Abstract: Described are polyphosphazenes which may be represented by the general formula ##STR1## in which R is a hydroxy-substituted or protected hydroxy-substituted saturated aliphatic group, R' is a hydrocarbyl group, R" is a residue of an alpha amino acid, n is from about 50 to about 25,000, and x is a number averaging from 0.05 to 1.00 per repeating unit and y is a number averaging from 0.95 to 0.00 per repeating unit so that per repeating unit the sum of x and y is 1. Removal of the protecting group in the R moiety renders the polymers water soluble. The polymers have a controllable set of properties including degree of hydrolytic stability, permeability, hydrophilicity, and bioacceptability. They may be used in the production of hydrogels for drug release systems, plasma extenders, and biomedical implants.

Abstract: A device for controlled release of one or more pharmacologically active substances within an animal which comprises (i) a body of a bioerodable solid state poly(amino acid ester) phosphazene polymer, and (ii) at least one pharmacologically active substance physically incorporated within said body. The device may comprise an implantable body in which the poly(amino acid ester)phosphazene polymer is a matrix within which such pharmacologically active substance is dispersed. Alternatively, the polymer may constitute a coating or container within which such pharmacologically active substance is physically encased--i.e., the polymer surrounds the active agent as in a capsule or in a microencapsulated form. Results of in vivo experiments using implants of poly[bis((ethyl glycino)phosphazene] containing 25% ethidium are described.

Abstract: The protecting group, Z, of protected alpha-amino acid esters of the formulaZ--NH--CH(R.sub.2)COOCH(R)COOR.sub.1is removed in the presence of a dibasic acid such as oxalic acid. This results in the formation of a new type of salt of an amino acid ester which may be represented by the formula ##STR1## In the above Q is a divalent hydrocarbyl residue of a dibasic acid, R is a hydrogen atom or hydrocarbyl group, R.sub.1 is a hydrocarbyl group, R.sub.2 is a hydrogen atom or hydrocarbyl group, and p is zero or one, preferably zero. When p is zero, the salts are oxalate salts. When p is one, the salts are salts of other dibasic acids. The salts (II) are useful as reactants in the synthesis of amino-acid substituted phosphazene polymers.