BLOCK-COPOLYMER MICELLES FOR DRUG-DELIVERY - LOADING AND RELEASE OF DOXORUBICIN

Micelles of poly(ethylene oxide)-block-poly(beta-benzyl-L-aspartate) ( PEO-PBLA) were loaded with doxorubicin (DOX) and were characterized in relation to their use as drug vehicles. First, an oil-in-water emulsi on method was developed to load DOX in PEO-PBLA micelles. The level of DOX in PEO-PBLA micelles was 5-12% w/w. Whereas the mean diameter of unloaded, PEO-PBLA micelles was ca., 19 nm, the mean diameter of PEO-P BLA micelles loaded with DOX was approximate to 37 nm. Minimal chemica l degradation of DOX occurred as a result of loading in PEO-PBLA micel les. In addition, DOX in PEO-PBLA micelles was less susceptible to che mical degradation than free DOX in aqueous solution. There was evidenc e for retention of DOX in PEO-PBLA micelles even after freeze-drying a nd reconstitution in water. Lastly, PEO-PBLA micelles served as drug d epots, slowly releasing DOX (days), even in the presence of 10% w/v se rum albumin. The results suggest a number of pharmaceutical advantages of PEO-PBLA micelles for the delivery of DOX. (C) 1997 Elsevier Scien ce B.V.