Method for treating pain or pruritis by administering κ-opioid receptor agonist comprising 2-phenylbenzothiazoline derivative

1. A method of treating pain or pruritis comprising administering to a patient in need thereof a pharmaceutically effective amount of a κ opioid receptor agonist comprising a compound having a chemical structure represented by the following formula [I] or a salt thereof,

wherein R is an alkyl group having an amino group as a substituent; and R 1 is acyl.

2. A method of treating pain or pruritis comprising administering to a patient in need thereof a pharmaceutically effective amount of a κ opioid receptor agonist comprising a compound represented by the following formula [II] or a salt thereof,

wherein R 1 is acyl;

R 2 and R 3 are the same or different and are hydrogen, halogen, alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, aryloxy, carboxyl or an ester thereof, alkylcarbonyl, arylcarbonyl, amino, alkylamino, arylamino, cyano or nitro, wherein the alkyl, cycloalkyl, aryl, alkoxy, aryloxy, alkylcarbonyl, arylcarbonyl, alkylamino or arylamino are unsubstituted or substituted by halogen, alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, aryloxy, carboxyl or an ester thereof, alkylcarbonyl, arylcarbonyl, amino, alkylamino, arylamino, cyano or nitro;

R 4 and R 5 , are the same or different, and are hydrogen, alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, aryloxy or acyl, wherein the alkyl, cycloalkyl, aryl, alkoxy, aryloxy or acyl are unsubstituted or substituted by a substituent selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, aryloxy, carboxyl or an ester thereof, alkylcarbonyl, arylcarbonyl, amino, alkylamino, arylamino, mercapto, alkylthio, arylthio, cyano, nitro and a heterocycle, and wherein the alkyl, cycloalkyl, aryl, alkoxy, aryloxy, alkylcarbonyl, arylcarbonyl, alkylamino, arylamino, alkylthio, arylthio or heterocycle substituent is unsubstituted or substituted by aryl, hydroxyl or an ester thereof, alkoxy, aryloxy, alkoxyalkoxy or carboxyl or an ester thereof; or

R 4 and R 5 are bonded to each other to form an unsubstituted heterocycle or a heterocycle substituted by halogen, alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, aryloxy or carboxyl or an ester thereof, and wherein the alkyl, cycloalkyl, aryl, alkoxy or aryloxy are unsubstituted or substituted by aryl, hydroxyl or an ester thereof, alkoxy, aryloxy, alkoxyalkoxy or carboxyl or an ester thereof; and

A 1 is alkylene.

3. The method as claimed in claim 2 , wherein R 2 and R 3 are the same or different and are hydrogen, halogen, alkoxy, unsubstituted alkyl or alkyl substituted by halogen.

4. The method as claimed in claim 2 , wherein R 4 and R 5 are the same or different and are hydrogen, alkyl, cycloalkyl, hydroxyl or an ester thereof or alkoxy, wherein the alkyl is unsubstituted or substituted by a substituent selected from the group consisting of alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, carboxyl or an ester thereof, mercapto, alkylthio and a heterocycle, and wherein the alkyl or alkoxy substituent is unsubstituted or substituted by hydroxyl or an ester thereof, alkoxy or alkoxyalkoxy.

5. The method as claimed in claim 2 , wherein R 4 and R 5 are bonded to each other to form a pyrrolidine ring or a piperidine ring, wherein the pyrrolidine ring or piperidine ring is unsubstituted or substituted by alkyl, hydroxyl or an ester thereof, alkoxy or carboxyl or an ester thereof, and wherein the alkyl is unsubstituted or substituted by hydroxyl or an ester thereof or alkoxy.

6. The method as claimed in claim 2 , wherein

R 1 is acyl,

R 2 is hydrogen, halogen or alkyl, wherein the alkyl is unsubstituted or substituted by halogen,

R 3 is halogen or alkoxy,

R 4 is hydrogen, alkyl or cycloalkyl, wherein the alkyl is unsubstituted or substituted by a substituent selected from the group consisting of alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof and alkoxy, and wherein the alkyl substituent is unsubstituted or substituted by hydroxyl or an ester thereof or alkoxy,

R 5 is alkyl, hydroxyl or an ester thereof or alkoxy, wherein the alkyl is unsubstituted or substituted by a substituent selected from the group consisting of cycloalkyl, aryl, hydroxyl or an ester thereof, alkoxy, carboxyl or an ester thereof, mercapto, alkylthio and a heterocycle, and wherein the alkoxy substituent is unsubstituted or substituted by hydroxyl or an ester thereof, alkoxy or alkoxyalkoxy, or

R 4 and R 5 are bonded with each other to form a pyrrolidine ring or a piperidine ring, wherein the pyrrolidine ring or piperidine ring is unsubstituted or substituted by a substituent selected from the group consisting of alkyl, hydroxyl or an ester thereof, alkoxy and carboxyl or an ester thereof, and wherein the alkyl substituent is unsubstituted or substituted by hydroxyl or an ester thereof or alkoxy, and

A 1 is alkylene.

7. The method as claimed in claim 2 , wherein

R 1 is acyl,

R 2 is hydrogen, halogen or alkyl, wherein the alkyl can be substituted by halogen,

R 3 is halogen or alkoxy,

R 4 is cycloalkyl or alkyl which is unsubstituted or substituted by alkyl, cycloalkyl, aryl, hydroxyl or an ester thereof or alkoxy,

R 5 is alkyl, hydroxyl or an ester thereof or alkoxy, wherein the alkyl is unsubstituted or substituted by a substituent selected from the group consisting of hydroxyl or an ester thereof, alkoxy, mercapto or alkylthio, and wherein the alkoxy substituent is unsubstituted or substituted by alkoxy or alkoxyalkoxy, or

R 4 and R 5 are bonded to each other to form a pyrrolidine ring, wherein the pyrrolidine ring is unsubstituted or substituted by alkyl, hydroxyl or an ester thereof or alkoxy, and the alkyl is unsubstituted or substituted by hydroxyl or an ester thereof or alkoxy, and

A 1 is alkylene.

8. The method as claimed in claim 1 , wherein the method is for treating pain caused by a rheumatic disease.

9. The method as claimed in claim 2 , wherein the method is for treating pain caused by a rheumatic disease.

10. The method as claimed in claim 3 , wherein the method is for treating pain caused by a rheumatic disease.

11. The method as claimed in claim 4 , wherein the method is for treating pain caused by a rheumatic disease.

12. The method as claimed in claim 5 , wherein the method is for treating pain caused by a rheumatic disease.

13. The method as claimed in claim 6 , wherein the method is for treating pain caused by a rheumatic disease.

14. The method as claimed in claim 7 , wherein the method is for treating pain caused by a rheumatic disease.