A Joint Technology Combining the Advantages of Capillary Microsampling with Mass Spectrometry Applied to the Trans-Resveratrol Pharmacokinetic Study in Mice.

Mice are the most frequently used animals in pharmacokinetic studies; however, collecting series of blood samples from mice is difficult because of their small sizes and tiny vessels. In addition, due to the small sample size, it is problematic to perform high required quantification. Thus, present work aims to find an effective strategy for overcoming these challenges using trans-resveratrol as a tool drug. Based on the idea of a joint technology, the capillary microsampling (CMS) was chosen for blood sample collection from mice after delivery of trans-resveratrol (150 mg/kg) by gavage, and a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of trans-resveratrol and its main metabolites. All the mouse blood samples were exactly collected by CMS without obvious deviation. This provided credible samples for subsequent quantitative analysis. The HPLC-MS/MS method was found to be sensitive, accurate, and repeatable, and the pharmacokinetic parameters for all analytes were comparable with those reported in previous studies. However, the present joint technology offers the advantages of less animal damage, easy for sample preparation, and improved reliability. It has overcome some of the major limitations revealed in previous pharmacokinetic studies in mice and therefore provides a more effective option for future studies.

The hepatotoxicity of Polygonum multiflorum: The emerging role of the immune-mediated liver injury.

Herbal and dietary supplements (HDS)-induced liver injury has been a great concern all over the world. Polygonum multiflorum Thunb., a well-known Chinese herbal medicine, is recently drawn increasing attention because of its hepatotoxicity. According to the clinical and experimental studies, P. multiflorum-induced liver injury (PM-DILI) is considered to be immune-mediated idiosyncratic liver injury, but the role of immune response and the underlying mechanisms are not completely elucidated. Previous studies focused on the direct toxicity of PM-DILI by using animal models with intrinsic drug-induced liver injury (DILI). However, most epidemiological and clinical evidence demonstrate that PM-DILI is immune-mediated idiosyncratic liver injury. The aim of this review is to assess current epidemiological, clinical and experimental evidence about the possible role of innate and adaptive immunity in the idiosyncratic hepatotoxicity of P. multiflorum. The potential effects of factors associated with immune tolerance, including immune checkpoint molecules and regulatory immune cells on the individual's susceptibility to PM-DILI are also discussed. We conclude by giving our hypothesis of possible immune mechanisms of PM-DILI and providing suggestions for future studies on valuable biomarkers identification and proper immune models establishment.

Reversing Epigenetic Alterations Caused by Alcohol: A Promising Therapeutic Direction for Alcoholic Liver Disease.

Alcoholic liver disease (ALD), a liver function disorder caused by excessive alcohol intake, is a serious threat to global public health and social development. Toxic metabolites and reactive oxygen species produced during the metabolism of alcohol can alter the epigenetic state including DNA methylation, histone modifications, and expression of microRNAs. Epigenetic alterations can conversely involve various signaling pathways, which could contribute to the initiation and progression of ALD. To elucidate the relationship between epigenetic alterations and alcohol damage not only reinforces our understanding on pathogenesis of ALD, but also provides novel targets for clinical diagnosis, treatment, and drug research of ALD. In this review, we have summarized the research progress of epigenetic alterations and related mechanisms caused by alcohol in the pathogenesis of ALD. Considering the invertibility of epigenetic alterations, treatment of ALD through epigenetic modification with common less harmful compounds is also related.

Effects of quercetin on pharmacokinetics of cefprozil in Chinese-Han male volunteers.

1. The primary objective of this study was to evaluate the effects of quercetin on the pharmacokinetics of cefprozil. The secondary objective was to evaluate the safety of the combined use of cefprozil and quercetin. 2. An open-label, two-period, crossover phase I trial among 24 Han Chinese male subjects was conducted. Participants were given 500 mg of quercetin orally once daily for 15 d followed by single dose of cefprozil (500 mg) on day 15. Serum concentrations of cefprozil were then measured in all participants on day 15. A 15-d washout period was then assigned after which a 500 mg dose of cefprozil was administered and measured in the serum on day 36. 3. All subjects completed the trial, and no serious adverse events were reported. We measured mean serum concentrations of cefprozil in the presence and absence of quercetin in all participants. The maximum serum concentration of cefprozil in the presence of quercetin was 8.18 ug/ml (95% CI: 7.55-8.81) versus a maximum cefprozil concentration of 8.35 ug/ml (95% CI: 7.51-9.19) in the absence of quercetin. We conclude that the concurrent use of quercetin has no substantial effect on serum concentrations of orally administered cefprozil. 4. Co-administration of quercetin showed no statistically significant effects on the pharmacokinetics of cefprozil in healthy Chinese subjects.

Quercetin significantly inhibits the metabolism of caffeine, a substrate of cytochrome P450 1A2 unrelated to CYP1A2*1C (-2964G>A) and *1F (734C>A) gene polymorphisms.

BACKGROUND: Quercetin is abundant in plants and human diets. Previous studies indicated that quercetin inhibited the activity of CYP1A2, and the combination of quercetin with the substrates of CYP1A2 might produce herb-drug interactions. This research aims to determine the effects of quercetin and the CYP1A2 gene polymorphisms, namely, CYP1A2*1C (-2964G>A) and *1F (734C>A), on the metabolism of caffeine. METHOD: The experiment was designed into two treatment phases separated by a 2-week washout period. Six homozygous individuals for the CYP1A2*1C/*1F (GG/AA) genotype and 6 heterozygous individuals for the CYP1A2*1C/*1F (GA/CA) genotype were enrolled in the study. Quercetin capsules (500 mg) were given to each volunteer once daily for 13 consecutive days, and after that, each subject was coadministrated 100 mg caffeine capsules with 500 mg quercetin on the 14th day. Then a series of venous blood samples were collected for HPLC analysis. Correlation was determined between pharmacokinetics of caffeine and paraxanthine with caffeine metabolite ratio. RESULTS: Quercetin significantly affected the pharmacokinetics of caffeine and its main metabolite paraxanthine, while no differences were found in the pharmacokinetics of caffeine and paraxanthine between GG/AA and GA/CA genotype groups. CONCLUSION: Quercetin significantly inhibits the caffeine metabolism, which is unrelated to CYP1A2*1C (-2964G>A) and *1F (734C>A) gene polymorphisms.

Pharmacokinetic interactions between ilaprazole and clarithromycin following ilaprazole, clarithromycin and amoxicillin triple therapy.

AIM: To investigate the drug interactions between ilaprazole, a new proton pump inhibitor, and clarithromycin following ilaprazole, clarithromycin and amoxicillin combination therapy. METHODS: Twelve healthy Chinese volunteers were recruited in a randomized, open-label, 3-period crossover study. All subjects were administered ilaprazole (5 mg), clarithromycin (500 mg) or a triple therapy, including ilaprazole (5 mg), clarithromycin (500 mg) and amoxicillin (1 g), twice daily for 6 consecutive days. On the 7th day, the drugs were given once, and blood samples were collected and analyzed using a well-validated HPLC/MS/MS method. RESULTS: Following the triple therapy, the peak concentration (C(max)) and the area under the concentration-time curve from 0 h to 12 h (AUC(0→12)) of ilaprazole were significantly decreased, as compared with the single medication group (C(max):1025.0±319.6 vs 1452.3±324.6 ng/mL; AUC(0→12): 9777.7±3789.8 vs 11363.1±3442.0 ng·h/mL). Similar changes were found for ilaprazole sulfone (C(max): 5.9±0.5 vs 9.3±1.7 ng/mL; AUC(0→12): 201.4±32.1 vs 277.1±66.2 ng·h/mL). The triple therapy significantly elevated the C(max) of clarithromycin (3161.5±702.2 vs 2541.9±476.2 ng/mL). CONCLUSION: The H pylori eradication therapy with clarithromycin, amoxicillin and ilaprazole may cause pharmacokinetic interactions that decrease the amount of ilaprazole and its metabolites and elevate that of clarithromycin.

Lack of effect of genetic polymorphisms of SLCO1B1 on the lipid-lowering response to pitavastatin in Chinese patients.

AIM: To investigate the SLCO1B1 388A>G and 521T>C polymorphisms in hyperlipidemia patients and evaluate the effect of the two polymorphisms on the lipid-lowering efficacy of pitavastatin. METHODS: The functional polymorphisms of SLCO1B1 (388A>G and 521T>C) were genotyped in 140 Chinese patients with essential hyperlipidemia using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and one-step tetra-primers ARMS-PCR. Eighty-five patients were enrolled in the clinical trial and given 2 mg of pitavastatin daily for 8 weeks. Total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) serum levels were measured at baseline, after 4 weeks and after 8 weeks of treatment. RESULTS: The allele frequencies of SLCO1B1 388A>G and 521T>C in essential hyperlipidemia patients were 71.1% and 11.1%, respectively. The 4- and 8-week treatment with pitavastatin significantly reduced TC, TG, and LDL levels, but there was no statistical difference among patients with wild type, SLCO1B1 388A>G or SLCO1B1 521T>C in the lipid-lowering efficacy of pitavastatin. CONCLUSION: The present study found that the allele frequencies of SLCO1B1 388A>G and 521T>C in Chinese patients with essential hyperlipidemia are comparable to those in healthy Chinese population. SLCO1B1 388A>G and 521T>C do not affect the lipid-lowering efficacy of pitavastatin.

An improved LC-MS/MS method for quantitative determination of ilaprazole and its metabolites in human plasma and its application to a pharmacokinetic study.

AIM: To improve and validate an analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the quantitative measurement of ilaprazole and its two metablites in human plasma. METHODS: Separation of analytes and the internal standard (IS), omeprazole, was performed on a Thermo HyPURITY C18 column (150x2.1 mm, 5 microm) with a mobile phase consisting of 10 mmol/L ammonium formate water-acetonitrile solution (50:50, v/v) at a flow rate of 0.25 mL/min. The API4000 triple quadruple mass spectrometer was operated in multiple reactions monitoring mode via positive electrospray ionization interface using the transition m/z 367.2 --> m/z184.0 for ilaprazole, m/z 383.3 --> m/z 184.1 for ilaprazole sulfone, m/z 351.2 --> m/z 168.1 for ilaprazole thiol ether and m/z 346.2 --> m/z 198.0 for omeprazole. RESULTS: The method was linear over the concentration range of 0.23-2400.00 ng/mL for ilaprazole, 0.05-105.00 ng/mL for ilaprazole thiol ether and 0.06-45.00 ng/mL for ilaprazole sulfone. The intra- and inter-day precisions were all less than 15% in terms of relative standard deviation (RSD), and the accuracy was within 15% in terms of relative error (RE) for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.23, 0.05 and 0.06 ng/mL with acceptable precision and accuracy for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether, respectively. CONCLUSION: The validated method offered sensitivity and a wide linear concentration range. This method was successfully applied for the evaluation of the pharmacokinetics of ilaprazole and its two metabolites after single oral doses of 5 mg ilaprazole to 12 healthy Chinese volunteers.

Lack of effect of Ginkgo biloba on voriconazole pharmacokinetics in Chinese volunteers identified as CYP2C19 poor and extensive metabolizers.

BACKGROUND: Ginkgo biloba is one of the most popular herbal supplements in the world. The supplement has been shown to induce the enzymatic activity of CYP2C19, the main cytochrome P450 isozyme involved in voriconazole metabolism. Because this enzyme exhibits genetic polymorphism, the inductive effect was expected to be modulated by the CYP2C19 metabolizer status. OBJECTIVE: To examine the possible effects of Ginkgo biloba as an inducer of CYP2C19 on single-dose pharmacokinetics of voriconazole in Chinese volunteers genotyped as either CYP2C19 extensive or poor metabolizers. METHODS: Fourteen healthy, nonsmoking volunteers-7 CYP2C19 extensive metabolizers (2C19(*)1/2C19(*)1) and 7 poor metabolizers (2C19(*)2/2C19(*)2)-were selected to participate in this study. Pharmacokinetics of oral voriconazole 200 mg after administration of Ginkgo biloba 120 mg twice daily for 12 days were determined for up to 24 hours by liquid chromatography-electrospray tandem mass spectrometry in a 2-phase randomized crossover study with 4-week washout between phases. RESULTS: For extensive metabolizers, the median value for voriconazole area under the plasma concentration-time curve from zero to infinity (AUC(0-)(infinity)) was 5.17 microg.h/mL after administration of voriconazole alone and 4.28 microg.h/mL after voriconazole with Ginkgo biloba (p > 0.05). The other pharmacokinetic parameters of voriconazole such as AUC(0-24), time to reach maximum concentration, half-life, and apparent clearance also did not change significantly for extensive metabolizers in the presence of Ginkgo biloba. Pharmacokinetic parameters followed a similar pattern for poor metabolizers. CONCLUSIONS: The results suggest that 12 days of treatment with Ginkgo biloba did not significantly alter the single-dose pharmacokinetics of voriconazole in either CYP2C19 extensive or poor metabolizers. Therefore, the pharmacokinetic interactions between voriconazole and Ginkgo biloba may have limited clinical significance.

Simultaneous action of the flavonoid quercetin on cytochrome P450 (CYP) 1A2, CYP2A6, N-acetyltransferase and xanthine oxidase activity in healthy volunteers.

1. Quercetin, one of the most abundant natural flavonoids, has been reported to modulate the activity of several drug-metabolising enzymes. The aim of the present study was to investigate the effects of quercetin on cytochrome P450 (CYP) 1A2, CYP2A6, N-acetyltransferase (NAT2) and xanthine oxidase (XO) activity in healthy volunteers using caffeine as a probe drug. 2. Twelve unrelated, healthy volunteers were recruited to the study. There were two phases to the study; in the first phase, each subject was given a single oral dose of caffeine (one 100 mg capsule) with 150 mL water; in the second phase, each subject was give a 500 mg quercetin capsule once daily for 13 continuous days and was coadministered a 100 mg caffeine capsule on the 13th day. Urinary caffeine metabolite ratios were used as indicators of the activity of CYP1A2, CYP2A6, NAT2 and XO. The pharmacokinetics of caffeine and its metabolites were determined by HPLC. 3. In the quercetin-treated group, CYP1A2 activity was decreased by 10.4% (95% confidence interval (CI), 1.1-29.8%; P = 0.039), whereas increases were observed in CYP2A6 (by 25.3%; 95% CI, 6.2-34.5%; P = 0.002), NAT2 (by 88.7%; 95% CI, 7.1-160.2%; P = 0.010) and XO activity (by 15.0%; 95% CI, 1.6-21.6%; P = 0.007). Plasma C(max) and the AUC((0-24 h)) of 1,7-dimethylxanthine were decreased by 17.2% (95% CI, 6.4-28.0%; P = 0.024) and 16.2% (95% CI, 3.9-28.5%; P = 0.032), respectively. The urinary excretion of 1,7-dimethylxanthine and 1-methylxanthine was significantly decreased by 32.4% (95% CI, 2.5-62.1%; P = 0.036) and 156.1% (95% CI, 53.3-258.9%; P = 0.004), respectively. The urinary excretion of 1,7-dimethylurate and 1-methylurate was increased by 82.9% (95% CI, 56.0-165.4%; P = 0.030) and 97.8% (95% CI, 12.1-183.5%; P = 0.029), respectively. No changes were observed in the urinary excretion of caffeine and 5-acetylamino-6-formylamino-3-methyluracil between the two study phases. 4. The results of the present study indicate that quercetin inhibits CYP1A2 function, but enhances CYP2A6, NAT2 and XO activity. Simultaneously, some pharmacokinetic parameters relating to 1,7-dimethylxanthine were affected by quercetin. Thus, we conclude that quercetin affects CYP1A2, CYP2A6, NAT2 and XO activity in vivo.

Effect of sinomenine on human cytochrome P450 activity.

BACKGROUND: Cytochrome P450s superfamily expressed widely in organisms are known to play an important role in the biotransformation of many endogenous and exogenous substances. Inhibition or induction of cytochrome P450 isozymes is one of the major causes for clinical drug-drug interactions. Sinomenine can be metabolized to at least 2 metabolites in human, rat in vivo and in human liver microsomes. The major metabolite was identified to be N-demethylsinomenine. However, which CYP450 isozymes mediated by sinomenine in vivo and in vitro is not known. METHOD: In vitro study, 6 probe drugs were incubated with or without sinomenine respectively to study the effect of sinomenine on different cytochrome P450s activities in human microsomes. In vivo study, a 5-drug cocktail approach was used to study the inhibitive and inducing effect of sinomenine at normal clinical dose on cytochrome P450s activities. RESULTS: Sinomenine (50 micromol/l) had no significant effects on the activities of CYP1A2, CYP3A4, CYP2C9, CYP2E1, and CYP2D6, but it decreased the activity of CYP2C19 by 69% (p=0.012) in human microsomes. In vivo, sinomenine showed almost no significant effects on the activities of CYP1A2, CYP3A4, CYP2E1, and CYP2D6, but enhanced the elimination of mephenytoin by 73% (p=0.032). CONCLUSION: Sinomenine (50 micromol/l) inhibited the activity of CYP2C19 in human microsomes, but in vivo sinomenine at normal clinical dose enhanced the elimination of mephenytoin.

Distributive characteristics of Ser49Gly and Gly389Arg genetic polymorphisms of beta1-adrenoceptor in Chinese Han and Dai populations.

AIM: Genetic polymorphisms causing Ser49Gly and Gly389Arg mutants of beta(1)-adrenoceptor may result in significant changes in the function of this receptor. The aim of the present study was to investigate the frequencies of the Ser49Gly and Gly389Arg mutant alleles in healthy Chinese populations and to investigate the differences between 2 Chinese ethnic groups (Han and Dai populations) with respect to the frequencies of these alleles. METHODS: A total of 225 Han Chinese and 175 Dai Chinese unrelated healthy volunteers were recruited for this study. Genomic DNA was extracted from peripheral blood leukocytes by using a standard manual chloroform-phenol extraction. Fragments spanning the 2 polymorphisms were amplified by using polymerase chain reaction with template genomic DNA and relevant primers. The DNA products including the polymorphic loci were subjected to restriction endonuclease digestion with Eco0109I and BcgI. Digested fragments were detected with an ultraviolet detector after electrophoresis (100 V for approximately 1.5 h). RESULTS: The frequencies of the Gly49 and Arg389 alleles were, respectively, 16.2% and 76.4% in the Han population and 14.6% and 75.7% in the Dai population. CONCLUSION: The polymorphisms causing the Ser49Gly and Gly389Arg mutations of the beta(1)-adrenoceptor existed in both healthy Han and Dai Chinese populations. The frequencies of the Ser49Gly and Gly389Arg mutant alleles were not significantly different in the Han and Dai populations. However, the frequency of the Gly389 variant seems to be significantly lower in these 2 populations than in an African-American population.

Gender specific association of CYP2C9*3 with hyperlipidaemia in Chinese.

AIMS: To investigate the association of CYP2C9*3 and *6 with hyperlipidaemia in Chinese. METHODS: Four hundred and seventy-six Chinese participated in the study, including 211 uncomplicated hyperlipidaemic patients and 265 healthy controls. PCR-RFLP was used to identify CYP2C9*3 and *6. RESULTS: CYP2C9*6 was not detected in this study. The allelic frequency of CYP2C9*3 was 0.039 (95% CI 0.022, 0.056). A nonsignificant difference existed in CYP2C9*3 frequencies between males and females (P = 0.605, OR = 1.194, 95% CI 0.610, 2.336), patients and controls (P = 0.063, OR = 0.506, 95% CI 0.244, 1.049) in the total population. However, in the female group, CYP2C9*3 frequency in patients with hyperlipidaemia was significantly lower than that in controls (P < 0.0001, OR = 0.062, 95% CI 0.008, 0.476). CONCLUSIONS: The association of CYP2C9*3 with hyperlipidaemia was specific for females in this Chinese population.

The distribution and gender difference of CYP3A activity in Chinese subjects.

AIMS: To investigate the distribution of CYP3A activity in the Chinese population, and to test for gender-related differences in CYP3A activity. METHODS: Using midazolam as a probe drug, CYP3A activity in 202 Chinese healthy subjects (104 men) was measured by plasma 1'-hydroxymidazolam:midazolam (1'-OH-MDZ:MDZ) ratio at 1 h after oral administration of 7.5 mg midazolam. The different phases of the menstrual cycle including preovulatory, ovulatory and luteal phases of 66 women phenotyped with midazolam were recorded. The concentrations of 1'-OH-MDZ and MDZ in plasma were measured by HPLC RESULTS: A 13-fold variation of CYP3A activity (log1'-OH-MDZ:MDZ: range -0.949-0.203) was shown. The CYP3A activity was normally distributed as indicated by the frequency distribution histogram, the probit plot and the Kolmogorov-Smirnov test (P > 0.05). The CYP3A activity of women was higher than that of men (median: -0.36 vs -0.43, P < 0.05; 95% CI for difference: -0.127, -0.012). There was a significant difference in CYP3A activity between the three phases of the menstrual cycle. The activity was highest in the preovulatory phase and decreased sequentially in the ovulatory and luteal phases (P < 0.05). CONCLUSIONS: A normal distribution of CYP3A activity was observed in the Chinese population. The CYP3A activity is higher in female subjects than in males. CYP3A activity differed across the phases of the menstrual cycle.

Isozyme-specific induction of low-dose aspirin on cytochrome P450 in healthy subjects.

OBJECTIVE: This study was designed to define the effect of low-dose aspirin administration on the activity of cytochrome P450 (CYP) in normal human subjects. METHODS: Aspirin, 50 mg daily, was given for 14 days to 18 nonsmoking healthy male volunteers. A modified 5-drug cocktail procedure consisting of caffeine, mephenytoin, metoprolol, chlorzoxazone, and midazolam was performed to simultaneously assess in vivo activity of CYP1A2, CYP2C19, CYP2D6, CYP2E1, and CYP3A, respectively. The activities were assessed on 4 occasions including at baseline, after 7 and 14 daily doses of aspirin, and at 7 days after discontinuation of aspirin. Concentrations of parent drugs and corresponding metabolites in biologic samples were assayed by reversed-phase HPLC. RESULTS: Both 7-day and 14-day aspirin intake increased the activity of CYP2C19 significantly, as indicated by 4-hydroxymephenytoin urinary recovery (P <.001). Induction of low-dose aspirin on CYP2C19 was time-dependent. CYP3A activity indices increased moderately but significantly by both 7-day and 14-day aspirin treatment (P <.05), but the percentage changes in CYP3A activity indices were not significant. Low-dose aspirin had no effect on CYP1A2, CYP2D6, and CYP2E1 in vivo activity by either 7-day or 14-day treatment. CONCLUSIONS: The effect of low-dose aspirin on CYPs was enzyme-specific. Both 7-day and 14-day low-dose aspirin induced the in vivo activities of CYP2C19 but did not affect the activities of CYP1A2, CYP2D6, and CYP2E1. The effect of low-dose aspirin on CYP3A activity awaits further confirmation. When low-dose aspirin is used in combination with drugs that are substrates of CYP2C19, doses of the latter should be adjusted to ensure their efficacy.