Process for purifying guar

Abstract

The present invention relates to processes for purifying guar comprising combining borate and guar in an aqueous solution and treating the aqueous solution with an organic solvent to induce precipitation of purified guar. Another embodiment of the present invention is directed to ophthalmic formulations comprising purified guar produced by the processes described.

1 . A process for manufacturing guar comprising:
 combining borate and guar in an aqueous solution; and   precipitating guar by adding an organic solvent to said aqueous solution.   
   
   
       2 . A process according to  claim 1  wherein said organic solvent is acetone. 
   
   
       3 . A process according to  claim 1  further comprising:
 filtering precipitated guar.   
   
   
       4 . A process according to  claim 3 , wherein said filtering comprises filtering precipitated guar using one or more filters having a pore size of 40 μm or less. 
   
   
       5 . A process according to  claim 4 , wherein said filters have a pore size selected from the group consisting of:
 40 μm, 20 μm, and 10 μm.   
   
   
       6 . A process according to  claim 1  wherein said combining comprises adding borate to an aqueous guar solution. 
   
   
       7 . A process according to  claim 6  wherein said aqueous guar solution is filtered before said adding of borate. 
   
   
       8 . A process according to  claim 1  wherein said borate is selected from the group consisting of:
 sodium borate, potassium borate, boric acid, alkyl borates, trimethyl borate, phenyl borates, and combinations thereof.   
   
   
       9 . A process according to  claim 1  wherein said borate is added during said combining to form a concentration of 0.05% to 0.05% w/v in said aqueous solution. 
   
   
       10 . A process according to  claim 1  wherein said guar is at a concentration of less than 1.0% w/v in said aqueous solution. 
   
   
       11 . Guar produced by a process of  claim 1 . 
   
   
       12 . The guar of  claim 11 , wherein said guar is hydroxyethyl guar, hydroxypropyl guar galactomannan, or carboxymethylhydroxypropyl guar. 
   
   
       13 . An ophthalmic formulation comprising:
 guar produced by a process of  claim 1  and one or more excipients.   
   
   
       14 . An ophthalmic formulation of  claim 13  wherein said guar is selected from the group consisting of:
 hydroxyethyl guar, hydroxypropyl guar galactomannan, carboxymethylhydroxypropyl guar, and combinations thereof.   
   
   
       15 . An ophthalmic formulation of  claim 13  wherein said guar is hydroxypropyl guar galactomannan. 
   
   
       16 . An ophthalmic formulation of  claim 13  wherein said guar is present at a concentration of 0.1% to 0.25% w/v.