Stable aqueous capsaicin injectable formulations and medical uses thereof

1. An aqueous, capsaicin injectable formulation, comprising

a. 0.04% (w/w) to 0.06% (w/w) of capsaicin;

b. 0.5% (w/w) to 1.5% (w/w) of a solubilizing agent, wherein the solubilizing agent comprises

and polyethylene glycol;

c. 0.005% (w/w) to 0.015% (w/w) of an antioxidant;

d. 0.2% (w/w) to 1% (w/w) of an alkali metal acetate;

e. 0.01% (w/w) to 0.05% (w/w) of a chelating agent;

f. 0.3% (w/w) to 0.9% (w/w) of a tonicity modifier;

g. at least 96% (w/w) water; and

having a pH in the range of 5 to 6.

2. The formulation of claim 1 , wherein the formulation does not contain any polysorbate or cyclodextrin.

3. The formulation of claim 1 , wherein the formulation does not contain any cyclodextrin, cellulose, or hyaluronic acid.

4. The formulation of claim 1 , wherein the solubilizing agent comprises (a) from 68% (w/w) to 72% (w/w) of a mixture of

and (b) from 28% (w/w) to 32% (w/w) polyethylene glycol.

5. The formulation of claim 2 , wherein the solubilizing agent comprises (a) from 68% (w/w) to 72% (w/w) of a mixture of

and (b) from 28% (w/w) to 32% (w/w) polyethylene glycol.

6. The formulation of claim 3 , wherein the solubilizing agent comprises (a) from 68% (w/w) to 72% (w/w) of a mixture of

and (b) from 28% (w/w) to 32% (w/w) polyethylene glycol.

7. The formulation of claim 1 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight in the range of 600 g/mol to 750 g/mol.

8. The formulation of claim 5 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight in the range of 600 g/mol to 750 g/mol.

9. The formulation of claim 6 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight in the range of 600 g/mol to 750 g/mol.

10. The formulation of claim 1 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight of about 660 g/mol.

11. The formulation of claim 5 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight of about 660 g/mol.

12. The formulation of claim 6 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight of about 660 g/mol.

13. The formulation of claim 1 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

14. The formulation of claim 2 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

15. The formulation of claim 3 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

16. The formulation of claim 5 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

17. The formulation of claim 6 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

18. An aqueous, capsaicin injectable formulation, comprising

a. 0.05% (w/w) of capsaicin;

b. 1% (w/w) of a solubilizing agent, wherein the solubilizing agent comprises (a) from 68% (w/w) to 72% (w/w) of a mixture of

and (b) from 28% (w/w) to 32% (w/w) polyethylene glycol;

c. 0.005% (w/w) to 0.015% (w/w) of dibutylhydroxytoluene;

d. 0.2% (w/w) to 1% (w/w) of sodium acetate;

e. 0.01% (w/w) to 0.05% (w/w) of ethylenediaminetetraacetic acid or a salt thereof;

f. 0.3% (w/w) to 0.9% (w/w) of sodium chloride;

g. at least 96% (w/w) water; and

having a pH of 5.5.

19. The formulation of claim 18 , wherein the formulation does not contain any polysorbate or cyclodextrin.

20. The formulation of claim 18 , wherein the formulation does not contain any cyclodextrin, cellulose, or hyaluronic acid.

21. The formulation of claim 18 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight in the range of 600 g/mol to 750 g/mol.

22. The formulation of claim 19 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight in the range of 600 g/mol to 750 g/mol.

23. The formulation of claim 20 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight in the range of about 600 g/mol to about 750 g/mol.

24. The formulation of claim 18 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight of about 660 g/mol.

25. The formulation of claim 19 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight of about 660 g/mol.

26. The formulation of claim 20 , wherein any polyethylene glycol or polyethylene glycolyl each independently have a weight-average molecular weight of about 660 g/mol.

27. The formulation of claim 18 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

28. The formulation of claim 19 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

29. The formulation of claim 20 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

30. The formulation of claim 21 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

31. The formulation of claim 22 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.

32. The formulation of claim 23 , wherein less than 0.5% of the capsaicin degrades upon storage of the formulation at 25° C. for 24 weeks.