All other reagents were used as supplied

All other reagents were used as supplied. four-fold, while CYP3A4 levels remained unchanged. Dental co-administration of rifampicin with the phytochemical sulforaphane for three days improved the permeability for darunavir by 50 % compared to rifampicin treatment only. These data display that PXR/CYP3A4-humanized mice can be used to study the inducing effects of xenobiotics on intestinal P-gp. experiments. Drug transport across Caco-2 Itga7 cells (only for passively transported medicines)1 and rodent intestinal cells2,3 provides a reliable indication of the portion absorbed in humans. Unfortunately, Sinomenine hydrochloride these models are less suitable for predicting drug-drug relationships at the Sinomenine hydrochloride level of the human being intestinal mucosa, especially when nuclear receptors are involved. For example, the pregnane X receptor (PXR), a xenobiotic receptor, is not indicated in Caco-2 cells4. PXR activation results in upregulation of many P450s, including CYP3A4, CYP3A5, CYP3A7, and the drug transporter P-glycoprotein (P-gp). Human being and mouse PXR show different activation profiles in response to xenobiotics5, thus explaining why rodents have limited predictive value with respect to nuclear receptor-mediated drug-drug relationships in humans. For example, rifampicin is a strong activator of human being PXR, but is only a poor activator of rodent PXR. Conversely, rat and mouse PXR are triggered by pregnenolone 16-carbonitrile, which does not activate human being PXR. Due to the limitations of both Caco-2 cells and rodent intestinal cells, a better model is required for predicting intestinal drug-drug relationships in humans. Rifampicin is currently being used like a first-line drug in the treatment of active tuberculosis. Regrettably, it is often the cause of drug-drug relationships as it induces many P450s and drug transporters6, therefore potentially limiting drug bioavailability. For example, the oral bioavailability of the P-gp substrate digoxin was shown to be significantly lower when co-administered with rifampicin, which can be explained by P-gp induction at the level of the intestine7. Furthermore, HIV/TB individuals receiving rifampicin should avoid HIV protease inhibitor (PI)-centered regimens because rifampicin affects the oral bioavailability of PIs, which are substrates of CYP3A4 and P-gp, resulting in sub-therapeutic plasma concentrations. Darunavir is definitely a second generation PI with antiviral effectiveness against HIV-1 with multiple resistance mutations to PIs8. Using the intestinal perfusion technique with mesenteric blood sampling9 in P-gp knockout and NMRI mice, P-gp was found to significantly Sinomenine hydrochloride limit the intestinal permeability for darunavir10,11. In these mice, P-gp mediated darunavir transport was inhibited by co-perfusion with the pharmacokinetic booster ritonavir, which is generally co-administered with PIs in order to increase their plasma levels. A transgenic mouse model, expressing both human being PXR and CYP3A4, was developed that can serve as a useful tool to study the effect of xenobiotics within the manifestation of CYP3A4 in humans12. We tested the hypothesis that this mouse model can also be used for predicting the induction of intestinal P-gp by xenobiotics in humans. By carrying out the intestinal perfusion technique in these PXR/CYP3A4-humanized mice, the effect of oral rifampicin treatment within the intestinal absorption of the PI darunavir was identified, thereby determining the relative contributions of both CYP3A4 and mouse P-gp (mdr1a/1b). The effect of rifampicin treatment within the intestinal CYP3A4 and P-gp protein levels was determined by Western blot analysis. The phytochemical sulforaphane is definitely created after hydrolysis of glucoraphanin in many cruciferous vegetables (including broccoli and cabbage)13. Sulforaphane offers previously been shown to inhibit CYP3A4 and P-gp induction after rifampicin treatment in main human being hepatocytes, therefore inhibiting PXR-mediated induction of drug clearance14, which would suggest its use to reduce PXR-mediated drug-drug relationships. However, experimental data concerning the use of sulforaphane look like inconclusive. In a recent clinical study in humans where rifampicin treatment decreased midazolam AUC by 70 %70 %, concomitant administration of sulforaphane did not reduce the effect of rifampicin15. These investigators suggested the hepatic sulforaphane concentrations were probably too low to inhibit PXR activation. In the current study, we tested.