Modified collagen

1. A matured collagen composition obtainable by a process comprising the steps of:

(a) obtaining isolated collagen;

(b) freeze-drying the isolated collagen to obtain freeze-dried collagen;

(c) maturing the freeze-dried collagen by storing the freeze-dried collagen at a temperature of at least 40° C. for a period of at least six weeks to obtain matured collagen;

(d) dispersing the matured collagen in an aqueous dispersion; and

(e) freeze-drying the dispersed matured collagen to obtain the matured collagen composition,

wherein a time required for degradation of 50% of a matured collagen composition sample relative to maximum possible degradation with collagenase is at least 25% shorter than a time required for degradation of 50% of a collagen composition sample comprising non-matured collagen relative to maximum possible degradation with collagenase,

wherein the non-matured collagen is obtainable by a process comprising steps (a), (b),

(d′) dispersing the matured collagen in an aqueous dispersion; and

(e′) freeze-drying the dispersed matured collagen to obtain the matured collagen composition,

but excluding step (c), and

wherein the degrading of a collagen composition sample comprises:

placing the collagen composition sample into a 15 mL solution of 0.2 N phosphate buffer (pH 7.4 with CaCl 2 )) maintained at a temperature of 37° C.;

adding 100 μl of 10 mg/mL Collagenase Type IA-S to the solution and agitating the solution by shaking at 120 rpm; and

measuring UV absorption spectra of the solution between 210 nm and 230 nm after 5, 10, 15, 25, 40, 60, and 90 minutes and calculating a degradation fraction at a corresponding time point relative to a maximum absorption at 90 minutes, wherein higher absorbance correlates with higher degradation.

2. The matured collagen composition according to claim 1 , further comprising bupivacaine or a pharmaceutically acceptable salt thereof.

3. The matured collagen composition according to claim 1 , wherein the storing is at a temperature of at least 40° C. for a period of at least six weeks and at a relative humidity of less than 80%.

4. The matured collagen composition according to claim 1 , wherein the storing is at a temperature of at least 40° C. for a period of at least six weeks and at a relative humidity of 75%.

5. The matured collagen composition according to claim 1 , wherein the storing is at a temperature of 40° C. for a period of six weeks to two months or six weeks to six months.

6. The matured collagen composition according to claim 1 , wherein the isolated collagen comprises a dispersion comprising collagen particles having a concentration of 3-30% (w/w).

7. The matured collagen composition according to claim 1 , wherein step (b) comprises freezing the isolated collagen to a temperature of −33° C. to −42° C.

8. The matured collagen composition according to claim 1 , wherein step (b) comprises removing the aqueous phase by reducing the pressure to 0.05 to 0.5 mbar.

9. The matured collagen composition according to claim 1 , wherein step (b) comprises increasing the temperature of the collagen to +30° C.

10. The matured collagen composition according to claim 1 , wherein step (b) comprises an equilibrating step, wherein the equilibrating step comprises maintaining the temperature constant for at least 10 mins.

11. The matured collagen composition according to claim 7 , wherein step (b) comprises six equilibrating steps, each equilibrating step being conducted when the temperature is increased by 10° C.

12. The matured collagen composition according to claim 1 , the process further comprising milling the freeze-dried collagen prior to maturing.

13. The matured collagen composition according to claim 1 , further comprising bupivacaine HCl.

14. The matured collagen composition according to claim 13 , wherein the concentration of bupivacaine HCl is from 25% w/w to 57% w/w.