scholarly journals Combination of Tenofovir and Emtricitabine plus Efavirenz: In Vitro Modulation of ABC Transporter and Intracellular Drug Accumulation

2008 ◽  
Vol 53 (3) ◽  
pp. 896-902 ◽  
Author(s):  
Laurence Bousquet ◽  
Alain Pruvost ◽  
Anne-Cécile Guyot ◽  
Robert Farinotti ◽  
Aloïse Mabondzo
Keyword(s):  
Mrna Expression ◽  
Organic Anion ◽  
Antiretroviral Drugs ◽  
Organic Anion Transporter ◽  
Target Cells ◽  
Efflux Transporter ◽  
Anion Transporter ◽  
Drug Concentrations ◽  
Transporter Expression

ABSTRACT Efflux proteins have been shown to greatly affect the uptake of antiretroviral drugs by cells and to hamper their access to the human immunodeficiency virus type 1 replication site. This study evaluated the factors that may lead to drug-drug interactions between emtricitabine (FTC), tenofovir (TFV), and efavirenz (EFV), including the modulation of efflux transporter expression and function. Peripheral blood mononuclear cells from healthy volunteers were used to determine whether or not an interaction between antiretroviral drugs and target cells occurred in any combination of FTC, TFV, EFV, FTC-TFV, TFV-EFV, or FTC-TFV-EFV. Following 20 h of treatment, intracellular drug concentrations were measured by liquid chromatography-tandem mass spectrometry. Efflux transporter functionality and inhibitor drug properties were assessed by measuring fluorescent dye efflux. ABCB1 (P-glycoprotein), ABCC 1 to 6 (multidrug resistance-associated protein), and OAT (organic anion transporter) expression in response to the treatments was quantified by semiquantitative real-time PCR. Cells treated with a double combination (FTC-TFV or TFV-EFV) or the triple combination (FTC-TFV-EFV) produced higher FTC and TFV intracellular concentrations than cells treated with FTC or TFV alone. However, no change in the EFV intracellular concentration was observed. FTC tended to induce abcc5 mRNA expression and EFV tended to induce abcc1 and abcc6 mRNA expression, whereas TFV tended to reduce mdr1, abcc1, abcc5, and abcc6 mRNA expression. Under these conditions, a decrease in the functionality of ABCC was observed, and this decrease was associated with the direct inhibitory actions of these drugs. This in vitro study reveals a benefit of the combination FTC-TFV-EFV in terms of the intracellular FTC and TFV concentrations and highlights the pharmacological mechanisms that lead to this effect.

scholarly journals Evaluation of Chinese-Herbal-Medicine-Induced Herb-Drug Interactions: Focusing on Organic Anion Transporter 1

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Chang-Ching Lin ◽  
Hsien-Yuan Fan ◽  
Chien-Wen Kuo ◽  
Li-Heng Pao
Keyword(s):  
Drug Interactions ◽  
Mrna Expression ◽  
Prescription Drugs ◽  
Drug Transport ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Chinese Herbal ◽  
Anion Transporter

The consumption of Chinese herbal medicines (CHMs) is increasing exponentially. Many patients utilize CHMs concomitantly with prescription drugs in great frequency. Herb-drug interaction has hence become an important focus of study. Transporter-mediated herb-drug interactions have the potential to seriously influence drug efficacy and toxicity. Since organic anion transporter 1 (OAT1) is crucial in renal active secretion and drug-drug interactions, the possibility of modulation of OAT1-mediated drug transport should be seriously concerned. Sixty-three clinically used CHMs were evaluated in the study. An hOAT1-overexpressing cell line was used for thein vitroCHMs screening, and the effective candidates were administered to Wistar rats to access renal hemodynamics. The regulation of OAT1 mRNA expression was also examined for further evidence of CHMs affecting OAT1-mediated transport. Among all the 63 CHMs, formulae Gui Zhi Fu Ling Wan (GZ) and Chia Wei Hsiao Yao San (CW) exhibited significant inhibitions on hOAT1-mediated [3H]-PAH uptakein vitroand PAH clearance and net secretionin vivo. Moreover, GZ showed concentration-dependent manners bothin vitroandin vivo, and the decrease of rOAT1 mRNA expression indicated that GZ not only inhibited function of OAT1 but also suppressed expression of OAT1.

scholarly journals Application of a PBPK Model of Rivaroxaban to Prospective Simulations of Drug-Drug-Disease Interactions with Protein Kinase Inhibitors in CA-VTE

2021 ◽  
Author(s):  
Eleanor Jing Yi Cheong ◽  
Daniel Zhi Wei Ng ◽  
Sheng Yuan Chin ◽  
Ziteng Wang ◽  
Eric Chun Yong Chan
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Pbpk Model ◽  
Organic Anion ◽  
Protein Kinase Inhibitors ◽  
Organic Anion Transporter ◽  
Pbpk Modelling ◽  
Anion Transporter

Background and Purpose Rivaroxaban is emerging as a viable anticoagulant for the pharmacological management of cancer associated venous thromboembolism (CA-VTE). Being eliminated via CYP3A4/2J2-mediated metabolism and organic anion transporter 3 (OAT3)/P-glycoprotein-mediated renal secretion, rivaroxaban is susceptible to drug-drug interactions (DDIs) with protein kinase inhibitors (PKIs), erlotinib and nilotinib. Physiologically based pharmacokinetic (PBPK) modelling was applied to interrogate the DDIs for dose adjustment of rivaroxaban in CA-VTE. Experimental Approach The inhibitory potencies of erlotinib and nilotinib on CYP3A4/2J2-mediated metabolism of rivaroxaban were characterized. Using prototypical OAT3 inhibitor ketoconazole, in vitro OAT3 inhibition assays were optimized to ascertain the in vivo relevance of derived inhibitory constants (K). DDIs between rivaroxaban and erlotinib or nilotinib were investigated using iteratively verified PBPK model. Key Results Mechanism-based inactivation (MBI) of CYP3A4-mediated rivaroxaban metabolism by both PKIs and MBI of CYP2J2 by erlotinib were established. The importance of substrate specificity and nonspecific binding to derive OAT3-inhibitory K values of ketoconazole and nilotinib for the accurate prediction of DDIs was illustrated. When simulated rivaroxaban exposure variations with concomitant erlotinib and nilotinib therapy were evaluated using published dose-exposure equivalence metrics and bleeding risk analyses, dose reductions from 20 mg to 15 mg and 10 mg in normal and mild renal dysfunction, respectively, were warranted. Conclusion and Implications We established the PBPK-DDI platform to prospectively interrogate and manage clinically relevant interactions between rivaroxaban and PKIs in patients with underlying renal impairment. Rational dose adjustments were proposed, attesting to the capacity of PBPK modelling in facilitating precision medicine.

scholarly journals In Vitro Evaluation of the Drug Interaction Potential of Doravirine

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
Kelly Bleasby ◽  
Kerry L. Fillgrove ◽  
Robert Houle ◽  
Bing Lu ◽  
Jairam Palamanda ◽  
...  
Keyword(s):  
Drug Interactions ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Reversible Inhibitor ◽  
Drug Metabolizing Enzymes ◽  
Cancer Resistance ◽  
Metabolizing Enzymes ◽  
Anion Transporter ◽  
Major Drug

ABSTRACT Doravirine is a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1 infection. In vitro studies were conducted to assess the potential for drug interactions with doravirine via major drug-metabolizing enzymes and transporters. Kinetic studies confirmed that cytochrome P450 3A (CYP3A) plays a major role in the metabolism of doravirine, with ∼20-fold-higher catalytic efficiency for CYP3A4 versus CYP3A5. Doravirine was not a substrate of breast cancer resistance protein (BCRP) and likely not a substrate of organic anion transporting polypeptide 1B1 (OATP1B1) or OATP1B3. Doravirine was not a reversible inhibitor of major CYP enzymes (CYP1A2, -2B6, -2C8, -2C9, -2C19, -2D6, and -3A4) or of UGT1A1, nor was it a time-dependent inhibitor of CYP3A4. No induction of CYP1A2 or -2B6 was observed in cultured human hepatocytes; small increases in CYP3A4 mRNA (≤20%) were reported at doravirine concentrations of ≥10 μM but with no corresponding increase in enzyme activity. In vitro transport studies indicated a low potential for interactions with substrates of BCRP, P-glycoprotein, OATP1B1 and OATP1B3, the bile salt extrusion pump (BSEP), organic anion transporter 1 (OAT1) and OAT3, organic cation transporter 2 (OCT2), and multidrug and toxin extrusion 1 (MATE1) and MATE2K proteins. In summary, these in vitro findings indicate that CYP3A4 and CYP3A5 mediate the metabolism of doravirine, although with different catalytic efficiencies. Clinical trials reported elsewhere confirm that doravirine is subject to drug-drug interactions (DDIs) via CYP3A inhibitors and inducers, but they support the notion that DDIs (either direction) are unlikely via other major drug-metabolizing enzymes and transporters.

OAT2 catalyses efflux of glutamate and uptake of orotic acid

2011 ◽  
Vol 436 (2) ◽  
pp. 305-312 ◽  
Author(s):  
Christian Fork ◽  
Tim Bauer ◽  
Stefan Golz ◽  
Andreas Geerts ◽  
Jessica Weiland ◽  
...  
Keyword(s):  
Orotic Acid ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Specific Substrate ◽  
Efflux Transporter ◽  
Anion Transporter ◽  
293 Cells ◽  
Solute Carrier ◽  
Laser Capture ◽  
Glutamate Efflux

OAT (organic anion transporter) 2 [human gene symbol SLC22A7 (SLC is solute carrier)] is a member of the SLC22 family of transport proteins. In the rat, the principal site of expression of OAT2 is the sinusoidal membrane domain of hepatocytes. The particular physiological function of OAT2 in liver has been unresolved so far. In the present paper, we have used the strategy of LC (liquid chromatography)–MS difference shading to search for specific and cross-species substrates of OAT2. Heterologous expression of human and rat OAT2 in HEK (human embryonic kidney)-293 cells stimulated accumulation of the zwitterion trigonelline; subsequently, orotic acid was identified as an excellent and specific substrate of OAT2 from the rat (clearance=106 μl·min−1·mg of protein−1) and human (46 μl·min−1·mg of protein−1). The force driving uptake of orotic acid was identified as glutamate antiport. Efficient transport of glutamate by OAT2 was directly demonstrated by uptake of [3H]glutamate. However, because of high intracellular glutamate, OAT2 operates as glutamate efflux transporter. Thus expression of OAT2 markedly increased the release of glutamate (measured by LC-MS) from cells, even without extracellular exchange substrate. Orotic acid strongly trans-stimulated efflux of glutamate. We thus propose that OAT2 physiologically functions as glutamate efflux transporter. OAT2 mRNA was detected, after laser capture microdissection of rat liver slices, equally in periportal and pericentral regions; previous reports of hepatic release of glutamate into blood can now be explained by OAT2 activity. A specific OAT2 inhibitor could, by lowering plasma glutamate and thus promoting brain-to-blood efflux of glutamate, alleviate glutamate exotoxicity in acute brain conditions.

Renal expression of organic anion transporter OAT2 in rats and mice is regulated by sex hormones

2007 ◽  
Vol 292 (1) ◽  
pp. F361-F372 ◽  
Author(s):  
Marija Ljubojević ◽  
Daniela Balen ◽  
Davorka Breljak ◽  
Marija Kušan ◽  
Naohiko Anzai ◽  
...  
Keyword(s):  
Gender Differences ◽  
Mrna Expression ◽  
Rat Kidney ◽  
Organic Anion ◽  
Staining Intensity ◽  
Protein Band ◽  
Organic Anion Transporter ◽  
Adult Rats ◽  
Anion Transporters ◽  
Anion Transporter

The renal reabsorption and/or excretion of various organic anions is mediated by specific organic anion transporters (OATs). OAT2 (Slc22a7) has been identified in rat kidney, where its mRNA expression exhibits gender differences [females (F) > males (M)]. The exact localization of OAT2 protein in the mammalian kidney has not been reported. Here we studied the expression of OAT2 mRNA by RT-PCR and its protein by Western blotting (WB) and immunocytochemistry (IC) in kidneys of adult intact and gonadectomized M and F, sex hormone-treated castrated M, and prepubertal M and F rats, and the protein in adult M and F mice. In adult rats, the expression of OAT2 mRNA was predominant in the outer stripe (OS) tissue, exhibiting 1) gender dependency (F > M), 2) upregulation by castration and downregulation by ovariectomy, and 3) strong downregulation by testosterone and weak upregulation by estradiol and progesterone treatment. A polyclonal antibody against rat OAT2 on WB of isolated renal membranes labeled a ∼66-kDa protein band that was stronger in F. By IC, the antibody exclusively stained brush border (BB) of the proximal tubule S3 segment (S3) in the OS and medullary rays (F > M). In variously treated rats, the pattern of 66-kDa band density in the OS membranes and the staining intensity of BB in S3 matched the mRNA expression. The expression of OAT2 protein in prepubertal rats was low and gender independent. In mice, the expression pattern largely resembled that in rats. Therefore, OAT2 in rat (and mouse) kidney is localized to the BB of S3, exhibiting gender differences (F > M) that appear in puberty and are caused by strong androgen inhibition and weak estrogen and progesterone stimulation.

scholarly journals Cytotoxicity of Antiviral Nucleotides Adefovir and Cidofovir Is Induced by the Expression of Human Renal Organic Anion Transporter 1

2000 ◽  
Vol 11 (3) ◽  
pp. 383-393 ◽  
Author(s):  
EDMUND S. HO ◽  
DEBORAH C. LIN ◽  
DIRK B. MENDEL ◽  
TOMAS CIHLAR
Keyword(s):  
Organic Anion ◽  
Critical Role ◽  
Antiviral Agents ◽  
Chinese Hamster ◽  
Organic Anion Transporter ◽  
Nucleotide Analogs ◽  
Anion Transporter ◽  
Organ Specific

Abstract. The transport of organic anions in proximal convoluted tubules plays an essential role in the active secretion of a variety of small molecules by the kidney. In addition to other anionic substrates, the human renal organic anion transporter 1 (hOAT1) is capable of transporting the nucleotide analogs adefovir and cidofovir. To investigate the involvement of hOAT1 in the mechanism of nephrotoxicity associated with these two clinically important antiviral agents, Chinese hamster ovary (CHO) cells were stably transfected with hOAT1 cDNA. The resulting CHOhOAT cells showed probenecid-sensitive and pH-dependent uptake of p-aminohippurate (Km = 15.4 μM, Vmax = 20.6 pmol/106 cells · min), a prototypical organic anion substrate. In addition, the stably expressed hOAT1 mediated efficient transport of adefovir (Km = 23.8 μM, Vmax = 46.0 pmol/106 cells · min) and cidofovir (Km = 58.0 μM, Vmax = 103 pmol/106 cells · min) such that the levels of intracellular metabolites of both nucleotides were >100-fold higher in CHOhOAT cells than in parental CHO. Consequently, adefovir and cidofovir were approximately 500-fold and 400-fold more cytotoxic, respectively, in CHOhOAT cells compared to CHO. The cytotoxicity of both drugs in CHOhOAT cells was markedly reduced in the presence of hOAT1 inhibitors. The cyclic prodrug of cidofovir, which exhibits reduced in vivo nephrotoxicity, was a poor substrate for hOAT1 and showed only marginally increased cytotoxicity in CHOhOAT cells. In conclusion, these studies demonstrate that hOAT1 plays a critical role in the organ-specific toxicity of adefovir and cidofovir, and indicates that CHOhOAT cells may represent a useful in vitro model to investigate the potential nephrotoxicity of clinically relevant organic anion agents.

scholarly journals Mammalian colonocytes possess a carrier-mediated mechanism for uptake of vitamin B3 (niacin): studies utilizing human and mouse colonic preparations

2013 ◽  
Vol 305 (3) ◽  
pp. G207-G213 ◽  
Author(s):  
Jeyan S. Kumar ◽  
Veedamali S. Subramanian ◽  
Rubina Kapadia ◽  
Moti L. Kashyap ◽  
Hamid M. Said
Keyword(s):  
Nicotinic Acid ◽  
Large Intestine ◽  
Protein Tyrosine Kinase ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Vitamin B3 ◽  
Regulatory Pathways ◽  
Anion Transporter

Niacin (vitamin B3; nicotinic acid) plays an important role in maintaining redox state of cells and is obtained from endogenous and exogenous sources. The latter source has generally been assumed to be the dietary niacin, but another exogenous source that has been ignored is the niacin that is produced by the normal microflora of the large intestine. For this source of niacin to be bioavailable, it needs to be absorbed, but little is known about the ability of the large intestine to absorb niacin and the mechanism involved. Here we addressed these issues using the nontransformed human colonic epithelial NCM460 cells, native human colonic apical membrane vesicles (AMV) isolated from organ donors, and mouse colonic loops in vivo as models. Uptake of3H-nicotinic acid by NCM460 cells was: 1) acidic pH (but not Na+) dependent; 2) saturable (apparent Km= 2.5 ± 0.8 μM); 3) inhibited by unlabeled nicotinic acid, nicotinamide, and probenecid; 4) neither affected by other bacterially produced monocarboxylates, monocarboxylate transport inhibitor, or by substrates of the human organic anion transporter-10; 5) affected by modulators of the intracellular protein tyrosine kinase- and Ca2+-calmodulin-regulatory pathways; and 6) adaptively regulated by extracellular nicotinate level. Uptake of nicotinic acid by human colonic AMV in vitro and by mouse colonic loops in vivo was also carrier mediated. These findings report, for the first time, that mammalian colonocytes possess a high-affinity carrier-mediated mechanism for nicotinate uptake and show that the process is affected by intracellular and extracellular factors.

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