Biodegradable poly(hydroxyalkyl)amino dicarboxylic acid) derivatives, a process for their preparation, and the use thereof for depot formulations with controlled deivery of active ingredient

A method of preparing a biodegradable active ingredient depot formulation with controlled delivery of a biologically active ingredient which comprises incorporating a biologically active ingredient into a controlled release agent which contains a poly (hydroxyalkyl) amino dicarboxylic acid derivative of the formula I ##STR6## in which n is 1 or 2, m is 2 to 6, x and y are 1 to 400, and z is 0 to 40, and in which the radicals R and R' are identical or, independently of one another, different and denote branched or unbranched, saturated or unsaturated alkyl, cycloalkyl, alkoxy or cycloalkyloxy groups having a total of 1-22 carbon atoms in the alkyl moiety, the alkyl moiety is not interrupted or is interrupted by a carbonyloxy group, or biologically inactive steroid alcohols bonded via their hydroxyl groups, there being random distribution in the polymer of the monomer units placed in square brackets.