Dilute Filtration Sterilization Process for Viscoelastic Biopolymers

Abstract

Manufactured hyaluronic acid products are used in numerous surgical applications including viscoelastic supplementation for the treatment of osteoarthritis; however, traditional sterilization techniques result in the breakdown of such high molecular o weight viscoelastic biopolymers and are thus unsuitable. Disclosed are processes for obtaining concentrated sterile solutions of high molecular weight biopolymers such as hyaluronic acid. The processes include filter sterilization with a dilute preparation of the biopolymer, and concentration of the dilute filter sterilized biopolymer by ultrafiltration to a desired concentration.

What is claimed is: 
     
         1 . A process for formulating hyaluronic acid, the process comprising:
 (i) dissolving bulk-manufactured hyaluronic acid having a high molecular weight of 3.0±0.6 megadaltons in an aqueous medium to form a hyaluronic acid solution having a concentration of less than 0.2%;   (ii) sterile-filtering the hyaluronic acid solution having a concentration of less than 0.2% by passage through a membrane suitable for sterile filtration at a pressure that does not adversely affect the high molecular weight of the hyaluronic acid, whereby the sterile-filtering retains the high molecular weight structure of the hyaluronic acid in the hyaluronic acid solution; and   (iii) subsequently concentrating the sterile-filtered hyaluronic acid by ultrafiltration with a membrane having a pore size of 0.002 to 0.1 microns under aseptic conditions to form a sterile solution formulation of a desired final concentration;   wherein the formulation is suitable for medicinal use by injection into a human without further purification following step (iii); and   wherein the concentrated hyaluronic acid in the sterile solution formulation has a high molecular weight of 3.0±0.6 megadaltons.   
     
     
         2 . The process according to  claim 1 , wherein the hyaluronic acid has an average molecular weight in the range from 2.8×10 6  to 3.2×10 6  daltons. 
     
     
         3 . The process according to  claim 1 , further comprising obtaining the bulk manufactured hyaluronic acid for step (i) by isolation of the hyaluronic acid from a culture broth of a fermented  Streptococcus  strain. 
     
     
         4 . The process according to  claim 3 , wherein the  Streptococcus  is a  Streptococcus  species selected from the group consisting of  Streptococcus equi, Streptococcus pyogenes, Streptococcus equisimilis, Streptococcus dysgalactiae  and  Streptococcus zooepidemicus  or another  Streptococcus  strain that is non-hemolytic and non-pathogenic. 
     
     
         5 . The process according to  claim 1 , wherein the bulk manufactured hyaluronic acid is substantially free of impurities. 
     
     
         6 . The process according to  claim 1 , wherein the concentration of the hyaluronic acid in step (i) is 0.10-0.13% w/v. 
     
     
         7 . The process according to  claim 1 , wherein the membrane suitable for sterile filtration has a pore size of 0.05 to 0.2 microns. 
     
     
         8 . The process according to  claim 1 , wherein the concentrating is carried out by ultrafiltration using a ceramic membrane. 
     
     
         9 . The process according to  claim 8 , wherein the ultrafiltration is carried out with a membrane having a pore size of about 50 nm. 
     
     
         10 . The process according to  claim 1 , wherein the desired final concentration in step (iii) is in the range from 0.8 to 3.0% w/v. 
     
     
         11 . The process according to  claim 9 , wherein the desired final concentration in step (iii) is about 1.0% w/v to about 2.0% w/v. 
     
     
         12 . The process according to  claim 9 , wherein the desired final concentration in step (iii) is in the range from 0.9 to 1.3% w/v. 
     
     
         13 . The process according to  claim 1 , further comprising aseptically filling a suitable packaging device with the hyaluronic acid solution obtained in step (iii). 
     
     
         14 . The process according to  claim 13 , wherein the packaging device is selected from the group consisting of a syringe, a vial, a catheter, and a nebulizer. 
     
     
         15 . The process according to  claim 1 , wherein the formulated hyaluronic acid has a pseudoplasticity index in the range from 500 to 4000. 
     
     
         16 . The process according to  claim 1 , further comprising including a microalgal polysaccharide in the formulation. 
     
     
         17 . The process according to  claim 16 , wherein the microalgal polysaccharide is a polysaccharide isolated from a  Porphyridium  microalga. 
     
     
         18 . The process according to  claim 1 , wherein all steps are performed under clean room conditions. 
     
     
         19 . The process according to  claim 1 , wherein the hyaluronic acid is not subjected to freeze drying at any stage of bulk manufacturing or formulation.