Abstract: A microparticle having a particle size ranging from 0.5 to 300 .mu.m, which is prepared by dissolving an antigen or a mixture of antigens in an aqueous solution, adding a water-soluble substance thereto, and removing water to obtain a core particle and coating the core particle with a biodegradable polymer; and a single-shot vaccine formulation prepared by dispersing the microparticles in an injection medium.

Abstract: The invention concerns orthoester and orthocarbonate polymers having a repeating mer comprising a hydrocarbon radical and a symmetrical dioxycarbon unit of the general formula: ##STR1## WHEREIN R.sub.1 is a multivalent hydrocarbon radical, R.sub.2 and R.sub.3 are hydrocarbon radicals with at least one of R.sub.2 or R.sub.3 bonded to the dioxycarbon through an oxygen linkage, and which polymers are synthesized by reacting a polyol with an orthoester or orthocarbonate. The polymers are useful for making articles of manufacture, including devices and coatings for delivering beneficial agents.

Abstract: Poly(orthoester carbonates) and poly(orthocarbonate carbonates) having a repeating linear carbonate unit and a recurring symmetrical dioxycarbon moiety with a plurality of organic groups pendant from the carbon atom thereof are disclosed. The polymers are represented by the structural formula: ##STR1## WHEREIN A IS 0 TO 1, B IS 2 TO 6 WHEN A IS 0, B IS 2 TO 5 WHEN A IS 1, AND N IS GREATER THAN 10.