Sook Jin Seong

Pattern Recognition Analysis for Hepatotoxicity Induced by Acetaminophen Using Plasma and Urinary 1H NMR-Based Metabolomics in Humans

Drug-induced liver injury (DILI) is currently an increasingly relevant health issue. However, available biomarkers do not reliably detect or quantify DILI risk. Therefore, the purpose of this study was to comparatively evaluate plasma and urinary biomarkers obtained from humans treated with acetaminophen (APAP) using a metabolomics approach and a proton nuclear magnetic resonance (NMR) platform. APAP (3 g/day, two 500 mg tablets every 8 h) was administered to 20 healthy Korean males (age, 20-29 years) for 7 days. Urine was collected daily before and during dosing and 6 days after the final dose. NMR spectra of these urine samples were analyzed using principal component analysis (PCA) and partial least-squares-discrimination analysis. Although the activities of aspartate aminotransferase and lactate dehydrogenase were significantly increased 7 days post-APAP treatment, serum biochemical parameters of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, γ-glutamyl transpeptidase, and lactate dehydrogenase were within normal range of hepatic function. However, urine and plasma (1)H NMR spectroscopy revealed different clustering between predosing and after APAP treatment for global metabolomic profiling through PCA. Urinary endogenous metabolites of trimethylamine-N-oxide, citrate, 3-chlorotyrosine, phenylalanine, glycine, hippurate, and glutarate as well as plasma endogenous metabolites such as lactate, glucose, 3-hydroxyisovalerate, isoleucine, acetylglycine, acetone, acetate, glutamine, ethanol, and isobutyrate responded significantly to APAP dosing in humans. Urinary and plasma endogenous metabolites were more sensitive than serum biochemical parameters. These results might be applied to predict or screen potential hepatotoxicity caused by other drugs using urinary and plasma (1)H NMR analyses.

Effect of age on the pharmacokinetics of fimasartan (BR-A-657)

Objectives: The aim of this study was to compare the pharmacokinetics (PK) and safety of fimasartan (BR-A-657), an angiotensin II receptor antagonist, between healthy young (19 – 45 years) and older (≥ 65 years) male subjects. Methods: To assess the effect of age on PK and safety, fimasartan was administered as a single 240 mg tablet to 12 young and 10 older male subjects, followed by serial blood sampling over 48 h. Plasma concentrations of fimasartan were analyzed using validated HPLC-MS/MS. Clinical and laboratory adverse events were assessed. Results: After oral administration of 240 mg fimasartan, the mean area under the plasma concentration-time curve from time zero to infinity (AUC0→∞) was 2899.0 ng/ml/h in the older, which was significantly greater than in young subjects (1767.4 ng/ml/h; p = 0.03). The geometric mean AUC0→∞ was 69.4% higher in older than in young subjects. The maximum plasma concentration (Cmax), time to reach Cmax and elimination half-life for fimasartan did not differ significantly between the older and young groups. Importantly, fimasartan was well tolerated during this study. Conclusions: While some PK parameters were statistically different between the two groups, the effect of age on the PK was modest (e.g., AUC increase < twofold in older subjects).

G Protein‐Coupled Receptor 120 Signaling Negatively Regulates Osteoclast Differentiation, Survival, and Function

G protein‐coupled receptor 120 (GPR120) plays an important role in the regulation of inflammation and lipid metabolism. In this study, we investigated the role of GPR120 in osteoclast development and found that GPR120 regulates osteoclast differentiation, survival and function. We observed that GPR120 was highly expressed in osteoclasts compared to their precursors, bone marrow‐derived macrophages (BMMs). Activation of GPR120 by its ligand GW9508 suppressed receptor activator of NF‐ κB ligand (RANKL)‐induced osteoclast differentiation and the expression of nuclear factor of activated T cells c1 (NFATc1), a key modulator of osteoclastogenesis. GPR120 activation further inhibited the RANKL‐stimulated phosphorylation of IκBα and JNK. In addition to osteoclast differentiation, GPR120 activation increased the apoptosis of mature osteoclasts by inducing caspase‐3 and Bim expression. Activation of GPR120 also interfered with cell spreading and actin cytoskeletal organization mediated by M‐CSF but not by RANKL. Coincident with the impaired cytoskeletal organization, GPR120 activation blocked osteoclast bone resorbing activity. Furthermore, knockdown of GPR120 using small hairpin RNA abrogated all these inhibitory effects on osteoclast differentiation, survival, and function. Together, our findings identify GPR120 as a negative modulator of osteoclast development that may be an attractive therapeutic target for bone‐destructive diseases. J. Cell. Physiol. 231: 844–851, 2016.

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.

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.

Docosahexaenoic acid signaling attenuates the proliferation and differentiation of bone marrow-derived osteoclast precursors and promotes apoptosis in mature osteoclasts

Docosahexaenoic acid (DHA), a component of omega-3 fatty acids, has been reported to protect against inflammatory bone diseases such as osteoporosis and rheumatoid arthritis. However, its exact mechanism in bone resorbing cells has not been elucidated. In this study, we investigated the effects and the molecular mechanism of DHA on the proliferation, differentiation, and survival of osteoclast lineage cells using mouse bone marrow-derived macrophages (BMMs). DHA suppressed the macrophage colony-stimulating factor (M-CSF)-induced proliferation of osteoclast precursors, BMMs, in a dose-dependent manner. The attenuated proliferation of DHA-treated BMMs was related to M-CSF inhibition that selectively decreased Akt activation and downregulated cyclin D1 and cyclin D2 expression. DHA also blocked receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation from BMMs. At the molecular level, DHA inhibited JNK, ERK, and p38 MAPKs. In addition, it inhibited NF-κB signaling cascades, as demonstrated by the suppression of RANKL-mediated IκBα phosphorylation, NF-κB subunit p65 nuclear translocation, and NF-κB transcriptional activation. Accordingly, DHA attenuated the induction of c-Fos and nuclear factor of activated T cells c1 (NFATc1). Furthermore, DHA accelerated the apoptosis of mature osteoclasts by inducing Bim expression, a critical modulator of osteoclast apoptosis. Collectively, our data demonstrate that DHA exerts an anti-osteoclastogenic effect by suppressing the proliferation and differentiation of BMMs and enhancing the apoptosis of mature osteoclasts, thereby resulting in a diminished number of bone-resorptive cells.

Influence of hepatic dysfunction on the pharmacokinetics and safety of fimasartan.

Abstract: This study was designed to assess the pharmacokinetics (PK) and safety of fimasartan, an angiotensin II type 1 receptor blocker, in hepatic impairment patients as compared with healthy subjects. An open-label, single-dose, parallel study was conducted in 6 healthy male volunteers and 12 subjects with hepatic impairment. Healthy subjects were matched with hepatic dysfunction patients on the basis of age, gender, and body weight. After a single 120-mg oral administration of fimasartan, PK parameters and safety were analyzed between the hepatic dysfunction groups and healthy group. Compared with the healthy subjects, the geometric mean ratio and 90% confidence intervals for the maximum plasma concentration and the mean area under the plasma concentration–time curve from 0 to infinity (AUC)inf were 0.77 (0.24–2.47) and 1.11 (0.50–2.46), respectively, for the mild hepatic impairment and 6.55 (3.56–12.03) and 5.17 (4.19–6.37), respectively, for moderate hepatic impairment. However, there was no significant difference in time to peak plasma concentration (tmax) and elimination half-life, and there were no serious or severe adverse events in all subjects. Subjects with mild hepatic impairment exhibited similar bioavailability compared with healthy subjects, whereas subjects with moderate hepatic impairment seemed to exhibit a higher level of systemic exposure to fimasartan than healthy subjects. In addition, all subjects were tolerable with fimasartan.

Population Pharmacokinetic/Pharmacodynamic Modeling of Clopidogrel in Korean Healthy Volunteers and Stroke Patients

Population pharmacokinetic (PK) and pharmacodynamic (PD) modeling of clopidogrel was developed from pooled data from healthy volunteers (n = 44) and stroke patients (n = 35). The PK modeling used plasma concentrations of the clopidogrel metabolite (SR26334), and the PD modeling used platelet aggregation. The models were developed using NONMEM and evaluated via visual predictive check (VPC). Data were analyzed by 2‐compartment modeling with Erlangs absorption and first‐order elimination. There was no statistically significant covariate for each model parameter. The typical point estimates of PK were ktr (identical transfer rate constant) = 5.97 h−1, ke (elimination rate constant) = 0.126 h−1, kd (distribution rate constant) = 0.212 h−1, V2 (volume of central compartment) = 21.0 L, and V3 (volume of peripheral compartment) = 38.8 L. The typical point estimates of PD were kin (input rate) = 27.9 h−1, Emax (maximum effect on input rate) = 0.292 h−1, EC50 (median effective concentration) = 0.00629 ng/mL, and BASE (predose aggregation) = 66.7%. The final model was used to estimate individual parameters using patient data and showed good predictions using VPC.

Pharmacokinetics of a New Once-Daily Controlled-Release Formulation of Aceclofenac in Korean Healthy Subjects Compared with Immediate-Release Aceclofenac and the Effect of Food

AbstractBackground: A new controlled-release formulation of aceclofenac 200 mg (Clanza CR®) developed by Korea United Pharm., Inc., South Korea, for once-daily (od) dosing provides biphasic aceclofenac release consisting of immediate release of 85 mg followed by sustained release of 115 mg. Food has been known to affect the rate and extent of absorption of several drugs, in both immediate-release and controlled-release formulations. Objective: The aim of this study was to evaluate the relative bioavailability of a new controlled-release formulation of aceclofenac (200 mg od; Clanza CR®) in comparison with immediate-release aceclofenac (100 mg twice daily [bid], Airtal®) and to assess the effect of food on the pharmacokinetics of the new controlled-release aceclofenac formulation. Methods: This study was designed as a randomized, open-label, three treatment-period, crossover, single-centre study with a 1-week washout in 41 healthy adults. The three treatments consisted of immediate-release aceclofenac 100 mg bid administered under fasting conditions; controlled-release aceclofenac 200 mg od administered under fasting conditions; and controlled-release aceclofenac 200 mg od administered immediately after a standardized high-fat breakfast. Plasma concentrations of aceclofenac were determined using a highperformance liquid chromatography method. Results: In the fasted state, the 90% confidence intervals (CIs) of the least squares geometric mean ratios (GMRs) for the area under the plasma concentration-time curve from time zero to 24 hours (AUC24) and the peak plasma concentration (Cmax) of aceclofenac for the controlled-release and immediate-release formulations of aceclofenac were all within the bioequivalence criteria range of 0.8–1.25. The 90% CIs of the GMRs for the AUC24 and Cmax of aceclofenac for the controlled-release formulation of aceclofenac in the fed and fasted states were also within the bioequivalence range. Both aceclofenac formulations were well tolerated in all subjects, and no serious adverse effects were observed. Conclusion: The results demonstrate that controlled-release aceclofenac 200 mg is equivalent to immediate-release aceclofenac 100 mg when administered at the same total daily dose. Additionally, the bioavailability of controlled-release aceclofenac was not affected by high-fat foods.

Liquid chromatography–tandem mass spectrometry quantification of levosulpiride in human plasma and its application to bioequivalence study

An improved method for determining levels of levosulpiride in human plasma using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and validated. The protein precipitation method was used for plasma sample preparation. Levosulpiride and an internal standard (IS) were isocratically separated on a UPLC BEH C(18) column with a mobile phase of ammonium formate buffer (1mM, adjusted to pH 3 with formic acid) and acetonitrile (60:40, v/v). MS/MS detection was performed by monitoring the parent-->daughter pair of levosulpiride and the IS at m/z 342-->112 and 329-->256, respectively. The method was linear from 2.5 to 200ng/mL and exhibited acceptable precision and percent recovery. The method was successfully demonstrated in pharmacokinetic and bioequivalence studies of two levosulpiride oral formulations administered to healthy volunteers. When compared to the previous LC-MS methods, the proposed method is faster, well-validated, and uses lesser plasma volume and a similar sensitivity. The use of UPLC allowed rapid and sensitive quantification of levosulpiride, making this method suitable for high-throughput clinical applications.