of 0-30% copolymer component. The tack then precipitously diminished between 40 and 50% copolymer component so that at 50% copolymer, the film was nearly tack free. Neither high nor low tack adhesives followed the trajectory of tack loss that would be expected if this were a typical blending phenomenon, i.e., an incremental loss of tack as less tacky substance is added to the adhesives.

Comparative Examples 20-37

Comparative Examples 20-25

[0039] The components that make up the pressure sensitive adhesive (the silicone polymer and the resin) were blended into the copolymer individually and evaluated for their ability to form a cohesive film. The copolymer used was Dow Corning® FA-4001 CM Silicone Acrylate available from Dow Corning Corporation.

[0040] The results are shown in Tables D and E. Examples 20-22 show the hydroxyl- functional silicone polymer used to create the silicone pressure sensitive adhesive blended with the copolymer and subjective evaluation of each whereas Examples 23-25 show the hydroxyl-functional silicone resin used to create the silicone pressure sensitive adhesive blended with the copolymer and subjective evaluation of each. Table D

Table E

[0041] These evaluations show that neither component that is used to create the silicone pressure sensitive adhesive can be blended with the copolymer to create an adequate film former. More objective measurements were not possible with these films due to their lack of cohesiveness. The films formed in Examples 23-25 were brittle such that they could not be measured with the tack test used above; they crumbled upon manipulation of the support film.

Comparative Examples 26-28

[0042] A silicone polymer and a resin were blended together in a ratio of 45 parts polymer to 55 parts resin. The silicone polymer used was a hydroxyl terminated polydiorganosiloxane with a viscosity between 7500 mPa.s and 20,000 mPa.s. at 25°C. The resin used was a resin copolymer comprising triorganosiloxy units of formula R ₃ SiOi _/2 and tetrafunctional siloxy units of formula Si0 _4/2 in a ratio of 0.6 to 0.9 triorganosiloxy units for each tetrafunctional siloxy unit.

[0043] The components that make up the silicone pressure sensitive adhesive (the silicone polymer and the resin) were blended together. This was a simple blend of the silicone polymer and the resin and was not a more fully-reacted (i.e., bodied or crosslinked) pressure sensitive adhesive as used in Examples 1-19. [0044] The resulting silicone pressure sensitive adhesive was then blended with a copolymer and evaluated. The copolymer used was Dow Corning® FA-4001 CM Silicone Acrylate available from Dow Corning Corporation.

[0045] Examples 26-28 show the blend of silicone resin and polymer used to create the silicone pressure sensitive adhesive blended with the copolymer. The resulting material was not crosslinked. The results of the testing are shown in Table F.

Table F

[0046] The films formed in Examples 27-28 were non-cohesive such that they could not be measured using the techniques employed for the other examples. Subjective evaluation showed that the blend of polymer and resin with 45% copolymer (Example 26) provided a similar film to reacted silicone pressure sensitive adhesive, further evaluation via texture analyzer showed significant improvements of the bodied (crosslinked) pressure sensitive adhesive over the analogous resin-polymer blend (not crosslinked) in both film strength and flexibility.

Comparative Examples 29-31 , 32-34 and Examples 35-37

[0047] Comparative examples (Examples 29-31 ) were prepared by blending Dow Corning® FA-4001 CM Silicone Acrylate available from Dow Corning Corporation with a low resin content, hydroxyl functional pressure sensitive adhesive, Dow Corning® BIO-PSA 7-4602 Silicone Pressure Sensitive Adhesive available from Dow Corning Corporation.

Table G

Comparative examples (Examples 32-34) were prepared by blending Dow Corning® FA- 4001 CM Silicone Acrylate available from Dow Corning Corporation with a low resin content, hydroxyl functional pressure sensitive adhesive, Dow Corning® BIO-PSA 7-4602 Silicone Pressure Sensitive Adhesive that was produced by reacting (bodying) a silicone resin and polymer and is commercially available from Dow Corning Corporation.

[0048] Examples 35-37 were prepared by blending a silicone polymer and a resin together in the same ratio as the BIO-PSA 7-4602. The silicone polymer used was a hydroxyl- terminated polydiorganosiloxane with a viscosity between 7500 mPa.s and 20,000 mPa.s. at 25°C. The resin used was a resin copolymer comprising triorganosiloxy units of formula R ₃ SiO-i/2 and tetrafunctional siloxy units of formula Si0 _4/2 in a ratio of 0.6 to 0.9 triorganosiloxy units for each tetrafunctional siloxy unit.

[0049] This was a simple blend of the silicone polymer and the resin and was not a more fully-reacted (i.e., bodied or crosslinked) pressure sensitive adhesive as used in Examples 32-34. All the prepared samples, 32-37, were tested to determine the strength and elasticity of the resulting films.

[0050] Film strength is reported as the force required for a rounded probe of Dextran™ construction moving at 2.54 mm/sec rate of speed to break the film. Film flexibility is recorded as the distance that the same probe can bend the film before the film gives or breaks. The film strength and film elasticity results are shown in Table H.

Table H

^* N/A - not applicable. Films prepared with this formulation were not cohesive enough to perform testing.

[0051] The data in Table H demonstrates the improved properties and formulation flexibility that is achievable when a bodied pressure sensitive adhesive is used instead of a blend of the ingredients. Both film strength and elasticity are important characteristics in a film former. [0052] The coefficient (CoF) of friction describes the ratio of the force of friction between two bodies and the force pressing them together. Static friction is friction between two solid objects that are not moving relative to each other, while kinetic friction occurs when two objects are moving relative to each other and rub together. A low coefficient of friction is indicative of low drag surfaces which are desirable in many film former applications.

Examples 38-43

[0053] Examples 38-43 were prepared to measure the static and kinetic coefficients of friction of the pressure sensitive adhesive and copolymer blends shown in Table I. Examples 38-43 were prepared by blending Dow Corning® FA-4001 CM Silicone Acrylate with either Dow Corning® BIO-PSA 7-4402 Silicone Pressure Sensitive Adhesive, a low tack, high resin content, hydroxyl functional pressure sensitive adhesive delivered in ethyl acetate or Dow Corning® BIO-PSA 7-4602, a high tack, low resin content, hydroxyl functional pressure sensitive adhesive delivered in ethyl acetate both available from Dow Corning Corporation.

[0054] The static and kinetic coefficients of friction of these pressure sensitive adhesive and copolymer blends are shown in Table J.

Table I

Table J

Examples 44-49 - Drug Loaded Formulations

Examples 44-46 - Estradiol

[0055] An estradiol masterbatch was prepared by dispersing 0.777 g estradiol and 3.869 g Kollidon® VA64 (available from BASF, Germany) into 4.671 g ethyl acetate. To the dispersion, 3.31 1 g 2-propanol was added to dissolve the estradiol and Kollidon® VA64. To this solution 4.510 g of oleic acid and 3.006 g dipropylene glycol were added.

[0056] These formulations were prepared by mixing the estradiol masterbatch, the pressure sensitive adhesive blend as detailed in Table K and ethyl acetate to achieve 30% solids. The final formulation compositions can be found in Table K.

Table K

Examples 47-49 - Ketoprofen

[0057] A ketoprofen masterbatch was prepared by dispersing 4.171 g ketoprofen and 2.580 g Kollidon® VA64 into 6.751 g ethyl acetate. To the dispersion, 3.395 g 2-propanol was added to dissolve the estradiol and Kollidon® VA64. To this solution 2.515 g oleic acid was added.

[0058] These formulations were prepared by mixing the ketoprofen masterbatch, the pressure sensitive adhesive blend as detailed in Table L and ethyl acetate to achieve 30% solids. The final formulation compositions can be found in Table L.

Table L

Flux Experiments for Examples 44-49

[0059] Formulation examples were dosed (15 μΙ_) using a micropipette in triplicate and the permeation through heat separated epidermis was measured using Franz static diffusion apparatus. The heat separated epidermis was prepared from full-thickness human cadaver skin. The receptor fluid was phosphate buffered saline pH 7.4 and the study was conducted at 32°C. Samples (1 ml.) of the receptor fluid were taken at 4, 8, 12, 24, 48, 72 and 96 hours with replacement using fresh phosphate buffered saline. Samples were analyzed for estradiol and ketoprofen concentration, respectively, using an appropriate UPLC method. The results are shown in Figure 1 for the estradiol samples and in Figure 2 for the ketoprofen samples.

Overall Results for Drug Loaded Formulations

[0060] These results demonstrate the ability to load and release a variety of active pharmaceutical substances with the inventive formulations. The relative similarity of the permeation (flux) results regardless of silicone pressure sensitive adhesive to copolymer ratio demonstrate that the formulations are robust so that deviations in the silicone pressure sensitive adhesive could be accommodated at a higher level in the manufacture without affecting the delivery efficiency.

[0061] While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.