%0 Journal Article %T Inhibitory effect of clemastine on P-glycoprotein expression and function: an in vitro and in situ study %J Iranian Journal of Basic Medical Sciences %I Mashhad University of Medical Sciences %Z 2008-3866 %A Mesgari Abbasi, Mehran %A Valizadeh, Hadi %A Hamishekar, Hamed %A Mohammadnejad, Leila %A Zakeri-Milani, Parvin %D 2016 %\ 04/01/2016 %V 19 %N 4 %P 423-429 %! Inhibitory effect of clemastine on P-glycoprotein expression and function: an in vitro and in situ study %K Clemastine %K Digoxin %K Intestinal Absorption %K P-glycoprotein %R 10.22038/ijbms.2016.6815 %X Objective(s):Transporters have an important role in pharmacokinetics of drugs. Inhibition or induction of drug transporters activity can affect drug absorption, safety, and efficacy. P-glycoprotein (P-gp) is the most important membrane transporter that is responsible for active efflux of drugs. It is important to understand which drugs are substrates, inhibitors, or inducers of P-gp to minimize or avoid unwanted interactions. The aim of this study was to investigate the effects of clemastine on the expression and function of P-gp. Materials and Methods: The effect of clemastine on P-gp function and expression was evaluated in vitro byrhodamine-123 (Rho123) efflux assay in Caco-2 cells and Western blot analysis. Rat in situ single pass intestinal permeability model was used to investigate the clemastine effect on digoxin Peff, as a known P-gp substrate. Digoxin levels in intestinal perfusates were assayed by high performance liquid chromatography (HPLC) method. Results:The Caco-2 intracellular accumulation of Rho123 in clemastine and verapamil treated cells was 90.8 ± 9.8 and 420.6±25.4 pg/mg protein, respectively which was significantly higher than that in control cells (50.2±6.0; P<0.05). Immunoblotting results indicated that clemastine decreased expression of P-gp in Caco-2 cells in vitro. More over effective intestinal permeability (Peff) of digoxin in the presence of clemastine, was significantly increased compare to control group. Conclusion: Findings of our study suggested dose dependent P-gp inhibition activity for clemastine               in vitro and in situ. Therefore co-administration of clemastine with P-gp substrates may result in unwanted interactions and side effects. %U https://ijbms.mums.ac.ir/article_6815_563c9975ba66430234720970c3946166.pdf