To prepare a microcapsule, comprising an amorphous and water-soluble type 2-piperazinone-1-acetic acid derivative and a high-molecular polymer, having a high uptake ratio of the compound useful as a therapeutic agent, etc., for circulatory diseases and hardly causing the initial release and adverse effects.
This microcapsule comprises an amorphous and water-soluble type compound of the formula [A1 and A2 are each a proton accepting group or a group convertible into the proton accepting group; D is a hetero-atom and/or a spacer of a 2 to 6 atomic chain; R1 is H or a hydrocarbon; R2 is H or a residue after removing CH(NH2)COOH from an α-amino acid; P is a hetero- atom and/or a spacer of a 1 to 10 atomic chain; Y is carboxyl; (n) is 0-8] or its salt and a high-molecular polymer (preferably a polymer of lactic acid- glycolic acid, etc.). (S)-4-(4-guanidinobenzoylamino)acetyl-3-[3-4- guanidinobenzoylamino)] propyl-2-oxopiperazine-1-acetic acid hydrochloride, etc., are preferred as the compound of the formula or its salt.
KUROKAWA TOMOFUMI
IWASA SUSUMU
