No abstract

Poly(D,L-Lactic-Co-Glycolic Acid) (PLGA) copolymers have been extensively used as controlled-release carriers for many hydrophilic drugs because they are non-toxic, biodegradable, bioavailable, and biocompatible. In general, PLGA particles have been produced by a solvent evaporation technique utilizing water-in-oil-in-water (W/O/W) emulsions. However, W/O/W emulsions are unstable, causing the outer and inner aqueous phases to easily fuse during particle preparation. Consequently, a sufficient amount of drug was not encapsulated inside the particles. In this study, we examined a new particle preparation method utilizing a solid-in-oil-in-water (S/O/W) emulsion technique. The advantages of S/O/W emulsions, wherein a surfactant-drug complex disperses into the oil phase, were as follows: 1) leakage of hydrophilic drugs from the emulsions was inhibited, and 2) facile control over the emulsion particle size. Thus, the PLGA particles prepared by this method showed high encapsulation efficiency of drugs and formation of fine particles of submicron size by membrane emulsification were achieved.