[Biodegradable polymer microparticles with entraped herbal extracts: preparation with supercritical carbon dioxide and use for tissue repair].

Biodegradable microparticles based on poly-D,L-lactide with entrapped mixture of herbal water-soluble extracts of Plantago major and Calendula officinalis were prepared. For preparation of these microparticles the previously developed method based on the usage of supercritical carbon dioxide (SC-CO2) was proposed. Microparticles were obtained by two techniques: 1) by preparing porous polymer monolith containing entrapped mixture of herbal extracts, which was then reduced to fine microparticles (ca. 0.1 mm) by dry ice grinding (called here as "monolithisation technique") and 2) by spraying of this polymer/extracts mixture through a jet (spray technique). In vitro release kinetic profile of herbal extract mixture was found to depend on the microparticle preparation technique, on the microparticle structure as well as on the initial ratio polymer/extracts (w/w). The microparticles were used for gastric ulcer treatment in a rat model. The extracts released from microparticles were found to accelerate tissue repair.