Oral Hypoglycemic Agents Absorption Mechanism In Caco-2 Cells, And Gliclazide Mr Bioavailability Study

The Caco-2 model, an in vitro model for drug absorption, has been widely used to study various intestinal transport processes. Caco-2 cell line originates from human colon adenocarcinnoma, and it is easy to be cultured and kept stable in vitro. The cultivated Caco-2 cells develop enterocytic differentiation spontaneously and form tight cell monolayer organisms and junctions. They show similarity to intestinal epithelial cells in the aspects of morphology, expression of marker enzymes and permeable property. Therefore, the Caco-2 cell model has been proved to be available to predict the absorptive mechanisms of drug, such as uptake, excretion and transcellular transport.In this paper, the Caco-2 cell model was established and validated to study the absorption properties and mechanism of 8 oral anti-diabetics including gliclazide, glipizide, gliquidone, metformin, glibenclamide, rosiglitazone, tolbutamide and nateglinide. The apparent permeability (P_app) was firstly determined for the 8 anti-diabetics, then the relation of P_app and physicochemical properties was investigated by the means of multiple regression using SAS software to determine the key influencing factor on absorption. The selected physicochemical parameters include pK_a, clogP, Mw, PSA% and so on. The determined P_app of each anti-diabetic is more than 1×10^-6 which indicates good absorption property. A regression equation with correlation coefficient of 0.9282 was obtained for the 8 drugs, which revealed the PSA% and Mw influence the absorption most significantly. The transport of glibenclamide was found to be inhibited by P-gp inhibitor, which indicated that the glibenclamide might be the substrate ofP-gP. Gliclazide is a new generation sulfonylurea oral hypoglycemic agent. In this paper, thedetailed absorptive mechanism of glicalzide was studied in Caco-2 cell model. The determined P_{app(AP→BL)}(2.79×10^-5) was 3.04 times as the P_{app(BL→AP)}(9.17×10^-6), which showed the transport of gliclazide had strong directionality. The P_app of glicalzide diminished with the increase of concentration (25, 50, and 100 μM). The transport of gliclazide was not influenced by the P-gp inhibitor. Therefore, it is presumed that transport of gliclazide may be partly mediated by some transport protein besides passive diffusion.The bioavailability of gliclazide modified release tablet was determined by LC-MS in healthy Chinese subjects and the bioequivalence of two formulations was also evaluated. The obtained...