Potential modulation on P-glycoprotein and CYP3A by soymilk and miso: in vivo and ex-vivo studies

Non-Nutritive Sweeteners Acesulfame Potassium and Sucralose Are Competitive Inhibitors of the Human P-glycoprotein/Multidrug Resistance Protein 1 (PGP/MDR1)

Non-nutritive sweeteners (NNS) are popular sugar replacements used in foods, beverages, and medications. Although NNS are considered safe by regulatory organizations, their effects on physiological processes such as detoxification are incompletely understood. Previous studies revealed that the NNS sucralose (Sucr) altered P-glycoprotein (PGP) expression in rat colon. We also demonstrated that early-life exposure to NNS Sucr and acesulfame potassium (AceK) compromises mouse liver detoxification. Building upon these initial discoveries, we investigated the impact of AceK and Sucr on the PGP transporter in human cells to assess whether NNS influence its key role in cellular detoxification and drug metabolism. We showed that AceK and Sucr acted as PGP inhibitors, competing for the natural substrate-binding pocket of PGP. Most importantly, this was observed after exposure to concentrations of NNS within expected levels from common foods and beverage consumption. This may suggest risks for NNS consumers, either when taking medications that require PGP as the primary detoxification transporter or during exposure to toxic compounds.

ABCB1 in dermatology: roles in skin diseases and their treatment

Adenosine triphosphate-binding cassette subfamily B member 1 (ABCB1), also known as permeability glycoprotein, multidrug-resistant protein 1, or cluster of differentiation 243 (CD243), is a crucial protein for purging foreign substances from cells. The functions of ABCB1 have been investigated extensively for their roles in cancer, stem cells, and drug resistance. Abundant pharmacogenetic studies have been conducted on ABCB1 and its association with treatment responsiveness to various agents, particularly chemotherapeutic and immunomodulatory agents. However, its functions in the skin and implications on dermatotherapeutics are far less reported. In this article, we reviewed the roles of ABCB1 in dermatology. ABCB1 is expressed in the skin and its appendages during drug delivery and transport. It is associated with treatment responsiveness to various agents, including topical steroids, methotrexate, cyclosporine, azathioprine, antihistamines, antifungal agents, colchicine, tacrolimus, ivermectin, tetracycline, retinoid acids, and biologic agents. Moreover, genetic variation in ABCB1 is associated with the pathogenesis of several dermatoses, including psoriasis, atopic dermatitis, melanoma, bullous pemphigoid, Behçet disease, and lichen planus. Further investigation is warranted to elucidate the roles of ABCB1 in dermatology and the possibility of enhancing therapeutic efficacy through ABCB1 manipulation.

Development and Characterization of MDR1 (Mdr1a/b) CRISPR/Cas9 Knockout Rat Model

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease (Cas9) technology is widely used as a tool for gene editing in rat genome site-specific engineering. Multidrug resistance 1 [MDR1 (also known as P-glycoprotein)] is a key efflux transporter that plays an important role not only in the transport of endogenous and exogenous substances, but also in tumor MDR. In this report, a novel MDR1 (Mdr1a/b) double-knockout (KO) rat model was generated by the CRISPR/Cas9 system without any off-target effect detected. Western blot results showed that MDR1 was completely absent in the liver, small intestine, brain, and kidney of KO rats. Further pharmacokinetic studies of digoxin, a typical substrate of MDR1, confirmed the deficiency of MDR1 in vivo. To determine the possible compensatory mechanism of Mdr1a/b (-/-) rats, the mRNA levels of the CYP3A subfamily and transporter-related genes were compared in the brain, liver, kidney, and small intestine of KO and wild-type rats. In general, a new Mdr1a/b (-/-) rat model has been successfully generated and characterized. This rat model is a useful tool for studying the function of MDR1 in drug absorption, tumor MDR, and drug target validation.

Food Bioactive Compounds and Their Interference in Drug Pharmacokinetic/Pharmacodynamic Profiles

Preclinical and clinical studies suggest that many food molecules could interact with drug transporters and metabolizing enzymes through different mechanisms, which are predictive of what would be observed clinically. Given the recent incorporation of dietary modifications or supplements in traditional medicine, an increase in potential food-drug interactions has also appeared. The objective of this article is to review data regarding the influence of food on drug efficacy. Data from Google Scholar, PubMed, and Scopus databases was reviewed for publications on pharmaceutical, pharmacokinetic, and pharmacodynamic mechanisms. The following online resources were used to integrate functional and bioinformatic results: FooDB, Phenol-Explorer, Dr. Duke's Phytochemical and Ethnobotanical Databases, DrugBank, UniProt, and IUPHAR/BPS Guide to Pharmacology. A wide range of food compounds were shown to interact with proteins involved in drug pharmacokinetic/pharmacodynamic profiles, starting from drug oral bioavailability to enteric/hepatic transport and metabolism, blood transport, and systemic transport/metabolism. Knowledge of any food components that may interfere with drug efficacy is essential, and would provide a link for obtaining a holistic view for cancer, cardiovascular, musculoskeletal, or neurological therapies. However, preclinical interaction may be irrelevant to clinical interaction, and health professionals should be aware of the limitations if they intend to optimize the therapeutic effects of drugs.

Aloe activated P-glycoprotein and CYP 3A: a study on the serum kinetics of aloe and its interaction with cyclosporine in rats

Aloe, the leaf juice of Aloe vera, is a popular functional food worldwide. The major constituents of aloe are polyphenolic anthranoids such as aloin, aloe-emodin and rhein. Cyclosporine (CSP), an immunosuppressant with a narrow therapeutic window, is a probe substrate of P-glycoprotein (P-gp), an efflux pump, and CYP 3A4. This study first investigated the serum kinetics of aloe, then evaluated the modulation effects of aloe on P-gp and CYP 3A through an aloe-CSP interaction study in rats. The serum kinetic study showed that aloe-emodin glucuronides (G) and rhein sulfates/glucuronides (S/G) were major molecules in the bloodstream. The aloe-CSP interaction study showed that the systemic exposure to CSP was significantly decreased by either a single dose or multiple doses of aloe. The results of in vitro studies indicated that aloe activated P-gp and aloe metabolites activated CYP 3A4. In conclusion, aloe ingestion activated the functions of P-gp and CYP 3A in rats.

Old and new oral anticoagulants: Food, herbal medicines and drug interactions

The most commonly prescribed oral anticoagulants worldwide are the vitamin K antagonists (VKAs) such as warfarin. Factors affecting the pharmacokinetics of VKAs are important because deviations from their narrow therapeutic window can result in bleedings due to over-anticoagulation or thrombosis because of under-anticoagulation. In addition to pharmacodynamic interactions (e.g., augmented bleeding risk for concomitant use of NSAIDs), interactions with drugs, foods, herbs, and over-the-counter medications may affect the risk/benefit ratio of VKAs. Direct oral anticoagulants (DOACs) including Factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and thrombin inhibitor (dabigatran) are poised to replace warfarin. Phase-3 studies and real-world evaluations have established that the safety profile of DOACs is superior to those of VKAs. However, some pharmacokinetic and pharmacodynamic interactions are expected. Herein we present a critical review of VKAs and DOACs with focus on their potential for interactions with drugs, foods, herbs and over-the-counter medications.

Relevance of P-glycoprotein in stroke prevention with dabigatran, rivaroxaban, and apixaban

BACKGROUND

The new oral anticoagulants (NOAC) dabigatran etexilate, rivaroxaban, and apixaban show similar efficacy for stroke prevention in patients with atrial fibrillation (AF) as the vitamin K antagonist warfarin. Absorption of NOACs is dependent on the intestinal P-glycoprotein (P-gp) system and P-gp activity is modulated by a variety of drugs and food components.

OBJECTIVE

The aim of this review is to give an overview of P-gp-associated drug-drug and drug-food interactions with NOACs in AF patients.

METHODS

A literature search was carried out by screening MEDLINE for the terms dabigatran, rivaroxaban, apixaban, P-glycoprotein, and atrial fibrillation from 1998 to 2013. Randomized clinical trials, longitudinal studies, case series, and case reports were included.

RESULTS

Concomitant medication with proton pump inhibitors, amiodarone, clarithromycin, and verapamil increased bioavailability whereas rifampicin decreased the bioavailability of dabigatran. Coadministration of erythromycin, clarithromycin, fluconazole, ketoconazole, and ritonavir increased rivaroxaban plasma concentrations. No data were found on apixaban and P-gp-modulating drugs or on NOACs and food components modulating P-gp. The clinical relevance of interactions between NOACs and P-gp-modulating drugs or food components is largely unknown as bleeding complications under NOACs and P-gp-inhibiting drugs are mainly reported from patients with concomitant renal failure.

CONCLUSION

There is an urgent need to investigate the role of P-gp-modulating substances as potential sources of drug-drug and drug-food interactions. A thorough analysis of the data accumulated in the three large NOAC trials regarding the role of P-gp-modulating drugs in bleeding and embolic events is desirable. Pharmacological studies should investigate the influence of P-gp-modulating drugs and food on NOAC plasma concentrations and coagulation parameters. When prescribing NOACs, patients should be informed about the potential interactions with drugs and herbal drugs. Patients who develop bleeding or embolic events under treatment with NOACs should be investigated for co-medications as well as for over-the-counter drugs and dietary habits. In post-marketing surveillance of NOACs, the association with drug or food intake with complications, bleeding, and embolic events should be registered.

Oral intake of curcumin markedly activated CYP 3A4: in vivo and ex-vivo studies

Curcumin, a specific secondary metabolite of Curcuma species, has potentials for a variety of beneficial health effects. It is nowadays used as a dietary supplement. Everolimus (EVL) is an immunosuppressant indicated for allograft rejection and cancer therapy, but with narrow therapeutic window. EVL is a substrate of P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4). This study investigated the effect of coadministration of curcumin on the pharmacokinetics of EVL in rats and the underlying mechanisms. EVL (0.5 mg/kg) was orally administered without and with 50 and 100 mg/kg of curcumin, respectively, in rats. Blood samples were collected at specific time points and EVL concentrations in blood were determined by QMS® immunoassay. The underlying mechanisms were evaluated using cell model and recombinant CYP 3A4 isozyme. The results indicated that 50 and 100 mg/kg of curcumin significantly decreased the AUC_0-540 of EVL by 70.6% and 71.5%, respectively, and both dosages reduced the C_max of EVL by 76.7%. Mechanism studies revealed that CYP3A4 was markedly activated by curcumin metabolites, which apparently overrode the inhibition effects of curcumin on P-gp. In conclusion, oral intake of curcumin significantly decreased the bioavailability of EVL, a probe substrate of P-gp/CYP 3A4, mainly through marked activation on CYP 3A4.