Dry powder fibrin sealant

Abstract

The invention provides a composition comprising a mixture of first microparticles that comprise fibrinogen and trehalose, and second microparticles that comprise thrombin and trehalose. The invention further provides methods for treating wounds by administering the novel microparticle composition.

What is claimed is: 
     
         1 . A dry powder fibrin sealant composition, comprising:
 a mixture of first microparticles that comprise 0.5 to 20% w/w fibrinogen and trehalose, and second microparticles that comprise 10 to 20,000 IU/g thrombin and trehalose,   wherein trehalose is the only stabilizing sugar in the first microparticles and second microparticles.   
     
     
         2 . The composition of  claim 1 , wherein the composition is sterilizable by gamma irradiation. 
     
     
         3 . The composition of  claim 2 , wherein the concentration of trehalose in the first microparticles is sufficient to preserve at least 70% of fibrinogen activity after exposure of the first microparticles to a 25 kGy dose of gamma irradiation delivered at a rate of 8 kGy/hour. 
     
     
         4 . The composition of  claim 3 , wherein fibrinogen activity is measured by ELISA. 
     
     
         5 . The composition of  claim 2 , wherein the first microparticles have a bioactivity of at least 10 mg fibrinogen per 100 mg microparticles after exposure to gamma irradiation. 
     
     
         6 . The composition of  claim 2 , wherein the second microparticles have a bioactivity of at least 70 units thrombin per 100 mg microparticles after exposure to gamma irradiation. 
     
     
         7 . The composition of  claim 5 , wherein the bioactivity is measured by ELISA. 
     
     
         8 . The composition of  claim 6 , wherein the bioactivity is measured by chromogenic assays. 
     
     
         9 . The composition of  claim 1 , wherein the mixture of first microparticles and second microparticles has a clot strength of at least 50 g after exposure to gamma irradiation. 
     
     
         10 . The composition of  claim 1 , wherein the concentration of trehalose in the first microparticles and second microparticles is sufficient to preserve at least 70% of expected clot strength after exposure of the mixture of microparticles to a 25 kGy dose of gamma irradiation delivered at a rate of 8 kGy/hour. 
     
     
         11 . The composition of  claim 1 , wherein the microparticles are spray-dried microparticles. 
     
     
         12 . The composition of  claim 11 , wherein the composition has a residual moisture content no greater than 5% (w/w). 
     
     
         13 . The composition of  claim 12 , wherein the residual content is no great than 3% (w/w). 
     
     
         14 . The composition of  claim 1 , wherein said first and second microparticles are mixed in a weight ratio of 1:1. 
     
     
         15 . A method for preparing a dry powder fibrin sealant composition comprising a mixture of first microparticles that comprise 0.5 to 20% w/w fibrinogen and trehalose and second microparticles that comprise 10 to 20,000 IU/g thrombin and trehalose, wherein trehalose is the only stabilizing sugar in the first microparticles and second microparticles, the method comprising:
 (i) spray-drying a first aqueous solution comprising fibrinogen and trehalose to produce said first microparticles, wherein said first aqueous solution does not include a second stabilizing sugar;   (ii) spray-drying a second aqueous solution comprising thrombin and trehalose to produce said second microparticles, wherein said second aqueous solution does not include a second stabilizing sugar; and   (iii) mixing the first and second microparticles.   
     
     
         16 . The method of  claim 15 , wherein the first microparticles have at least 70% of fibrinogen activity after exposure of the first microparticles to a 25 kGy dose of gamma irradiation delivered at a rate of 8 kGy/hour. 
     
     
         17 . The method of  claim 15 , wherein the mixture of the first and second microparticles preserves at least 70% of expected clot strength after exposure of the mixture of microparticles to a 25 kGy dose of gamma irradiation delivered at a rate of 8 kGy/hour. 
     
     
         18 . The method of  claim 15 , wherein each of the first and second aqueous solutions is spray-dried with an outlet temperature of at least about 80° C. 
     
     
         19 . The method of  claim 15 , wherein the dry powder fibrin sealant composition has a residual moisture content no greater than 5% (w/w). 
     
     
         20 . The method of  claim 15 , wherein step (iii) comprises mixing the first and second microparticles in a weight ratio of 1:1.