Mi-Ri Gwon

Lipocalin-2 inhibits osteoclast formation by suppressing the proliferation and differentiation of osteoclast lineage cells.

Lipocalin-2 (LCN2) is a member of the lipocalin superfamily and plays a critical role in the regulation of various physiological processes, such as inflammation and obesity. In this study, we report that LCN2 negatively modulates the proliferation and differentiation of osteoclast precursors, resulting in impaired osteoclast formation. The overexpression of LCN2 in bone marrow-derived macrophages or the addition of recombinant LCN2 protein inhibits the formation of multinuclear osteoclasts. LCN2 suppresses macrophage colony-stimulating factor (M-CSF)-induced proliferation of osteoclast precursor cells without affecting their apoptotic cell death. Interestingly, LCN2 decreases the expression of the M-CSF receptor, c-Fms, and subsequently blocks its downstream signaling cascades. In addition, LCN2 inhibits RANKL-induced osteoclast differentiation and attenuates the expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1), which are important modulators in osteoclastogenesis. Mechanistically, LCN2 inhibits NF-κB signaling pathways, as demonstrated by the suppression of IκBα phosphorylation, nuclear translocation of p65, and NF-κB transcriptional activity. Thus, LCN2 is an anti-osteoclastogenic molecule that exerts its effects by retarding the proliferation and differentiation of osteoclast lineage cells.

Synthesis and Evaluation of New Generation Cross-Bridged Bifunctional Chelator for (64)Cu Radiotracers.

Bifunctional chelators have been successfully used to construct (64)Cu-labeled radiopharmaceuticals. Previously reported chelators with cross-bridged cyclam backbones have various essential features such as high stability of the copper(II) complex, high efficiency of radiolabeling at room temperature, and good biological inertness of the radiolabeled complex, along with rapid body clearance. Here, we report a new generation propylene-cross-bridged chelator with hybrid acetate/phosphonate pendant groups (PCB-TE1A1P) developed with the aim of combining these key properties in a single chelator. The PCB-TE1A1P was synthesized from cyclam with good overall yield. The Cu(II) complex of our chelator showed good robustness in kinetic stability evaluation experiments, such as acidic decomplexation and cyclic voltammetry studies. The Cu(II) complex of PCB-TE1A1P remained intact under highly acidic conditions (12 M HCl, 90 °C) for 8 d and showed quasi-reversible reduction/oxidation peaks at -0.77 V in electrochemical studies. PCB-TE1A1P was successfully radiolabeled with (64)Cu ions in an acetate buffer at 60 °C within 60 min. The electrophoresis study revealed that the (64)Cu-PCB-TE1A1P complex has net negative charge in aqueous solution. The biodistribution and in vivo stability study profiles of (64)Cu-PCB-TE1A1P indicated that the radioactive complex was stable under physiological conditions and cleared rapidly from the body. A whole body positron emission tomography (PET) imaging study further confirmed high in vivo stability and fast clearance of the complex in mouse models. In conclusion, PCB-TE1A1P has good potential as a bifunctional chelator for (64)Cu-based radiopharmaceuticals, especially those involving peptides.

Pharmacokinetic and bioequivalence study of a telmisartan/S-amlodipine fixed-dose combination (CKD-828) formulation and coadministered telmisartan and S-amlodipine in healthy subjects

Purpose A new fixed-dose combination (FDC) formulation of telmisartan 80 mg and S-amlodipine 5 mg (CKD-828) has been developed to increase convenience (as only one tablet is required per day) and improve treatment compliance. Methods The pharmacokinetic characteristics and tolerability of an FDC of telmisartan and S-amlodipine were compared to those after coadministration of the individual agents in this randomized, open-label, single-dose, two-way, four-period, crossover study. To analyze the telmisartan and S-amlodipine plasma concentrations using a validated liquid chromatography–tandem mass spectrometry method, serial blood samples were collected up to 48 hours post-dose for telmisartan and 144 hours post-dose for S-amlodipine, in each period. Results Forty-eight healthy subjects were enrolled, and 43 completed the study. The mean peak plasma concentration (Cmax) and the area under the plasma concentration–time curve from time 0 to the last measurement (AUC0–t) values of telmisartan were 522.29 ng/mL and 2,475.16 ng·h/mL for the FDC, and 540.45 ng/mL and 2,559.57 ng·h/mL for the individual agents concomitantly administered, respectively. The mean Cmax and AUC0–t values of S-amlodipine were 2.71 ng/mL and 130.69 ng·h/mL for the FDC, and 2.74 ng/mL and 129.81 ng·h/mL for the individual agents concomitantly administered, respectively. The geometric mean ratio (GMR) and 90% confidence interval (CI) for the telmisartan Cmax and AUC0–t (FDC of telmisartan and S-amlodipine/concomitant administration) were 0.8509 (0.7353–0.9846) and 0.9431 (0.8698–1.0226), respectively. The GMR and 90% CI for the S-amlodipine Cmax and AUC0–t (FDC/concomitant administration) were 0.9829 (0.9143–1.0567) and 0.9632 (0.8798–1.0546), respectively. As the intrasubject variability of the Cmax for telmisartan administered individually was 42.94%, all 90% CIs of the GMRs fell within the predetermined acceptance range. Both treatments were well tolerated in this study. Conclusion CKD-828 FDC tablets were shown to be bioequivalent to coadministration of the individual agents with the respective strength, in healthy subjects under fasting conditions. There was no significant difference in safety profile between the two treatments.

Determination of sumatriptan in human plasma using liquid chromatography-mass spectrometry for pharmacokinetic study in healthy Korean volunteers

This study describes the development of an analytical method to determine sumatriptan levels in human plasma using high performance liquid chromatography (HPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS) and its application to a pharmacokinetic study in healthy Korean volunteers. A single 50 mg dose of sumatriptan was orally administered to twelve healthy volunteers (nine women and three men). The HPLC-MS/MS analytical method was validated with respect to its specificity, linearity, sensitivity, accuracy, precision, recovery, and stability. The calibration curve was linear over a concentration range of 0.3–100 ng/mL (r > 0.999). The lower limit of quantitation for sumatriptan in plasma was 0.3 ng/mL. The accuracy and precision of the analytical method were acceptable within 15% at all quality control levels. We compared plasma concentration-time curves as well as pharmacokinetic parameters such as the area under the curve (AUC) and maximum plasma concentration (Cmax). Both the mean AUC and Cmax of sumatriptan were 1.56 times higher in women than in men. These differences could be largely explained by the difference in body weight (44%) between women and men. The outcomes may provide insights into developing appropriate individualized treatment strategies.

Metabolomic analysis of healthy human urine following administration of glimepiride using a liquid chromatography-tandem mass spectrometry

Glimepiride, a third generation sulfonylurea, is an antihyperglycemic agent widely used to treat type 2 diabetes mellitus. In this study, an untargeted urinary metabolomic analysis was performed to identify endogenous metabolites affected by glimepiride administration. Urine samples of twelve healthy male volunteers were collected before and after administration of 2 mg glimepiride. These samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and then subjected to multivariate data analysis including principal component analysis and orthogonal partial least squares discriminant analysis. Through this metabolomic profiling, we identified several endogenous metabolites such as adenosine 3′, 5′-cyclic monophosphate (cAMP), quercetin, tyramine, and urocanic acid, which exhibit significant metabolomic changes between pre- and posturine samples. Among these, cAMP, which is known to be related to insulin secretion, was the most significantly altered metabolite following glimepiride administration. In addition, the pathway analysis showed that purine, tyrosine, and histidine metabolism was affected by pharmacological responses to glimepiride. Together, the results suggest that the pharmacometabolomic approach, based on LC-MS/MS, is useful in understanding the alterations in biochemical pathways associated with glimepiride action.

Pharmacokinetic and safety evaluation of MB12066, an NQO1 substrate

Objective This study evaluated the pharmacokinetics (PKs) and safety of a newly developed β-lapachone (MB12066) tablet, a natural NAD(P)H:quinone oxidoreductase 1 (NQO1) substrate, in healthy male volunteers. Methods In a randomized, double-blind, multiple-dose, two-treatment study, 100 mg MB12066 or placebo was given twice daily for 8 days to groups of eight or three fasted healthy male subjects, respectively, followed by serial blood sampling. Plasma concentrations for β-lapachone were determined using liquid chromatography–tandem mass spectrometry. PK parameters were obtained with non-compartmental analysis. Tolerability was assessed based on physical examinations, vital signs, clinical laboratory tests, and electrocardiograms. Results Following a single 100 mg MB12066 oral dose, maximum plasma concentration (Cmax) of β-lapachone was 3.56±1.55 ng/mL, and the median (range) time to reach Cmax was 3 h (2–5 h). After the 8 days of 100 mg twice daily repeated dosing was completed, mean terminal half-life was determined to be 18.16±3.14 h, and the mean area under the plasma concentration vs time curve at steady state was 50.44±29.68 ng·h/mL. Accumulation index was 2.72±0.37. No serious adverse events (AEs) were reported, and all reported intensities of AEs were mild. Conclusion The results demonstrated that MB12066 was safe and well tolerated in healthy volunteers and that there were no serious AEs. Accumulation in plasma with twice-daily administration was associated with a 2.72 accumulation ratio.

Fully Validated Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Fimasartan in Human Plasma.

Fimasartan is a novel angiotensin II receptor blocker with strong anti-hypertensive activity. In this study, a more rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to determine fimasartan in human plasma was developed and fully validated. The quantification of analytes was conducted by MS/MS in a multiple reaction monitoring mode at m/z 502.2 → 207.1 for fimasartan and m/z 526.3 → 207.1 for the internal standard (IS, BR-A-563). The method showed a linear response from 3 to 1000 ng/mL (r > 0.9950). The intra- and inter-day accuracy values were 86.9 - 98.2 and 93.3 - 100.1%, respectively. The intra- and inter-day precision values were 2.0 - 3.1 and 0.8 - 8.0%, respectively. This UPLC-MS/MS method was validated for specificity, linearity, precision, accuracy, recovery, system suitability, and stability, and was found to be acceptable for bioanalytical applications. Finally, this fully validated method was successfully applied to a pharmacokinetic study of fimasartan in healthy volunteers following oral administration.