A possible covalent xanthine oxidase inhibitor TS10: Inhibition mechanism, metabolites identification and PDPK assessment.

Xanthine oxidase (XO) inhibitors are widely used in the control of serum uric acid levels in the clinical management of gout. Our continuous efforts in searching novel amide-based XO inhibitors culminated in the identification of N-(4-((3-cyanobenzyl)oxy)-3-(1H-tetrazol-1-yl)phenyl)isonicotinamide (TS10), which exhibited comparable in vitro inhibition to that of topiroxostat (TS10, IC50 = 0.031 µM; topiroxostat, IC50 = 0.020 µM). According to the molecular modeling, we speculated that, as well as topiroxostat, TS10 would be biotransformed by XO to yield TS10-2-OH. In this work, TS10-2-OH was successfully identified in XO targeted metabolism study, demonstrated that TS10 underwent a covalent binding with XO via a TS10-O-Mo intermediate after anchoring in the XO molybdenum cofactor pocket. Furthermore, TS10-2-OH is a weak active metabolite, and its potency was explained by the molecular docking. In metabolites identification, TS10 could be oxidized by CYP2C9, CYP3A4 and CYP3A5 to generate two mono-hydroxylated metabolites (not TS10-2-OH); and could occur degradation in plasma to mainly generate a hydrolytic metabolite (TS10-hydrolysate). In pharmacokinetic assessment, the low oral system exposure was observed (Cmax = 14.73 ± 2.66 ng/mL and AUClast = 9.17 ± 1.42 h⋅ng/mL), which could be explained by the poor oral absorption property found in excretion studies. Nonetheless, in pharmacodynamic evaluation, TS10 exhibited significant uric acid-lowering effect after oral administration in a dose-dependent manner. Briefly, in addition to allopurinol and topiroxostat, TS10 is possibly another explicitly mechanism-based XO inhibitor with powerful covalent inhibition.

Analysis of risk factors, pathogenic bacteria of maternal sepsis in term pregnant women with positive blood culture during hospitalization.

ABSTRACT: The objective of this study was to evaluate the risk factors, pathogenic bacteria and drug sensitivity of maternal sepsis, and provide evidence for clinical prevention and treatment.A retrospective investigation of pregnant women with full-term maternal sepsis was performed to analyze the risk factors, pathogenic bacteria, and drug sensitivity of maternal sepsis.Univariate analysis showed that temperature, serum procalcitonin (PCT) and C-reactive protein (CRP) at admission, white blood cell count (WBC), PCT, CRP and neutrophilic granulocyte percentage (N%) during fever, premature rupture of membranes (PROM), antibiotic use within 1 week, mode of production, onset and duration of fever, between groups were statistically significant (P < .05). Logistic regression analysis showed that cesarean section was an independent risk factor for sepsis (OR = 11.839, 95%CI: 3.121-44.906). Apparent increase was found in body temperature (OR = 3.664, 95%CI: 1.722-7.795), duration of fever (OR = 1.953, 95%CI: 1.242-3.071), and PCT (OR = 1.080, 95%CI: 1.002-1.163). Also, increasing neutrophil ratio (OR = 1.180, 95%CI: 1.073-1.297) indicated a high possibility of maternal sepsis. The organism Escherichia coli (E. coli) was the most common pathogenic bacteria in the positive blood culture group (90%), and the sensitivity to carbapenems (meropenem and imipenem/cilastatin) was 100%, that to piperacillin-tazobactam and amoxicillin sulbactam was over 90%, and that to ceftazidime was 95%.Cesarean section was an independent risk factor for maternal sepsis in term pregnant women with positive blood culture. Besides, the E. coli was the most common pathogenic bacteria in the positive blood culture group. Antibiotics should be used in time and reasonably when the temperature was significantly increased with elevated PCT and N% after a cesarean section.

Comparative pharmacokinetics study of leonurine and stachydrine in normal rats and rats with cold-stagnation and blood-stasis primary dysmenorrhoea after the administration of Leonurus japonicus houtt electuary.

Leonurus japonicus houtt, a well-known herb of traditional Chinese medicine, is widely used to treat gynaecological diseases. In this study, a rapid and sensitive liquid chromatography with tandem mass spectrometry method for simultaneously quantifying leonurine and stachydrine, the two main bioactive components in Leonurus japonicus houtt, was developed and validated. Plasma samples were prepared by protein precipitation with acetonitrile and separation by a Hewlett Packard XDB-C8 column (150 × 4.6 mm, id, 5 µm) equipped with a gradient elution system containing methanol-water and 0.1% formic acid at a flow-rate of 0.4 mL/min. Components were then detected by a mass spectrometer in positive electrospray ionization mode. This method showed good linearity, precision, accuracy, recovery, stability, and negligible matrix effects, which were within acceptable ranges. The method was successfully applied to compare the pharmacokinetics in normal rats and rats with cold-stagnation and blood-stasis primary dysmenorrhoea treated with Leonurus japonicus houtt electuary. The result showed significant differences (p < 0.05) in the pharmacokinetic parameters between the primary dysmenorrhoea and normal groups. This result implied that Leonurus japonicus houtt electuary remained longer and was absorbed slower in rats with primary dysmenorrhoea and exhibited higher bioavailability and peak concentration.

Ultra-Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS)-Based Pharmacokinetics and Tissue Distribution Study of Koumine and the Detoxification Mechanism of Glycyrrhiza uralensis Fisch on Gelsemium elegans Benth.

Gelsemium elegans Benth. (G. elegans), which is a famous Chinese folk medicine, has been commonly used to treat certain types of skin ulcers and alleviate inflammation, headaches, and cancer pain. However, the extensive clinical use of G. elegans has been greatly hampered by its toxicity. As one of the most widely used herbal medicines, Glycyrrhiza uralensis Fisch, has a unique effect on detoxification of G. elegans. In the present study, a rapid and sensitive method using ultra-liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was established and validated for determination of koumine, the most abundant molecule among the alkaloids of G. elegans, in rat plasma, tissue, and liver microsome. The developed method was successfully applied to the pharmacokinetics, tissue distribution, and in vitro metabolism study in rat with or without pre-treated Glycyrrhiza uralensis Fisch extract. Meanwhile, the expression level of CYP3A1 mRNA was analyzed to explain the detoxification mechanism of Glycyrrhiza uralensis Fisch on G. elegans. As a result, our work demonstrated that Glycyrrhiza uralensis Fisch could significantly affect the pharmacokinetics and tissue distribution of koumine in rats. The detoxification mechanism of Glycyrrhiza uralensis Fisch on G. elegans may be its cytochrome enzyme up-regulation effect.

Simultaneous determination of lidamycin enediyne chromophore (LDC) and its aromatized derivative (LDCA) using puerarin as internal standard in rat plasma by LC-MS/MS.

Lidamycin (LDM), a promising enediyne antitumor antibiotic, was quantified by detecting lidamycin enediyne chromophore (LDC) using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the first time. A simple, rapid and reliable method was developed and validated to determine LDC and its aromatized derivative (LDCA) simultaneously in plasma. Puerarin was used as an internal standard (IS), and plasma samples were pretreated with one-step precipitation by acetonitrile. Separation was achieved on a reverse-phase C(18) column with a mobile phase composed of methanol and water containing 5 mm ammonium acetate at pH 3.5 in gradient elution mode. Detection was performed on a triple quadrupole tandem mass spectrometer using electrospray ionization (ESI) by multiple reaction monitoring (MRM) in the negative ion mode. Good linearity was obtained over the concentration range of 0.2-100 µg/mL for LDM. Precision and accuracy were validated by RSD% values in the range of 2.6-13.0% and RE% values between -4.6 and 3.8%, respectively. In addition, no specificity and matrix effects were observed. The recovery was found to be 99.2-111.0% and stability in various conditions was found to be acceptable. This method was applied in preclinical pharmacokinetic studies for routine monitoring of LDM in rat plasma.

[Lidamycin metabolism in vitro].

This paper is to report the study of the metabolism of lidamycin in vitro including in plasma and microsomes to guide clinical therapy. Lidamycin was quantified by detecting its active ingredient using HPLC-MS/MS. The metabolic stability of lidamycin in rat, Beagle dog, monkey and human plasma and liver microsomes, and its inhibition to cytochrome P450 isoforms in human liver microsomes were studied. Results showed that lidamycin was metabolized in the four species of plasma, and the sequence of metabolic rates in plasma were in rat > in dog > in human > in monkey. But among the four species of liver microsomes, lidamycin was metabolized only in monkey liver microsomes. There was almost no inhibition to cytochrome P450 isoforms at the concentrations of between 0.0005 and 10 ng x mL(-1). Therefore, the property of lidamycin metabolism in human is similar with that in dog, and metabolism of other drugs would not be decreased by cytochrome P450 as used along with lidamycin in clinic.