Patch

1. A patch, comprising:

a support layer; and

an adhesive agent layer formed on the support layer,

wherein the adhesive agent layer comprises free asenapine, a maleic acid alkali salt, and a rubber-based adhesive agent, the free asenapine and the maleic acid alkali salt are generated from an asenapine maleic acid salt and an alkali metal ion-containing desalting agent, the alkali metal ion-containing desalting agent is at least one of a metal hydroxide and an acetic acid metal salt and is in an amount of 0.5 to 6 equivalents to the asenapine maleic acid salt in terms of acid-base equivalence, the rubber-based adhesive agent has a content in a range of 10% by mass to 50% by mass in the adhesive agent layer and is at least one selected from the group consisting of a styrene-isoprene-styrene block copolymer, polyisobutylene, and a silicone rubber, and the maleic acid alkali salt has a content in a range of 0.5% by mass to 15% by mass in the adhesive agent layer.

2. The patch according to claim 1 , wherein the adhesive agent layer comprises at least one absorption enhancer selected from the group consisting of isostearyl alcohol, capric acid, propylene glycol monolaurate, isopropyl myristate, isopropyl palmitate, laurie acid diethanolamide, propylene glycol, and polyethylene glycol.

3. The patch according to claim 1 , wherein the alkali metal ion-containing desalting agent is in an amount of 0.75 to 4 equivalents to the asenapine maleic acid salt in terms of acid-base equivalence.

4. The patch according to claim 1 , wherein the maleic acid alkali salt is at least one of disodium maleate and monosodium maleate.

5. The patch according to claim 1 , wherein the content of the rubber-based adhesive agent in the adhesive agent layer is in a range of 12% by mass to 40% by mass.

6. The patch according to claim 2 , wherein the maleic acid alkali salt is at least one of disodium maleate and monosodium maleate.

7. The patch according to claim 3 , wherein the maleic acid alkali salt is at least one of disodium maleate and monosodium maleate.

8. The patch according to claim 1 , wherein the adhesive agent layer comprises at least one absorption enhancer selected from the group consisting of propylene glycol monolaurate and isopropyl palmitate.

9. The patch according to claim 5 , wherein the maleic acid alkali salt is at least one of disodium maleate and monosodium maleate.

10. The patch according to claim 8 , wherein the maleic acid alkali salt is at least one of disodium maleate and monosodium maleate.

11. The patch according to claim 2 , wherein a content of the rubber-based adhesive agent in the adhesive agent layer is in a range of 12% by mass to 40% by mass.

12. The patch according to claim 1 , wherein the alkali metal ion-containing desalting agent is a metal hydroxide.

13. The patch according to claim 1 , wherein the alkali metal ion-containing desalting agent is an acetic acid metal salt.

14. The patch according to claim 2 , wherein the alkali metal ion-containing desalting agent is a metal hydroxide.

15. The patch according to claim 2 , wherein the alkali metal ion-containing desalting agent is an acetic acid metal salt.

16. The patch according to claim 3 , wherein the alkali metal ion-containing desalting agent is a metal hydroxide.

17. The patch according to claim 3 , wherein the alkali metal ion-containing desalting agent is an acetic acid metal salt.

18. The patch according to claim 4 , wherein the alkali metal ion-containing desalting agent is a metal hydroxide.

19. The patch according to claim 4 , wherein the alkali metal ion-containing desalting agent is an acetic acid metal salt.

20. The patch according to claim 5 , wherein the alkali metal ion-containing desalting agent is one of a metal hydroxide and an acetic acid metal salt.