In vitro drug release kinetics of the conjugate PEG-GFL-pNA. (a)
Release kinetics of pNA from PEG-GFL-pNA and Leu-pNA in the homogenates
of rat intestinal brush border in isotonic phosphate buffer at pH
6.8 assayed by HPLC; (b) representative HPLC spectra of the released
products: (1) pNA and Leu-pNA standard, (2) PEG-GFL-pNA in vitro release at 1 h, (3) Leu-pNA in
vitro release at 1 h. HPLC conditions: analytical C18 reverse column
(250 mm × 4.6 mm, i.d., 5 μm particle size) with a mobile
phase of H2O/actonitrile (40:60, v/v) with 0.05% trifluoroacetic acid, flow rate of 1.0 mL/min
and UV detector set at 375 nm.