Process for the recovery of lipophilic proteins

A pharmaceutical composition comprising a therapeutically effective amount of unglycosylated recombinant human interferon-.beta. (IFN-.beta.) dissolved in a non-toxic, therapeutically compatible aqueous-based carrier medium comprising as a stabilizer at pH of 6.8 to 7.8 wherein said stabilizer comprises human serum albumin wherein the composition is produced by a process comprising:

• 1) recovering the recombinant human IFN-.beta. from a bacterial host transformed to produce it;
• 2) isolating and purifying the recombinant human IFN-.beta. in a solution containing a solubilizer;
• 3) adjusting the pH of the solution to about 10.5 to 12.5;
• 4) diafiltering the solution at a pH of about 10.5 to 12.5 against pure water or water/aliphatic alcohol mixtures adjusted to a pH of about 11 to remove free or IFN-.beta.-bound solubilizer.
• 5) adding an aqueous-based carrier medium of a pH of about 10.5 to 12.5 to the diafiltered solution containing the recombinant human IFN-.beta.;
• 6) maintaining the resulting solution at a pH of about 10.5 to 12.5 for 1 to 15 minutes;
• 7) lowering the pH of the resulting solution to between about 6.8 and 7.8;
• wherein the pharmaceutical composition contains less than 10 ppm of solubilizer when the solubilizer is sodium dodecyl sulfate, and wherein the stabilizer in the aqueous-based carrier medium is effective to stabilize the recombinant human IFN-.beta. against denaturation and loss of biological activity and to prevent precipitation of the recombinant human IFN-.beta. from aqueous-based carrier medium.