CASEIN MICROSPHERES - PREPARATION AND EVALUATION AS A CARRIER FOR CONTROLLED DRUG-DELIVERY

A method for the preparation of smooth, spherical, glutaraldehyde-cros slinked microspheres of the amphiphilic protein, casein, is reported. Casein microspheres (CAS/MS) were found to be even more hydrophilic th an comparable microspheres made from bovine serum albumin by the metho d developed in this laboratory several years ago and were readily disp ersed in water without aggregation. Enzymatic degradation studies with the enzyme protease suggested that the CAS/MS with lower crosslink de nsity degraded faster than those with higher crosslink density. Methot rexate (MTX) was incorporated into the CAS/MS during microsphere synth esis to the extent of 15 wt% loading, and in vitro release was examine d in phosphate buffer at 37 degrees C. Drug release of 35% was observe d in 24 h, suggesting that most of the incorporated drug was strongly associated with the CAS/MS. Similar release was observed for MTX loade d albumin spheres prepared in the same manner. Based on these studies, casein appears to be a highly promising, low-cost, bioacceptable prot ein for the synthesis of drug conjugates and microsphere carrier syste ms for targeted drug delivery.