Hae Won Lee

Rapid determination of sumatriptan in human plasma by ultra performance liquid chromatography–tandem mass spectrometry and its application to clinical pharmacokinetic study

A sensitive and simple detection method coupling ultra-performance liquid chromatography with tandem mass spectrometry was developed and validated to analyze sumatriptan levels in human plasma. The plasma sample preparations for the analysis were based on liquid-liquid extraction with ethyl acetate, evaporation, and reconstitution. MS/MS detection was performed on a triple-quadrupole tandem mass spectrometer by monitoring the protonated parent→daughter ion pairs at m/z 296→58 and m/z 388→71 for sumatriptan and terazosin (internal standard), respectively. The method was validated with respect to its specificity, linearity, sensitivity, accuracy, precision, recovery, and stability. The calibration curve was linear from 0.5 to 50 ng/mL (r>0.999). The mean extraction recovery for sumatriptan was higher than 62.3%. The method accuracy was within 97.4%, and the relative standard deviation of the intra- and inter-day precision values was within 11.7% at all quality control levels. Plasma samples that contained sumatriptan were stable under three freeze-thaw cycles, short- and long-term storage, and autosampler conditions. This method was successfully applied to a pharmacokinetic study conducted with 10 healthy volunteers. After oral administration of 50-mg sumatriptan and serial blood sampling over 12 h, the mean area under the plasma concentration-time curve from time 0 to 12 h and the maximum plasma concentration were 116.2 ng h/mL and 33.2 ng/mL, respectively.

Single-dose pharmacokinetics and dose proportionality of intravenous pazufloxacin mesilate in healthy Korean volunteers

Objective: The aim of this study was to investigate the pharmacokinetics and dose proportionality of a single, intravenous dose of pazufloxacin mesilate, an injectable fluoroquinolone antibiotic, in healthy Korean male volunteers. Methods: In this open-label, four-dose, parallel study, subjects were randomized to receive a single dose of pazufloxacin mesilate 300, 500, 600, and 1,000 mg (n = 6, 20, 6, and 8, respectively) administered as a 1-h intravenous infusion. Blood and urine samples were collected serially from 0 to 24 h after drug administration and analyzed using a validated HPLC method. Tolerability was assessed by monitoring clinical laboratory parameters and adverse events. Results: After single-dose intravenous administration of pazufloxacin mesilate, the mean Cmax for groups treated with 300, 500, 600, and 1,000 mg doses ranged from 5.11 to 18.06 μg/mL; the mean AUC0-t ranged from 13.70 to 58.60 μg × h/mL. Pazufloxacin exhibits lack of dose proportionality over the dose range of 300 – 1,000 mg, based on linear regression model and power model. At all four dosages studied, pazufloxacin mesilate was well tolerated. Conclusions: Our data suggest that all regimens of pazufloxacin administration were well tolerated. Pazufloxacin exhibits lack of dose proportionality over the dose range of 300 – 1,000 mg.

The effects of fexofenadine at steady-state on sleep architecture: a study using polysomnography in healthy Korean volunteers

Objectives: To compare the effects of a first-generation antihistamine, chlorpheniramine, with those of the second-generation antihistamine, fexofenadine, at steady-state, on nocturnal sleep architecture in healthy Korean volunteers using polysomnography and the Multiple Sleep Latency Test. We evaluated whether a genetic polymorphism of multi-drug resistance 1 gene (MDR1) could produce variations in pharmacokinetic and pharmacodynamic parameters of fexofenadine. Design/methods: Ten healthy male volunteers received one capsule of fexofenadine 180 mg once each morning or chlorpheniramine 6 mg (2 mg in the morning and 4 mg after 12 h) for 3 days, in a single-site, randomized, double-blind, two-treatment, multiple-dosing, two-way crossover study, with a washout period of 7 days. Overnight polysomnography was measured on the second night of the treatment period. The Multiple Sleep Latency Test was carried out the next morning. Blood samples were taken for the assessment of fexofenadine pharmacokinetics and MDR1 genotyping on the third day. Results: Compared with baseline and fexofenadine, chlorpheniramine significantly increased the latency in rapid eye movement (REM) sleep, with no significant decrease in the percentage of REM sleep. No significant change in latency for REM sleep or percentage REM sleep after dosing with fexofenadine was observed. There was no significant change in the daytime sleepiness with fexofenadine and chlorpheniramine. The effects of MDR1 genotypes and haplotypes on the pharmacokinetics and pharmacodynamics of fexofenadine were not significant. Conclusions: Our findings suggest that fexofenadine and chlorpheniramine at steady-state have no significant effect on nocturnal sleep variables and daytime sleepiness, when compared to baseline.

Pharmacometabolomic Approach to Predict QT Prolongation in Guinea Pigs

Drug-induced torsades de pointes (TdP), a life-threatening arrhythmia associated with prolongation of the QT interval, has been a significant reason for withdrawal of several medicines from the market. Prolongation of the QT interval is considered as the best biomarker for predicting the torsadogenic risk of a new chemical entity. Because of the difficulty assessing the risk for TdP during drug development, we evaluated the metabolic phenotype for predicting QT prolongation induced by sparfloxacin, and elucidated the metabolic pathway related to the QT prolongation. We performed electrocardiography analysis and liquid chromatography–mass spectroscopy-based metabolic profiling of plasma samples obtained from 15 guinea pigs after administration of sparfloxacin at doses of 33.3, 100, and 300 mg/kg. Principal component analysis and partial least squares modelling were conducted to select the metabolites that substantially contributed to the prediction of QT prolongation. QTc increased significantly with increasing dose (ru200a=u200a0.93). From the PLS analysis, the key metabolites that showed the highest variable importance in the projection values (>1.5) were selected, identified, and used to determine the metabolic network. In particular, cytidine-5′-diphosphate (CDP), deoxycorticosterone, L-aspartic acid and stearic acid were found to be final metabolomic phenotypes for the prediction of QT prolongation. Metabolomic phenotypes for predicting drug-induced QT prolongation of sparfloxacin were developed and can be applied to cardiac toxicity screening of other drugs. In addition, this integrative pharmacometabolomic approach would serve as a good tool for predicting pharmacodynamic or toxicological effects caused by changes in dose.

Assessment of pharmacokinetic proportionality of levofloxacin and cyclosporine over a 100-fold dose range in healthy human volunteers

Objective: Levofloxacin and cyclosporine show different pharmacokinetic properties, but are known to be dose proportional within the therapeutic range. The authors evaluated the pharmacokinetic proportionality of levofloxacin and cyclosporine over a 100-fold dose range in healthy human volunteers, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods: Two independent, randomized, crossover studies were performed. For levofloxacin, eight volunteers were randomly assigned in a 1:1 ratio to receive a low dose (7.5 mg) orally or intravenously, followed by a 1-week washout period and administration via the alternate route. After another 1-week washout period, a therapeutic dose (750 mg) was administered to all eight subjects. For cyclosporine, another eight volunteers received a low dose (2 mg) or a therapeutic dose (200 mg) orally with a 1-week washout period. Drug concentrations were determined by LC-MS/MS. Results: For levofloxacin, the mean values for dose-normalized Cmax and AUClast with the two doses were as follows: therapeutic dose, 15.2 ± 4.6 ng/ml/mg and 103.6 ± 15.5 ng·h/ml/mg, respectively; low dose, 17.1 ± 6.5 ng/ml/mg and 72.6 ± 8.7 ng·h/ml/mg, respectively. For cyclosporine, the mean values for dose-normalized Cmax and AUClast were as follows: therapeutic dose, 4.9 ± 1.5 ng/ml/mg and 15.4 ± 4.9 ng·h/ml/mg, respectively; low dose, 1.6 ± 0.6 ng/ml/mg and 9.3 ± 7.3 ng·h/ml/mg, respectively. Conclusion: In this study levofloxacin, which is completely absorbed and primarily eliminated renally without modification, showed better pharmacokinetic proportionality than cyclosporine, which is poorly absorbed and extensively metabolized.

Estrogen-related receptor γ negatively regulates osteoclastogenesis and protects against inflammatory bone loss: KIM et al.

Estrogen‐related receptor γ (ERRγ) is an orphan nuclear receptor that plays an important role in various metabolic processes under physiological and pathophysiological conditions. Here, we report that ERRγ functions as a negative regulator in receptor activator of nuclear factor κΒ ligand (RANKL)–induced osteoclast differentiation. We observed that ERRγ was strongly expressed in osteoclast precursors, bone marrow–derived macrophages (BMMs) while its expression was significantly reduced by RANKL during osteoclastogenesis. Overexpression of ERRγ in BMMs suppressed the formation of multinucleated osteoclasts and attenuated the induction of c‐Fos and nuclear factor of activated T cells c1, which are critical modulators in osteoclastogenesis. Similarly, the treatment of ERRγ agonists, N‐(4‐(diethylaminobenzylidenyl)‐N‐(4‐hydroxybenzoyl)‐hydrazine (DY131) or GSK4716, also inhibited osteoclast generation and the expression of these key modulators. On the other hand, shRNA‐mediated knockdown of ERRγ accelerated the formation of bone‐resorbing cells and the expression of osteoclastogenic markers. Forced expression of ERRγ blocked RANKL‐stimulated phosphorylation of the nuclear factor κB (NF‐κB) inhibitor IκBα and suppressed NF‐κB transcriptional activity induced by RANKL or the NF‐κB subunit p65. Furthermore, by employing a pharmacological approach, we showed that the ERRγ agonist DY131 protected against inflammatory bone loss induced by lipopolysaccharide in vivo. Together, our findings reveal that ERRγ is a pivotal regulator in RANKL‐mediated osteoclastogenesis and suggest that ERRγ may have potential as a therapeutic target for pathological bone loss.

A Comprehensive In Vivo and In Vitro Assessment of the Drug Interaction Potential of Red Ginseng

Purpose: Red ginseng is one of the worlds most popular herbal medicines; it exhibits a wide range of pharmacologic activities and is often co-ingested with other herbal and conventional medicines. This open-label, randomized, 3-period study investigated the in vivo herb-drug interaction potential for red ginseng extract with cytochrome P-450 (CYP) enzymes and organic anion-transporting polypeptide (OATP) 1B1.nnnMETHODSnFifteen healthy male volunteers (22-28 years; 57.1-80.8 kg) were administered a single dose of cocktail probe substrates (caffeine 100 mg, losartan 50 mg, omeprazole 20 mg, dextromethorphan 30 mg, midazolam 2 mg, and pitavastatin 2 mg) and single or multiple doses of red ginseng extract for 15 days.nnnFINDINGSnThe pharmacokinetic profiles of the probe substrates and metabolites after single- or multiple-dose administration of red ginseng extracts were comparable to the corresponding profiles of the control group. The geometric mean ratio of AUC0-t and 90% CIs for the probe substrate drugs between the control and multiple doses of red ginseng for 15 days were within 0.8 to 1.25 (CYP2C9, CYP3A4, and OATP1B1 probe substrates) or slightly higher (CYP1A2, CYP2C19, and CYP2D6 probe substrates). Additional assessments of the in vitro drug interaction potential of red ginseng extracts and the ginsenoside Rb1 on drug-metabolizing enzymes and transporters using human liver microsomes, cryopreserved human hepatocytes, and transporter-overexpressed cells were negative.nnnIMPLICATIONSnRed ginseng poses minimal risks for clinically relevant CYP- or OATP-mediated drug interactions and is well tolerated. Clinical Research Information Service registry no.

Population pharmacokinetic and pharmacodynamic modeling of transformed binary effect data of triflusal in healthy Korean male volunteers: a randomized, open-label, multiple dose, crossover study

BackgroundTriflusal is a drug that inhibits platelet aggregation. In this study we investigated the dose-exposure-response relationship of a triflusal formulation by population pharmacokinetic (PK) and pharmacodynamic (PD) modeling of its main active metabolite, hydroxy-4-(trifluoromethyl) benzoic acid (HTB).MethodsThis study was a randomized, open-label, multiple-dose, two-period, two-treatment, comparative crossover design. All volunteers received a single oral loading dose of 900xa0mg of triflusal on Day 1, followed by a dose of 600xa0mg/day from Day 2 to 9. Using data from 34 healthy volunteers, 476 HTB plasma concentration data points and 340 platelet aggregation data points were used to construct PK and PD models respectively using NONMEM (version 6.2). As the PD endpoint was qualitative, we implemented binary analysis of ‘inhibition’ and ‘non-inhibition’ rather than using the actual value of the test. The final PK-PD model was evaluated using a visual predictive check (VPC) and bootstrap.ResultsThe time-concentration profile of HTB over the entire dosing period was described by a one-compartment model with a first-order formation rate constant for HTB. Weight was selected as a covariate for clearance and volume of triflusal, respectively. The structure and the population estimates for triflusal PK were as follows: oral clearance (CL/F)u2009=u20090.2u2009·u2009(weight/71.65)0.845u2009L/h, oral volume of distribution (V/F)u2009=u20098.3u2009·u2009(weight/71.65) L, and kfu2009=u20090.341xa0h-1. A sigmoid relationship between triflusal concentration and the probability of significant inhibition with shape factor was chosen as the final PD model. No time delay between concentration and response was identified. The final structure between predicted concentration Cpred,ijy and the probability of inhibition of platelet aggregation (IPA) relationship was as follows: Probability of IPA=Cpred,ij19/84.919μg/mL+Cpred,ij19. Thus, we concluded this relationship is more like quantal concentration-response relationship. The current dosing regimen was considered to be efficacious based on the EC50 estimate of 84.9xa0μg/mL obtained in this study.ConclusionsA PK and binary probability PD model of triflusal was successfully developed for Korean healthy volunteers. The model may be used to further prediction inhibition of platelet aggregation by triflusal.Trial registrationClinical Research Information Service (CRIS), KCT0001299 (Registered December 5, 2014)