Biopharmaceutics & Drug Disposition最新文献

The blood–brain barrier (BBB) expresses a high abundance of transporters, particularly P-glycoprotein (P-gp), that regulate endogenous and exogenous molecule uptake and removal of waste. This review discusses key drug metabolism and pharmacokinetic considerations for the efflux transporter P-gp at the BBB in drug discovery and development. We highlight the differences in P-gp expression and protein levels across species but the limited observations of species-specific substrates. Given the impact of age and disease on BBB biology, we summarise the modulation of P-gp for several neurological disorders and ageing and exemplify several disease-specific hurdles or opportunities for drug exposure in the brain. Furthermore, the review includes observations of CNS-related drug-drug interactions due to the inhibition or induction of P-gp at the BBB in animal studies and humans and the need for continued evaluation especially for compounds with a narrow therapeutic window. This review focusses primarily on small molecules but also considers the impact of new chemical entities, particularly beyond Ro5 molecules and their potential to be recognised as P-gp substrates as well as advanced drug delivery systems which offer an alternative approach to achieve and sustain central nervous system exposure.

It was reported that high-dose cyclosporine at 500 mg daily increases edoxaban exposure. We investigated whether cyclosporine <500 mg daily leads to edoxaban-induced bleeding in the clinical setting. This case series study included patients receiving edoxaban and cyclosporine at Mie University Hospital. The outcomes were bleeding and anticoagulant markers, including activated partial thromboplastin time (APTT), prothrombin time (PT), and the international normalized ratio of prothrombin time (PT-INR). We examined the genotypes of cytochrome P450 3A5 (CYP3A5), multidrug resistance 1 (ABCB1), and solute carrier organic anion transporter 1B1 (SLCO1B1). Trends in anticoagulant markers were analyzed. Thirteen patients received edoxaban (standard dose; n = 3 and reduced dose; n = 10) and cyclosporine (1.94 ± 1.42 mg/kg). A bleeding event occurred in one patient receiving a standard dose of edoxaban plus cyclosporine of 25 mg daily (HAS-BLED score of 2 and genotypes; CYP3A5*3/*3, ABCB1 3435CT, and SLCO1B1*1a/*1b). After edoxaban treatment, anticoagulant markers were prolonged (APTT; 27.95 ± 3.64 s vs. 31.11 ± 3.90 s, p < 0.001, PT; 11.53 ± 1.01 s vs. 13.03 ± 0.98 s, p = 0.002, PT-INR; 0.98 ± 0.09 vs. 1.11 ± 0.11, p = 0.007). In summary, the genotypes of CYP3A5, ABCB1, and SLCO1B1 and the dosage of edoxaban may affect the risk of bleeding by edoxaban when co-administered with cyclosporine, even at low doses.

HepaRG cells are highly-differentiated human hepatoma cells, which are increasingly recognized as a convenient cellular model for in vitro evaluation of hepatic metabolism, transport, and/or toxicity of drugs. The present study was designed to evaluate whether HepaRG cells can also be useful for studying drug-mediated inhibition of canalicular and/or sinusoidal hepatic efflux of bile acids, which constitutes a major mechanism of drug-induced liver toxicity. For this purpose, HepaRG cells, initially loaded with the bile acid taurocholate (TC), were reincubated in TC-free transport assay medium, in the presence or absence of calcium or drugs, before analysis of TC retention. This method allowed us to objectivize and quantitatively measure biliary and sinusoidal efflux of TC from HepaRG cells, through distinguishing cellular and canalicular compartments. In particular, time-course analysis of the TC-free reincubation period of HepaRG cells, that is, the efflux period, indicated that a 20 min-efflux period allowed reaching biliary and sinusoidal excretion indexes for TC around 80% and 60%, respectively. Addition of the prototypical cholestatic drugs bosentan, cyclosporin A, glibenclamide, or troglitazone during the TC-free efflux phase period was demonstrated to markedly inhibit canalicular and sinusoidal secretion of TC, whereas, by contrast, incubation with the noncholestatic compounds salicylic acid or flumazenil was without effect. Such data therefore support the use of human HepaRG cells for in vitro predicting drug-induced liver toxicity (DILI) due to the inhibition of hepatic bile acid secretion, using a biphasic TC loading/efflux assay.

The estimation of the contributions of UDP-glucuronosyl transferase (UGT) isoforms to the overall metabolism still suffers from technical difficulties due to limited information on enzyme levels in recombinant systems and specific inhibitors, unlike the case for cytochrome P450s (CYPs). The protein expression levels of UGT in both recombinant system microsomes (RM) and human liver microsomes (HLM) were quantified using liquid chromatography-tandem mass spectrometry, and the relative expression factor (REF) value of HLM to recombinant microsomes was estimated to evaluate the fractions of drug metabolism by a single UGT enzyme (fmUGT) of UGT substrates. The REF values of UGT1A1, UGT1A3, UGT1A9, UGT2B4, UGT2B7, and UGT2B17 were 0.228, 0.0714, 0.0665, 0.420, 0.118, and 0.0442, respectively. fmUGTs in HLM were estimated for several typical UGT substrates utilizing these values and metabolic clearances in RM. These values were comparable to the reported values estimated by various methods. This study provided useful information on REF values, which promote a robust estimation of fmUGT values for UGT substrates when evaluating the contribution of UGT isoforms to total metabolic clearance.

Fourteen isoforms of the monocarboxylate transporter (MCT) have been reported. Among the MCT isoforms, MCT1, MCT2, and MCT4 play a role in l-lactate/proton cotransport and are involved in the balance of intracellular energy and pH. Therefore, MCT1, MCT2, and MCT4 are associated with energy metabolism processes in normal and pathological cells. In the present study, we evaluated the expression of MCT1, MCT2, and MCT4 and the contribution of these three MCT isoforms to l-lactate uptake in hepatocellular carcinoma (HCC) cells. In HepG2 and Huh-7 cells, l-lactate transport was pH-dependent, which is characteristic of MCT1, MCT2, and MCT4. Furthermore, l-lactate uptake was selectively inhibited by MCT1 and MCT4 inhibitors in HepG2 and Huh-7 cells. Kinetic analysis of HepG2 cells demonstrated that l-lactate uptake was biphasic. Although the knockdown of MCT1 and MCT4 in the HepG2 cells decreased the uptake of l-lactate, the knockdown of MCT2 had no effect on the uptake of l-lactate. Consequently, we concluded that both MCT1 and MCT4 were involved in the transport of l-lactate in HepG2 and Huh-7 cells at pH 6.0. In contrast, PXB-cells, freshly isolated hepatocytes from humanized mouse livers, showed lower MCT4 expression and l-lactate uptake at pH 6.0 compared to that in HCC cell lines. In conclusion, MCT4, which contributes to l-lactate transport in HCC cells, is significantly different in HCC compared to normal hepatocytes, and has potential as a target for HCC treatment.

Valproic acid (VPA) is well-known as a histone deacetylase (HDAC) inhibitor. It has been reported that HDAC inhibitors enhance basal and aryl hydrocarbon receptor (AhR) ligand-induced aryl hydrocarbon receptor-responsive gene expression. Other studies suggested that HDAC inhibition might significantly activate the NF-E2-related factor-2 (Nrf2). Moreover, VPA activates mitogen-activated protein kinases (MAPKs). MAPK pathways regulate Nrf2 transactivation domain activity. Uridine 5′-diphospho-glucuronosyltransferase (UGT) 1A6 is one of the important isoforms to affect drug pharmacokinetics. UGT1A6 gene is regulated transcriptionally by AhR and Nrf2. The present study aimed to investigate whether UGT1A6 expression was changed by VPA and to elucidate the mechanism of the alteration. Following VPA treatment for 72 h in Caco-2 cells, UGT1A6 mRNA was increased by 7.9-fold. Moreover, UGT1A6 mRNA was increased by other HDAC inhibitors, suggesting that HDAC inhibition caused the UGT1A6 mRNA induction. AhR and Nrf2 proteins in the nucleus of Caco-2 cells were increased by 1.5- and 1.7-fold, respectively, following the VPA treatment. However, VPA treatment did not activate the extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) pathways in Caco-2 cells. In conclusion, we observed that VPA induced UGT1A6 mRNA expression via AhR and Nrf2 pathways, but not via the ERK or JNK pathways.

Sofosbuvir is a direct acting antiviral (DAA) approved for the treatment of hepatitis C virus (HCV). Sofosbuvir is a substrate of P-glycoprotein (P-gp). For this reason, inhibitors, or inducers of intestinal P-gp may alter the plasma concentration of sofosbuvir and increase or decrease its efficacy causing a significant change in its pharmacokinetic parameters. The purpose of the study was to evaluate the pharmacokinetic interaction between either aged garlic or ginkgo biloba extracts with sofosbuvir through targeting P-gp as well as possible toxicities in rats. Rats were divided into four groups and treated for 14 days with saline, verapamil (15 mg/kg, PO), aged garlic extract (120 mg/kg, PO), or ginkgo biloba extract (25 mg/kg, PO) followed by a single oral dose of sofosbuvir (40 mg/kg). Validated LC-MS/MS was used to determine sofosbuvir and its metabolite GS-331007 in rat plasma. Aged garlic extract caused a significant decrease of sofosbuvir AUC_(0−t) by 36%, while ginkgo biloba extract caused a significant increase of sofosbuvir AUC_(0−t) by 11%. Ginkgo biloba extract exhibited a significant increase of the sofosbuvir t_1/2 by 60%, while aged garlic extract significantly increased the clearance of sofosbuvir by 63%. The pharmacokinetic parameters of GS-331007 were not affected. The inhibitory action of ginkgo biloba on P-gp and the subsequent increase in the sofosbuvir plasma concentration did not show a significant risk of renal or hepatic toxicity. Conversely, although aged garlic extracts increased intestinal P-gp expression, they did not alter the C_max and T_max of sofosbuvir and did not induce significant hepatic or renal toxicities.

Hemorrhage events occur most frequently in anticoagulant therapy for non-valvular atrial fibrillation (NVAF). Rivaroxaban is used widely for routine anticoagulation care. Genetic polymorphisms are thought to contribute to the wide intraindividual variability seen in rivaroxaban metabolism and the anticoagulant response. The aim of this study was to evaluate the effect of drug transport related single-nucleotide polymorphisms (SNPs) on rivaroxaban metabolism and on the risk of a hemorrhage event. A total of 216 Chinese patients with NVAF were enrolled in the study. Rivaroxaban was used for anticoagulation therapy. Rivaroxaban plasma concentrations were detected using a validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. Seven SNPs in four genes were genotyped using the Sanger dideoxy DNA sequencing method. Associations between genotype variants, the incidence of hemorrhage events, and the time of bleeding were analyzed. ABCB1 2677G (rs2032582) variation was highly associated with the dose-adjusted rivaroxaban peak concentration in plasma (C_max/D) (p = 0.025, FDR = 0.042). The ABCB1 G allele carriers had a higher rivaroxaban C_max/D than non-carriers. Logistic regression showed that rivaroxaban C_max/D and ABCB1 genotype variants were associated with a higher incidence of hemorrhage events. No statistically significant difference was found between ABCB1 genotypes and the time of bleeding after anticoagulant therapy in 30 days. These results indicated that ABCB1 2677G (rs2032582) genetic variant affects the rivaroxaban C_max/Dose and the incidence of hemorrhage events significantly.

In the adult liver, drug-metabolizing enzymes such as cytochrome P450 (CYP) efficiently metabolize drugs by forming an expression pattern called “zonation” structure around the central veins (CV). However, most previous studies on CYPs have focused on the expression levels of CYP mRNA and proteins in the whole liver. In this study, we analyzed not only the expression levels of Cyp2c family mRNAs and proteins in mice during fetal liver development, but also the relationship with their localization. In the whole fetal liver, Cyp2c mRNA and protein were hardly expressed. On the other hand, zonation analysis results showed that only some cells around the CV of the fetal liver expressed Cyp2c. In addition, the protein expression level of Cyp2c in the whole liver during the neonatal period started from postnatal day (P) 7 in both males and females, while the zonation was weakly formed from P5. This study suggested that fetal liver cannot metabolize Cyp2c substrate drugs transferred from mother to fetus due to the low expression of Cyp2c and unformed zonation. The expression level of Cyp2c protein in neonates was lower than that in adult liver, and the zonation structure was not clear, suggesting that drug metabolism was not sufficient. Furthermore, this study revealed that the expression level of Cyp2c does not correlate with the formation of zonation structures, because Cyp2c expression is found in hepatocytes near the CV even in the fetal and neonatal stages, when Cyp2c protein expression is hardly detectable in the whole liver.

Febuxostat is recommended by the American College of Rheumatology Gout Management Guidelines as a first-line therapy for lowering the level of urate in patients with gout. At present, this drug is being prescribed mainly based on the clinical experience of doctors. The potential effects of clinical and demographic variables on the bioavailability and therapeutic effectiveness of febuxostat are not being considered. In this study a physiologically based pharmacokinetic (PBPK) model of febuxostat was developed, thereby providing a theoretical basis for the individualized dosing of this drug in gout patients. The plasma concentration–time profiles corresponding to healthy subjects and gout patients with normal kidney function were simulated and validated; then, the model was used to predict the pharmacokinetic (PK) data of the drug in gout patients suffering from varying degrees of impaired kidney function. The error values (the predicted value/observed value) were used to validate the simulated PK parameters predicted by the PBPK model, including the area under the plasma concentration–time curve, the maximum plasma concentration, and time to maximum plasma concentration. Considering that to all error fold changes were smaller than 2, the PBPK model was. In subjects suffering from mild kidney impairment, moderate kidney impairment, severe kidney impairment, and endstage kidney disease (ESRD), the predicted AUC_0-24h values increased by 1.62, 1.74, 2.27, and 2.65-fold, respectively, compared to gout patients with normal kidney function. Overall, the results showed that the PBPK model constructed in this study predict the pharmacokinetic changes in gout patients suffering from varying degrees of impaired kidney function.