CONTROLLED RELEASE OF LHRH-DT FROM BIOERODIBLE HYDROGEL MICROSPHERES

Bioerodible hydrogels prepared from water-soluble unsaturated polyesters, crosslinked through the double bonds, can immobilise a vaccine preparation such as LHRH-DT. The release of the entrapped macromolecule takes place by hydrolytic cleavage of the ester linkage in the polymer backbone. The in vitro rate of hydrolysis and vaccine release can be controlled by synthesising polyesters with varying proportions of esters activated by electron-withdrawing substituents placed vicinally to the ester group and by varying the crosslink density of the hydrogel. The in vitro release of the vaccine from three different crosslinking densities and two different pendant unsaturated polymers is studied.