Proton pump inhibitors inhibit methotrexate transport by renal basolateral organic anion transporter hOAT3

Proton pump inhibitors and cancer treatments: Emerging evidence against coadministration

BACKGROUND

Proton pump inhibitors (PPIs) are widely used in cancer patients despite accumulating data showing that they can impact the efficacy of major anticancer drugs. This is particularly important with tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (CPIs).

RESULTS

Most TKIs require gastric acidity for their absorption and some retrospective series demonstrated that coprescription decreases the survival benefit of some TKI use (erlotinib, gefitinib and pazopanib). Relations between microbiota, the immune system, and the efficacy of immunotherapy are now obvious, just as modifications to gut flora after PPIs use are well-known. Many retrospective articles, including articles based on individual-participant data from randomized studies, demonstrated that patients treated with CPIs have a poorer outcome (overall survival, progression-free survival and response rate) when they received PPIs concomitantly, while there was no impact of such coprescription among patients in control arms, not treated with immunotherapies. Similar data were also observed in patients treated with palbociclib.

CONCLUSION

For these interactions, it is very important to use the precautionary principle and warn patients and physicians about this. In patients who require acid suppression because of severe symptoms, using antacids or H2 blockers could be recommended.

Contribution of human organic anion transporter 3-mediated transport of a major linezolid metabolite, PNU-142586, in linezolid-induced thrombocytopenia

Thrombocytopenia, a common adverse effect of linezolid, often occurs in patients lacking typical risk factors. In this study, we investigated the key risk factors for linezolid-induced thrombocytopenia using two real-world clinical databases and explored its underlying mechanism through in vitro and in vivo experiments. In a retrospective analysis of 150 linezolid-treated patients, multivariate analysis identified coadministration of lansoprazole, a proton pump inhibitor, as a significant independent risk factor for thrombocytopenia (odds ratio: 2.33, p = 0.034). Additionally, analysis of the Food and Drug Administration Adverse Event Reporting System database revealed a reporting odds ratio of thrombocytopenia for lansoprazole of 1.64 (95% CI: 1.25-2.16). In vitro studies showed that the uptake of PNU-142586, a major linezolid metabolite, was significantly higher in human organic anion transporter 3-expressing HEK293 (HEK-hOAT3) cells compared to HEK-pBK cells. The apparent IC50 value of lansoprazole against hOAT3-mediated transport of PNU-142586 was 0.59 ± 0.38 µM. In a pharmacokinetic study using rats, coadministration of linezolid with lansoprazole intravenously resulted in approximately a 1.7-fold increase in the area under the plasma concentration-time curve of PNU-142586, but not linezolid and PNU-142300. Moreover, PNU-142586, but not linezolid, exhibited concentration-dependent cytotoxicity in a human megakaryocytic cell line. These findings suggest that linezolid-induced thrombocytopenia should be due to delayed elimination of PNU-142586. Furthermore, delayed elimination of PNU-142586 due to renal failure and hOAT3-mediated transport inhibition by lansoprazole should exacerbate linezolid-induced thrombocytopenia.

The regulation of human organic anion transporter 4 by insulin-like growth factor 1 and protein kinase B signaling

Human organic anion transporter 4 (hOAT4), mainly expressed in the kidney and placenta, is essential for the disposition of numerous drugs, toxins, and endogenous substances. Insulin-like growth factor 1 (IGF-1) is a hormone generated in the liver and plays important roles in systemic growth, development, and metabolism. In the current study, we explored the regulatory effects of IGF-1 and downstream signaling on the transport activity, protein expression, and SUMOylation of hOAT4. We showed that IGF-1 significantly increased the transport activity, expression, and maximal transport velocity Vmax of hOAT4 in kidney-derived cells. This stimulatory effect of IGF-1 on hOAT4 activity was also confirmed in cells derived from the human placenta. The increased activity and expression were correlated well with the reduced degradation rate of hOAT4 at the cell surface. Furthermore, IGF-1 significantly increased hOAT4 SUMOylation, and protein kinase B (PKB)-specific inhibitors blocked the IGF-1-induced regulations on hOAT4. In conclusion, our study demonstrates that the hepatic hormone IGF-1 regulates hOAT4 expressed in the kidney and placenta through the PKB signaling pathway. Our results support the remote sensing and signaling theory, where OATs play a central role in the remote communications among distal tissues.

Proton-Pump Inhibitors and Serum Concentrations of Uremic Toxins in Patients with Chronic Kidney Disease

Use of proton-pump inhibitors (PPIs) is common in patients with chronic kidney disease (CKD). PPIs and many uremic toxins (UTs) are eliminated by the kidney's tubular organic anion transporter system. In a cross-sectional study, we sought to evaluate the association between PPI prescription and serum concentrations of various UTs. We studied a randomly selected sub-group of participants in the CKD-REIN cohort (adult patients with a confirmed diagnosis of CKD and estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m²) with available frozen samples collected at baseline. PPI prescription was recorded at baseline. Serum concentrations of 10 UTs were measured using a validated liquid chromatography tandem mass spectrometry technique. Multiple linear regression was performed, with the log UT concentration as the dependent variable. Of the 680 included patients (median age: 68 years; median eGFR: 32 mL/min/1.73 m²), 31% had PPI prescriptions at baseline. Patients using PPIs had higher levels of certain UTs in comparison to other patients, including total and free indoxyl sulfate (IS), total and free p-cresylsulfate, total and free p-cresylglucuronide (PCG), phenylacetylglutamine (PAG), free kynurenine, and free hippuric acid. After adjustment for baseline co-morbidities, number of co-prescribed drugs, and laboratory data, including eGFR, associations between PPI prescription and elevated serum concentrations of free and total IS, free and total PCG, and PAG remained significant. Our results indicate that PPI prescription is independently associated with serum UT retention. These findings are interesting to better understand the factors that may modulate serum UT concentration in CKD patients, however, they will need to be confirmed by longitudinal studies.

A critical review of methotrexate clinical interactions: role of transporters

INTRODUCTION

Methotrexate (MTX) is an anti-folate and immunosuppressive drug prescribed for various malignancies and immune diseases. However, delayed elimination of MTX associated with concomitant use of some medications can lead to severe and life-threatening adverse effects.

AREAS COVERED

This paper investigated drug-MTX interactions that lead to elevated MTX levels and related adverse effects due to the role of transporters. Methotrexate toxicity occurs at both low and high doses administrations. According to the studies we reviewed in this paper, most interaction records with methotrexate occurred with co-administration of indomethacin, ketoprofen, omeprazole, piperacillin/tazobactam, ciprofloxacin, co-trimoxazole, probenecid, and imatinib, mainly due to the role of transporters. However, most studies were performed as case reports or series, and confirming the exact drug-methotrexate interaction still needs further clinical investigations.

EXPERT OPINION

Our findings showed no firm evidence of interactions of proton pump inhibitors (PPIs), levetiracetam, and NSAIDS with MTX. Moreover, patients' risk factors, hypoalbuminemia, renal failure, third space fluid retention, the elderly, polypharmacy, and transport inhibition are the most critical factors for MTX toxicity. If substitution or temporary discontinuation is not possible, healthcare providers should be aware of interactions, especially in patients with risk factors for MTX toxicity.

Kidney Drug Transporters in Pharmacotherapy

The kidney functions not only as a metabolite elimination organ but also plays an important role in pharmacotherapy. The kidney tubule epithelia cells express membrane carriers and transporters, which play an important role in drug elimination, and can determine drug nephrotoxicity and drug-drug interactions, as well as constituting direct drug targets. The above aspects of kidney transport proteins are discussed in the review.

Renal Transporter Alterations in Patients with Chronic Liver Diseases: Nonalcoholic Steatohepatitis, Alcohol-Associated, Viral Hepatitis, and Alcohol-Viral Combination

Alterations in hepatic transporters have been identified in precirrhotic chronic liver diseases (CLDs) that result in pharmacokinetic variations causing adverse drug reactions (ADRs). However, the effect of CLD on the expression of renal transporters is unknown despite the overwhelming evidence of kidney injury in CLD patients. This study determines the transcriptomic and proteomic expression profiles of renal drug transporters in patients with defined CLD etiology. Renal biopsies were obtained from patients with a history of CLD etiologies, including nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), alcohol-associated liver disease (ALD), viral hepatitis C (HCV), and combination ALD/HCV. A significant decrease in organic anion transporter (OAT)-3 was identified in NASH, ALD, HCV, and ALD/HCV (1.56 ± 1.10; 1.01 ± 0.46; 1.03 ± 0.43; 0.86 ± 0.57 pmol/mg protein) relative to control (2.77 ± 1.39 pmol/mg protein). Additionally, a decrease was shown for OAT4 in NASH (24.9 ± 5.69 pmol/mg protein) relative to control (43.8 ± 19.9 pmol/mg protein) and in urate transporter 1 (URAT1) for ALD and HCV (1.56 ± 0.15 and 1.65 ± 0.69 pmol/mg protein) relative to control (4.69 ± 4.59 pmol/mg protein). These decreases in organic anion transporter expression could result in increased and prolonged systemic exposure to drugs and possible toxicity. Renal transporter changes, in addition to hepatic transporter alterations, should be considered in dose adjustments for CLD patients for a more accurate disposition profile. It is important to consider a multiorgan approach to altered pharmacokinetics of drugs prescribed to CLD patients to prevent ADRs and improve patient outcomes. SIGNIFICANCE STATEMENT: Chronic liver diseases are known to elicit alterations in hepatic transporters that result in a disrupted pharmacokinetic profile for various drugs. However, it is unknown if there are alterations in renal transporters during chronic liver disease, despite strong indications of renal dysfunction associated with chronic liver disease. Identifying renal transporter expression changes in patients with chronic liver disease facilitates essential investigations on the multifaceted relationship between liver dysfunction and kidney physiology to offer dose adjustments and prevent adverse drug reactions.

Sensitive and valid assay for reliable evaluation of drug interactions mediated by human organic anion transporter 1 and 3 using 5-carboxyfluorescein

Drug interactions can induce significant clinical impacts, either by increasing adverse effects or by decreasing the therapeutic effect of drugs, and thus, need to be explored thoroughly. Clinically significant drug interactions can be induced by organic anion transporter 1 (OAT1) and OAT3 when concomitant medications competitively interact with the transporters. The purposes of this study were to develop and validate a sensitive and selective analytical method for 5-carboxyfluorescein (5-CF) and optimize the experimental conditions for interaction studies. An analytical method using high-performance liquid chromatography (HPLC) equipped with a fluorescence detector was validated for accuracy, precision, matrix effect, recovery, stability, dilutional integrity, and carry-over effect. In addition, the 5-CF concentration, incubation period, and washing conditions for interaction study were optimized. Using a valid analytical method and optimized conditions, we performed an interaction study for OAT1 and OAT3 using 26 test articles. Some of the test articles showed strong inhibitory potency for the transporters, with IC₅₀ values close to or less than 10 μM. The valid analysis method and optimized systems developed in this study can be utilized to improve the predictability of drug interactions in humans and consequently aid in successful disease treatment by maintaining appropriate systemic exposures.

Pancytopenia Due to Possible Drug-Drug Interactions Between Low-Dose Methotrexate and Proton Pump Inhibitors

Methotrexate (MTX) has been widely used with a wide range of doses in the treatment of certain neoplastic diseases, severe psoriasis, and rheumatoid arthritis. At higher dose, monitoring of serum MTX elimination is performed because delayed elimination can result in serious and potentially life-threatening toxicities. A number of medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), salicylates, phenylbutazone, phenytoin, sulfonamides, and some oral antibiotics, are known to interact with MTX therapy through various mechanisms. Accumulating evidence suggests that concomitant use of MTX (primarily at high doses) and proton pump inhibitors (PPIs) such as omeprazole, esomeprazole, and pantoprazole may decrease MTX clearance. The majority of the reported cases occurred with the administration of high-dose MTX in patients receiving doses of 300 mg/m² to 12 g/m². However, there were also cases of patients taking PPI and experiencing toxicity at doses as low as 10 mg of MTX per week. Although the dosage of MTX is small, the presence of side effect may be delayed and still dangerous. After literature review, it was found that common toxicities associated with low-dose MTX used for inflammatory arthritis include gastrointestinal adverse effects (>10%; ie nausea, stomatitis) and central nervous system toxicity (~20%; ie fatigue, malaise, dizziness, impaired cognition) with weekly administration. Bone marrow suppression (<3%; ie leukopenia, neutropenia, thrombocytopenia) and hepatotoxicity (~15%; ie reversible elevations in transaminases) are less common, and rarely MTX can also cause pulmonary (<1%) and other toxicities. Here, we report two cases who presented with severe pancytopenia 8 and 13 days after taking low-dose MTX and PPI. We highlight that in absence of risk/benefit ratio correctly set, an assessment of appropriateness of PPI prescription before MTX therapy can limit an iatrogenic risk.

The key role of organic anion transporter 3 in the drug-drug interaction between tranilast and methotrexate

Tranilast, N-(3',4'-dimethoxycinnamoyl)-anthranilic acid, is an anti-allergic drug and is considered for use in the treatment of rheumatoid arthritis. Methotrexate, an antimetabolite and folate antagonist to treat some cancers, is also a first-line drug for RA. The aim of this study was to understand whether tranilast could inhibit renal uptake transporters (Oat1, Oat3, and Oct2) and whether MTX combined with TL would have drug-drug interactions. The results of kidney slices and HEK293T-OAT3 cell uptake experiments showed that TL (10 μM) could inhibit the uptake of penicillin G and MTX, which are substrates of OAT3. When TL (10 mg/kg) was combined with MTX (5 mg/kg), the area under the curve and peak concentration of MTX increased by 46.46% and 113.51%, respectively, while the pharmacokinetic process of tranilast (10 mg/kg) was not changed by methotrexate (5 mg/kg). TL could increase plasma exposure of MTX by inhibiting Oat3 in vitro and in vivo.

The Prescription of Drugs That Inhibit Organic Anion Transporters 1 or 3 Is Associated with the Plasma Accumulation of Uremic Toxins in Kidney Transplant Recipients

The renal elimination of uremic toxins (UTs) can be potentially altered by drugs that inhibit organic anion transporters 1/3 (OAT1/OAT3). The objective of the present study was to determine whether the prescription of at least one OAT1/OAT3 inhibitor was associated with the plasma accumulation of certain UTs in kidney transplant recipients. We included 403 kidney transplant recipients. For each patient, we recorded all prescription drugs known to inhibit OAT1/OAT3. Plasma levels of four UTs (trimethylamine N-oxide (TMAO), indole acetic acid (IAA), para-cresylsulfate (pCS), and indoxylsulfate (IxS) were assayed using liquid chromatography-tandem mass spectrometry. Plasma UT levels were significantly higher among patients prescribed at least one OAT inhibitor (n = 311) than among patients not prescribed any OAT inhibitors (n = 92). Multivariate analysis revealed that after adjustment for age, estimated glomerular filtration rate (eGFR), plasma level of albumin and time since transplantation, prescription of an OAT1/OAT3 inhibitor was independently associated with the plasma accumulation of pCS (adjusted odds ratio (95% confidence interval): 2.11 (1.26; 3.61]). Our results emphasize the importance of understanding the interactions between drugs and UTs and those involving UT transporters in particular.

Systematic Review of Pharmacogenetic Factors That Influence High-Dose Methotrexate Pharmacokinetics in Pediatric Malignancies

Methotrexate (MTX) is a mainstay therapeutic agent administered at high doses for the treatment of pediatric and adult malignancies, such as acute lymphoblastic leukemia, osteosarcoma, and lymphoma. Despite the vast evidence for clinical efficacy, high-dose MTX displays significant inter-individual pharmacokinetic variability. Delayed MTX clearance can lead to prolonged, elevated exposure, causing increased risks for nephrotoxicity, mucositis, seizures, and neutropenia. Numerous pharmacogenetic studies have investigated the effects of several genes and polymorphisms on MTX clearance in an attempt to better understand the pharmacokinetic variability and improve patient outcomes. To date, several genes and polymorphisms that affect MTX clearance have been identified. However, evidence for select genes have conflicting results or lack the necessary replication and validation needed to confirm their effects on MTX clearance. Therefore, we performed a systematic review to identify and then summarize the pharmacogenetic factors that influence high-dose MTX pharmacokinetics in pediatric malignancies. Using the PRISMA guidelines, we analyzed 58 articles and 24 different genes that were associated with transporter pharmacology or the folate transport pathway. We conclude that there is only one gene that reliably demonstrates an effect on MTX pharmacokinetics: SLCO1B1.

CP-25 ameliorates methotrexate induced nephrotoxicity via improving renal apoptosis and methotrexate excretion

Paeoniflorin-6'-O-benzene sulfonate (CP-25) is a derivative of Paeoniflorin. We investigate beneficial effect of CP-25 on methotrexate (MTX) induced nephrotoxicity in rats. Plasma blood urea nitrogen (Bun), plasma creatinine (CREA), urine CREA and protein in the rats were quantitatively measured. Renal tissues were pathologically observed, and apoptosis was detected. Apoptosis related proteins and organic anion transporter-3 (OAT3) expression were determined by western blotting analysis. MTX induced nephrotoxicity and hematotoxicity in rats with abnormal levels of serum Bun, serum CERA, 24 h urine protein excretion, white blood cells, platelets, plateletcrit and abnormal renal pathological appearance. Either pre-treatment or treatment of CP-25 restored normal levels of hematological and renal function parameters, and improved histopathology in rats treated with MTX. CP-25 prevented MTX induced apoptosis of renal tubular cells, and the effect was further confirmed by its regulatory effects on abnormal expression of Bax, cleaved-caspase-3, cleaved-caspase-8, Cyt-c, Bcl-2. The other important finding is co-administration of CP-25 with MTX significantly increased MTX renal excretion in the damaged rats, and the effect is supposed to be linked with its regulation on abnormal renal OAT3 expression. Taken together, CP-25 shows well protective activity against MTX induced nephrotoxicity, and this effect is via its anti-apoptosis and detoxification properties.

Investigation of Potential Drug-Drug Interactions between Peficitinib (ASP015K) and Methotrexate in Patients with Rheumatoid Arthritis

BACKGROUND

Methotrexate is frequently used to treat rheumatoid arthritis. Peficitinib (ASP015K; Smyraf®), an oral Janus kinase inhibitor indicated for the treatment of rheumatoid arthritis, may be coadministered with methotrexate.

OBJECTIVE

The objective of this study was to investigate potential drug-drug interactions of peficitinib with methotrexate and the short-term safety of coadministration.

PATIENTS AND METHODS

This phase I, open-label, single-sequence study included patients with rheumatoid arthritis taking a stable dose of methotrexate. Patients received their prescribed methotrexate dose (Day 1) and then peficitinib (100 mg) twice daily from Day 3 until the morning of Day 9; a second methotrexate dose was coadministered with peficitinib on Day 8. Serial blood samples were collected for methotrexate concentration after dosing on Days 1 (methotrexate alone) and 8 (methotrexate plus peficitinib) and for peficitinib concentration after dosing on Days 7 (peficitinib alone) and 8 (methotrexate plus peficitinib). Pre-dose concentrations of peficitinib were measured (Days 3-8).

RESULTS

Peficitinib concentrations reached steady state on Day 5. Administration of peficitinib did not result in changes to methotrexate area under the concentration-time curve from time zero to infinity or maximum observed concentration following a methotrexate dose (15-25 mg), and there was no significant effect of methotrexate (15-25 mg) on peficitinib area under the concentration-time curve within a 12-hour dosing interval. There were no new tolerability or safety signals after coadministration of peficitinib and methotrexate. One patient experienced two serious adverse events and withdrew from the study without receiving peficitinib.

CONCLUSIONS

Pharmacokinetic results showed no significant interactions between peficitinib and methotrexate. CLINICALTRIALS.

GOV IDENTIFIER

NCT01754805.

Regulation of organic anion transporters: Role in physiology, pathophysiology, and drug elimination

The members of the organic anion transporter (OAT) family are mainly expressed in kidney, liver, placenta, intestine, and brain. These transporters play important roles in the disposition of clinical drugs, pesticides, signaling molecules, heavy metal conjugates, components of phytomedicines, and toxins, and therefore critical for maintaining systemic homeostasis. Alterations in the expression and function of OATs contribute to the intra- and inter-individual variability of the therapeutic efficacy and the toxicity of many drugs, and to many pathophysiological conditions. Consequently, the activity of these transporters must be highly regulated to carry out their normal functions. This review will present an update on the recent advance in understanding the cellular and molecular mechanisms underlying the regulation of renal OATs, emphasizing on the post-translational modification (PTM), the crosstalk among these PTMs, and the remote sensing and signaling network of OATs. Such knowledge will provide significant insights into the roles of these transporters in health and disease.

Clinical Implications of Folate Transport in the Central Nervous System

Folates are essential for key biosynthetic processes in mammalian cells and play a crucial role in the maintenance of central nervous system homeostasis. Mammals lack the metabolic capacity for folate biosynthesis; hence, folate requirements are largely met through dietary sources. To date, three major folate transport pathways have been characterized: the folate receptors (FRs), reduced folate carrier (RFC), and proton-coupled folate transporter (PCFT). This article reviews current knowledge on the role of folate transport systems in mediating folate delivery to vital tissues, particularly the brain, and how these pathways are modulated by various regulatory mechanisms. We will also briefly highlight the clinical significance of cerebral folate transport in relation to neurodevelopmental disorders associated with folate deficiency.

Drug interactions in the treatment of rheumatoid arthritis and psoriatic arthritis

BACKGROUND

Treating patients with inflammatory joint diseases (rheumatoid arthritis, psoriatic arthritis) according to established treatment algorithms often requires the simultaneous use of three or more medications to relieve symptoms and prevent long-term joint damage as well as disability.

OBJECTIVE

To assess and give an overview on drug-drug interactions in the pharmacotherapy of inflammatory joint diseases with regards to their clinical relevance.

METHODS

All possible drug combinations were evaluated using three commercially available drug interaction programs. In those cases where only limited/no data were found, a comprehensive hand search of Pubmed was carried out. Finally, the drug-drug interactions of all possible combinations were classified according to evidence-based medicine and a specifically generated relevance-based system.

RESULTS

All three interaction software programs showed consistent results. All detected interactions were combined in clearly structured tables.

CONCLUSION

A concise overview on drug-drug interactions is given. Especially in more sophisticated cases extensive knowledge of drug interactions supports optimisation of therapy and results in improved patient safety.

Effect of proton pump inhibitors on high-dose methotrexate elimination: a systematic review and meta-analysis

Background Drug interaction is one factor which may influence high-dose methotrexate (MTX) elimination. Proton pump inhibitors are commonly used as an adjuvant drugs in chemotherapy. However, the effect of proton pump inhibitors on high-dose MTX elimination is currently controversial. Objective To perform a systematic review and meta-analysis to assess the association between co-administration of proton pump inhibitors with plasma MTX concentration and delayed MTX elimination. Setting The Hospital of Kunming Medical University, China. Method We followed the PRISMA guidelines in this meta-analysis and systemic review. We searched PubMed, the Cochrane Database, Embase, the WHO International Clinical Trials Registry Platform, the Wanfang database, the Chinese National Knowledge Infrastructure, the VIP database and the Chinese BioMedical Literature Database. Main outcome measure The main outcome measures are: (1) the plasma MTX concentration at 24 h, 48 h and 72 h.; (2) the frequency of patients with delayed MTX elimination. Results Ten retrospective cohort studies were included in the meta-analysis, with a total of 2760 cycles of high-dose MTX treatment. A meta-analysis revealed that compared to patients who did not receive proton pump inhibitors, patients who received proton pump inhibitors had a significantly higher plasma MTX concentration at 24 h (mean difference 2.71 μM, 95% confidence interval 0.55 to 4.87; p = 0.01) and at 48 h (mean difference 0.14 μM, 95% confidence interval 0.06 to 0.21; p < 0.01) after the MTX infusion. Furthermore, delayed MTX elimination was more frequent in patients that received PPIs (risk ratio 0.59, 95% confidence interval 0.41 to 0.84; p = 0.004). Conclusion This systematic review and meta-analysis reveals that the co-administration of proton pump inhibitors with methotrexate is associated with delayed high-dose MTX elimination. Proton pump inhibitors should be cautiously given when co-administered with high-dose MTX treatment.

Concomitant febuxostat enhances methotrexate-induced hepatotoxicity by inhibiting breast cancer resistance protein

Methotrexate (MTX) is an antifolate agent used for the treatment of various malignancies and is eliminated by breast cancer resistance protein (BCRP). Because febuxostat (FBX) is known to inhibit BCRP activity, FBX might exacerbate MTX-related adverse effects. In this study, we examined the drug-drug interaction between FBX and MTX in BCRP-expressing membrane vesicles. Moreover, we retrospectively investigated the impact of FBX on MTX-related adverse effects in 38 patients (144 cycles) receiving high-dose MTX therapy (HDMTX). The Food and Drug Administration Adverse Event Reporting System (FAERS) database and human hepatocellular carcinoma cell line HepG2 cells were used to evaluate the effects of FBX on MTX-induced hepatotoxicity. In the membrane vesicle study, FBX significantly inhibited BCRP-mediated transport of MTX. Concomitant FBX significantly increased the incidence of hepatotoxicity, but not of nephrotoxicity and hematological toxicity in patients receiving HDMTX. FAERS database analyses revealed that the reporting odds ratio of FBX for MTX-induced hepatotoxicity was 4.16 (95% CI: 2.89-5.98). Co-incubated FBX significantly decreased the cell viability and increased cytotoxicity in MTX-treated HepG2 cells. These findings suggest that concomitant FBX enhances MTX-induced hepatotoxicity by inhibiting hepatic BCRP. These findings provide important information for the safe management of HDMTX therapy in clinical settings.

Activation of Protein Kinase A Stimulates SUMOylation, Expression, and Transport Activity of Organic Anion Transporter 3

Organic anion transporter 3 (OAT3) plays a vital role in removing a broad variety of anionic drugs from kidney, thus avoiding their possible toxicity in the body. We earlier established that activation of protein kinase C (PKC) enhances OAT3 ubiquitination, which promotes OAT3 internalization from the cell plasma membrane to intracellular endosomes and consequent degradation. As a result, OAT3 expression and transport activity are reduced. In the current study, we discovered that protein kinase A (PKA) had an opposite effect to PKC on the regulation of OAT3. We showed that activation of PKA by Bt2-cAMP stimulated OAT3 transport activity, which was largely caused by an enhanced plasma membrane expression of the transporter, kinetically reflected as an augmented maximal transport velocity V_max without notable alteration in substrate-binding affinity K_m. Additionally, we showed that PKA activation accelerated the rate of OAT3 recycling from intracellular compartments to the plasma membrane and decelerated the rate of OAT3 degradation. We further showed that OAT3 is subjected to post-translational modification by SUMO-2 and SUMO-3 not by SUMO-1. PKA activation enhanced OAT3 SUMOylation, which was accompanied by a reduced OAT3 ubiquitination. Finally, insulin-like growth factor 1 significantly stimulated OAT3 transport activity and SUMOylation through PKA signaling pathway. In conclusion, this is the first demonstration that PKA stimulated OAT3 expression and transport activity by altering the trafficking kinetics of OAT3 possibly through the crosstalk between SUMOylation and ubiquitination. Our studies are consistent with a remote sensing and signaling model for transporters (Wu et al. in Mol Pharmacol. 79(5):795-805, 2011).

The mechanistic links between insulin and human organic anion transporter 4

Human organic anion transporter 4 (hOAT4) belongs to a class of organic anion transporters that exert critical function in the secretion, absorption, and distribution of numerous drugs in the body, such as anti-viral drugs, anti-cancer therapeutics, antibiotics, antihypertensive medicine, and anti-inflammatory drugs. hOAT4 is richly existent in the kidney and placenta. We previously established that serum- and glucocorticoid-inducible kinases (sgk) stimulate hOAT4 expression and transport activity by abrogating the inhibitory effect of a ubiquitin ligase Nedd4-2. Insulin is one of the upstream signaling molecules for sgk. We therefore investigated the effect of insulin on hOAT4 function. We showed that insulin stimulated hOAT4 expression and transport activity, and the action of insulin was abolished in cells overexpressing Nedd4-2-specific siRNA to knockdown the endogenous Nedd4-2. We further showed that insulin phosphorylated serine 327 on Nedd4-2 and weakened the interaction between hOAT4 and Nedd4-2. Interestingly, in cells overexpressing sgk2, the stimulatory effect of insulin on hOAT4 was diminished. In addition, the stimulatory effect of insulin on hOAT4 was blocked by wortmannin and buparlisib, two PI3K inhibitors. In conclusion, our study demonstrated that insulin stimulates hOAT4 expression and transport activity by abrogating the inhibition effect of Nedd4-2 on the transporter. Moreover, insulin regulates hOAT4 by competing with sgk2 rather than through sgk2.

Enantioselective Drug Recognition by Drug Transporters

Drug transporters mediate the absorption, tissue distribution, and excretion of drugs. The cDNAs of P-glycoprotein, multidrug resistance proteins (MRPs/ABCC), breast cancer resistance protein (BCRP/ABCG2), peptide transporters (PEPTs/SLC15), proton-coupled folate transporters (PCFT/SLC46A1), organic anion transporting polypeptides (OATPs/SLCO), organic anion transporters (OATs/SLC22), organic cation transporters (OCTs/SLC22), and multidrug and toxin extrusions (MATEs/SLC47) have been isolated, and their functions have been elucidated. Enantioselectivity has been demonstrated in the pharmacokinetics and efficacy of drugs, and is important for elucidating the relationship with recognition of drugs by drug transporters from a chiral aspect. Enantioselectivity in the transport of drugs by drug transporters and the inhibitory effects of drugs on drug transporters has been summarized in this review.

[Renal toxicity of high-dose methotrexate]

INTRODUCTION

High-dose methotrexate (at least 1g/m²) is used to treat haematologic malignancies and osteosarcomas. Acute kidney injury is a well-known adverse-event after high-dose methotrexate and may lead to delayed drug elimination. Besides usual therapeutics (hyperhydration, urine alkalinisation, leucovorin rescue, renal replacement therapy), a costly specific enzymatic treatment (glucarpidase) is now available but its clinical impact remains elusive.

PATIENTS AND METHODS

We analysed high-dose methotrexate prescription charts in 11 clinical centres during the last 15 years to identify and describe adult patients who developed acute kidney injury (according to KDIGO classification). Glucarpidase use was recorded (French temporary regulatory approval criteria: methotrexate at least 10μmol/L at 48h or at least 3μmol/L at 48h associated with acute kidney injury).

RESULTS

Seventy-six acute kidney injury cases have been studied. Mean peak creatinine was 206μmol/L after a mean delay of 5.6 days, with 19 cases of stage 1 acute kidney injury (25%), 29 cases of stage 2 (38%) and 27 cases of stage 3 (36%). Anuria (one case) and need for renal replacement therapy (four cases) were unusual whereas fluid overload was often observed (29%). Three months after high-dose methotrexate treatment, mortality-rate was 17%, and 12% of surviving patients developed renal sequelae.

CONCLUSION

Sixty-one percent of patients received a glucarpidase perfusion during acute kidney injury. Despite a dramatic decrease of methotrexate serum levels, glucarpidase as compared with conservative treatment did not modify acute kidney injury stage, recovery delay, need for renal replacement therapy or the incidence of extrarenal toxicities. Net clinical benefit was not observed even after stratification according to eligibility criteria for glucarpidase use. Glucarpidase has probably no or little effects on methotrexate localized into tubular lumen or proximal tubular cells and that may account for the absence of nephroprotective effect for enzymatic treatment.

Transporter-mediated interaction of indican and methotrexate in rats

Indican (indoxyl-β-D-glucoside) is present in several Chinese herbs e.g. Isatis indigotica, Polygonum tinctorium and Polygonum perfoliatum. The major metabolite of indican was indoxyl sulfate (IS), an uremic toxin which was a known substrate/inhibitor of organic anion transporter (OAT) 1, OAT 3 and multidrug resistance-associated protein (MRP) 4. Methotrexate (MTX), an important immunosuppressant with narrow therapeutic window, is a substrate of OAT 1, 2, 3, 4 and MRP 1, 2, 3, 4. We hypothesized that IS, the major metabolite of oral indican, might inhibit the renal excretion of MTX mediated by OAT 1, OAT 3 and MRP 4. Therefore, this study investigated the effect of oral indican on the pharmacokinetics of MTX. Rats were orally given MTX with and without indican (20.0 and 40.0 mg/kg) in a parallel design. The serum MTX concentration was determined by a fluorescence polarization immunoassay. For mechanism clarification, phenolsulfonphthalein (PSP, 5.0 mg/kg), a probe substrate of OAT 1, OAT 3, MRP 2 and MRP 4, was intravenously given to rats with and without a intravenous bolus of IS (10.0 mg/kg) to measure the effect of IS on the elimination of PSP. The results indicated that 20.0 and 40.0 mg/kg of oral indican significantly increased the area under concentration–time curve_0-t (AUC_0-t) of MTX by 231% and 259%, prolonged the mean residence time (MRT) by 223% and 204%, respectively. Furthermore, intravenous IS significantly increased the AUC_0-t of PSP by 204% and decreased the Cl by 68%. In conclusion, oral indican increased the systemic exposure and MRT of MTX through inhibition on multiple anion transporters including OAT 1, OAT 3 and MRP 4 by the major metabolite IS.

Inhibition of Methotrexate Uptake via Organic Anion Transporters OAT1 and OAT3 by Glucuronides of Nonsteroidal Anti-inflammatory Drugs

Combination therapy of non-steroidal anti-inflammatory drugs (NSAIDs) and methotrexate (MTX) sometimes triggers adverse effects, such as liver injury, renal failure, gastrointestinal disorders, and myelosuppression, owing to the reduction of MTX clearance. Previous reports have suggested that NSAIDs inhibit renal MTX uptake via organic anion transporters (OATs) and reduced folate transporter (RFC)-1 and efflux via multidrug resistance-associated proteins (MRPs). Recently, our laboratory found inhibitory effects of NSAIDs-glucuronide (NSAIDs-Glu), a major metabolite of NSAIDs, on MRP-mediated MTX transport as a new site of interaction between MTX and NSAIDs. However, it remains unclear that whether NSAIDs-Glu inhibit renal uptake of MTX. Therefore, the present study aimed to evaluate inhibitory effects of several NSAIDs-Glu (diclofenac, R- and S-ibuprofen, R- and S-flurbiprofen, and R- and S-naproxen) on human OAT1 and OAT3-mediated MTX transport. In this study, [³H]MTX uptake was observed by using human OAT1 and OAT3-overexpressing HEK293 cells in the presence or absence of NSAIDs-Glu. All examined NSAIDs-Glu exhibited concentration-dependent inhibitory effects on MTX uptake via OAT1 and OAT3. Our results indicated that NSAIDs-Glu are more potent (5- to 15-fold) inhibitors of OAT3 than OAT1. Moreover, stereoselective inhibitory effects of NSAIDs-Glu on OATs-mediated MTX uptake were not observed, unlike on MRPs-mediated transport. These findings suggest that inhibition of OAT1 and OAT3-mediated renal uptake of MTX by plasma NSAIDs-Glu may be one of the competitive sites underlying complex drug interaction between MTX and NSAIDs.

Stereoselective Inhibition of Renal Basolateral Human Organic Anion Transporter 3 by Lansoprazole Enantiomers

Lansoprazole, a proton pump inhibitor, potently inhibits human organic anion transporter, hOAT3 (SLC22A8). Lansoprazole has an asymmetric atom in its structure and is clinically administered as a racemic mixture of (R)-and (S)-enantiomers. However, little is known about the stereoselective inhibitory potencies of lansoprazole against hOAT3 and its homolog, hOAT1. In the present study, the stereoselective inhibitory effect of lansoprazole was evaluated using hOAT1-and hOAT3-expressing cultured cells. hOAT1 and hOAT3 transported [14C]p-aminohippurate and [3H]estrone-3-sulfate (ES) with Michaelis-Menten constants of 29.8 ± 4.0 and 30.1 ± 9.0 µmol/L respectively. Lansoprazole enantiomers inhibited hOAT1- and hOAT3-mediated transport of each substrate in a concentration-dependent manner. The IC50 value of (S)-lansoprazole against hOAT3-mediated transport of [3H]ES (0.61 ± 0.08 µmol/L) was significantly lower than that of (R)-lansoprazole (1.75 ± 0.31 µmol/L). In contrast, stereoselectivity was not demonstrated for the inhibition of hOAT1. Furthermore, (S)-lansoprazole inhibited hOAT3-mediated transport of pemetrexed and methotrexate (hOAT3 substrates) more strongly than the corresponding (R)-lansoprazole. This study is the first to demonstrate that the stereoselective inhibitory potency of (S)-lansoprazole against hOAT3 is greater than that of (R)-lansoprazole. The present findings provide novel information about the drug interactions associated with lansoprazole.

Drug Repositioning of Proton Pump Inhibitors for Enhanced Efficacy and Safety of Cancer Chemotherapy

Proton pump inhibitors (PPIs), H⁺/K⁺-ATPase inhibitors, are the most commonly prescribed drugs for the treatment of gastroesophageal reflux and peptic ulcer diseases; they are highly safe and tolerable. Since PPIs are frequently used in cancer patients, studies investigating interactions between PPIs and anticancer agents are of particular importance to achieving effective and safe cancer chemotherapy. Several studies have revealed that PPIs inhibit not only the H⁺/K⁺-ATPase in gastric parietal cells, but also the vacuolar H⁺-ATPase (V-ATPase) overexpressed in tumor cells, as well as the renal basolateral organic cation transporter 2 (OCT2) associated with pharmacokinetics and/or renal accumulation of various drugs, including anticancer agents. In this mini-review, we summarize the current knowledge regarding the impact of PPIs on the efficacy and safety of cancer chemotherapeutics via inhibition of targets other than the H⁺/K⁺-ATPase. Co-administration of clinical doses of PPIs protected kidney function in patients receiving cisplatin and fluorouracil, presumably by decreasing accumulation of cisplatin in the kidney via OCT2 inhibition. In addition, co-administration or pretreatment with PPIs could inhibit H⁺ transport via the V-ATPase in tumor cells, resulting in lower extracellular acidification and intracellular acidic vesicles to enhance the sensitivity of the tumor cells to the anticancer agents. In the present mini-review, we suggest that PPIs enhance the efficacy and safety of anticancer agents via off-target inhibition (e.g., of OCT2 and V-ATPase), rather than on-target inhibition of the H⁺/K⁺-ATPase. The present findings should provide important information to establish novel supportive therapy with PPIs during cancer chemotherapy.

Renal organic anion transporters in drug-drug interactions and diseases

The kidney plays a vital role in maintaining systemic homeostasis. Active tubular secretion and reabsorption, which are mainly mediated by transporters, is an efficient mechanism for retaining glucose, amino acids, and other nutrients and for the clearance of endogenous waste products and xenobiotics. These substances are recognized by uptake transporters located in the basolateral and apical membranes of renal proximal tubule cells and are extracted from plasma and urine. Organic anion transporters (OATs) belong to the solute carrier (SLC) 22 superfamily and facilitate organic anions across the plasma membranes of renal proximal tubule cells. OATs are responsible for the transmembrane transport of anionic and zwitterionic organic molecules, including endogenous substances and many drugs. The alteration in OAT expression and function caused by diseases, drug-drug interactions (DDIs) or other issues can thus change the renal disposition of substrates, induce the accumulation of toxic metabolites, and lead to unexpected clinically outcome. This review summarizes the recent information regarding the expression, regulation, and substrate spectrum of OATs and discusses the roles of OATs in diseases and DDIs. These findings will enables us to have a better understanding of the related disease therapy and the potential risk of DDIs mediated by OATs.

Effects of proton pump inhibitors and famotidine on elimination of plasma methotrexate: Evaluation of drug-drug interactions mediated by organic anion transporter 3

Methotrexate (MTX) is an antifolate agent used in the treatment of numerous types of cancer, and eliminated by active tubular secretion via organic anion transporter 3 (OAT3). Gastric antisecretory drugs, such as proton pump inhibitors (PPIs) and histamine H₂ receptor antagonists, are widely used among patients with cancer in clinical practice. The aim of the present study was to analyse the potential drug-drug interactions between MTX and gastric antisecretory drugs in high-dose MTX (HD-MTX) therapy. The impact of PPIs on the plasma MTX concentration on 73 cycles of HD-MTX therapy was analysed retrospectively in 43 patients. Also investigated was the involvement of OAT3 in PPI-MTX drug interaction in an in vitro study using human OAT3 expressing HEK293 cells. In a retrospective study, patients who received a PPI had significantly higher MTX levels at 48 h (0.38 vs. 0.15 μmol l^-1 , respectively, p = 0.000018) and 72 h (0.13 vs. 0.05 μmol l^-1 , respectively, p = 0.0002) compared with patients who did not receive a PPI (but received famotidine). Moreover, in vitro experiments demonstrated that PPIs (esomeprazole, lansoprazole, omeprazole and rabeprazole) inhibited hOAT3-mediated uptake of MTX in a concentration-dependent manner (IC₅₀ values of 0.40-5.5 μ m), with a rank order of lansoprazole > esomeprazole > rabeprazole > omeprazole. In contrast to PPIs, famotidine showed little inhibitory effect on hOAT3-mediated MTX uptake. These results demonstrated that co-administration of PPI, but not famotidine, could result in a pharmacokinetic interaction that increases the plasma MTX levels, at least in part, via hOAT3 inhibition.

Delayed methotrexate elimination: Incidence, interaction with antacid drugs, and clinical consequences?

The aim of this retrospective cohort study was to investigate the incidence of delayed methotrexate elimination in patients treated with high-dose methotrexate (≥1 g/m² ) for haematological malignancy and to identify the impact of interacting drugs, especially proton-pump inhibitors (PPIs) and ranitidine. All patients treated with high-dose methotrexate over a 6 year period in the haematology department of the Lyon Sud University Hospital (Hospices Civils de Lyon, France) were included. Potential risk factors for delayed methotrexate elimination were tested in a generalized linear model by univariate analysis: patient age, gender, methotrexate dose, administration of PPI or ranitidine, and concomitant nephrotoxic drugs. A total of 412 cycles of methotrexate were administered to 179 patients. Proton-pump inhibitors were co-administered with methotrexate in 127 cycles and ranitidine in 192 cycles. Ninety-three cycles included no antacid drugs. A total of 918 plasma methotrexate assays were performed. Methotrexate concentrations were checked at 24 hours in 92% of cycles. Delayed methotrexate elimination was observed in 20.9% of cycles. A total of 63 cycles with delayed methotrexate elimination were only identified on plasma methotrexate measures at 72 hours: ie, plasma methotrexate was in the normal range at 24 and 48 hour post injection. Use of PPI/ranitidine or no antacid drugs did not increase risk of delayed elimination, with respectively delayed methotrexate elimination in 20.5%, 21.9%, and 19.4% of cycles (P = .89). Impaired baseline creatinine clearance showed significant association in univariate analysis. Fifteen patients showed grade 1 acute kidney injury, 1 grade 2, 2 grade 3, and none grade 4. For half of these cases, delayed methotrexate elimination was observed and the 2 grade 3 events appeared in patients treated with PPIs. This retrospective study suggests that there is no association between concomitant use of proton-pump inhibitors (pantoprazole and esomeprazole) or ranitidine and delayed methotrexate elimination.

Renal Drug Transporters and Drug Interactions

Transporters in proximal renal tubules contribute to the disposition of numerous drugs. Furthermore, the molecular mechanisms of tubular secretion have been progressively elucidated during the past decades. Organic anions tend to be secreted by the transport proteins OAT1, OAT3 and OATP4C1 on the basolateral side of tubular cells, and multidrug resistance protein (MRP) 2, MRP4, OATP1A2 and breast cancer resistance protein (BCRP) on the apical side. Organic cations are secreted by organic cation transporter (OCT) 2 on the basolateral side, and multidrug and toxic compound extrusion (MATE) proteins MATE1, MATE2/2-K, P-glycoprotein, organic cation and carnitine transporter (OCTN) 1 and OCTN2 on the apical side. Significant drug-drug interactions (DDIs) may affect any of these transporters, altering the clearance and, consequently, the efficacy and/or toxicity of substrate drugs. Interactions at the level of basolateral transporters typically decrease the clearance of the victim drug, causing higher systemic exposure. Interactions at the apical level can also lower drug clearance, but may be associated with higher renal toxicity, due to intracellular accumulation. Whereas the importance of glomerular filtration in drug disposition is largely appreciated among clinicians, DDIs involving renal transporters are less well recognized. This review summarizes current knowledge on the roles, quantitative importance and clinical relevance of these transporters in drug therapy. It proposes an approach based on substrate-inhibitor associations for predicting potential tubular-based DDIs and preventing their adverse consequences. We provide a comprehensive list of known drug interactions with renally-expressed transporters. While many of these interactions have limited clinical consequences, some involving high-risk drugs (e.g. methotrexate) definitely deserve the attention of prescribers.

Potential Drug Interactions Mediated by Renal Organic Anion Transporter OATP4C1

Organic anion-transporting polypeptide 4C1 (OATP4C1) is an organic anion transporter expressed in the basolateral membrane of the renal proximal tubules. It plays a major role in the urinary excretion of both exogenous drugs and endogenous compounds. Our previous studies have indicated the importance of OATP4C1 in pathologic and physiologic conditions; however, the majority of its pharmacologic characteristics remained unclear. Therefore, to provide essential information for clinical drug therapy decisions and drug development, we clarified drug interactions mediated by OATP4C1. To elucidate potential drug interactions via OATP4C1, we screened 53 representative drugs commonly used in clinical settings. Next, we evaluated the IC₅₀ values of drugs that inhibited OATP4C1 by more than 50%. To apply our results to clinical settings, we calculated the drug-drug interaction (DDI) indices. The screening analysis using an OATP4C1-expressing cell system demonstrated that 22 out of 53 therapeutic drugs inhibited OATP4C1-mediated triiodothyronine transport. In particular, OATP4C1-mediated transport was strongly inhibited by 10 drugs. The IC₅₀ values of 10 drugs-nicardipine, spironolactone, fluvastatin, crizotinib, levofloxacin, clarithromycin, ritonavir, saquinavir, quinidine, and verapamil-obtained in this study were 51, 53, 41, 24, 420, 200, 8.5, 4.3, 100, and 110 µM, respectively. The IC₅₀ values of these drugs were higher than the plasma concentrations obtained in clinical practice. However, ritonavir showed the highest DDI index (1.9) for OATP4C1, suggesting that it may strongly influence this transporter and thus cause drug interactions seen in clinical settings. Our finding gives new insight into the role of OATP4C1 in clinical DDIs.

Clinical pharmacokinetics of methotrexate in oncology

Methotrexate is an antifolate agent used in the treatment of autoimmune diseases and various types of cancers. It is a unique antiproliferative agent because it can be administered by multiple routes with a wide variation of dosing. Methotrexate pharmacokinetics have generated numerous papers focusing on descriptive data and pharmacodynamics. Methotrexate is one of the rare anticancer agents which pharmacokinetics are routinely monitoring to control excessive toxicity when administrated at high dose (>1 g/m2). The identification of transporters involved in its disposition has permitted the understanding and the prevention of most drug interactions. Pharmacogenetic factors affecting the expression of MRP2 and OATP1B1 partly explain the interindividual variability of methotrexate clearance. The remaining challenge in methotrexate pharmacokinetics is to further understand unexplained delayed renal elimination despite the implementation of preventive measures.

Evaluation of para-Aminosalicylic Acid as a Substrate of Multiple Solute Carrier Uptake Transporters and Possible Drug Interactions with Nonsteroidal Anti-inflammatory Drugs In Vitro

para-Aminosalicylic acid (PAS) is a second-line antituberculosis drug that has been used to treat multidrug-resistant and extensively drug-resistant tuberculosis for more than 60 years. Renal secretion and glomerular filtration are the major pathways for the elimination of PAS. We comprehensively studied PAS transport by using cell lines that overexpressed various transporters and found that PAS acts as a novel substrate of an organic anionic polypeptide (OATP1B1), organic cationic transporters (OCT1 and OCT2), and organic anion transporters (OAT1 and OAT3) but is not a substrate of any ATP-binding cassette (ABC) transporters. Net PAS uptake was measured, and the transport affinities (K_m values) for OATP1B1, OCT1, OCT2, OAT1, and OAT3 were found to be 50.0, 20.3, 28.7, 78.1, and 100.1 μM, respectively. The net uptake rates suggested that renal OAT1 and OAT3 play relatively major roles in PAS elimination. The representative inhibitors rifampin for OATP1B1, probenecid for OAT1 and OAT3, and verapamil for OCT1 and OCT2 greatly inhibited PAS uptake, suggesting that PAS is dependent on multiple transporters for uptake. We also evaluated nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs), and metformin for the inhibition of PAS uptake via these transporters. Half-maximal (50%) inhibitory concentrations (IC₅₀s) were kinetically determined and used to predict the drug-drug interactions (DDIs) affecting these transporters' activity toward PAS. We found that rifampin, probenecid, ibuprofen, naproxen, cimetidine, and quinidine each exhibited a significant potential for in vivo DDIs with PAS. In this study, PAS was found to be a novel substrate of several transporters, and drugs that inhibit these transporters can reduce PAS elimination.

Organic anion transporters 1 (OAT1) and OAT3 meditated the protective effect of rhein on methotrexate-induced nephrotoxicity

Rhein protects methotrexate induced kidney damage mediated by OAT1 and OAT3.

Inhibitory Interaction Potential of 22 Antituberculosis Drugs on Organic Anion and Cation Transporters of the SLC22A Family

Twenty-two currently marketed antituberculosis drugs were comprehensively evaluated for their inhibitory effect on organic anionic transporter (OAT)- and organic cation transporter (OCT)-mediated uptake using stably transfected HEK293 cells in vitro We observed moderate to strong inhibitory effects on OAT1- and OAT3-mediated para-aminohippurate (PAH) uptake and OCT1- and OCT2-mediated N-methyl-4-phenylpylidinium acetate (MPP+) uptake. Ciprofloxacin, linezolid, para-aminosalicylic acid (PAS), and rifampin were observed to have strong inhibitory effects, with the concentrations for a 50% inhibitory effect (IC50s) being 35.1, 31.1, 37.6, and 48.1 μM, respectively, for OAT1 and >100, 21.9, 24.6, and 30.2 μM, respectively, for OAT3. Similarly, pyrazinamide, rifabutin, and levofloxacin were observed to have inhibitory effects, with IC50 values being 36.5, 42.7, and 30.3 μM, respectively, for OCT1 and with the IC50 value for PAS being 94.2 μM for OCT2. In addition, we used zidovudine and metformin as clinically prescribed substrates of OATs and OCTs, respectively, and zidovudine and metformin uptake was also strongly inhibited by the antituberculosis drugs. Among the tested drugs, the highest drug-drug interaction (DDI) indexes were found for PAS, which were 9.3 to 13.9 for OAT1 and 12.0 to 17.7 for OAT3, and linezolid, which were 1.18 to 2.15 for OAT1 and 1.7 to 3.01 for OAT3. Similarly, the DDI indexes of pyrazinamide and levofloxacin were 0.57 and 0.30, respectively, for OCT1, and the DDI index of PAS was 3.8 for OCT2, suggesting a stronger possibility (DDI index value cutoff, >0.1) of in vivo DDIs. This is the first comprehensive report of the inhibitory potential of anti-TB drugs on OAT- and OCT-mediated uptake of prototype and clinically prescribed substrate drugs in vitro, providing an ability to predict DDIs between anti-TB drugs and other coprescribed drugs in clinical studies in vivo.

Lansoprazole Exacerbates Pemetrexed-Mediated Hematologic Toxicity by Competitive Inhibition of Renal Basolateral Human Organic Anion Transporter 3

Pemetrexed, a multitargeted antifolate, is eliminated by tubular secretion via human organic anion transporter 3 (hOAT3). Although proton pump inhibitors (PPIs) are frequently used in cancer patients, the drug interaction between PPIs and pemetrexed remains to be clarified. In this study, we examined the drug interaction between pemetrexed and PPIs in hOAT3-expressing cultured cells, and retrospectively analyzed the impact of PPIs on the development of hematologic toxicity in 108 patients who received pemetrexed and carboplatin treatment of nonsquamous non-small cell lung cancer for the first time between January 2011 and June 2015. We established that pemetrexed was transported via hOAT3 (Km = 68.3 ± 11.1 µM). Lansoprazole, rabeprazole, pantoprazole, esomeprazole, omeprazole, and vonoprazan inhibited hOAT3-mediated uptake of pemetrexed in a concentration-dependent manner. The inhibitory effect of lansoprazole was much greater than those of other PPIs and the apparent IC50 value of lansoprazole against pemetrexed transport via hOAT3 was 0.57 ± 0.17 µM. The inhibitory type of lansoprazole was competitive. In a retrospective study, multivariate analysis revealed that coadministration of lansoprazole, but not other PPIs, with pemetrexed and carboplatin was an independent risk factor significantly contributing to the development of hematologic toxicity (odds ratio: 10.004, P = 0.005). These findings demonstrated that coadministration of lansoprazole could exacerbate the hematologic toxicity associated with pemetrexed, at least in part, by competitive inhibition of hOAT3. Our results would aid clinicians to make decisions of coadministration drugs to avoid drug interaction-induced side effects for achievement of safe and appropriate chemotherapy with pemetrexed.

P-gp, MRP2 and OAT1/OAT3 mediate the drug-drug interaction between resveratrol and methotrexate

The purpose of present study was to investigate the effect of resveratrol (Res) on altering methotrexate (MTX) pharmacokinetics and clarify the related molecular mechanism. Res significantly increased rat intestinal absorption of MTX in vivo and in vitro. Simultaneously, Res inhibited MTX efflux transport in MDR1-MDCK and MRP2-MDCK cell monolayers, suggesting that the target of drug interaction was MDR1 and MRP2 in the intestine during the absorption process. Furthermore, there was a significant decrease in renal clearance of MTX after simultaneous intravenous administration. Similarly, MTX uptake was markedly inhibited by Res in rat kidney slices and hOAT1/3-HEK293 cell, indicating that OAT1 and OAT3 were involved in the drug interaction in the kidney. Additionally, concomitant administration of Res decreased cytotoxic effects of MTX in hOAT1/3-HEK293 cells, and ameliorated nephrotoxicity caused by MTX in rats. Conversely, intestinal damage caused by MTX was not exacerbated after Res treatment. In conclusion, Res enhanced MTX absorption in intestine and decreased MTX renal elimination by inhibiting P-gp, MRP2, OAT1 and OAT3 in vivo and in vitro. Res improved MTX-induced renal damage without increasing intestinal toxicity.

[Proton Pump Inhibitor and High-dose Methotrexate: Two Cases Reports]

Methotrexate (MTX) is a cytotoxic agent prescribed at high dose in treatment of malignancy. Association of MTX to proton pump inhibitor (PPI) is not recommended if doses are more than 20 mg per weeks and only to take into account for smaller doses. Review relate some cases of delayed elimination of methotrexate in patients taking PPI, which increase risk of toxic event. However, currently there is no status quo on interaction between PPI and MTX according to available data. We report two clinical cases illustrating one more time a toxic event to MTX in presence of PPI. In absence of risk/benefit ratio set correctly, an assessment of appropriateness of PPI prescription before MTX therapy can limit an iatrogenic risk.