Methods and compositions for treating chronic pain

1. A method of treating pain comprising administering an effective amount of an EPAC inhibitor having a general formula of:

where R 1 and R 2 are independently substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycle, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl to a subject in need of such treatment.

2. The method of claim 1 , wherein R 1 is a substituted isoxazole.

3. The method of claim 2 , wherein the substituted isoxazole has linear alkyl, branched alkyl, or cycloalkyl substitution.

4. The method of claim 2 , wherein the substituted isoxazole is methyl, ethyl, n-propyl, iso-propyl), n-butyl, sec-butyl, iso-butyl, tert-butyl, neo-pentyl, n-pentyl, or isopenyl substituted isoxazole.

5. The method of claim 2 , wherein R 1 is a 5-methyl isoxazole or a 5-tert-butyl isoxazole.

6. The method of claim 1 , wherein R 2 is a substituted or unsubstituted phenyl.

7. The method of claim 6 , wherein R 2 is a substituted phenyl having one or more substituent selected from bromo, fluoro, chloro, iodo, or combinations thereof.

8. The method of claim 6 , wherein R 2 is a 3-chlorophenyl; 2-chlorophenyl; 4-chlorophenyl; phenyl; 3,6-dichlorophenyl; 3-methylphenyl, 3-trifluoromethylphenyl; 3-nitrophenyl; 4-methylphenyl, 3,5-dichlorophenyl; 4-bromophenyl; 3-bromophenyl; 3,6-dimethylphenyl; benzopyridine; 2,3-dichlorophenyl; 3-ethynyl; benzoic acid ethyl ester; 3-benzonitrile; 3-acetylphenyl; 2,3-methylphenyl; 3-ethoxyphenyl; indane; 3,5-di-trifluoromethylphenyl; 6-chloro-benzoic acid; or 3-chloro, 4-hydroxyphenyl.

9. The method of claim 1 , wherein the compound is selected from N-(5-tert-Butyl-isoxazol-3-yl)-2-[(3-chlorophenyl)-hydrazono]-2-cyanoacetamide (HJC0683); 2-[(3-Chlorophenyl)-hydrazono]-2-cyano-N-(5-methyl-isoxazol-3-yl)acetamide (HJC0692); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(2-chlorophenyl)-hydrazono]-3-oxo-propionitrile (HJC0693); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(4-chlorophenyl)-hydrazono]-3-oxo-propionitrile (HJC0694); 3-(5-tert-Butyl-isoxazol-3-yl)-3-oxo-2-(phenyl-hydrazono)-propionitrile (HJC0695); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(2,5-dichlorophenyl)-hydrazono]-3-oxo-propionitrile (HJC0696); 3-(5-tert-Butyl-isoxazol-3-yl)-3-oxo-2-(m-tolyl-hydrazono)propionitrile (HJC0712); 3-(5-tert-Butyl-isoxazol-3-yl)-3-oxo-2-[(3-trifluoromethyl-phenyl)-hydrazono]propionitrile (HJC0720); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(3-nitrophenyl)-hydrazono]-3-oxo-propionitrile (HJC0721); 3-(5-tert-Butyl-isoxazol-3-yl)-3-oxo-2-(p-tolyl-hydrazono)propionitrile (HJC0724); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(3,5-dichlorophenyl)-hydrazono]-3-oxo-propionitrile (HJC0726); 2-[(4-Bromophenyl)-hydrazono]-3-(5-tert-butyl-isoxazol-3-yl)-3-oxo-propionitrile (HJC0742); 2-[(3-Bromophenyl)-hydrazono]-3-(5-tert-butyl-isoxazol-3-yl)-3-oxo-propionitrile (HJC0743); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(2,5-dimethylphenyl)-hydrazono]-3-oxo-propionitrile (HJC0744); 3-(5-tert-Butyl-isoxazol-3-yl)-3-oxo-2-(quinolin-6-yl-hydrazono)propionitrile (HJC0745); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(2,3-dichlorophenyl)-hydrazono]-3-oxo-propionitrile (HJC0750); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(3-ethynyl-phenyl)-hydrazono]-3-oxo-propionitrile (HJC0751); 3-{N-[2-(5-tert-Butyl-isoxazol-3-yl)-1-cyano-2-oxo-ethylidene]-hydrazino}benzoic acid ethyl ester (HJC0752); 3-{N-[2-(5-tert-Butyl-isoxazol-3-yl)-1-cyano-2-oxo-ethylidene]-hydrazino}benzonitrile (HJC0753); 2-[(3-Acetyl-phenyl)-hydrazono]-3-(5-tert-butyl-isoxazol-3-yl)-3-oxo-propionitrile (HJC0754); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(2,3-dimethylphenyl)-hydrazono]-3-oxo-propionitrile (HJC0755); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(3-hydroxymethylphenyl)-hydrazono]-3-oxo-propionitrile (HJC0756); 3-(5-tert-Butyl-isoxazol-3-yl)-2-(indan-5-yl-hydrazono)-3-oxo-propionitrile (HJC0757); 2-[(3,5-Bis-trifluoromethyl-phenyl)-hydrazono]-3-(5-tert-butyl-isoxazol-3-yl)-3-oxo-propionitrile (HJC0758); 2-{N-[2-(5-tert-Butyl-isoxazol-3-yl)-1-cyano-2-oxo-ethylidene]-hydrazino}-6-chloro-benzoic acid (HJC0759); 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(3-chloro-4-hydroxy-phenyl)-hydrazono]-3-oxo-propionitrile (HJC0760); 2-[(3-Chloro-phenyl)-hydrazono]-3-(5-methyl-isoxazol-3-yl)-3-oxo-propionitrile (HJC0768); or 2-[(3,5-Dichlorophenyl)-hydrazono]-3-(5-methyl-isoxazol-3-yl)-3-oxo-propionitrile (HJC0770).

10. The method of claim 1 , wherein the EPAC inhibitor is 3-(5-tert-Butyl-isoxazol-3-yl)-2-[(3-chlorophenyl)-hydrazono]-3-oxo-propionitrile (HJC0680, ESI-09).

11. The method of claim 1 , wherein the pain is chronic or neuropathic pain.

12. The method of claim 11 , wherein the chronic pain is chemotherapy-associated chronic pain.