DRUG-DELIVERY USING BIODEGRADABLE MICROSPHERES

Rational delivery systems for leuprorelin acetate, a potent LHRH agoni st, have been achieved by developing a microsphere system using biodeg radable polymers, poly(lactic/glycolic acid) (PLGA) and polylactic aci d, which sustainedly release the drug depending on the biodegradation of polymer used and persistently suppress steroidogenesis for over one and 3 months, respectively, following a single injection. To produce these systems we established a novel microencapsulation technique, the in-water drying method, and microspheres with a high trap ratio and s mall initial burst were obtained. A microsphere: system of TRH prepare d using PLGA could also continuously release the drug for 2 or 4 weeks . Using these systems effectively reduced the required dose compared w ith that needed with daily injection due to more continuous receptor h its on the target organs and could improve patient compliance. Chemoem bolization using PLGA microspheres containing an angiogenesis inhibito r, TNP-470, resulted in dramatic regression of VX-2 carcinoma in rabbi ts. The microsphere system using biodegradable polymers is very useful in designing controlled release delivery and targeted delivery to att ain potent and rational therapy.