Hwa Jeong Lee

Effects of silymarin and formulation on the oral bioavailability of paclitaxel in rats

The aims of the present study were to investigate the effects of silymarin, an inhibitor of the P-glycoprotein efflux pump, on oral bioavailability of paclitaxel in rats, and to compare pharmacokinetic parameters of paclitaxel between a commercial formulation of paclitaxel (Taxol®) and a paclitaxel microemulsion. Oral bioavailability of paclitaxel in a Taxol® formulation was enhanced in the combination with silymarin (10 and 20mg/kg). In particular, the mean maximum plasma concentration (C(max)) and the mean area under the plasma concentration-time curve (AUC(0-)(t)) of paclitaxel in the Taxol® formulation were significantly increased 3-fold and 5-fold compared with control, respectively, following oral co-administration with 10mg/kg of silymarin (p<0.01). When the paclitaxel microemulsion was co-administered with silymarin (20mg/kg) orally, it caused a maximum increase in the absolute bioavailability of paclitaxel (19%). In addition, the relative bioavailability of the paclitaxel microemulsion was 184% as compared to Taxol® after oral dosing, whereas the mean time required to reach C(max) (T(max)) of paclitaxel was decreased in the microemulsion formulation compared with Taxol®, suggesting faster absorption. Based on these results, we conclude that oral bioavailability of paclitaxel is significantly improved by co-administration with silymarin, an inhibitor of the P-gp efflux pump and by microemulsion formulation.

Development of lipidomic platform and phosphatidylcholine retention time index for lipid profiling of rosuvastatin treated human plasma

A simple and fast methodology to detect and identify multiple classes of lipid from human plasma is developed utilizing ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF) as lipidomics platform. All the conditions for the sample preparation and analytical instruments were optimized in detail to detect nine lipid classes (phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), triacylglyceride (TG), phosphatidylinositol (PI), lysophosphatidylcholine (LysoPC), lysophosphatidic acid (LysoPA), and sphingomyelin (SM)), which are the most important biologically active lipids but have different characteristics. Finally, the plasma was prepared after a liquid-liquid extraction with a mixture of chloroform/methanol (1:2v/v) including salting out by adding 0.15M of NaCl and the residue after evaporation was reconstituted with a mixture of chloroform/methanol (1:1v/v) to dissolve all lipids which have different polarity. The chromatographic conditions were set up such that mobile phase (A) comprised 10mM ammonium acetate in 40% acetonitrile and mobile phase (B) comprised 10mM ammonium acetate in acetonitrile:isopropanol=10:90(v/v) with ACQUITY BEH C18 as the stationary phase. In particular, a retention time index of PC was constructed by analyzing known standards to confirm each variant of PC without the use of any additional standards in every experiment. The lipidomic methodology and the retention time index of PC were applied to analyze the lipidomic profiling of human plasma from rosuvastatin (lipid lowering drug) treated subjects. In the developed lipidomic platform, all lipids were successfully analyzed within 16min and PCs could be confirmed with the PC retention time index. In rosuvastatin treatment, the lipid profiling was changed in all the eight lipid classes. The level of SM, TG, PI and PE decrease significantly but LysoPCs and PCs were whether decreased or increased. Those results indicated that the plasma level of overall lipids decreased by drug response, however, the changes in the lipids which are important components for biological membrane such as LysoPC and PC were more complicated, and it could be related to the side effect of rousuvastatin. In conclusion, it was found that our lipidomic methodology and the PC retention time index provided not only overall lipidomic information but also profiled specific information of drug response.

Quantitative analysis of acetaminophen and its six metabolites in rat plasma using liquid chromatography/tandem mass spectrometry

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug. It is mainly metabolized by phase 1 and 2 reactions in the liver, and thus it could be involved in many drug-drug interactions. Therefore, the study of APAP metabolism is important in toxicological and pharmacokinetic studies. The objective of this study was to develop a rapid and sensitive method for the determination of APAP and its six metabolites in rat plasma for the pharmacokinetic studies. APAP and its metabolites were separated through a Capcell Pak MGII C(18) column and quantitated with a 16 min run in a triple-quadruple mass spectrometer. The mobile phases were composed of 0.1% formic acid in either 95% water or 95% acetonitrile and analysis was performed twice in positive and negative modes. Validations such as accuracy, precision, recovery, matrix effect and stability were found to be within acceptance criteria of validation guidelines, indicating that the assay was applicable to the determination of the plasma concentrations of drug and its six metabolites. In conclusion, we developed an LC-MS/MS method for the quantitative analysis of APAP and its six metabolites in rat plasma, and this method appears to be useful for pharmacokinetic/toxicokinetic studies of APAP and its metabolites in rats.

Application of column-switching HPLC method in evaluating pharmacokinetic parameters of zaltoprofen and its salt.

The objective of this study was to compare the pharmacokinetic parameters of zaltoprofen and those of its sodium salt in rats. Zaltoprofen, a potent non-steroidal anti-inflammatory agent, was virtually insoluble in water, but its sodium salt had excellent water solubility. To investigate the effect of aqueous solubility differences upon their pharmacokinetic parameters, minicapsules containing the drug powders were administrated orally to rats, and blood samples were taken via the common carotid artery. A column-switching high-performance liquid chromatographic analytical procedure was developed and validated for the quantitation of zaltoprofen in rat plasma samples. Our study demonstrated that the time required to reach maximum plasma concentration (T(max)) of zaltoprofen sodium was significantly reduced and its maximum plasma concentration (C(max)) was increased 1.5-fold, relative to the values for zaltoprofen. It is anticipated that the sodium salt of zaltoprofen will allow the rapid onset of the drugs action in the treatment of inflammatory diseases.

Quantitative determination of daumone in rat plasma by liquid chromatography-mass spectrometry.

Daumone, 6-(3,5-dihydroxy-6-methyl-tetrahydro-pyran-2-yloxy)-heptanoic acid is a pheromone secreted by Caenorhabditis elegans, and has been known as a pivotal regulator of chemosensory processes in development and ageing. A quantification method using mass spectrometry was developed for the determination of daumone in rat plasma. After simple protein precipitation with acetonitrile including an internal standard, the analytes were chromatographed on a reversed-phase column and detected by liquid chromatography/tandem mass spectrometry with electrospray ionization. The accuracy and precision of the assay were in accordance with FDA regulations for validation of bioanalytical methods. This method was applied to measure the plasma daumone concentrations after a single intravenous administration of daumone in rats.

Evaluation of pharmacokinetic differences of acetaminophen in pseudo germ-free rats

To evaluate the metabolic interaction between host and gut microflora on drug metabolism, pseudo germ‐free rats were prepared with an antibiotics cocktail to change their gut conditions. The usefulness of the pseudo germ‐free model was evaluated for observing the DMPK of acetaminophen (APAP). Pseudo germ‐free rats were prepared by orally administering antibiotic cocktails consisting of bacitracin, streptomycin and neomycin, and then APAP was orally administered to control and pseudo germ‐free rats. The plasma concentration of APAP and its six metabolites were quantified using a validated LC‐MS/MS method. A non‐compartment model estimated the pharmacokinetic parameters of APAP and its metabolites, and the ratios of the area under curve (AUC; AUCmetabolite/AUCAPAP) were also observed to evaluate the change of APAP metabolism. The AUCs of APAP and APAP‐Glth (glutathione) were higher and the AUCAPAP‐Sul/AUCAPAP (metabolic efficiency of sulfate conjugation) was lower in pseudo germ‐free rats than those in the control rats. The decrease in metabolic efficiency of sulphate conjugation could result from the reduction of the sulphate supply, causing an increase of the AUC of APAP and APAP‐Glth. The activities of gut microflora can affect the state of hepatic sulphate for drug conjugation, indirectly leading to characteristic APAP metabolism. These results indicate that gut microflora may play an important role in the pharmacokinetics and metabolism of APAP. Thus, the metabolic interaction between host and gut microflora should be considered upon drug administration and pseudo germ‐free rats prepared in the present study can be competent for investigating the metabolic interaction between host and gut microflora on drug metabolism. Copyright

Development of simultaneous analysis of tryptophan metabolites in serum and gastric juice - an investigation towards establishing a biomarker test for gastric cancer diagnosis.

To evaluate changes in tryptophan metabolism and discover diagnostic biomarkers for gastric cancer, a quantitative method was developed for tryptophan and its seven metabolites (indole-3-lactic acid, anthranilic acid, serotonin, nicotinic acid, kynurenic acid, kynurenine and 3-indoxyl sulfate) in both human serum and gastric juice using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum and gastric juice were prepared with a simple protein precipitation using aqueous 0.1% formic acid and acetonitrile. As a result, it was found that the kynurenine pathway of tryptophan metabolism was activated in gastric cancer and that the metabolic ratio of kynurenine/tryptophan, which reflects the enzyme activity of indoleamine-2,3-dioxygenase, was associated with the observed metabolic changes. Finally, the investigation of tryptophan metabolites, especially kynurenic acid, in serum and gastric juice might serve as biomarkers for gastric cancer. The findings in this study provide critical information of tryptophan metabolism which can be applied to a serum-based diagnostic test for gastric cancer.

Determination of a novel low-voltage-activated calcium channel blocker (HYP-10) in rat plasma by liquid chromatography-mass spectrometry.

A novel T-type calcium channel blocker, 4-amino-1-{4-[(4-chloro-phenyl)-phenyl-methyl]-piperazin-1-yl}-butan-1-one (HYP-10) has been synthesized, and the compound has shown promise as both a nociceptive and inflammatory pain reliever as well as an analgesic in a rat neuropathic pain model. A quantification method was developed for the determination of HYP-10 in rat plasma. After simple protein precipitation with methanol, HYP-10 and the internal standard, methaqualone were chromatographed on a reversed-phase column and detected by liquid chromatography/tandem mass spectrometry with electrospray ionization. The accuracy and precision of the assay were in accordance with FDA regulations for validation of bioanalytical methods. This method was applied to measure the plasma HYP-10 concentration after a single intravenous administration of the compound in rats.

Determination of daumone in mouse plasma by HPLC/MS-MS

Daumone, a pheromone secreted by Caenorhabditis elegans, is an essential regulator of chemosensory processes in development and aging. A quantification method using HPLC/MS-MS was developed for the determination of daumone in mouse plasma. After simple protein precipitation with acetonitrile including methaqualone (an internal standard), the analytes were chromatographed on a reversed-phase column and detected by liquid chromatography/tandem mass spectrometry with electrospray ionization. The accuracy and precision of the assay were in accordance with FDA regulations for validation of bioanalytical methods. This method was applied to measure the plasma daumone concentrations following a 5-week repeated oral administration of daumone in mice.

Regulation of endogenic metabolites by rosuvastatin in hyperlipidemia patients: An integration of metabolomics and lipidomics

Rosuvastatin is a statin used to treat metabolic syndrome conditions, such as hyperlipidemia. It is relatively safe; however, fatal rhabdomyolysis or skeletal myopathy can sometimes occur. Therefore, to investigate the overall effects of rosuvastatin, including lipid lowering and adverse effects, metabolic profiling was performed using metabolomics and lipidomics after rosuvastatin administration. Specifically, the metabolic profiles between healthy subjects and patients with hyperlipidemia were compared and the metabolic changes related to the mechanism of the drug effect were proposed. Healthy volunteers (nu202f=u202f32) and hyperlipidemic patients (nu202f=u202f14) were orally administered rosuvastatin (20u202fmg) once a day for 3-8 weeks, and plasma and urine were collected. Metabolomics and lipidomics were performed using UHPLC-LTQ/Orbitrap/MS/MS for non-targeted analysis and UHPLC-TQ-MS/MS for targeted analysis. Using non-targeted analysis, we successfully profiled and identified 73 and 87 metabolites in healthy subjects and hyperlipidemia subjects, respectively. Through targeted analysis, we have also quantified 188 metabolites, including amino acids, biogenic amines, glycerophospholipids, and sphingolipids. The levels of L-carnitine, diacylglycerol, and acylcarnitines significantly decreased after rosuvastatin administration regardless of the group. The overall levels of fatty acids (FA) and lysophosphatidylcholines (LysoPC) increased, while phosphatidylcholines (PC) decreased only in the patient group. β-Oxidation decreased overall, while the production of polyunsaturated FA increased only in the hyperlipidemic patients. Using metabolic profiling, we have evaluated the alterations in the biochemical pathways, which may aid in a more detailed understanding of the effect of rosuvastatin. Patient-specific metabolomic and lipidomic profiles may serve as valuable markers for the understanding of the adverse effects associated with statin treatment.