Biodegradable targetable microparticle delivery system

A process for making a particulate carrier for the delivery of at least one biologically active material to a host, comprising the steps of:

• (a) mixing an organic solvent phase comprising an α-hydroxy acid polymer with an aqueous composition comprising dispersed or dissolved biologically active material to form a first water-in-oil emulsion, said α-hydroxy acid polymer having a molecular weight of about 5,000 to about 40,000 daltons and having the general formula:
• wherein:
• R1, R2 and R5 are selected independently and are selected from the group consisting of H, linear or branched alkyl groups;
• R3 and R4 are H;
• R6 is H;
• X is selected from the group consisting of an O or S group;
• and
• x and y are integers such that at least 95% of the polymer is comprised of α-hydroxy acid residues;
• (b) dispersing the first water-in-oil emulsion into an aqueous detergent phase to form a second water-in-oil-in-water double emulsion;
• (c) removing water from the second double emulsion to form microspheres;
• and
• (d) collecting the microspheres and having said biological material entrapped therein.