Transdermal patch

1. A transdermal patch comprising:

a removable protective layer,

a matrix layer consisting of a single layer which contains a physiologically effective amount of buprenorphine or pharmaceutically acceptable salts thereof,

an adhesive layer, and

a cover layer,

wherein the cover layer is at least partially bi-elastic and the adhesive layer comprises an acrylic copolymer having hydroxyl functional groups, and

wherein the matrix layer is in contact with the removable protective layer.

2. The transdermal patch according to claim 1 , wherein the matrix layer is arranged to be in contact with the protective layer and in contact with the adhesive layer but not in contact with the cover layer, and

the adhesive layer is arranged to be in contact with the cover layer and is optionally in contact with the protective layer.

3. The transdermal patch according to claim 1 , wherein a separating layer is between the matrix layer and the adhesive layer.

4. The transdermal patch according to claim 1 , wherein the cover layer has an elasticity in the longitudinal and transverse direction of 20% or more.

5. The transdermal patch according to claim 1 , wherein the cover layer has an elasticity in the longitudinal direction of 40-60%.

6. The transdermal patch according to claim 1 , wherein the cover layer has an elasticity in the transverse direction of 35% or more.

7. The transdermal patch according to claim 1 , wherein the acrylic copolymer having hydroxyl functional groups is crosslinked.

8. The transdermal patch according to claim 1 , wherein the acrylic copolymer comprises a combination of 2-ethylhexyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, and vinyl acetate.

9. The transdermal patch according to claim 1 , wherein the acrylic copolymer comprises a combination of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and vinyl acetate.

10. The transdermal patch according to claim 1 , wherein the adhesive layer does not comprise buprenorphine.

11. A transdermal patch comprising:

a removable protective layer,

a matrix layer consisting of a single layer which contains a physiologically effective amount of buprenorphine,

an adhesive layer, and

a cover layer,

wherein the cover layer is at least partially bi-elastic and the adhesive layer comprises an acrylic copolymer having hydroxyl functional groups.

12. A method for treating or alleviating pain, comprising:

administering a transdermal patch according to claim 1 to a patient in need thereof.

13. A process for preparing a transdermal patch, comprising the following steps:

providing a composition comprising buprenorphine and producing a buprenorphine-containing matrix layer therefrom,

providing a composition comprising an acrylic copolymer having hydroxyl functional groups and producing an adhesive layer therefrom,

providing a protective layer,

providing a bi-elastic cover layer, and

producing a transdermal patch according to claim 1 .

14. A process for producing a transdermal patch according to claim 1 , comprising the steps of:

producing a first laminate comprising a buprenorphine-containing matrix layer and a protective layer,

preparing a second laminate comprising an adhesive layer, which includes an acrylic copolymer having hydroxyl functional groups, and a cover layer,

connecting the first laminate comprising the matrix with the second laminate comprising the adhesive layer to produce the transdermal patch.

15. The process according to claim 14 , wherein a top surface of the buprenorphine-containing matrix layer is covered with a separating layer.

16. The process according to claim 14 , wherein the second laminate comprising the adhesive layer further comprises an interim protective layer on the surface of the adhesive layer, which is removed before connecting the second laminate with the first laminate comprising the matrix.

17. The process according to claim 14 , further comprising cutting the transdermal patch into single doses.