CLONAZEPAM RELEASE FROM CORE-SHELL TYPE NANOPARTICLES IN-VITRO

Block copolymers consisting of poly(gamma-benzyl L-glutamate) (PBLG) a s the hydrophobic block and poly(ethylene oxide) (PEG) as the hydrophi lic block were synthesized and characterized. Core-shell type nanopart icles of the block copolymers (abbreviated as GE) were prepared by the diafiltration method. The particle size diameter obtained by dynamic light scattering of GE-1 (PBLG content: 60.5 mol %), GE-2 (PBLG conten t: 40.0 mol %), GE-3 (PBLG content: 12.4 mol %) copolymer was 309.9+/- 160.9, 251.9+/-220.6 and 200.5+/-177.1 nm, respectively. The shape of the nanoparticles by SEM or TEM was almost spherical. The critical mic elle concentration of the block copolymers obtained by fluorescence sp ectroscopy was dependent on the chain length of hydrophobic PBLG. The micelle structure of the copolymer nanoparticle was very stable agains t sodium dodecyl sulfate. Clonazepam (CZ) was loaded onto the core par t of the nanoparticle as the crystalline state. Release of CZ from the nanoparticles in vitro was dependent on the drug loading contents and PBLG chain length. (C) 1998 Elsevier Science B.V.