The effect of tween excipients on expression and activity of P-glycoprotein in Caco-2 cells

Abstract

Purpose: The present study was designed to investigate the effects of Tween excipients (polysorbates; Tween 20, Tween 40 and Tween 80) on the activity and expression of P-glycoprotein (P-gp). Methods: An MTT (3-[4,5-dimethylthiazol-2- yl]-2,5-diphenyl tetrazolium bromide) assay test was conducted to determine the non-toxic concentration of the excipients. Moreover, the uptake of Rhodamine-123, a P-gp fluorescence substrate, was measured through Caco-2 cell monolayer encountering with excipients overnight to investigate whether sub-toxic concentrations of Tween excipients are able to affect the P-gp activity. Furthermore, Western blotting was performed to investigate the P-gp protein expression. Results: The results showed that Tween 20 and Tween 80 at concentrations below 0.01% (w/v), and Tween 40 at concentrations below 0.05% (w/v) were non-toxic to Caco-2 cells. Results from the Rho-123 uptake test assay and Western blotting showed that Tween 20 at concentration of 0.01% (w/v) and Tween 40 at concentration of 0.05% (w/v) were able to block P-gp significantly. Conclusion: Based on the obtained results it is concluded that Tween excipients at the defined concentrations could be used to inhibit the P-gp efflux transporter resulting in an altered bioavailability of drugs.