Preparation of biogically active substances bearing -nh.sub.2 groups in

Abstract

Polymeric form of a biologically active compound containing at least one -NH.sub.2 group in its molecule, adapted for the protracted release of said biologically active compound by enzymatic cleavage of the polymer in vivo in the organism. The active compound is bonded by its -NH.sub.2 group to the carboxylic group of an L-amino acid as for instance, .beta.-phenylalanine, tyrosine, tryptophane, lysine, arginine, glycine, alanine, leucine, citruline or ornithine, which latter is in twin bonded by its amino group to the terminal carboxylic group of the side chain of a substituted amide or ester of acrylic or methacrylic acid, said side chain constituting a linear moiety containing at least 3 carbon atoms. The latter compound or monomer is copolymerized with a hydrophilic monomer such as, N-alkylmethacrylamide, N-alkylacrylamide, N,N-dialkylacrylamide, wherein alkyl has 1-6 carbon atoms and may contain 1 to 3 OH groups, or glycol acrylate or methacrylate alone or in admixture, and which copolymer may contain further monomeric components, for example, cross-linking agents. It is the copolymer which constitutes the subject matter of the invention, i.e., the biologically active substance bearing -NH.sub.2 groups in a form releasable by enzymatic cleavage. The copolymer can also be prepared using as the monomer a compound containing the bonded L-amino acid and in which the terminal carboxylic group has been converted to the reactive ester. The active compound is then bonded to the thusly prepared reactive polymer. The enzymatic release of the active compound bearing -NH.sub.2 groups can be controlled, i.e., regulated by the size of the side chain carrying the L-amino acid.