Hoechst Aktiengesellschaft

Diether Ruppel

Axel Walch

Hubert Bader

Merten Schlingmann

Karl-Heinz Keil

Michael Magerstadt

Hebert Bader

Polyelectrolyte membrane capsules are composed of a semi-permeable membrane and an active material enclosed by it, the membrane being formed of a biocompatible, non-toxic polyacid and a polybase; the polybase is composed of repeating monomer units of the formula (I) ##STR1## in which R.sup.1 and R.sup.2 have the indicated meanings.

Microencapsulation of biologically active material

The invention relates to biodegradable poly((hydroxyalkyl)amino dicarboxylic acid) derivatives of the formula I ##STR1## in which n, m, x, y, z, R and R' have the indicated meanings, and to a process for their preparation and to the use thereof for depot formulations with controlled delivery of active ingredient.

Biodegradable poly(hydroxyalkyl)amino dicarboxylic acid) derivatives, a

Polyamides in which amino acids are incorporated in the polymer backbone via two amino or carboxyl groups and which carry in the .alpha.-position to the amide structure a functional group which is responsible for degradation and active compound release are highly suitable for the preparation of biologically degradable active compound depot preparations having controlled release of the active compound.

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Frankfurt am Main, Germany

Diether Ruppel