Pharmacokinetics, Tissue Distribution and Excretion of a Novel Diuretic (PU-48) in Rats.

Methyl 3-amino-6-methoxythieno [2,3-b] quinoline-2-carboxylate (PU-48) is a novel diuretic urea transporter inhibitor. The aim of this study is to investigate the profile of plasma pharmacokinetics, tissue distribution, and excretion by oral dosing of PU-48 in rats. Concentrations of PU-48 within biological samples are determined using a validated high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. After oral administration of PU-48 (3, 6, and 12 mg/kg, respectively) in self-nanomicroemulsifying drug delivery system (SNEDDS) formulation, the peak plasma concentrations (Cmax), and the area under the curve (AUC0⁻∞) were increased by the dose-dependent and linear manner, but the marked different of plasma half-life (t1/2) were not observed. This suggests that the pharmacokinetic profile of PU-48 prototype was first-order elimination kinetic characteristics within the oral three doses range in rat plasma. Moreover, the prototype of PU-48 was rapidly and extensively distributed into thirteen tissues, especially higher concentrations were detected in stomach, intestine, liver, kidney, and bladder. The total accumulative excretion of PU-48 in the urine, feces, and bile was less than 2%. This research is the first report on disposition via oral administration of PU-48 in rats, and it provides important information for further development of PU-48 as a diuretic drug candidate.

Interaction between 3,4­dichlorophenyl­propenoyl­sec.­butylamine (3,4­DCPB), an antiepileptic drug, and cytochrome P450 in rat liver microsomes and recombinant human enzymes in vitro.

The compound 3,4­dichlorophenyl­propenoyl­sec.­butylamine (3,4­DCPB) is an antiepileptic drug. The purpose of the present research was to identify cytochrome P450 (CYP450) responsible for the metabolism of 3,4­DCPB and evaluate the effects of 3,4­DCPB on the activities of CYP450 enzymes. 3,4­DCPB was incubated with rat liver microsomes (RLMs) plus six CYP450 enzyme-specific inhibitors, or six recombinant human CYP450 enzymes (rhCYP450s). The concentrations of 3,4­DCPB and six CYP450 enzyme-activities probe drugs were detected by high-performance liquid chromatographic (HPLC). The results showed that the prototype of 3,4­DCPB was metabolized by multiple CYP450 enzymes into three metabolites, and the predominant isoforms were CYP2D6 (metabolite M1), CYP1A2 (M2), CYP2C19 and CYP3A4 (M3), respectively., in the presence of ß-NADPH (1 mM) in RLMs or rhCYP450s. Compared with the control (PB-), phenobarbital pre-treatment (PB+) significantly enhanced levels (all of p < 0.01) of hydroxylmethytobutamide (CYP2C9), 4­hydroxy­mephenytoin (CYP2C19), acetaminophen (CYP1A2), 6­hydroxychlorzoxazone (CYP2E1) and oxidized nifedipine (CYP3A4), respectively, in spite of dextrophan (CYP2D6) was not markedly enhanced in RLMs. Conversely, the inhibitory ratios of 3,4­DCPB (16 µg/mL, 59 µM) on the activities of CYP2C9, CYP2C19, CYP1A2 and CYP2D6 were 97.6%, 59.0%, 53.5% and 36.5%, respectively. However, CYP2E1 (both of PB- and PB+) and CYP3A4 (PB+) were not inhibited by 3,4­DCPB in RLMs. In conclusion, the present study showed that 3,4­DCPB was metabolized by multiple CYP450 enzymes. 3,4­DCPB inhibited the activities of CYP2C9, CYP2C19, CYP1A2 and CYP2D6, rather than that CYP2E1 and CYP3A4 enzymes, suggesting that the different effects of 3,4­DCPB on the CYP450 enzymes might influence metabolic drug-drug interaction in antiepileptics therapy.

Effects of UGT1A1, CYP3A5 and ABCB1 Genetic Variants on Pharmacokinetics of Antihistamine Drug Mizolastine in Chinese Healthy Volunteers.

Mizolastine is a selective histamine H1 receptor antagonist for chronic urticaria or allergic rhinitis. We investigated whether the variant genotypes of metabolic enzymes UGT1A1, CYP3A5 and transporter ABCB1 influence pharmacokinetic phenotype of substrate mizolastine in Chinese volunteers. Genotyping of single nucleotide polymorphisms in UGT1A1*6 (G211A), CYP3A5*3 (A6986G) and ABCB1 (C3435T) was determined by the pyrosequencing method. After a single oral dose of 10 mg mizolastine, the plasma concentrations were measured using validated high-performance liquid chromatography in 24 Chinese healthy volunteers. The results showed that the distributions of wild-type homozygotes and variant allele carriers (the sum of variant heterozygotes and variant homozygotes) were as follows: 17 cases (70.8%) versus seven cases (29.2%) in UGT1A1*6 genotypes, five cases (20.8%) versus 19 cases (79.2%) in CYP3A5*3 genotypes and seven cases (29.2%) versus 17 cases (70.8%) in ABCB1 3435T genotypes, respectively. There were no significant differences in pharmacokinetic parameters of mizolastine between the variant allele UGT1A1*6, CYP3A5*3 and ABCB1 3435T carriers and the wild-type homozygotes, and the ratios were as follows: Cmax was 101.03%, 86.02% and 105.78%; Tmax was 162.35%, 98.98% and 144.90%; AUC0-28 was 113.04%, 77.35% and 112.71%; and t1/2 was 95.77%, 72.40% and 100.97%, respectively. In conclusion, these results suggested that the UGT1A1, CYP3A5 and ABCB1 genetic polymorphisms might be not contributed to the interindividual variation of mizolastine pharmacokinetic phenotype in the Chinese population.

Development and validation of an LC-MS/MS method for the determination of a novel thienoquinolin urea transporter inhibitor PU-48 in rat plasma and its application to a pharmacokinetic study.

A specific, sensitive and stable high-performance liquid chromatographic-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitative determination of methyl 3-amino-6-methoxythieno [2,3-b]quinoline-2-carboxylate (PU-48), a novel diuretic thienoquinolin urea transporter inhibitor in rat plasma. In this method, the chromatographic separation of PU-48 was achieved with a reversed-phase C18 column (100 × 2.1 mm, 3 µm) at 35°C. The mobile phase consisted of acetonitrile and water with 0.05% formic acid added with a gradient elution at flow rate of 0.3 mL/min. Samples were detected with the triple-quadrupole tandem mass spectrometer with multiple reaction monitoring mode via electrospray ionization source in positive mode. The retention time were 6.2 min for PU-48 and 7.2 min for megestrol acetate (internal standard, IS). The monitored ion transitions were mass-to-charge ratio (m/z) 289.1 → 229.2 for PU-48 and m/z 385.3 → 267.1 for the internal standard. The calibration curve for PU-48 was linear over the concentration range of 0.1-1000 ng/mL (r2 > 0.99), and the lower limit of quantitation was 0.1 ng/mL. The precision, accuracy and stability of the method were validated adequately. The developed and validated method was successfully applied to the pharmacokinetic study of PU-48 in rats.

Effects of crystalline state and self-nanoemulsifying drug delivery system (SNEDDS) on oral bioavailability of the novel anti-HIV compound 6-benzyl-1-benzyloxymethyl-5-iodouracil in rats.

The objective of this study was to investigate the effect of crystalline state and a formulation of self-nanoemulsifying drug delivery system (SNEDDS) on oral bioavailability of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor, in rats. The crystalline states of W-1 were characterized by scanning electron microscope (SEM), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). The SNEDDS was formulated by medium-chain lipids, characterized by droplet particle size. The plasma concentrations of W-1 were measured by high performance liquid chromatography (HPLC). The results indicated that W-1 compound were presented as crystalline forms, A and B, the degree of crystallization in form B was higher than that in form A. The SNEDDS of W-1 displayed a significant increase in the dissolution rate than W-1 powder. Furthermore, after oral administration of W-1 (100 mg/kg), the pharmacokinetic parameters of form A, form B, and W-1 SNEDDS were as follows: AUC0-t 526.4 ± 123.5, 305.1 ± 58.5 and 2297 ± 451 ng h/mL (p < .05, when W-1 SNEDDS were compared with either form A or form B), respectively. With SNEDDS formulation, the relative bioavailabilities were enhanced by 4.36-fold and 7.53-fold over the form A and form B of W-1, respectively. In conclusion, the present results suggested that the crystalline states of W-1 might lead to the lower oral bioavailability, and SNEDDS formulation is a promising strategy of improving bioavailability, in spite of that crystalline states usually carry small lot-to-lot variability.

Effects of functional CYP2C8,CYP2C9,CYP3A5,and ABCB1 genetic variants on the pharmacokinetics of insulin sensitizer pioglitazone in Chinese Han individuals.

BACKGROUND AND OBJECTIVES: Pioglitazone is a thiazolidinedione antihyperglycemic drug with insulin-sensitizing properties. We investigated whether the variant genotypes of cytochrome P450 2C8 (CYP2C8), CYP2C9, CYP3A5 and transporter ABCB1 influence the pharmacokinetic phenotype of the substrate pioglitazone in Chinese individuals. PARTICIPANTS AND METHODS: Single-nucleotide polymorphisms were determined by the PCR-restriction fragment length polymorphism method in 244 (CYP2C8 and CYP2C9) healthy Chinese Han individuals. After a single oral dose of 30 mg pioglitazone, the plasma concentrations of the parent drug and of two major active metabolites M-III and M-IV were measured using a validated LC-MS/MS in 21 (genotyping CYP3A5 and ABCB1) of these 244 volunteers. RESULTS: The results confirmed that the unique frequencies of CYP2C8*2 (0.0%), CYP2C8*3 (0.0%), and CYP2C9*2 (0.0%) alleles were significantly different from those reported in Whites and Africans, and there were only 10 variant CYP2C9*1/*3 heterozygous (CYP2C9*3 carriers) among 244 Chinese individuals. These results were similar to those reported in Asian ethnic populations, including the Chinese. Unexpectedly, the pioglitazone AUC0-48 in CYP2C9*3 carriers was lower (50.8%), whereas the AUC0-48 ratios of metabolites M-III/pioglitazone and M-IV/pioglitazone increased to 134.3 and 155.8%, respectively, compared with the wild-type CYP2C9*1/*1 homozygous. Moreover, this phenomenon was not observed in individuals with genetic variants of CYP3A5*3 and ABCB1 (C1236T). CONCLUSION: The present research suggests that the CYP2C8, CYP3A5, and ABCB1 genes play no significant role in the interindividual variation of pioglitazone pharmacokinetics, whereas CYP2C9*3 carriers are likely to accelerate the metabolism of this antidiabetic drug in the Chinese Han ethnic population.

Identification of cytochrome P450s involved in the metabolism of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1) using human recombinant enzymes and rat liver microsomes in vitro.

1. The aim of this study was to identify the hepatic metabolic enzymes, which involved in the biotransformation of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) in rat and human in vitro. 2. The parent drug of W-1 was incubated with rat liver microsomes (RLMs) or recombinant CYPs (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP3A5, respectively) in the presence or absence of nicotinamide adeninedinucleotide phosphate (NADPH)-regenerating system. The metabolites of W-1 were analyzed with liquid chromatography-ion trap-time of flight-mass spectrometry (LC-IT-TOF-MS). 3. The parent drug of W-1 was metabolized in a NADPH-dependent manner in RLMs. The kinetic parameters of prototype W-1 including Km, Vmax, and CLint were 2.3 µM, 3.3 nmol/min/mg protein, and 1.4 mL/min/mg protein, respectively. Two metabolites M1 and M2 were observed in shorter retention times (2.988 and 3.188 min) with a higher molecular ion at m/z 463.0160 (both M1 and M2) than that of the W-1 parent drug (6.158 min with m/z 447.0218). The CYP selective inhibition and recombinant enzymes also showed that two hydroxyl metabolites M1 and M2 are mainly mediated by CYP2C19 and CYP3A4. 4. The identification of CYPs involved in W-1 biotransformation is important to understand and minimize, if possible, the potential of drug-drug interactions.

Profile of disposition, tissue distribution and excretion of the novel anti-human immunodeficiency virus (HIV) agent W-1 in rats.

The purpose of this study was to characterize the disposition, distribution, excretion and plasma protein binding of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1) in rats. Concentrations of W-1 within biological samples were determined using a validated high performance liquid chromatography method. The plasma protein binding of W-1 was examined by equilibrium dialysis method. After oral administration of W-1 (50, 100 and 200 mg/kg, respectively) in self-microemulsifying drug delivery system formulation, the pharmacokinetic parameters of W-1 were as follows: the peak plasma concentrations (C max) were 0.42, 1.50 and 2.55 µg/mL, the area under the curve (AUC0-t) were 0.89, 2.27 and 3.96 µg/h mL and the plasma half-life (t 1/2) were 5.15, 3.77 and 3.77 h, respectively. Moreover, the prototype of W-1 was rapidly and extensively distributed into fifteen tissues, especially higher concentrations were detected in intestine, stomach and liver, respectively. The plasma protein binding of W-1 in rat, beagle dog and human were in the range of 97.96-99.13 %. This study suggested that W-1 has an appropriate pharmacokinetics in rats, such as rapid absorption, moderate clearance, and rapid distribution to multiple tissues. Those properties provide important information for further development W-1 as an anti-HIV-1 drug candidate.

Novel single nucleotide polymorphisms (SNPs) of CYP2W1 gene in Chinese Uygur and Han populations.

Cytochrome P450 2W1 (CYP2W1) is expressed specially in certain cancers and could metabolize some substances into cytotoxic antitumor drugs in Caucasian ethnic population. To investigate the genetic polymorphism of CYP2W1 in Chinese, all the nine exons and exon-intron junctions were sequenced by dideoxy chain termination method among 385 Chinese subjects (including 223 Han and 162 Uygur). The present results showed that 40 single nucleotide polymorphisms (SNPs) were detected (14 in the exons and 26 in the introns), 10 were novel variants of which in Chinese. There were 7 novel SNPs in the exons and other 3 novel SNPs in the introns. Four of the 6 novel non-synonymous variations in exons, 131T > C (Leu44Pro), 1289C > A (Ala88Glu), 2027G > A (Arg187Gln) and 5070C > T (Thr383Met) were computationally predicted to affect CYP2W1 protein function, in spite of these variants were heterozygotes. Moreover, the allele frequencies in 6 known SNPs including CYP2W1*2 (2008G > A) and CYP2W1*3 (173A > C) were analyzed, which were significantly lower in Chinese Han (2.9% and 0.0%, respectively) and Uygur (5.2% and 0.0%, respectively) individuals, than those reported previously in Caucasians (9.1% and 33.1%, respectively, P < 0.05). These data provide useful information on the pharmacogenetic studies of CYP2W1 among Chinese and other ethnic populations.

Quantitative and qualitative analysis of the novel antitumor 1,3,4-oxadiazole derivative (GLB) and its metabolites using HPLC-UV and UPLC-QTOF-MS.

Fructose-based 3-acetyl-2,3-dihydro-1,3,4-oxadiazole (GLB) is a novel antitumor agent and belongs to glycosylated spiro-heterocyclic oxadiazole scaffold derivative. This research first reported a simple, specific, sensitive and stable high performance liquid chromatography-ultraviolet detector (HPLC-UV) method for the quantitative determination of GLB in plasma. In this method, the chromatographic separation was achieved with a reversed phase C18 column. The calibration curve for GLB was linear at 300 nm. The lower limit of quantification was 10 ng/mL. The precision, accuracy and stability of the method were validated adequately. This method was successfully applied to the pharmacokinetic study in rats for detection of GLB after oral administration. Moreover, the structures of parent compound GLB and its two major metabolites M1 and M2 were identified in plasma using an ultra performance liquid chromatography-electrospray ionization-quadrupole-time of flight- mass spectrometry (UPLC-ESI-QTOF-MS) method. Our results indicated that the di-hydroxylation (M1) and hydroxylation (M2) of GLB are the major metabolites. In conclusion, the present study provided valuable information on an analytical method for the determination of GLB and its metabolites in rats, can be used to support further developing of this antitumor agent.

Development and validation of a high performance liquid chromatography method for determination of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor and its application to a pharmacokinetic study in rats.

A sensitive and selective high-performance liquid chromatographic (HPLC) method for determination of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor in rat plasma, was developed and validated. Chromatographic separation of W-1 and megestrol acetate (internal standard) was achieved on a reversed-phase C18 column at 25°C. The mobile phase was consisted of acetonitrile-water (60:40, v/v) and pumped at a flow rate of 1.0 mL/min. The ultraviolet (UV) detector was set at the absorption wavelength of 284 nm. The calibration curve for W-1 was linear over the concentration range of 0.01-8 µg/mL and the lower limit of quantification was 10 ng/mL. The intra- and inter-day precision and accuracy were <8.9 and 5.3%, respectively. The extraction recoveries ranged from 97.9 to 101.6%. The validated HPLC method was successfully applied to a pharmacokinetic study of W-1 in rats.

[LC-MSn analysis of metabolites of 1,2-[bis (1,2-benzisoselenazolone-3(2H)-ketone)]-ethane, a novel anti-cancer agent in rat].

This study is to elucidate the metabolic pathway of 1,2-[bis (1,2-benzisoselenazolone-3 (2H)-ketone)]-ethane (BBSKE) in rats. Rats were administrated with a single dose of BBSKE 200 mg x kg(-1). The metabolites in rat urine, feces, bile and plasma were identified by LC-MSn analysis. The characterization of fragment ions from LC-MSn chromatography and mass spectrometry was applied to the investigation of structures of metabolites. Three phase I metabolites were detected in rat urine and feces. Two of them were also found in plasma and one existed in bile. These products were derived from oxidized, methylated and S-methylated BBSKE, separately. One phase II glucuronide of BBSKE was also found in bile. Therefore, it is possible that BBSKE was metabolized by oxidization, methylation and glucuronidation.

Influence of CYP3A5 and MDR1 genetic polymorphisms on urinary 6 beta-hydroxycortisol/cortisol ratio after grapefruit juice intake in healthy Chinese.

Interindividual variability of cytochrome P450 (CYP) 3A inhibition by grapefruit juice was investigated in relation to CYP3A5 and multidrug resistance gene (MDR) 1 genetic polymorphisms in Chinese Han, Uygur, and Kazakh healthy subjects. The measurement of urinary 6 beta-hydroxycortisol/cortisol ratio was used to evaluate CYP3A activity in vivo by high-performance liquid chromatography. CYP3A5*3 and MDR1 C1236T, G2677T/A, and C3435T polymorphisms were analyzed by polymerase chain reaction restriction fragment length polymorphism. After grapefruit juice intake, urinary ratios significantly decreased in 3 Chinese ethnic groups (P < .001). Kazakh had a larger decrease of urinary ratio compared to that of Han (P < .05), and the latter had similar decrease with Uygur. Furthermore, Chinese healthy subjects carrying CYP3A5*3/*3 and MDR1(1236-2677-3435) T-T-T/T-T-T genotypes were found to have the largest reduction of urinary ratio (mean, 61.4%; 95% confidence interval, 53.4%-69.5%), whereas *1/*3 subjects carrying MDR1(1236-2677-3435) C-G-C/C-G-C genotypes had the lowest reduction (mean, 25.9%; 95% confidence interval, 3.1%-48.8%; P < .01). In conclusion, both CYP3A5*3 and MDR1 variants influenced the extent of CYP3A inhibition by grapefruit juice in Chinese healthy subjects. The genetic variations influencing the CYP3A inhibitive phenotype might be helpful to explain the individual variability of grapefruit juice-drug interactions.

Development of a rapid and sensitive liquid chromatography/tandem mass spectrometry method for the determination of 1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel anti-cancer agent in rat plasma.

A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method has been developed to determine 1, 2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel antineoplastic agent, in rat plasma. The analytes were separated on a C18 column with a mobile phase of methanol-water (75:25, v/v) and detected using a triple-quadrupole mass spectrometer in positive mode with the selective reaction monitoring. The characteristic ion dissociation transitions were m/z 603.0 --> 448.9 for derivatized BBSKE and m/z 631.0 --> 476.8 for derivatized internal standard. The assay was linear over a range of 1-1000 ng/mL with a lower limit of quantification of 1 ng/mL. Intra- and inter-day precisions were less than 9.6 and 5.0%, respectively, and the accuracy ranged from -5.2 to 4.0%. The validated method was successfully applied to the characterization of pharmacokinetic profile of BBSKE after oral administration in rats. Cop

Effect of berberine on hepatocyte proliferation, inducible nitric oxide synthase expression, cytochrome P450 2E1 and 1A2 activities in diethylnitrosamine- and phenobarbital-treated rats.

This study investigated the effect of berberine on the early phase of hepatocarcinogenesis stimulated by diethylnitrosamine (DEN, 150 mg/kg, 4 weeks) plus phenobarbital (PB, 75 mg/kg, 7 days) in rats. The expressions of proliferating cell nuclear antigen (PCNA) and inducible nitric oxide synthase (iNOS) were evaluated by immunohistochemistry. The activities of CYP isoenzymes were analyzed using different probe drugs including chlorzoxazone (CYP2E1) and phenacetin (CYP1A2) by high-performance liquid chromatography (HPLC) in vivo or in vitro. Results showed that the expressions of PCNA and iNOS were induced by DEN plus PB in liver tissues. Oral administration of berberine (50mg/kg) inhibited the hepatocyte proliferation and iNOS expression, decreased cytochrome P450 content, inhibited activities of CYP2E1 and CYP1A2 in DEN-plus-PB-treated rats in vivo. Moreover, berberine (10, 50 and 100 microM) inhibited the activities of CYP2E1 and CYP1A2 in microsomes isolated from DEN-plus-PB-treated rats in vitro, suggesting that anti-hepatocarcinogenetic potential of berberine might be due to inhibiting oxidative metabolic activities of CYP 2E1 and CYP1A2, and decreasing NO production in rats.

Effects of Ganoderma lucidum polysaccharide on CYP2E1, CYP1A2 and CYP3A activities in BCG-immune hepatic injury in rats.

The purpose of the present study was to investigate the effect of Ganoderma lucidum polysaccharide (GLPS), a major active component in Chinese medicinal fungus, on cytochrome P450 metabolic activity in Bacillus Calmette Guérin (BCG)-induced immune hepatic injury in rats. The enzyme kinetics of the probes including chlorzoxazone (CYP2E1), phenacetin (CYP1A2) and nifedipine (CYP3A) were evaluated by HPLC. The results showed that BCG-pretreatment (125 mg/kg) significantly increased serum levels of alanine transaminase (ALT), nitrite and malondialdehyde (MDA), inhibited activities of superoxide dismutase (SOD) and decreased P450 total content in microsomes (p<0.05). Administration of GLPS (50 and 200 mg/kg) reversed above hepatic injury stimulated by BCG in vivo. Moreover, GLPS dose-dependently inhibited activities of CYP2E1, CYP1A2 and CYP3A in hepatic microsomes in vitro, suggesting that inhibition of GLPS on P450 oxidative metabolism might participate in the hepatoprotective mechanism, and also suggested that pharmacokinetics might be changed by drug-herb interaction.

Polymorphisms of tumor necrosis factor-alpha, interleukin-10, cytochrome P450 3A5 and ABCB1 in Chinese liver transplant patients treated with immunosuppressant tacrolimus.

BACKGROUND: Cytokine production in the host immune response after transplantation may contribute to the variable CYP3A-dependent drug disposition. We investigated the effect of TNF-alpha, IL-10, CYP3A5 and ABCB1 polymorphisms on immunosuppressant tacrolimus pharmacokinetics in liver transplant patients. METHODS: Genetic polymorphisms in TNF-alpha, IL-10, CYP3A5 and ABCB1 were studied in 70 liver transplant recipients and 70 donors. Tacrolimus dosage and blood concentration were investigated at 1, 2 and 3 weeks after transplantation. RESULTS: The IL-10 G-1082A polymorphism in recipients was significantly associated with tacrolimus concentration/dose (C/D) ratios (IL-10-1082GG < GA < AA) within the first 3weeks posttransplantation (P < 0.05). Recipients with the capacity for low IL-10 production (-1082AA) carrying CYP3A5 non-expressor (CYP3A5()3/()3) liver had the highest C/D ratios (mean: 172.4, 161.7, 160.3 for 1, 2 and 3 weeks posttransplantation, respectively), whereas recipients with intermediate or high production of IL-10 (-1082GA or GG) engrafted with CYP3A5 expressor (CYP3A5()1 carrier) liver were found to have the lowest ratios (96.4, 78.0 and 75.4, respectively, P < 0.01). CONCLUSIONS: The IL-10 G-1082A and CYP3A5()3 polymorphisms may influence the interindividual variability of tacrolimus pharmacokinetics in Chinese liver transplant patients. This finding provided a new interpretation for the variable immunosuprressant disposition after transplantation.

High performance liquid chromatographic determination of 1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel organoselenium compound, in dog plasma using pre-column derivatization and its application in pharmacokinetic study.

A novel HPLC-UV method with pre-column derivatization by using 2-mercaptoethanol was established for determination of 1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE) in dog plasma. The derivatives were identified by mass spectrometry. The method had a good linear range of 0.05-2 microg/ml (r(2)=0.9995). The lower limit of quantification (LOQ) was 0.05 microg/ml. The precision and accuracy were less than 7%. After dosing of BBSKE (30 mg/kg, p.o. and 0.79 mg/kg, i.v.) in dogs, AUC(0-t) were 5.72+/-2.42 and 1.35+/-0.41 microg h/ml; t(1/2) were 4.6+/-2.1 and 1.7+/-0.6h, respectively. The method was successfully applied to the pharmacokinetic study in dogs.

Pharmacokinetics and metabolism of 3,4-dichlorophenyl-propenoyl-sec.-butylamine in rats by high performance liquid chromatography-ion trap mass spectrometry.

The pharmacokinetics (PK) and metabolism of 3,4-dichlorophenyl-propenoyl-sec.-butylamine (3,4-DCPB), a novel antiepileptic drug, were investigated after its oral administration to rats (100 mg/kg) by HPLC. The absorption and elimination of 3,4-DCPB were rapid. 3,4-DCPB was found to undergo extensive metabolism as the major route of elimination. Structures of the metabolites present in rat plasma were identified with liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). It was concluded that 3,4-DCPB was involved in the multiple metabolic pathways (hydrolysis, dealkylation and oxidation) and the hydrolysis product, 3,4-dichloro-cinnamic acid (M1) appeared to be the major metabolite.

[A clinical pharmacokinetic study of multi-dose oral tetra-arsenic tetra-sulfide combination therapy in acute promyelocytic leukemia].

OBJECTIVE: To study the pharmacokinetics of multi-dose oral tetra-arsenic tetra-sulfide (As(4)S(4)) in acute promyelocytic leukemia (APL) patients and its major side effects. METHODS: Clinical pharmacokinetic study of As(4)S(4) was carried out in 7 patients who had never used arsenic before. The total concentration of arsenic in blood, urine and hair was determined with hydride generation-atomic absorption spectrometry. RESULTS: These patients were administrated oral As(4)S(4) complex capsule 20 mg/kg three times a day for 14 days. From day 10 and to day 14, the blood arsenic concentration and urinary arsenic excretion reached a steady state. The average minimal concentration (Cmin) and maximal concentration (Cmax) of blood arsenic was (53.3 +/- 9.0) microg/L and (70.7 +/- 10.8) microg/L. t 1/2 was prolonged to (70.7 +/- 31.7) hour, and area under curve (AUC) was (448.9 +/- 71.8) microg. h(-1).L(-1). Median time to peak concentration (Tmax) was 1 (range 0.5 - 8) hour. During As(4)S(4) therapy, 24-hour arsenic content in urine was (6170.8 +/- 3141.8) microg/L and it accounted for about (0.152 +/- 0.082)% of the total daily dosage. It decreased steadily over time after drug withdrawal, arsenic accumulated in hair and the concentration could be ten-fold higher than that before treatment. CONCLUSION: Multi-dose oral As(4)S(4) is safe and has been relatively well tolerated in APL patients in spite of the tendency of its retention in some tissues after long time administration.