Targeted drug delivery systems 6. Intracellular bioreductive activation, uptake and transport of an anticancer drug delivery system across intestinalCaco-2 cell monolayers
L. Gharat et al., Targeted drug delivery systems 6. Intracellular bioreductive activation, uptake and transport of an anticancer drug delivery system across intestinalCaco-2 cell monolayers, INT J PHARM, 219(1-2), 2001, pp. 1-10
We demonstrate transport across, intracellular accumulation and bioreductiv
e activation of a conformationally constrained, anticancer drug delivery sy
stem (the CH3-TDDS) using Caco-2 cell monolayers (CCMs) as an in vitro mode
l of the human intestinal mucosa. Reverse-phase High Performance Liquid Chr
omatography (HPLC) coupled with UV detection was used to detect CH3-TDDS, t
he bioreduction product (lactone) and the released drug (melphalan methyl e
ster; MME). Upon incubation of the CH3-TDDS with the apical (AP) surface of
21-day-old CCM, we observed rapid decrease in the AP concentration of the
CH3-TDDS (60%/hr) as a result of cellular uptake. Rapid intracellular accum
ulation of the CH3-TDDS was followed by bioreductive activation to deplete
the cellular levels of CH3-TDDS. The drug part (MME) and lactone, as well a
s CH3-TDDS, were detected in the basolateral (BL) chamber. Intracellular Ca
co-2 levels of TDDS and lactone were also detectable. Bioreductive activati
on of the CH3-TDDS was additionally confirmed by formation of lactone after
incubation of the CH3-TDDS in the presence of freshly prepared Caco-2 cell
homogenates. During transport studies of melphalan or MME alone (as contro
l), the intact drug was not detected in the intracellular compartment or in
the BL chamber. These observations demonstrate that CH3-TDDS has potential
for improving intestinal delivery of MME. TDDS could be useful in facilita
ting oral absorption of MME as well as the oral delivery of other agents. (
C) 2001 Elsevier Science B.V. All rights reserved.