Transdermal drug delivery system containing donepezil

Abstract

Certain embodiments of the invention relates to a transdermal drug delivery system containing donepezil or a pharmaceutically acceptable salt thereof as an active ingredient, more specifically to a transdermal drug delivery system containing a drug-containing matrix layer comprising donepezil or its pharmaceutically acceptable salt, a styrene copolymer, a hydrogenated rosin glycerol ester, and optionally a hydrocarbon resin.

Claims

1. A transdermal drug delivery system comprising: a drug containing matrix layer consisting of: 7-15% by weight of donepezil or a pharmaceutically acceptable salt thereof based on a total weight of the drug-containing matrix layer; 33-55% by weight of a styrene copolymer based on a total weight of the drug-containing matrix layer; and 8-38% by weight of a hydrocarbon resin and a hydrogenated rosin glycerol ester based on a total weight of the drug-containing matrix layer.

2. The transdermal drug delivery system of claim 1, wherein the styrene copolymer is one or more selected from the group consisting of styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene/butylene-styrene copolymer and styrene-ethylene/propylene-styrene copolymer.

3. The transdermal drug delivery system of claim 1, wherein weight ratio of the hydrogenated rosin glycerol esters to hydrocarbon resin is from 1:1 to 1:4.

4. The transdermal drug delivery system of claim 1, wherein the hydrocarbon resin is selected from the group consisting of cyclic, acyclic, or aromatic hydrocarbon resin.

5. The transdermal drug delivery system of claim 1, wherein the hydrocarbon resin is selected from the group consisting of C.sub.5-9 acyclic hydrocarbon resin, C.sub.5-9 cyclic hydrocarbon resin.

6. A transdermal drug delivery system consisting of a backing layer, a drug-containing matrix layer, and a release layer, wherein the drug containing matrix layer consists of: 7-15% by weight of donepezil or a pharmaceutically acceptable salt thereof based on a total weight of the drug-containing matrix layer; 33-55% by weight of a styrene copolymer based on a total weight of the drug-containing matrix layer; and 8-38% by weight of a hydrocarbon resin and a hydrogenated rosin glycerol ester based on a total weight of the drug-containing matrix layer.

7. A transdermal drug delivery system comprising: a drug containing matrix layer consisting of: donepezil or a pharmaceutically acceptable salt thereof; a styrene copolymer; a hydrocarbon resin; a hydrogenated rosin glycerol ester; and a plasticizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Certain aspects of the invention provides a transdermal drug delivery system comprising a drug containing matrix layer containing donepezil or its salt as an active ingredient, wherein the matrix layer contains a styrene copolymer, a hydrogenated rosin glycerol esters and optionally a hydrocarbon resin.

(2) In one embodiment, the transdermal drug delivery provides not only high skin penetration rate but also continuous maintenance of therapeutically effective concentration of drug in plasma for at least 24 hours.

(3) In another embodiment, the transdermal drug delivery system reduces or prevents crystallization of donepezil even after long period of storage and minimizes skin irritation.

(4) Thus, certain embodiments of the invention provide a transdermal drug delivery system containing donepezil having high skin penetration continuously more than 24 hours, excellent stability, and reduced skin irritation.

(5) In accordance with an aspect of some embodiments of the invention, there is provided a transdermal drug delivery system comprising a drug-containing matrix layer containing donepezil or its salt as an active ingredient, wherein the matrix layer contains a styrene copolymer, and a hydrogenated rosin glycerol ester. The transdermal delivery system of this and other embodiments of the invention may further comprise a hydrocarbon resin. An alternative embodiment of the invention may further contains a plasticizer. A non-exhaustive list of plasticizers that can be used include: petroleum-based oils (for example, paraffinic process oil, naphthenic process oil, aromatic process oil and the like), squalane, squalene, vegetable oils (for example, olive oil, camellia oil, tall oil, peanut oil, castor oil and the like), silicone oil, dibasic acid esters (for example, dibutyl phthalate, dioctyl phthalate and the like), liquid rubber (for example, polybutene, liquid isoprene rubber and the like), a liquid fatty acid ester (isopropyl myristate, hexyl laurate, diethyl sebacate, diisopropyl sebacate and the like), diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol and the like.

(6) In an alternative embodiment of the invention, the transdermal drug delivery system may consist of a backing layer, the drug-containing matrix layer, and a release layer.

(7) In the transdermal drug delivery system according to certain embodiments of the invention, donepezil or its pharmaceutically acceptable salt is present in an amount ranging from 2 to 25% by weight, preferably 5-20% by weight, and more preferably 7-15% by weight based on the total weight of the drug-containing matrix layer.

(8) The styrene copolymer is one or more selected from among styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene/butylene-styrene copolymer and styrene-ethylene/propylene-styrene copolymer. The styrene copolymer is included in an amount ranging from 10 to 85% by weight, preferred 20-70% by weight, more preferably 30-65% by weight, and most preferably 33-55% by weight based on the total weight of the drug-containing matrix layer.

(9) The transdermal drug delivery system according to certain embodiments of the invention may further comprise hydrogenated rosin glycerol esters and/or hydrocarbon resin in an amount ranging from 5-85% by weight, preferably 10-65% by weight, and more preferably 20-50% by weight, and most preferably 30-50% by weight, based on the total weight of the drug-containing matrix layer and the weight ratio of the hydrogenated rosin glycerol esters to hydrocarbon resin is from 1:1 to 1:4.

(10) In the transdermal drug delivery system according to another embodiment of the invention, the hydrocarbon resin is present in an amount ranging from 10 to 85% by weight, preferred 20-70% by weight, more preferably 30-65% by weight, and most preferably 33-55% by weight based on the total weight of the drug-containing matrix layer.

(11) The transdermal drug delivery system according to certain embodiments of the invention may contain a hydrogenated rosin glycerol ester is present in an amount ranging from 2 to 40% by weight, preferred 5-50% by weight, more preferably 5-20% by weight, and most preferably 5-15% by weight based on the total weight of the drug-containing matrix layer.

(12) In certain embodiments of the invention, the hydrocarbon resin added is contained in the styrene copolymer. The amount of the styrene copolymer containing a hydrocarbon resin may range from 10 to 85% by weight, preferably 20-85% by weight, more preferably 30-85% by weight, and most preferably 50-85% by weight based on the total weight of the drug-containing matrix layer.

(13) The transdermal drug delivery system according to certain embodiments of the invention provides a drug containing matrix containing: a styrene copolymer; a hydrogenated rosin glycerol ester; and optionally a hydrocarbon resin. In one embodiment, the transdermal drug delivery system provides not only increased skin penetration rate for donepezil, but also maintains consistent therapeutically effective concentration of donepezil in plasma for at least 24 hours or longer. In further embodiment, the transdermal drug delivery system can inhibit crystallization of donepezil during the storage over the long period and reduce skin irritation. Therefore, the transdermal drug delivery system according to certain embodiments of the invention can improve drug compliance of patients suffering from Alzheimer's disease.

(14) In the transdermal drug delivery system according to certain embodiments of the invention, the donepezil or its pharmaceutically acceptable salt may be used in an amount sufficient to obtain a therapeutically effective blood concentration, for example, in an amount ranging from 2 to 25% by weight, preferably from 5 to 20% by weight, more preferably 10-17% by weight, and more preferably 7-15% by weight based on the total weight of the drug-containing matrix layer. If the amount of donepezil or its pharmaceutically acceptable salt is more than 25% by weight, drug crystals may be formed in the transdermal drug delivery system, which results in reducing adhesive force or lowering absorption rate of the drug.

(15) The transdermal drug delivery system according to certain embodiments of the invention contains styrene copolymers as a matrix forming material. The styrene copolymer assists formation of the matrix and also helps to maintain the structure of the matrix. Donepezil or its pharmaceutically acceptable salt can be dispersed through the styrene copolymer matrix evenly. The styrene copolymer is one or more selected from among styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene/butylene-styrene copolymer and styrene-ethylene/propylene-styrene copolymer. In another embodiment, the styrene copolymer is one or more selected from among commercially available copolymers. The commercially available styrene copolymers include, but not limited to, Kraton D1161 (Kraton Performance Polymers Inc., Huston, Tex., USA), Kraton D1102. The amount of the styrene copolymer is enough to form the matrix, or 20-70%, preferably 20-50% or more preferably 20-40% by weight based on the total weight of the drug-containing matrix layer.

(16) The hydrogenated rosin glycerol ester in the transdermal drug delivery system of certain embodiments of the invention functions as tackifier, not only improving the adhesiveness of the transdermal drug delivery system, but also inhibiting crystallization of donepezil within the drug-containing matrix. Without being bound to any particular theory, a hydrogenated rosin glycerol ester, such as Foral85 (Pinova, Inc., Brunswick, Ga., USA), has optimum polarity to contribute to improve solubility of donepezil within the drug-containing matrix comprising hydrophobic styrene copolymer. However, the inventors have also found that if the hydrogenated rosin glycerol ester is used as the only tackifier, the absorption or the skin penetration of donepezil can decrease and also skin irritation would increase.

(17) In an alternative embodiment, the inventors also found that the problem is solved by using a hydrocarbon resin in combination. In other words, when a hydrogenated rosin glycerol ester and hydrocarbon resin was added to the matrix containing styrene copolymer, the tackiness of the drug containing matrix is improved, skin penetration of donepezil from the drug containing matrix is increased, and skin irritation is reduced significantly. On the other hand, preparing the drug containing matrix using styrene copolymer and hydrocarbon resin only, without the hydrogenated rosin glycerol ester produced more crystallization of donepezil after long storage. See Table 6. On the other hand, when a hydrogenated rosin glycerol ester and hydrocarbon resin are used in combination for the styrene copolymer containing matrix, crystallization of the drug, donepezil, is effective decreased as confirmed in certain embodiments of the invention.

(18) The hydrocarbon resin of certain embodiments of the invention includes cyclic, acyclic, or aromatic hydrocarbon resin. Hydrocarbon resin is, for example, C.sub.5-9 saturated acyclic hydrocarbon resin, C.sub.5-9 saturated cyclic hydrocarbon resin. In addition, saturated hydrocarbon resin is selected from commercially available resin, such as Escorez 5380 (ExxonMobil Chemical Company, Houston, Tex., USA), Quintone R100 (Zeon Chemicals L.P., Louisville, Ky., USA), or others. In one embodiment, styrene copolymer containing hydrocarbon is used for the transdermal drug delivery system is Duro-Tak 87-6911 (Henkel Corporation, Bridgewater, N.J., USA), and others.

(19) In the transdermal drug delivery system of certain embodiments of the invention, the total amount of the hydrogenated rosin glycerol ester and hydrocarbon resin based on the total weight of the drug containing matrix is 10-75 wt %, preferably 40-60 wt %, or more preferably 30-50%. Furthermore, the weight ratio of the hydrogenated rosin glycerol is from 1:1 to 2:9 or 8-38 wt % based on the total weight of the matrix. When the total weight % of the hydrogenated rosin glycerol ester and the hydrocarbon resin is more than 38%, it is possible to have a side effect such as skin rash and reduced patient compliance due to the rash, or to have reduced skin penetration. On the other hand, when the total weight % of the hydrogenated rosin glycerol ester and the hydrocarbon resin is less than 8%, it is likely to have the drug crystallized out.

(20) In one embodiment of the invention there is provided a transdermal drug delivery system comprising a drug containing matrix layer containing donepezil or its salt as an active ingredient, wherein the matrix layer contains a styrene copolymer, and optionally a hydrogenated rosin glycerol ester, provided that there is no absorption enhancer.

(21) In another embodiment of the invention, an absorption enhancer-free transdermal drug delivery system is provided. In this alternative embodiment, a transdermal drug delivery system according to this aspect of the invention comprises a drug-containing matrix comprising donepezil or its pharmaceutically acceptable salt; a styrene copolymer; a hydrogenated rosin glycerol ester; and hydrocarbon resin but is absorption enhancer-free. The transdermal drug delivery system of certain embodiments of the invention possesses superior properties such as high skin penetration and thus, unlike conventional transdermal systems, it is possible to have a transdermal drug delivery system without an absorption enhancer. In other words, the transdermal drug delivery system of certain embodiments of the invention can avoid use of absorption enhancer such as lauryl alcohol, citric acid triethyl ester, myristic acid isopropyl ester, lactic acid cetyl ester, oleyl alcohol, sorbitan monoolate, polyethylene glycol monostearate, lauromacrogol, N-methyl-2-pyrrolidone, triacetin, pyrrothiodecane, sodium acetate, etc. Absorption enhancer-free transdermal delivery system can avoid the problems of conventional transdermal delivery system such as skin irritation, safety problem, and more.

(22) The transdermal drug delivery system of certain embodiments of the invention may be prepared by forming the drug-containing matrix layer on a release layer and then forming a backing layer thereon. For the release layer, conventional release liners or their laminates used in the field of a transdermal drug delivery system may be used. For example, there may be used a film, a paper, or a laminates thereof, which is made of polyethylene, polyester, polyvinyl chloride, polyvinylidene chloride, etc. coated with silicone resin or fluoride resin. And also, drug non-absorbable and flexible materials conventionally used in the field of a transdermal drug delivery system may be used as the backing layer (also referred to as backing membrane). For example, there may be used polyolefin, polyether, a multi-layer ethylene vinyl acetate film, polyester, polyurethane, etc. The transdermal drug delivery system of certain embodiments of the invention may be prepared, for example by dissolving donepezil or its pharmaceutically acceptable salt and an acrylate-rubber hybrid adhesive, optionally along with an absorption enhancer and/or a crystallization-inhibiting agent, in an appropriate solvent (e.g., ethyl acetate, etc.), casting the resulting solution on a release liner coated with silicone followed by drying the mixture, and then laminating a backing layer.

(23) It should be understood that the components of the transdermal drug delivery system described above may be prepared using varying combinations of the components described above, and that the particular embodiments described above are non-limiting examples of these combinations. For instance, transdermal drug delivery systems prepared according to the invention may include or exclude: an absorption enhancer, a hydrogenated rosin glycerol ester or a plasticizer. The inclusion or absence of these components is determined on an individual basis, selected by the artisan in order to prepare a transdermal system with a desirable release profile.

(24) The high diffusion rate provided by the transdermal drug delivery system of the present invention confers the advantage of allowing for a reduced patch size compared to less efficient transdermal patches known in the art. As a result, in certain embodiments the size of the patch according to the invention can range from about 2 cm.sup.2 to about 20 cm.sup.2, including e.g. 3.5, 5, 7, 10, 10.5, or 15 cm.sup.2, depending on the area to be applied. In certain embodiments, smaller sizes such as 2 cm.sup.2 are preferred as the small size minimizes patient discomfort and encourages compliance with the treatment regimen.

EXAMPLES

(25) Selected embodiments of the invention will be described in further detail with reference to the following experimental and comparative examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

Examples 1-4

(26) Transdermal drug delivery systems were prepared according to the components and amounts shown in Table 1. To a mixture of donepezil, a styrene copolymer, a hydrogenated rosin glycerol ester, and hydrocarbon resin, was added a mixture of cyclohexane and chloroform (1:2, v/v) as a solvent so as to attain to 30% of solid content while stirring. After stirring each mixture, the resulting each solution was casted on a release liner coated with silicone, and dried. A polyethylene film was laminated onto the resulting each layer to form a backing membrane, so as to prepare each donepezil-containing transdermal drug delivery system.

(27) TABLE-US-00001 TABLE 1 Example (% by weight) category Component 1 2 3 4 Active ingredient Donepezil 10 10 10 10 Styrene Copolymer Kraton D1161 37 37 Kraton D1102 37 37 Hydrogenated rosin Foral 85 16 12 16 12 glycerol ester Hydrocarbon resin Escorez 5380 32 36 32 36 Plasticizer Liquid paraffin 5 5 5 5

Examples 5-6

(28) Transdermal drug delivery systems were prepared according to the components and amounts shown in Table 2. To a mixture of donepezil, a styrene copolymer containing a hydrocarbon resin, i.e. Duro-Tak 87-6911, and a hydrogenated rosin glycerol ester, was added a mixture of hexane and chloroform (1:4, v/v) as a solvent so as to attain to 50% of solid content while stirring. After stirring each mixture, the resulting each solution was casted on a release liner coated with silicone, and dried. A polyethylene film was laminated onto the resulting each layer to form a backing membrane, so as to prepare each donepezil-containing transdermal drug delivery system.

(29) TABLE-US-00002 TABLE 2 Example (% by weight) category Component 5 6 Active ingredient Donepezil 10 12.5 Styrene Copolymer containing Duro-Tak 87-6911 80 77.5 a hydrocarbon resin Hydrogenated rosin glycerol Foral85 10 10 ester

Comparative Examples 1-8

(30) Transdermal drug delivery systems were prepared according to the components and amounts shown in Table 3. To a mixture of donepezil, a styrene copolymer and a tackifier (a hydrogenated rosin glycerol ester, and optionally a hydrocarbon resin), was added a mixture of cyclohexane and chloroform (1:2, v/v) as a solvent so as to attain to 30% of solid content while stirring. After stirring each mixture, the resulting each solution was casted on a release liner coated with silicone, and dried. A polyethylene film was laminated onto the resulting each layer to form a backing membrane, so as to prepare each donepezil-containing transdermal drug delivery system.

(31) TABLE-US-00003 TABLE 3 Comparative Example (% by weight) category Component 1 2 3 4 5 6 7 8 Active ingredient Donepezil 10 10 10 10 10 10 10 10 Styrene Kraton 37 37 37 32 27 Copolymer D1161 Kraton 37 37 37 D1102 Hydrogenated Foral85 0 48 8 48 75 53 58 rosin glycerol ester Hydrocarbon Escorez 48 40 48 40.5 resin 5380 Plasticizer Liquid 5 5 5 5 5 5 5 5 paraffin

Comparative Example 9

(32) To a mixture of donepezil (10 wt %) and a styrene copolymer containing a hydrocarbon resin, i.e. Duro-Tak 87-6911, was added a mixture of hexane and chloroform (1:4, v/v) as a solvent so as to attain to 50% of solid content while stirring. After stirring the mixture, the resulting each solution was casted on a release liner coated with silicone, and dried. A polyethylene film was laminated onto the resulting each layer to form a backing membrane, so as to prepare each donepezil-containing transdermal drug delivery system.

Experimental Example 1. Measurement of Skin Penetration Rate

(33) The transdermal drug delivery systems prepared in Examples 1, 3, and 4, Comparative Examples 2, 5, 7 and 8 were applied onto hairless mouse skins, for determining their skin penetration rates. Specifically, skins were excised from hairless mice (6 to 8 weeks old) right before the experiment. Each transdermal drug delivery system was cut in a size of 2 cm.sup.2 and then attached to the isolated skins. Each resulting skin was fixed in each Flow-Through Diffusion Cell with a clamp thereof. To the receiver thereof, was added an isotonic phosphate buffer solution (pH 6.0). While the diffusion cell was maintained at 37 C. with stirring by a magnetic stirrer, samples were collected at an interval of 4 hours for 24 hours. The samples were subject to quantitative analysis using high-performance liquid chromatography under the conditions in Table 4.

(34) TABLE-US-00004 TABLE 4 Column C-18 (Gemini, 10 cm, 5 m) Mobile phase Acetonitrile/phosphate buffer (pH 2.7) = 70/30 Flow rate 1 mL/min Wavelength 315 nm Temperature 30 C.

(35) Table 5 shows the results obtained by measuring skin penetration rates as in the above.

(36) TABLE-US-00005 TABLE 5 Skin Penetration Rate (g/cm.sup.2/h) (Average Standard Deviation) Example 1 13.21 1.01 Example 3 16.29 0.71 Example 4 18.03 2.50 Comparative Example 2 10.36 0.95 Comparative Example 5 9.59 0.50 Comparative Example 7 9.06 0.40 Comparative Example 8 7.37 0.23

(37) From the results shown in Table 5, it can be seen that the transdermal drug delivery system obtained by using a hydrogenated rosin glycerol ester and hydrocarbon resin in combination certain embodiments of the invention showed remarkably increased skin penetration rate, in comparison with those obtained by using a hydrogenated rosin glycerol ester only.

Experimental Example 2. Evaluation of Crystallization

(38) The transdermal drug delivery systems prepared in Examples 1-6 and Comparative Examples 1, 3, 4, 6 and 9 were stored at room temperature for 3 months, formation of crystals in these samples were monitored visually. The result is presented in Table 6.

(39) TABLE-US-00006 TABLE 6 Evaluation of Crystallization in the Transdermal Drug Delivery System Example 1 No crystal was observed. Example 2 No crystal was observed. Example 3 No crystal was observed. Example 4 No crystal was observed. Example 5 No crystal was observed. Example 6 No crystal was observed. Comparative Example 1 Crystal was formed after one day. Comparative Example 3 Crystal was formed after two months. Comparative Example 4 Crystal was formed after one day. Comparative Example 6 Crystal was formed after two months. Comparative Example 9 Crystal was formed after one month.

(40) From the result in Table 6, it is confirmed that no crystals were observed in the transdermal drug delivery systems prepared by the present invention. However, in Comparative Examples 1, 3, 4, 6, and 9 whose transdermal drug delivery systems were prepared using only hydrocarbon resin as the tackifier, formation of donepezil crystal was observed in all of them.

Experimental Example 3. Evaluation of Skin Irritation

(41) The transdermal drug delivery systems prepared in Examples 5 and 6 and Comparative Examples 2 and 5 were cut in size of 4 cm.sup.2 and applied to skins of three (3) volunteers to evaluate the skin irritation properties. The result is presented in Table 7.

(42) TABLE-US-00007 TABLE 7 Evaluation of Skin Irritation Example 5 No skin irritation was observed. Example 6 No skin irritation was observed. Comparative Example 2 Skin irritation was observed. Comparative Example 5 Skin irritation was observed.

(43) From the result in Table 7, it is confirmed that no skin irritation was observed by the transdermal drug delivery systems prepared by the present invention. However, Comparative Examples 2 and 5 both showed skin irritation.