Polyanhydrides with therapeutically useful degradation products

A having constitutional repeating unit (I) is a anhydride, wherein Ar is an aromatic ring of the substituted or un-substituted, comprising the anhydride groups and structure thereof is a functional group on each Ar substituted. Further comprises an aromatic dicarboxylic acid anhydride monomer and a ortho-substituted and an aromatic dicarboxylic acid for intermediate claimed is ortho-substituted, and other is anhydride can embedded a medical device, r3 is a completely reconstitution to the frame, drug release system; The oral form a method of treatment used.