In vitro evaluation of the effects of Polymers and preservatives on intestinal efflux pump

Abstract

Background: P-glycoprotein (P-gp; ABCB1), an integral membrane protein in the apical surface of human intestinal epithelial cells, plays a crucial role in the intestinal transport and efflux leading to changes in the bioavailability of oral pharmaceutical compounds. Aim: This study was set to examine the potential effects of various excipients and preservatives on the expression and the activity of P-gp efflux pump in human colon cancer cell line (Caco-2) grown in transwells. Methods: The least non-cytotoxic concentrations of the excipients and preservatives were assessed in Caco-2 cells by the MTT assay. Then the uptake of Rho-123 into Caco-2 monolayers was determined using a fluorescence spectrophotometer. Besides, the changes in the expression of the P-gp in cells exposed to the tested compounds were investigated using Western-blotting analysis. Results: Nontoxic concentrations of the excipients which were retrieved from MTT assay were used in the Rho-123 uptake assay and Western-blotting. The results showed that most of the excipients which was used did not demonstrate a significant variation in P-gp expression where Eudragit S100, Carbopol 934, Vitamin E and Methylcellulose showed 61%, 43%, 27.2% and 50.9% rise in Rhodamine accumulation and P-gp expression in comparison to the control group, respectively (P<0.001). Conclusion: This study suggests that using proper concentrations of the Eudragit S100, Carbopol 934, Vitamin E and Methylcellulose may improve the bioavailability and help drug intestinal permeability and absorption. Although further tests like gut perfusion or pharmacokinetic studies in animals or more specific assays which target specific binding sites on P-glycoprotein should be carried out, later.