Mechanistic Study of Icaritin-Induced Inactivation of Cytochrome P450 2C9.

Icaritin (ICT) is a prenylflavonoid derivative that has been approved by National Medical Products Administration for the treatment of hepatocellular carcinoma. This study aims to evaluate the potential inhibitory effect of ICT against cytochrome P450 (CYP) enzymes and to elucidate the inactivation mechanisms. Results showed that ICT inactivated CYP2C9 in a time-, concentration-, and NADPH-dependent manner with Ki = 1.896 µM, Kinact = 0.02298 minutes-1, and Kinact/Ki = 12 minutes-1 mM-1, whereas the activities of other CYP isozymes was minimally affected. Additionally, the presence of CYP2C9 competitive inhibitor, sulfaphenazole, superoxide dismutase/catalase system, and GSH all protected CYP2C9 from ICT-induced activity loss. Moreover, the activity loss was neither recovered by washing the ICT-CYP2C9 preincubation mixture nor the addition of potassium ferricyanide. These results, collectively, implied the underlying inactivation mechanism involved the covalent binding of ICT to the apoprotein and/or the prosthetic heme of CYP2C9. Furthermore, an ICT-quinone methide (QM)-derived GSH adduct was identified, and human glutathione S-transferases (GST) isozymes GSTA1-1, GSTM1-1, and GSTP1-1 were shown to be substantially involved in the detoxification of ICT-QM. Interestingly, our systematic molecular modeling work predicted that ICT-QM was covalently bound to C216, a cysteine residue located in the F-G loop downstream of substrate recognition site (SRS) 2 in CYP2C9. The sequential molecular dynamics simulation confirmed the binding to C216 induced a conformational change in the active catalytic center of CYP2C9. Lastly, the potential risks of clinical drug-drug interactions triggered by ICT as a perpetrator were extrapolated. In summary, this work confirmed that ICT was an inactivator of CYP2C9. SIGNIFICANCE STATEMENT: This study is the first to report the time-dependent inhibition of CYP2C9 by icaritin (ICT) and the intrinsic molecular mechanism behind it. Experimental data indicated that the inactivation was via irreversible covalent binding of ICT-quinone methide to CYP2C9, while molecular modeling analysis provided additional evidence by predicting C216 as the key binding site which influenced the structural confirmation of CYP2C9's catalytic center. These findings suggest the potential of drug-drug interactions when ICT is co-administered with CYP2C9 substrates clinically.

Unraveling a Combined Inactivation Mechanism of Cytochrome P450s by Genipin, the Major Reactive Aglycone Derived from Gardeniae Fructus.

Genipin (GP) is the reactive aglycone of geniposide, the main component of traditional Chinese medicine Gardeniae Fructus (GF). The covalent binding of GP to cellular proteins is suspected to be responsible for GF-induced hepatotoxicity and inhibits drug-metabolizing enzyme activity, although the mechanisms remain to be clarified. In this study, the mechanisms of GP-induced human hepatic P450 inactivation were systemically investigated. Results showed that GP inhibited all tested P450 isoforms via distinct mechanisms. CYP2C19 was directly and irreversibly inactivated without time dependency. CYP1A2, CYP2C9, CYP2D6, and CYP3A4 T (testosterone as substrate) showed time-dependent and mixed-type inactivation, while CYP2B6, CYP2C8, and CYP3A4 M (midazolam as substrate) showed time-dependent and irreversible inactivation. For CYP3A4 inactivation, the kinact/KI values in the presence or absence of NADPH were 0.26 or 0.16 min-1 mM-1 for the M site and 0.62 or 0.27 min-1 mM-1 for the T site. Ketoconazole and glutathione (GSH) both attenuated CYP3A4 inactivation, suggesting an active site occupation- and reactive metabolite-mediated inactivation mechanism. Moreover, the in vitro and in vivo formation of a P450-dependent GP-S-GSH conjugate indicated the involvement of metabolic activation and thiol residues binding in GP-induced enzyme inactivation. Lastly, molecular docking analysis simulated potential binding sites and modes of GP association with CYP2C19 and CYP3A4. We propose that direct covalent binding and metabolic activation mediate GP-induced P450 inactivation and alert readers to potential risk factors for GP-related clinical drug-drug interactions.

Development and validation of an LC-MS/MS method for simultaneous determination of SH-1028, an irreversible third-generation EGFR TKI, and two of its metabolites in human plasma: application in clinical pharmacokinetics.

SH-1028 is a novel, potent, and highly selective epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) developed for the treatment of T790M Mutation-positive non-small cell lung cancer (NSCLC). The objective was to develop an LC-MS/MS method for the simultaneous determination of SH-1028 and its metabolites, Imp2 and Imp3, in human plasma.The plasma samples were extracted through protein precipitation with acetonitrile on wet ice conditions. A rapid, sensitive, and specific method was developed and successfully applied to evaluate the pharmacokinetic (PK) properties of SH-1028 in patients with advanced NSCLC following single and multiple doses of SH-1028 (60 mg).After single-dose administration, the Cmax of SH-1028, Imp2, and Imp3 was 11.2, 50.2, and 7.99 ng/mL, respectively. The mean AUC0-24 h was 138, 602, and 76.7 h*ng/mL, respectively. And the terminal half-life time was 19.9, 14.4, and 26.1 h, respectively. After multiple-dose administration, SH-1028 exhibited a slight accumulation, with a mean accumulation ratio (RAUC) of 2.00.The study assessed the PK properties of SH-1028 following single and multiple doses in patients with advanced NSCLC and would provide meaningful information for the further development of SH-1028.

Subacute oral toxicology and toxicokinetics of pterostilbene, a novel Top1/Tdp1 inhibiting anti-tumor reagent.

This study evaluated the subacute toxicity and toxicokinetics of a potential anti-cancer drug candidate, pterostilbene, in rats. Animals were orally administered at two repeated doses of 200 and 500 mg/kg for 28 days. No mortality was observed during the 28 days of continuous administration of pterostilbene. Body weight and food consumption in each group increased steadily, while no significant difference was found. Liver weight in the 500 mg/kg female, but not male group increased with mild cytoplasmic vacuoles observed in histopathological study. Toxicokinetics was assessed by measuring plasma concentrations of pterostilbene on the first and 28th day of administration using UPLC-MS/MS. Toxicokinetic parameters showed that AUC0-t significantly increased in all animals, while the increase in females was greater than males. System exposure of pterostilbene appeared to be linear within the administrated dose range. In conclusion, our findings suggested a minimal subacute toxicity profile of pterostilbene, which could strongly support further development of this compound as a novel anti-cancer agent.

Music therapy for people with substance use disorders.

BACKGROUND: Substance use disorder (SUD) is the continued use of one or more psychoactive substances, including alcohol, despite negative effects on health, functioning, and social relations. Problematic drug use has increased by 10% globally since 2013, and harmful use of alcohol is associated with 5.3% of all deaths. Direct effects of music therapy (MT) on problematic substance use are not known, but it may be helpful in alleviating associated psychological symptoms and decreasing substance craving. OBJECTIVES: To compare the effect of music therapy (MT) in addition to standard care versus standard care alone, or to standard care plus an active control intervention, on psychological symptoms, substance craving, motivation for treatment, and motivation to stay clean/sober. SEARCH METHODS: We searched the following databases (from inception to 1 February 2021): the Cochrane Drugs and Alcohol Specialised Register; CENTRAL; MEDLINE (PubMed); eight other databases, and two trials registries. We handsearched reference lists of all retrieved studies and relevant systematic reviews. SELECTION CRITERIA: We included randomised controlled trials comparing MT plus standard care to standard care alone, or MT plus standard care to active intervention plus standard care for people with SUD. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodology. MAIN RESULTS: We included 21 trials involving 1984 people. We found moderate-certainty evidence of a medium effect favouring MT plus standard care over standard care alone for substance craving (standardised mean difference (SMD) -0.66, 95% confidence interval (CI) -1.23 to -0.10; 3 studies, 254 participants), with significant subgroup differences indicating greater reduction in craving for MT intervention lasting one to three months; and small-to-medium effect favouring MT for motivation for treatment/change (SMD 0.41, 95% CI 0.21 to 0.61; 5 studies, 408 participants). We found no clear evidence of a beneficial effect on depression (SMD -0.33, 95% CI -0.72 to 0.07; 3 studies, 100 participants), or motivation to stay sober/clean (SMD 0.22, 95% CI -0.02 to 0.47; 3 studies, 269 participants), though effect sizes ranged from large favourable effect to no effect, and we are uncertain about the result. There was no evidence of beneficial effect on anxiety (mean difference (MD) -0.17, 95% CI -4.39 to 4.05; 1 study, 60 participants), though we are uncertain about the result. There was no meaningful effect for retention in treatment for participants receiving MT plus standard care as compared to standard care alone (risk ratio (RR) 0.99, 95% 0.93 to 1.05; 6 studies, 199 participants). There was a moderate effect on motivation for treatment/change when comparing MT plus standard care to another active intervention plus standard care (SMD 0.46, 95% CI -0.00 to 0.93; 5 studies, 411 participants), and certainty in the result was moderate. We found no clear evidence of an effect of MT on motivation to stay sober/clean when compared to active intervention, though effect sizes ranged from large favourable effect to no effect, and we are uncertain about the result (MD 0.34, 95% CI -0.11 to 0.78; 3 studies, 258 participants). There was no clear evidence of effect on substance craving (SMD -0.04, 95% CI -0.56 to 0.48; 3 studies, 232 participants), depression (MD -1.49, 95% CI -4.98 to 2.00; 1 study, 110 participants), or substance use (RR 1.05, 95% CI 0.85 to 1.29; 1 study, 140 participants) at one-month follow-up when comparing MT plus standard care to active intervention plus standard care. There were no data on adverse effects. Unclear risk of selection bias applied to most studies due to incomplete description of processes of randomisation and allocation concealment. All studies were at unclear risk of detection bias due to lack of blinding of outcome assessors for subjective outcomes (mostly self-report). We judged that bias arising from such lack of blinding would not differ between groups. Similarly, it is not possible to blind participants and providers to MT. We consider knowledge of receiving this type of therapy as part of the therapeutic effect itself, and thus all studies were at low risk of performance bias for subjective outcomes.  We downgraded all outcomes one level for imprecision due to optimal information size not being met, and two levels for outcomes with very low sample size.  AUTHORS' CONCLUSIONS: Results from this review suggest that MT as 'add on' treatment to standard care can lead to moderate reductions in substance craving and can increase motivation for treatment/change for people with SUDs receiving treatment in detoxification and short-term rehabilitation settings. Greater reduction in craving is associated with MT lasting longer than a single session. We have moderate-to-low confidence in our findings as the included studies were downgraded in certainty due to imprecision, and most included studies were conducted by the same researcher in the same detoxification unit, which considerably impacts the transferability of findings.

Metabolites identification and species comparison of Oroxylin A, an anti-cancer flavonoid, in vitro and in vivo by HPLC-Q-TOF-MS/MS.

Oroxylin A, the main component of Scutellaria baicalensis Georigi has been widely studied due to its well-known pharmacological effects. According to previous studies, Oroxylin A with low bioavailability was converted into glucuronidation and sulphonated metabolites, which had high exposure in plasma and generated certain activities. It is necessary to study the metabolites and metabolic pathways of Oroxylin A.This study aimed to explore the metabolites of Oroxylin A in liver microsomes, primary hepatocyte incubation samples of five different species (human, monkey, dog, mouse, rat), and in bile, urine and faeces of rats.It would provide a systematic description of metabolic pathway of Oroxylin A. Also, a method of high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry detector (HPLC-Q-TOF-MS/MS) for identification of each metabolite in various biological matrices was developed.This experiment illustrated that phase II metabolites were the main form of Oroxylin A in vitro and in excretion of rats, accompanied with a small amount of phase I metabolites.Furthermore, there were obvious species differences among the metabolism in vitro, especially in phase II. Monkeys and rats may be more suitable for preclinical research than dogs and mice as non-rodent or rodent species.

Effects of ginkgo leaf tablet on the pharmacokinetics of rosiglitazone in rats and its potential mechanism.

CONTEXT: Ginkgo leaf tablet (GLT), a traditional Chinese herbal formula, is often combined with rosiglitazone (ROS) for type 2 diabetes mellitus treatment. However, the drug-drug interaction between GLT and ROS remains unknown. OBJECTIVE: To investigate the effects of GLT on the pharmacokinetics of ROS and its potential mechanism. MATERIALS AND METHODS: The pharmacokinetics of 10 mg/kg ROS with 100/200 mg/kg GLT as single-dose and 10-day multiple-dose administration were investigated in Sprague-Dawley rats. In vitro, the effects of GLT on the activity of CYP2C8 and CYP2C9 were determined in recombinant human yeast microsomes and rat liver microsomes with probe substrates. RESULTS: The t1/2 of ROS increased from 2.14 ± 0.38 (control) to 2.79 ± 0.37 (100 mg/kg) and 3.26 ± 1.08 h (200 mg/kg) in the single-dose GLT administration. The AUC0-t (139.69 ± 45.46 vs. 84.58 ± 39.87 vs. 66.60 ± 15.90 h·µg/mL) and t1/2 (2.75 ± 0.70 vs. 1.99 ± 0.44 vs. 1.68 ± 0.35 h) decreased significantly after multiple-dose GLT treatment. The IC50 values of quercetin, kaempferol, and isorhamnetin, GLT main constituents, were 9.32, 7.67, and 11.90 µmol/L for CYP2C8, and 27.31, 7.57, and 4.59 µmol/L for CYP2C9. The multiple-dose GLT increased rat CYP2C8 activity by 44% and 88%, respectively. DISCUSSION AND CONCLUSIONS: The metabolism of ROS is attenuated in the single dose of GLT by inhibiting CYP2C8 and CYP2C9 activity, and accelerated after the multiple-dose GLT treatment via inducing CYP2C8 activity in rats, indicating that the clinical dose of ROS should be adjusted when co-administrated with GLT.

Identification of Triterpene Acids in Poria cocos Extract as Bile Acid Uptake Transporter Inhibitors.

Literature reports that Poria cocos reduces blood lipid levels; however, the underlying mechanism remains unclear. Blood lipid levels are closely related to the enterohepatic circulation of bile acids, where uptake transporters playing a significant role. P. cocos extract is commonly used in traditional prescriptions and food supplements in China. We investigated the effects of P. cocos and its five triterpene acids on bile acid uptake transporters, including intestinal apical sodium-dependent bile acid transporter (ASBT) and hepatic sodium/taurocholate cotransporting polypeptide (NTCP). Triterpene acids were fingerprinted by high-performance liquid chromatography-TripleTOF and quantified by ultraperformance liquid chromatography/tandem mass spectrometry. The inhibitory effect of P. cocos and its five major representative triterpene acids on ASBT and NTCP was investigated by in vitro assays using Xenopus oocytes expressing ASBT and NTCP. P. cocos extract exhibited significant inhibitory effects with half-maximum inhibition constants of 5.89 µg/ml and 14.6 µg/ml for NTCP and ASBT, respectively. Among five triterpene acids, poricoic acid A, poricoic acid B, and polyporenic acid C significantly inhibited NTCP function. Poricoic acid A, poricoic acid B, and dehydrotumulosic acid significantly inhibited ASBT function. The representative triterpene acid, poricoic acid A, was identified as a competitive inhibitor of NTCP with an inhibitory constant of 63.4 ± 18.7 µM. In conclusion, our results indicate that both P. cocos extract and its major triterpenes are competitive inhibitors of ASBT and NTCP. Accordingly, it was suggested that competitive inhibition of these bile acid transporters is one of the underlying mechanisms for the hypolipidemic effect of P. cocos. SIGNIFICANCE STATEMENT: Poria cocos, a commonly used Chinese herbal medicine and food supplement, demonstrates significantly inhibitory effects on the function of apical sodium-dependent bile acid transporter and sodium/taurocholate cotransporting polypeptide. P. cocos has potential to reduce the blood lipid through inhibition of these uptake transporters in enterohepatic circulation of bile acid.

Population pharmacokinetics, safety and dosing optimization of voriconazole in patients with liver dysfunction: A prospective observational study.

AIMS: Voriconazole is a broad-spectrum antifungal agent for the treatment of invasive fungal infections. There is limited information about the pharmacokinetics and appropriate dosage of voriconazole in patients with liver dysfunction. This study aimed to explore the relationship between voriconazole trough concentration (Ctrough ) and toxicity, identify the factors significantly associated with voriconazole pharmacokinetic parameters and propose an optimised voriconazole dosing regimen for patients with liver dysfunction. METHODS: The study prospectively enrolled 51 patients with 272 voriconazole concentrations. Receiver operating characteristic curves were used to explore the relationship between voriconazole Ctrough and toxicity. The pharmacokinetic data was analysed with nonlinear mixed-effects method. Dosing simulations stratified by total bilirubin (TBIL, TBIL-1: TBIL < 51 µmol/L; TBIL-2: 51 µmol/L ≤ TBIL < 171 µmol/L; TBIL-3: TBIL ≥ 171 µmol/L) were performed. RESULTS: Receiver operating characteristic curve analysis revealed that voriconazole Ctrough of ≤ 5.1 mg/L were associated with significantly lower the incidence of adverse events. A 1-compartment pharmacokinetic model with first-order absorption and elimination was used to describe the data. Population pharmacokinetic parameters of clearance, volume of distribution and oral bioavailability were 0.88 L/h, 148.8 L and 88.4%, respectively. Voriconazole clearance was significantly associated with TBIL and platelet count. The volume of distribution increased with body weight. Patients with TBIL-1 could be treated with a loading dose of 400 mg every 12 hours (q12h) for first day, followed by a maintenance dose of 100 mg q12h administered orally or intravenously. TBIL-2 and TBIL-3 patients could be treated with a loading dose of 200 mg q12h and maintenance doses of 50 mg q12h or 100 mg once daily and 50 mg once daily orally or intravenously, respectively. CONCLUSIONS: Lower doses and longer dosing intervals should be considered for patients with liver dysfunction. TBIL-based dosing regimens provide a practical strategy for achieving voriconazole therapeutic range and therefore maximizing treatment outcomes.

Characterization of Preclinical Pharmacokinetic Properties and Prediction of Human PK Using a Physiologically Based Pharmacokinetic Model for a Novel Anti-Arrhythmic Agent Sulcardine Sulfate.

PURPOSE: Sulcardine sulfate (Sul) is a novel antiarrhythmic agent with promising pharmacological properties, which is currently being evaluated in several clinical trials as an oral formulation. To meet the medication needs of patients with acute conditions, the injection formulation of Sul has been developed. The objective of this study was to systemically investigate the pharmacokinetic profiles of Sul after intravenous infusion. METHODS: This research included the plasma protein binding and metabolic stability studies in vitro, plasma pharmacokinetics, biodistribution, excretion studies in animals, and the prediction of the clinical PK of Sul injection using a physiologically based pharmacokinetics (PBPK) model. RESULTS: The metabolic stability was similarly in dogs and humans but lower in rats. The plasma protein binding rates showed a concentration-dependent manner and species differences. The pharmacokinetic behavior after intravenous administration was linear in rats within the dose range of 30-90 mg/kg, but nonlinear in dogs within 30-60 mg/kg. Sul could be rapidly and widely distributed in multiple tissues after intravenous administration. About 12% of the parent compound were excreted via the urine and only a small fraction via bile and feces,and eight metabolites were found and identified in the rat excretion. The PBPK models were developed and simulated the observed PK date well in both rats and dogs. The PBPK model refined with human data predicted the PK characteristics of the first intravenous infusion of Sul in human. CONCLUSIONS: Our study systematically explored the pharmacokinetic characteristics of Sul and successfully developed the PBPK model to predict of its clinical PK.

Influences of ABC transporter and CYP3A4/5 genetic polymorphisms on the pharmacokinetics of lenvatinib in Chinese healthy subjects.

PURPOSE: To investigate whether the CYP3A4/5 and ABC transporter genetic polymorphisms could affect the pharmacokinetics of lenvatinib in Chinese healthy subjects. METHODS: Thirty-two healthy Chinese volunteers were enrolled and took oral administration of 8 mg lenvatinib. Plasma concentration of lenvatinib was determined by UPLC-MS/MS, the CYP3A4*1G, CYP3A5*3, ABCB1 (3435 C>T, 1236 C>T, 2677 G>T/A), ABCG2 (421 C>A, 34 G>A), and ABCC2-24 C>T genotypes were determined by SnapShot Technique. RESULTS: In ABCB1 3435T carriers (n = 19), AUC0-120h (815.7 (701.9-923.9) ng·h/mL) and AUC0-∞ (843.3 (722.2-977.7) ng·h/mL) were significantly higher than ABCB1 3435CC homozygous subjects (n = 13, 575.3 (513.7-756.9) ng·h/mL and 590.0 (540.5-782.0) ng·h/mL, respectively); on the contrary, the clearance (CL/F) of ABCB1 3435T carriers was significantly lower (9.5 (8.2-11.1) L/h vs. 13.6 (10.4-14.8) L/h). And the Cmax in CYP3A4*1G/*1G allele carrier subjects was higher than *1 carrier (73.4 ng/mL vs. 53.5 (46.1-60.6) ng/mL), but did not reach the level of significantly statistical difference. Genetic polymorphisms of ABCC2, ABCG2, and CYP3A5 could not influence pharmacokinetic parameters of lenvatinib. CONCLUSIONS: This work presented an evidence that the ABCB1 3435 C>T polymorphism could significantly affect the exposure and clearance of lenvatinib. These findings may explain the reasons for the huge inter-individual differences in lenvatinib, and should contribute to clinical individualized treatment.

ABCC2 c.-24 C>T single-nucleotide polymorphism was associated with the pharmacokinetic variability of deferasirox in Chinese subjects.

PURPOSE: Our aim was to evaluate the influence of genetic polymorphisms involved in the metabolism and transportation of deferasirox on deferasirox pharmacokinetics in the Chinese population. METHODS: Thirty-eight healthy Chinese subjects were administered with a single dose of 20 mg kg-1 deferasirox. Allelic discriminations for eight single-nucleotide polymorphisms (SNPs) in UDP-glucuronosyltransferase 1A1, 1A3 (UGT1A1, UGT1A3), multidrug resistance protein 2 (MRP2, ABCC2), and breast cancer resistance protein (BCRP, ABCG2) were performed. The concentrations of deferasirox in the plasma were determined by UPLC-MS/MS. RESULTS: Subjects carrying ABCC2 c.-24 T allele had a 65% higher clearance (CL/F) and 42% lower area under the concentration-time curve from 0 to 72 h (AUC0-72h) as compared with non-carriers (P = 0.008, P = 0.011, respectively). ABCC2 c.-24 T was also associated with 59% shorter half-life (T1/2) and 17% shorter mean residence time (MRT) (P = 0.030, P = 0.014, respectively). ABCC2 1249A was associated with a marginal increase in deferasirox Cmax (P = 0.07). Genetic polymorphisms of UGT1A1, UGT1A3, and ABCG2 did not significantly influence the pharmacokinetics of deferasirox. Subjects with UGT1A1 211GG-(-1352)CC-(-3156)GG haplotype had higher AUC0-72h than others. Since only two subjects were recruited in the GG-CC-GG group, further confirmative studies were warranted. CONCLUSIONS: ABCC2 c.-24 C>T was associated with the pharmacokinetic variability of deferasirox in Chinese subjects. This study revealed an important role of MRP2 in the pharmacokinetics of deferasirox and drew attention to drug combination with MRP2 inhibitors like cyclosporine and methotrexate in deferasirox therapy.

Determination of oroxylin A, oroxylin A 7-O-glucuronide, and oroxylin A sodium sulfonate in beagle dogs by using UHPLC MS/MS Application in a pharmacokinetic study.

Oroxylin A, obtained from the root of Scutellaria baicalensis Georgi, is a flavonoid with antitumor and other pharmacological activities. Our previous studies showed for the first time that it is mainly metabolized to oroxylin A sodium sulfonate by sulfotransferase enzymes in beagle dogs. In this study, rapid, universal, selective, and robust ultra-high-performance liquid chromatography-tandem mass spectrometry methods were established and fully validated to quantitatively detect oroxylin A, oroxylin A 7-O-glucuronide, and oroxylin A sodium sulfonate in beagle dog plasma. The quantitative analysis for oroxylin A sodium sulfonate was reported for the first time. Plasma samples were processed with acetonitrile, a universal protein precipitant. Gradient elution was performed to resolve carryover effects and to achieve separation efficiency and sufficient chromatographic retention. The linear relationships of oroxylin A, oroxylin A 7-O-glucuronide, and oroxylin A sodium sulfonate in plasma were in the range of 2.0-500.0, 5.0-500.0, and 1.881-940.5 ng/mL, respectively. The assay method was successfully applied to pharmacokinetic study. This is the first paper that reveals the pharmacokinetic profile of oroxylin A, oroxylin A 7-O-glucuronide, and oroxylin A sodium sulfonate after single-dose intravenous and oral administration of Oroxylin A in beagle dogs.

Effects of the ABCB1 and ABCG2 polymorphisms on the pharmacokinetics of afatinib in healthy Chinese volunteers.

1. Afatinib is an oral, selective tyrosine kinase inhibitor (TKI) primarily transported by P-glycoprotein (MDR1, gene code ABCB1) and breast cancer resistance protein (BCRP, gene code ABCG2). In the present study, the effects of ABCB1 and ABCG2 genetic polymorphisms on the pharmacokinetics of afatinib in healthy Chinese were investigated.2. Blood samples from 24 healthy participants who received afatinib were used for genotyping ABCB1 (1236C>T, 2677G > T/A, 3435C>T) and ABCG2 (34G>A, 421C>A) polymorphisms. Subsequently, the association between afatinib plasma concentrations and target single-nucleotide polymorphisms (SNPs) was analyzed.3. Among the five polymorphisms, plasma concentrations of afatinib in healthy subjects with ABCB1 1236CC-3435CC were remarkably higher than in other genotype subjects. No significant differences of afatinib exposure were found between the ABCG2 wild-type and heterozygous groups.4. The ABCB1 genetic polymorphism influenced the plasma exposure of afatinib, and gene testing before drug administration may be useful for clinically individualized use of afatinib. Our data suggest the usefulness of afatinib pharmacogenetics in treatment optimization.

Development of a sensitive UPLC-MS/MS assay for domperidone and pharmacokinetics of domperidone tablet formulations in fasting and fed Chinese healthy subjects
.

OBJECTIVE: The objective of this study was to evaluate and compare the pharmacokinetics of domperidone tablets in Chinese healthy subjects both under fasting and fed conditions. MATERIALS AND METHODS: A total of 36 subjects were recruited to the monocentric pharmacokinetic study. All subjects were randomly divided into two groups. One group was given a single 10-mg oral dose of domperidone tablet after ~ 10 hours of fasting, and the other group was given the same oral dose of domperidone tablet 30 minutes after a high-fat meal. 18 blood samples were collected over 24 hours for every subject. Plasma concentrations of domperidone were analyzed by a rapid and sensitive UPLC-MS/MS assay, and the pharmacokinetic parameters were determined by the standard non-compartmental method. RESULTS: A significant difference was observed in the pharmacokinetics of domperidone between fasting and fed subjects. The AUC0-24h (area under curve of plasma concentration until the last concentration observed) was 75.71 h×µg/L in the fed subjects, which was much higher than AUC0-24h (56.76 h×µg/L) in the fasting subjects. For the fasting test, the T1/2 (elimination half-life) was 7.15 hours, Cmax (the maximum plasma concentration) was 16.97 µg/L, and tmax; was 0.79 hours. For the fed test, the T1/2 was 8.72 hours, Cmax was 15.11 µg/L, and tmax was 1.66 hours. T1/2 and tmax were both prolonged under fed condition when comparing fed condition to fasting condition. CONCLUSION: In this study, the absorption and elimination of domperidone was slowed down by a high-fat meal, with the mean tmax being 52% longer and T1/2 18% longer in fed subjects than in fasting subjects. In addition, a high-fat meal increased the exposure of domperidone, with the mean AUC being 25% more in fed subjects than in fasting subjects, which provided an important reference for the clinical application of domperidone in the Chinese population.

Clinically significant drug-drug interaction between tacrolimus and fluconazole in stable renal transplant recipient and literature review.

WHAT IS KNOWN AND OBJECTIVE: Clinical use of fluconazole against fungal infections in renal transplant patients is complicated by the potentially marked and unpredictable drug-drug interactions (DDIs). We report a case of tacrolimus-fluconazole DDI in a stable renal transplant recipient and describe the mechanism, magnitude and duration of this DDI through a literature review. CASE SUMMARY: A 38-year-old woman experienced a 9.1-fold increase in dose-normalized tacrolimus trough level (trough concentration/weight-normalized daily dose) and an 87% decrease in weight-normalized daily dose (daily dose/body weight) in the treatment of documented Candida albicans oesophagitis by fluconazole. After discontinuation of fluconazole for 161 day, a 26% reduction in weight-normalized daily dose was required to maintain therapeutic exposure. WHAT IS NEW AND CONCLUSION: Oral fluconazole has a more significant impact on its drug interactions with tacrolimus than intravenous fluconazole. Gene screening for CYP3A5 6986 A>G and ABCB1 3435 C>T in organ transplant recipients may help in preventing DDI and facilitating tacrolimus dose adjustment.

A rapid HPLC-MS/MS method for determining busulfan in hemolytic samples from children with hematopoietic stem cell transplantation.

A rapid and sensitive method for the quantitative detection of busulfan (BU) in children's hemolytic samples by HPLC-tandem mass spectrometry (MS/MS) was established. In this study, the sample preparation procedure involved a one-step protein precipitation with acetonitrile (ACN) solution, and the HPLC-MS/MS method used Hypersil GOLD C18 . The mobile phase consisted of 10 mM ammonium acetate solution (containing 0.1% formic acid) and ACN with a flow rate of 0.4 mL/min. Multiple reaction monitoring modes were used for quantitative analysis and the ion pairs of BU and BU-d8 were m/z 263.9 → 150.9 and 272.0 → 159.0, respectively. BU had a good linearity in the range of 0.01-10 µg mL-1 . The intra- and inter-day relative error was between -7.21% and 8.26%, and the coefficient of variation was less than 12.64%. The average extraction recovery rate in plasma samples was 99.76% ± 6.53%, and the matrix in normal plasma and hemolyzed plasma had no significant effect on the detection results. Normal and hemolytic samples could maintain good stability at 4, 25 and -40°C. As a result, this method is particularly suitable for determining BU in hemolytic samples from children with hematopoietic stem cell transplantation (HSCT), and this study provides the methodological basis for further research on the pharmacokinetics of BU in children with HSCT.

Inhalable dry powder prepared from folic acid-conjugated docetaxel liposomes alters pharmacodynamic and pharmacokinetic properties relevant to lung cancer chemotherapy.

Pulmonary delivery of anti-cancer drugs in the form of nanoparticulate dry powders is considered a promising modality for treating lung cancer. However, it is not known whether the pharmacodynamics and pharmacokinetics of nano-preparations are altered after co-spray drying. In this study, we compared the physicochemical property, anti-cancer activity, tumor targeting and pharmacokinetic behavior of docetaxel-loaded folic acid-conjugated liposomes (LPs-DTX-FA) with those of dry powder prepared by co-spray-drying LPs-DTX-FA. The particle size and PDI after re-dispersion of the powder were increased. The re-dispersed liposomes showed increased cellular uptake via micropinocytosis and exhibited higher cytotoxicity than LPs-DTX-FA. Tumor targeting of re-dispersed liposomes was less effective compared with LPs-DTX-FA but the metabolism of re-dispersed liposomes was decreased. Tracheal administration resulted in a 45-fold higher concentration of docetaxel in the lung of Sprague Dawley rats at 30 min as compared with intravenous administration. Our results indicated that co-spray drying did change the properties, while tracheal administration of the dry powder provided higher drug exposure at the tumor site without increasing the exposure of other organs. Thus, inhaled dry powders might be clinically effective for treatment of lung cancer.

Determination of GL-V9, a derivative of wogonin, in rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study after oral and pulmonary administration.

GL-V9, a derivative of wogonin, shows much more potent anticancer properties than wogonin. In this study, a selective, sensitive and rapid ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of GL-V9 in rat plasma. Plasma samples were processed using methanol to precipitate protein. Chromatographic separation of analytes was achieved on a C18 column using gradient elution within 4.5 min. The mobile phase consisted of acetonitrile and water including 0.1% (v/v) formic acid and 5 mm ammonium acetate. GL-V9 and caffeine (internal standard) were monitored by positive electrospray triple quadrupole mass spectrometer and quantified using multiple reaction monitoring (MRM) mode with the transitions of m/z 410.20 → 126.10 (GL-V9) and 195.10 → 138.00 (IS: caffeine), respectively. Good linearity was obtained over the range of 2-1000 ng/mL (R2 > 0.99) and the extraction recovery was 101.91 ± 11.34%. The intra- and inter-day precision variations were small (RSD 1.35-6.96%) and the relative error (RE) of accuracy was -7.35-6.27%. The established and validated UPLC-MS/MS method was successfully applied to study the pharmacokinetic behavior of GL-V9 after administration through different delivery routes. The results demonstrated that pulmonary delivery exhibited a greater advantage in terms of improving bioavailability compared with oral administration.

Mechanistic study of absorption and first-pass metabolism of GL-V9, a derivative of wogonin.

GL-V9, a derivative of wogonin, has potent anti-cancer activity. The absorption and metabolism of this compound have not been investigated systematically. This study aims to illustrate the pharmacokinetic characters of GL-V9 by exploring its metabolic status under different administration routes. To further clarify the absorption mechanism of GL-V9, an in situ single-pass perfusion model and a Caco-2 cell monolayer model were used. Meanwhile, a microsomal incubation system was used to evaluate the enzyme kinetic parameters. In vivo, the obtained gastrointestinal availability (Fa × Fg ) was 21.28 ± 5.38%. The unmetabolized fraction in the gut wall (Fgut wall ) was 98.59 ± 9.74%, while the hepatic bioavailability (Fh ) was 29.11 ± 5.22%. These results indicated that poor absorption and extensive metabolism may contribute greatly to the low bioavailability of GL-V9. The effective permeability (Peff ) in the duodenum and jejunum was 1.34 ± 0.50 × 10-4 and 0.90 ± 0.27 × 10-4  cm/s, respectively. The high permeability of GL-V9 indicated that other unknown factors (such as metabolism) may account for its systemic exposure problem. Studies in rat liver microsomal (RLMs) confirmed this hypothesis, and the Clint, CYP450s and UGT of GL-V9 was 0.20 ml/min/mg protein. In conclusion, these results suggest that GL-V9 possesses higher permeability than wogonin and the metabolism of GL-V9 is related to its disposition in rat intestine and liver.