Cost-Effectiveness Analysis of FOLFIRI-Based First-Line Regimens for Metastatic Colorectal Cancer Using Clinical Decision Analysis.

OBJECTIVE: Metastatic colorectal cancer with KRAS wild type is treated using a range of drug regimens, including fluorouracil, irinotecan, and Leucovorin(FOLFIRI)plus bevacizumab(Bmab), cetuximab(Cmab), or panitumumab(Pmab). The present study aimed to identify the optimal regimen using a decision analysis method, in combination with clinical and economic evidence. METHOD: A simple Markov model with a monthly cycle time was constructed. Probabilistic variables for input into the model were derived from randomized controlled trials. Direct costs for the drugs, laboratory analyses, and medical staff were calculated and used in the model. RESULTS: The expected survival times and costs of FOLFIRI alone and combination therapies were 20.9 months and 2,299,198 yen for FOLFIRI, 29.9 months and 8,929,888 yen for Bmab, 27.8 months and 11,811,849 yen for Cmab, and 22.6 months and 8,795,622 yen for Pmab. The incremental cost-effectiveness ratios to FOLFIRI were 736,743 yen/month for Bmab, 1,378,645 yen/month for Cmab, and 3,821,426 yen/month for Pmab. CONCLUSIONS: These findings suggested that these regimens were not sufficiently cost-effective, although they have excellent therapeutic efficacy. From the economic point of view, these combination regimens were inferior to FOLFIRI alone.

Cost-Effectiveness Analysis of Cyclin-Dependent Kinase 4/6 Inhibitor Palbociclib for Inoperable or Recurrent Breast Cancer.

BACKGROUND: Palbociclib and endocrine therapy has been approved to treat hormone receptor-positive/human epidermal growth factor receptor 2-negative inoperable or recurrent breast cancer in Japan. However, this cotherapy imposes an economic burden on both patients and society because of its high cost. In this study, we assessed the cost-effectiveness of cotherapy with palbociclib and fulvestrant compared to fulvestrant monotherapy for inoperable or recurrent breast cancer. METHODS: The three-state Markov model was built by taking into count health stats in inoperable or recurrent breast cancer. The clinical outcomes of the therapies were drawn from published randomized controlled trials. Total regimen cost was calculated from medical receipts of patients at the Yamagata University Hospital. The cost-effectiveness was evaluated by the incremental cost-effectiveness ratio(ICER), in case that it was below 400,000 Yen per month. Markov chain Monte Carlo simulation was performed to assess probability. RESULTS: Acquisition cost of palbociclib and fulvestrant and fulvestrant monotherapy was 6,209,554 JPY and 780,870 JPY, and 25.7 and 22.8 months were achieved, respectively. ICER for the cotherapy was 1,847,721 JPY/quality adjusted life month(QALM)gained. CONCLUSIONS: The palbociclib and fulvestrant therapy provided better health outcomes than conventional fulvestrant monotherapy, but were costly and suggested to be less cost-effective.

The Effectiveness of Antidiabetic Drugs in Treating Dementia: A Peek into Pharmacological and Pharmacokinetic Properties.

Dementia dramatically affects the activities of daily living and quality of life; thus, many therapeutic approaches for overcoming dementia have been developed. However, an effective treatment regimen is yet to be developed. As diabetes is a well-known risk factor for dementia, drug repositioning and repurposing of antidiabetic drugs are expected to be effective dementia treatments. Several observational studies have been useful for understanding the effectiveness of antidiabetic drugs in treating dementia, but it is difficult to conclusively analyze the association between antidiabetic drug treatment and the risk of developing dementia after correcting for potential confounding factors. Mechanism-based approaches may provide a better understanding of the effectiveness of antidiabetic drugs for treating dementia. Since the peripheral circulation and the central nerve system are separated by the blood-brain barrier, it is important to understand the regulation of the central glucose metabolism. In this review, we discuss the pharmacological and pharmacokinetic properties of antidiabetic drugs in relation to treating dementia.

Binding of Citrate-Fe3+ to Plastic Culture Dishes, an Artefact Useful as a Simple Technique to Screen for New Iron Chelators.

NaCT mediates citrate uptake in the liver cell line HepG2. When these cells were exposed to iron (Fe3+), citrate uptake/binding as monitored by the association of [14C]-citrate with cells increased. However, there was no change in NaCT expression and function, indicating that NaCT was not responsible for this Fe3+-induced citrate uptake/binding. Interestingly however, the process exhibited substrate selectivity and saturability as if the process was mediated by a transporter. Notwithstanding these features, subsequent studies demonstrated that the iron-induced citrate uptake/binding did not involve citrate entry into cells; instead, the increase was due to the formation of citrate-Fe3+ chelate that adsorbed to the cell surface. Surprisingly, the same phenomenon was observed in culture wells without HepG2 cells, indicating the adsorption of the citrate-Fe3+ chelate to the plastic surface of culture wells. We used this interesting phenomenon as a simple screening technique for new iron chelators with the logic that if another iron chelator is present in the assay system, it would compete with citrate for binding to Fe3+ and prevent the formation and adsorption of citrate-Fe3+ to the culture well. This technique was validated with the known iron chelators deferiprone and deferoxamine, and with the bacterial siderophore 2,3-dihydroxybenzoic acid and the catechol carbidopa.

Metabolic Alteration Analysis of Steroid Hormones in Niemann-Pick Disease Type C Model Cell Using Liquid Chromatography/Tandem Mass Spectrometry.

Niemann-Pick disease type C (NPC) is an autosomal recessive disease caused by a functional deficiency of cholesterol-transporting proteins in lysosomes, and exhibits various clinical symptoms. Since mitochondrial dysfunction in NPC has recently been reported, cholesterol catabolism to steroid hormones may consequently be impaired. In this study, we developed a comprehensive steroid hormone analysis method using liquid chromatography/tandem mass spectrometry (LC-MS/MS) and applied it to analyze changes in steroid hormone concentrations in NPC model cells. We investigated the analytical conditions for simultaneous LC-MS/MS analysis, which could be readily separated from each other and showed good reproducibility. The NPC phenotype was verified as an NPC model with mitochondrial abnormalities using filipin staining and organelle morphology observations. Steroid hormones in the cell suspension and cell culture medium were also analyzed. Steroid hormone analysis indicated that the levels of six steroid hormones were significantly decreased in the NPC model cell and culture medium compared to those in the wild-type cell and culture medium. These results indicate that some steroid hormones change during NPC pathophysiology and this change is accompanied by mitochondrial abnormalities.

High-throughput liquid chromatography/electrospray ionization-tandem mass spectrometry method using in-source collision-induced dissociation for simultaneous quantification of imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib in human plasma.

Recent studies have shown that therapeutic drug monitoring of tyrosine kinase inhibitors (TKIs) could improve treatment efficacy and safety. A simple analytical method using high-performance LC/electrospray ionization-tandem mass spectrometry has been developed and validated for simultaneous quantification of BCR-ABL and Bruton's TKIs used for chronic leukemia (imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib) in human plasma. Although these structures and physical properties are similar, owing to their different linear ranges, simultaneously determining the plasma levels of these five TKIs by applying optimal MS parameters remains difficult. A quantitative range exceeding 60,000-fold was required, and the linear dynamic ranges of imatinib, bosutinib, and nilotinib were limited because of the presence of a saturated detection signal. In this study, we applied the in-source collision-induced dissociation technique to control the ion amounts in mass spectrometry. This new method allowed rapid determination within 5 min with simple pretreatment. The method was validated according to the US Food and Drug Administration guidelines. Moreover, all samples of patients with chronic leukemia were successfully measured and their values were within the linear range of measurement. Therefore, our high-throughput analytical system is useful to measure the plasma concentrations of imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib in clinical practice.

Development of a simultaneous analytical method for clozapine and its metabolites in human plasma using liquid chromatography/electrospray ionization tandem mass spectrometry with linear range adjusted by in-source collision-induced dissociation.

Clozapine (CLZ) is a key drug in treatment-resistant schizophrenia. Therapeutic drug monitoring (TDM) of CLZ and its metabolites, N-desmethylclozapine and clozapine N-oxide, is required to monitor and manage the risks of side effects. Although quantification methods for TDM have been developed for CLZ and its metabolites, they were not sufficiently accurate for the quantification of CLZ owing to the upper limits of the calibration curves. An analytical method using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry was developed and validated for the simultaneous measurement of CLZ and its metabolites in human plasma. To expand the concentration range of the calibration curves, we used a linear range shift technique using in-source collision-induced dissociation (CID). Using our approach, the linearity and quantitative range were improved compared to those reported by previous studies, and were sufficient for TDM in clinical practice. The intra- and inter-assay accuracy was 84.6%-114.8%, and the intra- and inter-assay precisions were ≤9.1% and ≤9.9%, respectively. Moreover, all samples from patients with treatment-resistant schizophrenia were successfully quantified. Therefore, our novel analytical method using in-source CID had the appropriate performance to measure the plasma concentrations of CLZ and its metabolites for TDM in clinical practice.

Simultaneous analysis of drugs administered to lung-transplanted patients using liquid chromatography-tandem mass spectrometry for therapeutic drug monitoring.

Several drugs are administered to lung-transplanted patients, which are monitored using therapeutic drug monitoring (TDM). Therefore, we developed and validated a liquid chromatography-tandem mass spectrometry method to simultaneously analyze immunosuppressive drugs such as mycophenolic acid, antifungal drugs such as voriconazole and itraconazole, and its metabolite hydroxyitraconazole. Chromatographic separation was achieved using a C18 column and gradient flow of mobile phase comprising 20 mM aqueous ammonium formate and 20 mM ammonium formate-methanol solution. A simple protein precipitation treatment was performed using acetonitrile/methanol and mycophenolic acid-2 H3 , voriconazole-2 H3 , itraconazole-2 H4 , and hydroxyitraconazole-2 H4 as internal standards. The linearity ranges of mycophenolic acid, voriconazole, itraconazole, and hydroxyitraconazole were 100-20,000, 50-10,000, 5-1000, and 5-1000 ng/mL, respectively. The retention time of each target was less than 2 min. The relative errors in intra- and inter-day were within ±7.6%, the coefficient of variation was 8.9% or less for quality control low, medium, and high, and it was 15.8% or less for lower limit of quantitation. Moreover, the patient samples were successfully quantified, and they were within the linear range of measurements. Therefore, our new method may be useful for TDM in lung-transplanted patients.

Development of a Diagnostic Screening Strategy for Niemann-Pick Diseases Based on Simultaneous Liquid Chromatography-Tandem Mass Spectrometry Analyses of N-Palmitoyl-O-phosphocholine-serine and Sphingosylphosphorylcholine.

Early diagnosis of Niemann-Pick diseases (NPDs) is important for better prognosis of such diseases. N-Palmitoyl-O-phosphocholine-serine (PPCS) is a new NPD biomarker possessing high sensitivity, and with its combination with sphingosylphosphocholine (SPC) it may be possible to distinguish NPD-C from NPD-A/B. In this study, a rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method (method 1) and a validated LC-MS/MS analysis (method 2) of PPCS and SPC were developed, and we have proposed a diagnostic screening strategy for NPDs using a combination of serum PPCS and SPC concentrations. Nexera and API 5000 were used as LC-MS/MS systems. C18 columns with lengths of 10 and 50 mm were used for method 1 and 2, respectively. 2H3-Labeled PPCS and nor-SPC were used as internal standards. Selective reaction monitoring in positive-ion mode was used for MS/MS. Run times of 1.2 and 8 min were set for methods 1 and 2, respectively. In both methods 1 and 2, two analytes showed high linearity in the range of 1-4000 ng/mL. Method 2 provided high accuracy and precision in method validation. Serum concentrations of both analytes were significantly higher in NPD-C patients than those of healthy subjects in both methods. Serum PPCS correlated between methods 1 and 2; however, it was different in the case of SPC. The serum PPCS/SPC ratio was different in healthy subjects, NPD-C, and NPD-A/B. These results suggest that using a combination of the two LC-MS/MS analytical methods for PPCS and SPC is useful for diagnostic screening of NPDs.

Altered bile acid composition and disposition in a mouse model of non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is a progressive inflammatory and fibrotic disease. However, the progression mechanism of NASH is not well understood. Bile acids are endogenous molecules that regulate cholesterol homeostasis, lipid solubilization in the intestinal lumen, and metabolic signaling via several receptors. In this study, we investigated the relationship between bile acid composition and NASH-associated fibrosis using a mouse model fed choline-deficient, L-amino-acid-defined, high-fat diet with 0.1% methionine (CDAHFD). C57BL/6 J mice fed CDAHFD developed NASH and fibrosis within few weeks. With the progress of NASH-associated liver fibrosis, altered bile acid composition was observed in the liver, bile, and peripheral plasma. Decreased mRNA levels of bile acid metabolizing enzymes such as Cyp7a1 and Baat were observed in contrast to increased Sult2a1 level in the liver. Increased mRNA levels of Ostß and Abcc4 and decreased in mRNA levels of Bsep, Abcc2, Ntcp, and Oatp1b2, suggesting that bile acids efflux from hepatocytes into the peripheral plasma rather than into bile. In conclusion, the changes in bile acid metabolizing enzymes and transporters expression, resulting in increasing the total bile acid concentration in the plasma, signify a protection mechanism by the hepatocyte to reduce hepatotoxicity during disease progression to NASH but may promote liver fibrosis.

Transport Mechanisms for the Nutritional Supplement ß-Hydroxy-ß-Methylbutyrate (HMB) in Mammalian Cells.

PURPOSE: ß-Hydroxy-ß-methylbutyrate (HMB), a nutritional supplement, elicits anabolic activity in muscle. Here we investigated the mechanism of HMB uptake in muscle cells. METHODS: Murine muscle cells (C2C12) and human mammary epithelial cells (MCF7) were used for uptake. As HMB is a monocarboxylate, focus was on monocarboxylate transporters, monitoring interaction of HMB with H+-coupled lactate uptake, and influence of H+ directly on HMB uptake. Involvement of MCT1-4 was studied using selective inhibitors and gene silencing. Involvement of human Na+/monocarboxylate transporter SMCT1 was also assessed using Xenopus oocytes. RESULTS: H+-coupled lactate uptake was inhibited by HMB in both mammalian cells. HMB uptake was H+-coupled and inhibited by lactate. C2C12 cells expressed MCT1 and MCT4; MCF7 cells expressed MCT1-4; undifferentiated C2C12 cells expressed SMCT1. SMCT1 mediated Na+-coupled HMB transport. Inhibitors of MCT1/4, siRNA-mediated gene silencing, and expression pattern showed that MCT1-4 were responsible only for a small portion of HMB uptake in these cells. CONCLUSION: HMB uptake in C2C12 and MCF7 cells is primarily H+-coupled and inhibited by lactate, but MCT1-4 are only partly responsible for HMB uptake. SMCT1 also transports HMB, but in a Na+-coupled manner. Other, yet unidentified, transporters mediate the major portion of HMB uptake in C2C12 and MCF7 cells.

Carbidopa is an activator of aryl hydrocarbon receptor with potential for cancer therapy.

Carbidopa is used with l-DOPA (l-3,4-dihydroxyphenylalanine) to treat Parkinson's disease (PD). PD patients exhibit lower incidence of most cancers including pancreatic cancer, but with the notable exception of melanoma. The decreased cancer incidence is not due to l-DOPA; however, the relevance of Carbidopa to this phenomenon has not been investigated. Here, we tested the hypothesis that Carbidopa, independent of l-DOPA, might elicit an anticancer effect. Carbidopa inhibited pancreatic cancer cell proliferation both in vitro and in vivo Based on structural similarity with phenylhydrazine, an inhibitor of indoleamine-2,3-dioxygenase-1 (IDO1), we predicted that Carbidopa might also inhibit IDO1, thus providing a molecular basis for its anticancer effect. The inhibitory effect was confirmed using human recombinant IDO1. To demonstrate the inhibition in intact cells, AhR (aryl hydrocarbon receptor) activity was monitored as readout for IDO1-mediated generation of the endogenous AhR agonist kynurenine in pancreatic and liver cancer cells. Surprisingly, Carbidopa did not inhibit but instead potentiated AhR signaling, evident from increased CYP1A1 (cytochrome P450 family 1 subfamily A member 1), CYP1A2, and CYP1B1 expression. In pancreatic and liver cancer cells, Carbidopa promoted AhR nuclear localization. AhR antagonists blocked Carbidopa-dependent activation of AhR signaling. The inhibitory effect on pancreatic cancer cells in vitro and in vivo and the activation of AhR occurred at therapeutic concentrations of Carbidopa. Chromatin immunoprecipitation assay further confirmed that Carbidopa promoted AhR binding to its target gene CYP1A1 leading to its induction. We conclude that Carbidopa is an AhR agonist and suppresses pancreatic cancer. Hence, Carbidopa could potentially be re-purposed to treat pancreatic cancer and possibly other cancers as well.

Fructose suppresses uric acid excretion to the intestinal lumen as a result of the induction of oxidative stress by NADPH oxidase activation.

BACKGROUND: A high intake of fructose increases the risk for hyperuricemia. It has been reported that long-term fructose consumption suppressed renal uric acid excretion and increased serum uric acid level. However, the effect of single administration of fructose on excretion of uric acid has not been clarified. METHODS: We used male Wistar rats, which were orally administered fructose (5g/kg). Those rats were used in each experiment at 12h after administration. RESULTS: Single administration of fructose suppressed the function of ileal uric acid excretion and had no effect on the function of renal uric acid excretion. Breast cancer resistance protein (BCRP) predominantly contributes to intestinal excretion of uric acid as an active homodimer. Single administration of fructose decreased BCRP homodimer level in the ileum. Moreover, diphenyleneiodonium (DPI), an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox), recovered the suppression of the function of ileal uric acid excretion and the Bcrp homodimer level in the ileum of rats that received single administration of fructose. CONCLUSIONS: Single administration of fructose decreases in BCRP homodimer level, resulting in the suppression the function of ileal uric acid excretion. The suppression of the function of ileal uric acid excretion by single administration of fructose is caused by the activation of Nox. The results of our study provide a new insight into the mechanism of fructose-induced hyperuricemia.

Functional characterization of 5-oxoproline transport via SLC16A1/MCT1.

Thyrotropin-releasing hormone is a tripeptide that consists of 5-oxoproline, histidine, and proline. The peptide is rapidly metabolized by various enzymes. 5-Oxoproline is produced by enzymatic hydrolysis in a variety of peptides. Previous studies showed that 5-oxoproline could become a possible biomarker for autism spectrum disorders. Here we demonstrate the involvement of SLC16A1 in the transport of 5-oxoproline. An SLC16A1 polymorphism (rs1049434) was recently identified. However, there is no information about the effect of the polymorphism on SLC16A1 function. In this study, the polymorphism caused an observable change in 5-oxoproline and lactate transport via SLC16A1. The Michaelis constant (Km) was increased in an SLC16A1 mutant compared with that in the wild type. In addition, the proton concentration required to produce half-maximal activation of transport activity (K0.5, H (+)) was increased in the SLC16A1 mutant compared with that in the wild type. Furthermore, we examined the transport of 5-oxoproline in T98G cells as an astrocyte cell model. Despite the fact that 5-oxoproline is an amino acid derivative, Na(+)-dependent and amino acid transport systems scarcely contributed to 5-oxoproline transport. Based on our findings, we conclude that H(+)-coupled 5-oxoproline transport is mediated solely by SLC16A1 in the cells.

Determination of ω-6 and ω-3 PUFA metabolites in human urine samples using UPLC/MS/MS.

The ω-6 and ω-3 polyunsaturated fatty acids (PUFAs) such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are the precursors of various bioactive lipid mediators including prostaglandins, thromboxanes, leukotrienes, hydroxyeicosatetraenoic acid, isoprostanes, lipoxins, and resolvins (Rvs). These lipid mediators play important roles in various physiological and pathological processes. The quantitative determination of PUFA metabolites seems necessary for disease research and for developing biomarkers. However, there is a paucity of analytical methods for the quantification of ω-6 and ω-3 PUFA metabolites­the specialized pro-resolving mediators (SPMs) present in the human urine. We developed a method for the quantification of ω-6 and ω-3 PUFA metabolites present in human urine using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS). The developed method shows good linearity, with a correlation coefficient >0.99 for all of the analytes. The validation results indicate that our method is adequately reliable, accurate, and precise. The method was successfully used to examine urine samples obtained from 43 healthy volunteers. We could identify 20 PUFA metabolites, and this is the first report of the quantitative determination of RvD1, 17(R)-RvD1, 11-dehydro thromboxane B3, RvE2, and 5(S)-HETE in human urine. The urinary 8-iso PGF(2α) and PGE2 levels were significantly higher in the men smokers than in the men nonsmokers (p < 0.05). In this study, we developed an accurate, precise, and novel analytical method for estimating the ω-6 and ω-3 PUFA metabolites, and this is the first report that the SPMs derived from EPA and DHA are present in human urine.

Regorafenib is transported by the organic anion transporter 1B1 and the multidrug resistance protein 2.

Regorafenib is a small molecule inhibitor of tyrosine kinases, and has been shown to improve the outcomes of patients with advanced colorectal cancer and advanced gastrointestinal stromal tumors. The transport profiles of regorafenib by various transporters were evaluated. HEK293/organic anion transporting polypeptide 1B1 (OATP1B1) cells exhibited increased drug sensitivity to regorafenib. Regorafenib inhibited the uptake of 3H-estrone sulfate by HEK293/OATP1B1 cells in a dose-dependent manner, but did not affect its elimination by P-glycoproteins. The concentration of regorafenib was significantly lower in LLC-PK1/multidrug resistance protein 2 (MRP2) cells than in LLC-PK1 cells treated with the MRP2 inhibitor, MK571. MK571 abolished the inhibitory effects of regorafenib on intracellular accumulation in LLC-PK1/MRP2 cells. The uptake of regorafenib was significantly higher in HEK293/OATP1B1 cells than in OATP1B1-mock cells. Transport kinetics values were estimated to be Km=15.9 µM and Vmax=1.24 nmol/mg/min. No significant difference was observed in regorafenib concentrations between HEK293/OATP1B3 and OATP1B3-mock cells. These results indicated that regorafenib is a substrate for MRP2 and OATP1B1, and also suggest that the substrate preference of regorafenib may implicate the pharmacokinetic profiles of regorafenib.

Immunoprotective effect of epigallocatechin-3-gallate on oral anticancer drug-induced α-defensin reduction in Caco-2 cells.

The aim of this study was to determine the effect of interaction between tegafur (FT) and epigallocatechin-3-gallate (EGCG) on the expression of α-defensins (HD-5: human α-defensin 5, HD-6: human α-defensin 6) by using a Caco-2 cell line as a model of human intestinal epithelial cells. This is the first study in which the effect of interaction of an oral anticancer drug and functional food on the innate immune system was examined. α-Defensins are abundant constituents of mouse and human paneth cells and play a role in the innate immune system in intestine. We detected HD-5 and HD-6 mRNA in Caco-2 cells and evaluated the effects of FT and EGCG on these mRNA levels. HD-5 and HD-6 mRNA levels were decreased by exposure to FT. Production of reactive oxygen species (ROS) was induced by exposure to FT as well as H2O2 exposure, and EGCG suppressed FT-induced production of ROS. Furthermore, FT-induced decrease in HD-5 and HD-6 mRNA levels was almost completely suppressed by EGCG. These results indicate that EGCG restored the decrease of α-defensins induced by FT at the transcriptional level in Caco-2 cells, suggesting that EGCG can be used as adjunctive therapy in chemotherapy.

Alteration of pharmacokinetics of grepafloxacin in type 2 diabetic rats.

PURPOSE: Patients with type 2 diabetes are generally treated with various pharmacological compounds and are exposed to a high risk of drug-drug interactions. However, alterations of pharmacokinetics in a type 2 diabetes model have been obscure. The present study was undertaken to investigate the effects of type 2 diabetes on the pharmacokinetics of the fluoroquinolone grepafloxacin (GPFX) and the expression level of P-glycoprotein (P-gp), one of the drug efflux transporters. METHODS: We used Goto-Kakizaki (GK) rats, a lean model of type 2 diabetes. Plasma concentration and intestinal, renal, and biliary clearance of GPFX were measured after intravenous and intraintestinal administration in Wistar and GK rats. Real-time PCR and Western blotting were used to assess mRNA and protein expression levels. RESULTS: We found a significant increase in the plasma concentrations of GPFX at 90, 120 and 240 minutes after intraintestinal administration in GK rats compared with the concentrations in Wistar rats but not after intravenous administration. The increase in plasma GPFX concentration was associated with reduction in jejunal clearance of GPFX caused by a decrease in secretory transport of GPFX. However, there was no correlation between the decrease in secretory transport of GPFX and P-gp expression level. CONCLUSION: Type 2 diabetic conditions alter P-gp function as well as expression level and correlate poorly with each other.

Intestinal P-glycoprotein expression is multimodally regulated by intestinal ischemia-reperfusion.

PURPOSE: Reactive oxygen species (ROS) have multiple physiological effects that are amount-dependent. ROS are one of the causes of intestinal ischemia-reperfusion (I/R) injury. In this study, we investigated whether the amount of ROS and the degree of intestinal I/R injury affect the expression level of P-glycoprotein (P-gp). METHODS: . We used hydrogen peroxide (H2O2) as ROS in in vitro experiments. Intestinal I/R model rats, which were subjected 15-min ischemia (I/R-15), were used in in vivo experiments. RESULTS: P-gp expression in Caco-2 cells was increased in response to 1 µM of H2O2 but decreased upon exposure to 10 mM of H2O2. We previously reported that P-gp expression is decreased after intestinal I/R with 30-min ischemia (I/R-30), which time a large amount of ROS is generated. I/R-15 induced slightly less mucosal and oxidative injury than did I/R-30. P-gp expression in the jejunum was increased at 1 h after I/R-15, and ileal paracellular permeability was increased. The blood concentration of tacrolimus, a P-gp substrate, was lower during 0-20 min but was higher during 40-90 min post-administration compared with that in the sham-operated rats. P-gp expression in the ileum was decreased at 6 h after I/R-15, due to abnormal localization of P-gp, resulting in a high blood tacrolimus concentration in rats reperfused for 6 h. CONCLUSIONS: ROS multimodally regulate P-gp expression depending on its amount. This is important for understanding the pattern of P-gp expression after intestinal I/R.

Quercetin-3-rhamnoglucoside (rutin) stimulates transport of organic anion compounds mediated by organic anion transporting polypeptide 2B1.

Quercetin-3-rhamnoglucoside (rutin) has a wide spectrum of biochemical and pharmacological activities. Rutin is absorbed mainly in its unmetabolized form. Organic anion transporting polypeptide (OATP) 2B1 is a major uptake transporter in the intestine. Thus, it is important for the prevention of adverse events to understand drug interactions mediated by OATP2B1 in the absorption process. This study assessed the effect of rutin on transport by OATP2B1. Rutin stimulated the uptake of estrone-3-sulfate (E-3-S), taurocholic acid (TCA), cholic acid (CA) and rosuvastatin by OATP2B1, but not p-coumaric acid or ferulic acid. The EC50 of rutin for transport by OATP2B1 was 2.32 µm. The Km value of E-3-S for OATP2B1 in the presence of rutin (9.21 µm) was almost the same as that in the absence of rutin (8.53 µm). On the other hand, the Vmax of E-3-S transport by OATP2B1 in the presence of rutin (270 pmol/mg protein/min) was 1.2-fold higher than that in the absence of rutin (218 pmol/mg protein/min). Moreover, the expression level of OATP2B1 on the cell membrane was increased by treatment with rutin for 5 min without alteration of the total OATP2B1 expression level. Moreover, the increase in the localization of OATP2B1 at the cell surface was detected by the immunocytochemistry. The stimulatory effect of rutin is a little weak but may affect the absorption of OATP2B1 substrates, because rutin is taken daily in foods and its intestinal concentration would reach the stimulatory range of OATP2B1.