Hideyuki Motohashi

Expression Levels of Renal Organic Anion Transporters (OATs) and Their Correlation with Anionic Drug Excretion in Patients with Renal Diseases

AbstractPurpose. Because the urinary excretion of drugs is often decreased in renal diseases, dosage regimens are adjusted to avoid adverse drug reactions. The aim of present study was to clarify the alteration in the levels of renal drug transporters and their correlation with the urinary drug excretion in renal diseases patients. Methods. We quantified the mRNA levels of human organic anion transporters (hOATs) by real-time polymerase chain reaction and examined the excretion of the anionic drug, cefazolin, in renal disease patients. Moreover, transport of cefazolin by hOAT1 and hOAT3 were examined using HEK293 transfectants. Results. Among four hOATs, the level of hOAT1 mRNA was significantly lower in the kidney of patients with renal diseases than in the normal controls. The elimination constant of cefazolin showed a significant correlation with the values of phenolsulfonphthalein test and mRNA levels of hOAT3. The uptake study using HEK293 transfectants revealed that cefazolin and phenolsulfonphthalein were transported by hOAT3. Conclusions. These results suggest that hOAT3 plays an important role for anionic drug secretion in patients with renal diseases and that the expression levels of drug transporters may be related to the alteration of renal drug secretion.

Analysis of regulatory polymorphisms in organic ion transporter genes (SLC22A) in the kidney.

AbstractOrganic cation transporters (OCTs) and organic anion transporters (OATs) (SLC22A family) play crucial roles in the renal secretion of various drugs. Messengar ribonucleic acid (mRNA) expression of transporters can be a key factor regulating interindividual differences in drug pharmacokinetics. However, the source of variations in mRNA levels of transporters is unclear. In this study, we focused on single nucleotide polymorphisms (SNP) in the promoter region [regulatory SNPs (rSNPs)] as candidates for the factor regulating mRNA levels of SLC22A. We sequenced the promoter regions of OCT2 and OAT1–4 in 63 patients and investigated the effects of the identified rSNPs on transcriptional activities and mRNA expression. In the OCT2 promoter region, one deletion polymorphism (−578_−576delAAG) was identified; −578_−576delAAG significantly reduced OCT2 promoter activity (p < 0.05), and carriers of −578_−576delAAG tend to have lower OCT2 mRNA levels, but the difference is not significant. There was no rSNP in the OAT1 and OAT2 genes. The five rSNPs of OAT3 and one rSNP of OAT4 were unlikely to influence mRNA expression and promoter activity. This is the first study to investigate the influences of rSNPs on mRNA expression of SLC22A in the kidney and to identify a regulatory polymorphism affecting OCT2 promoter activity.

Pharmacokinetic Significance of Renal OAT3 (SLC22A8) for Anionic Drug Elimination in Patients with Mesangial Proliferative Glomerulonephritis

PurposeOur previous studies showed that the mRNA level of human organic anion transporter (hOAT) 3 in the kidney was correlated with the rate of elimination of an anionic antibiotic cefazolin. However, the correlation coefficient was not so high. In the present study, therefore, we enrolled more patients to examine whether additional factors were responsible for the correlation.MethodshOAT mRNA levels in renal biopsy specimens were quantified using the real-time polymerase chain reaction method. The elimination rates for the free fraction of cefazolin were determined in patients with various renal diseases.ResultsIn the present study, the coefficient of correlation between the hOAT3 mRNA level and the elimination rates for the free fraction of cefazolin was not so high in the patients overall as in our previous study (r = 0.536). However, following the classification of renal diseases, a better correlation was obtained in patients with mesangial proliferative glomerulonephritis (r = 0.723). In contrast, multiple regression analyses including gender, age, and liver function did not result in any improvements in the correlation coefficients.ConclusionsThese results suggest that the hOAT3 mRNA level is a significant marker of pharmacokinetics with which to predict the rate of elimination of cefazolin in patients with mesangial proliferative glomerulonephritis.

Common single nucleotide polymorphisms of the MDR1 gene have no influence on its mRNA expression level of normal kidney cortex and renal cell carcinoma in Japanese nephrectomized patients

AbstractIn this study, we have quantified the mRNA expression levels of multidrug resistance gene 1 (MDR1) in the normal kidney cortex and renal cell carcinoma (RCC) segments from 24 Japanese nephrectomized patients by real-time polymerase chain reaction (PCR). The mRNA expression level of MDR1 in RCC segments was significantly decreased in comparison with each normal segment (P=0.0042, by Students paired t-test). In addition, the ten common single nucleotide polymorphisms (SNPs) of the MDR1 gene in the patients were assessed using the PCR-restriction enzyme fragment length polymorphism method to investigate the influence of these SNPs on its mRNA expression levels. The allele frequencies of these SNPs were comparable with our previous report in the Japanese recipients of living-donor liver transplantation (Goto et al., Pharmacogenetics 12:451-457; 2002). MDR1 expression levels in the normal kidney cortex were independent on the five SNPs, which were polymorphic in the Japanese population. Furthermore, the effect of the SNPs on expression levels of MDR1 mRNA in RCC segments was not recognized. These findings suggest that the common SNPs in the MDR1 gene have no influence on the expression of its transcript in RCC segments as well as in the normal kidney cortex.

Pharmacokinetics and pharmacodynamics of paclitaxel with carboplatin or gemcitabine, and effects of CYP3A5 and MDR1 polymorphisms in patients with urogenital cancers

BackgroundWe investigated the pharmacokinetics and pharmacodynamics of paclitaxel with carboplatin or gemcitabine in patients with urogenital cancer to clarify the significance of monitoring of the serum concentration of paclitaxel.MethodsPaclitaxel was administered at 175 mg/m2 or 150 mg/m2 to patients with hormone-refractory prostate cancer (n = 10) or advanced transitional cell carcinoma (n = 6) along with carboplatin or gemcitabine, respectively. The relationships between pharmacokinetic parameters and hematological adverse effects, as well as pharmacological effects, were examined. The effects of patient characteristics, including single-nucleotide polymorphisms of MDR1(ABCB1), CYP2C8, CYP3A4, and CYP3A5, on the total body clearance of paclitaxel were evaluated.ResultsTotal body clearance and volume of distribution at a steady-state after the intravenous infusion of paclitaxel were not significantly different between patients with carboplatin or gemcitabine. The percent decreases in neutrophils and platelets for the regimen with gemcitabine were significantly greater than those with carboplatin, and showed a significant positive relationship with the observed concentration at the end of infusion or time above 0.1-µM concentration of paclitaxel. Post-therapy decreases in prostate-specific antigen were not positively correlated with the extent of paclitaxel exposure in the prostate cancer patients. Neither the polymorphisms at exon 26 (C3435T) and at exon 21 (G2677A/T) in MDR1 nor the CYP3A5*1 allele significantly affected the total body clearance of paclitaxel.ConclusionThe hematological side effects of paclitaxel were intensified by gemcitabine, and were correlated with paclitaxel pharmacokinetics. Monitoring of the serum concentration of paclitaxel will facilitate the therapy, with less myelosuppression and without any loss of therapeutic efficacy.

Effects of tacrolimus and cyclosporin A on peptide transporter PEPT1 in Caco-2 cells.

Tacrolimus and cyclosporin A (CsA) are used as immunosuppressive agents in clinical medicine, particularly in the area of organ transplantation. Despite the beneficial immunosuppressive effects of tacrolimus and CsA in clinical transplantation, both immunosuppressants appear to have adverse effects such as nephrotoxicity, hepatotoxicity and neurotoxicity (1,2). Gastrointestinal side effects of these immunosuppressants such as nausea, bloating, and diarrhea have also been reported in humans (1,2). In liver transplant recipients, severe gastrointestinal toxicity was associated with chronic tacrolimus therapy (3). In normal rats, weight gain was reduced by high-dose CsA whether given orally or by subcutaneous injection (4). Oral CsA reduced in vivo fat absorption from the diet, and all doses and routes of administration of CsA caused reduction of both active glucose uptake and of passive fatty acid absorption by the intestine in vitro (4). The peptide transporter in the small intestine has been considered to play a key role in maintenance of protein nutrition (5–7). This transporter is specific for peptides consisting of two or three amino acids. The physiological role of the peptide transport system is to mediate the absorption of small peptides generated by the digestion of dietary proteins. It has been shown that the absorption of protein digestion in the small intestine occurs primarily in the form of small peptides. In addition, it was suggested that enteral solutions containing small peptides may provide an absorptive advantage in patients with severely reduced intestinal absorptive area and in those who are acutely catabolic (6). This enteral peptide transporter was cloned as PEPT1 and it is considered as an intestinal peptide transporter (5–7). In the present study, we investigated the effects of tacrolimus and CsA on the intestinal peptide transporter in the human colon adenocarcinoma cell line Caco-2, which is a useful model to study intestinal epithelial transport.

Hypokalemia and Related Symptoms by Yokukansan in Patients withBehavioral and Psychological Symptoms of Dementia (BPSD): ARetrospective Study of Elderly Inpatients

Yokukansan is a Japanese traditional medicine that has been used for behavioral and psychological symptoms of dementia. Although the efficacy of Yokukansan have been reported, few studies have focused on its adverse effects. In this study, the adverse effects in hospitalized patients treated with Yokukansan were evaluated retrospectively and compared with those listed in the Japanese Adverse Drug Event Report database from the Pharmaceutical and Medical Device Agency. A total of 21 patients who were prescribed Yokukansan at Rakuwakai Otowa Hospital from April 2013 to September 2013 were registered as subjects for this study. Patient profiles, such as age, gender, serum potassium levels, AST and ALT, were evaluated. Serum potassium levels decreased significantly from 4.3 ± 0.6 mEq/L to 3.6 ± 0.4 mEq/L after treatment with Yokukansan, and 61.9% of the patients demonstrated hypokalemia. In addition, the pre-treatment serum potassium levels were associated with the induction of hypokalemia by Yokukansan. The onset date of hypokalemia was varied from 2 to 1,154 days in Otowa data and from 2 to 1,533 days in JADER data. In terms of the number of days to the onset of hypokalemia, there was no significant difference between the Rakuwakai Otowa Hospital and results of Japanese Adverse Drug Event Report database. It is necessary to pay attention to patients during the treatment with Yokukansan, even if treatment period was long term.