The present invention provides a method for forming compounds of Formula HO--C(.dbd.O)R.sup.1--X--R.sup.2--X--R.sup.1--C(.dbd.O)--O--H wherein compound (I) can be polymerized to provide a polymer that contains therapeutically active compounds. In the compounds of the invention, each R.sup.1 is group that will provide the therapeutically active compound upon hydrolysis of the polymer; each X is independently an ester linkage or an amide linkage; and R.sup.2 is a linking group.