• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.321-329
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• 2018

It was recently reported that the $C_{max}$ and AUC of rosuvastatin increases when it is coadministered with telmisartan and cyclosporine. Rosuvastatin is known to be a substrate of OATP1B1, OATP1B3, NTCP, and BCRP transporters. The aim of this study was to explore the mechanism of the interactions between rosuvastatin and two perpetrators, telmisartan and cyclosporine. Published (cyclosporine) or newly developed (telmisartan) PBPK models were used to this end. The rosuvastatin model in Simcyp (version 15)'s drug library was modified to reflect racial differences in rosuvastatin exposure. In the telmisartan-rosuvastatin case, simulated rosuvastatin $C_{maxI}/C_{max}$ and $AUC_I/AUC$ (with/without telmisartan) ratios were 1.92 and 1.14, respectively, and the $T_{max}$ changed from 3.35 h to 1.40 h with coadministration of telmisartan, which were consistent with the aforementioned report ($C_{maxI}/C_{max}$: 2.01, $AUC_I/AUC$:1.18, $T_{max}:5h{\rightarrow}0.75h$). In the next case of cyclosporine-rosuvastatin, the simulated rosuvastatin $C_{maxI}/C_{max}$ and $AUC_I/AUC$ (with/without cyclosporine) ratios were 3.29 and 1.30, respectively. The decrease in the $CL_{int,BCRP,intestine}$ of rosuvastatin by telmisartan and cyclosporine in the PBPK model was pivotal to reproducing this finding in Simcyp. Our PBPK model demonstrated that the major causes of increase in rosuvastatin exposure are mediated by intestinal BCRP (rosuvastatin-telmisartan interaction) or by both of BCRP and OATP1B1/3 (rosuvastatin-cyclosporine interaction).

• Journal of Korean Medical Science
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• v.33 no.53
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• pp.298.1-298.10
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• 2018

Background: The renal function of individuals is one of the reasons for the variations in therapeutic response to various drugs. Patients with renal impairment are often exposed to drug toxicity, even with drugs that are usually eliminated by hepatic metabolism. Previous study has reported an increased plasma concentration of indoxyl sulfate and decreased plasma concentration of $4{\beta}$-hydroxy (OH)-cholesterol in stable kidney transplant recipients, implicating indoxyl sulfate as a cytochrome P450 (CYP) inhibiting factor. In this study, we aimed to evaluate the impact of renal impairment severity-dependent accumulation of indoxyl sulfate on hepatic CYP3A activity using metabolic markers. Methods: Sixty-six subjects were enrolled in this study; based on estimated glomerular filtration rate (eGFR), they were classified as having mild, moderate, or severe renal impairment. The plasma concentration of indoxyl sulfate was quantified using liquid chromatography-mass spectrometry (LC-MS). Urinary and plasma markers ($6{\beta}$-OH-cortisol/cortisol, $6{\beta}$-OH-cortisone/cortisone, $4{\beta}$-OH-cholesterol) for hepatic CYP3A activity were quantified using gas chromatography-mass spectrometry (GC-MS). The total plasma concentration of cholesterol was measured using the enzymatic colorimetric assay to calculate the $4{\beta}$-OH-cholesterol/cholesterol ratio. The correlation between variables was assessed using Pearson's correlation test. Results: There was a significant negative correlation between MDRD eGFR and indoxyl sulfate levels. The levels of urinary $6{\beta}$-OH-cortisol/cortisol and $6{\beta}$-OH-cortisone/cortisone as well as plasma $4{\beta}$-OH-cholesterol and $4{\beta}$-OH-cholesterol/cholesterol were not correlated with MDRD eGFR and the plasma concentration of indoxyl sulfate. Conclusion: Hepatic CYP3A activity may not be affected by renal impairment-induced accumulation of plasma indoxyl sulfate.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.11a
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• pp.51-58
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• 2002

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.11a
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• pp.43-50
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• 2002

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.207-216
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• 2009

Fluconazole is used as an orally administrated antifungal drug for the treatment of tinea corporis, candidiasis including skin mycotic pneumonia infections. The dosage of fluconazole varies with indication ranging from 50 mg/day to 400 mg/day. The fluconazole capsule 50 mg (3 capsules daily) is already available in Korean market. To improve the patient compliance, a fluconazole tablet 150 mg (once a day administration) was developed recently. The purpose of this study was to evaluate the bioequivalence of three doses of fluconazole capsule 50 mg (Diflucan 50 mg, Pfizer Korea Inc., as a reference drug) and a single dose of fluconazole tablet 150 mg (Plunazol 150 mg, Daewoong Pharm. Co., Korea) according to the guidelines of the Korea Food and Drug Administration (KFDA). The bioequivalence for three capsules of Diflucan 50 mg and a single tablet of Plunazol 150 mg was investigated in twenty-four healthy male volunteers under a randomized 2${\times}$2 crossover trial design. The average age of twenty-four volunteers was 24.78${\pm}$3.27 year-old, average height was 175.56${\pm}$5.45 cm and average weight was 67.24${\pm}$6.86 kg. After three capsules of Diflucan 50 mg or a single tablet of Plunazol 150 mg were orally administered, blood was taken at predetermined time intervals and the plasma concentrations of fluconazole in plasma were determined using LC-MS-MS. The 90% confidence intervals for the main parameters of statistical results after logarithmic transformation were AUCt 0.9272-1.0084 and Cmax 0.8423-0.9544 respectively, which are in the range of log 0.8 to log 1.25 and the statistical results of additional parameters (AUClast, t1/2 and MRT) were also in the 90% confidence interval that is in the range of log 0.8 to log 1.25. Therefore, the results of this study confirm the bioequivalence of three capsules of Diflucan 50 mg to one tablet of Plunazol 150 mg.

• Journal of Radiation Protection and Research
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• v.42 no.4
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• pp.189-196
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• 2017

Background: The effects of radiation on tissues vary depending on the radiation type. In this study, a minipig model was used to compare the effects of ${\beta}$-rays from $^{166}Ho$ and ${\gamma}$-rays from $^{60}Co$ on the skin. Materials and Methods: In this study, the detrimental effects of ${\beta}$- and ${\gamma}$-irradiation on the skin were assessed in minipigs. The histopathological changes in the skin from 1 to 12 weeks after exposure to 50 Gy of either ${\beta}$- (using $^{166}Ho$ patches) or ${\gamma}$- (using $^{60}Co$) irradiation were assessed. Results and Discussion: The skin irradiated by ${\beta}$-rays was shown to exhibit more severe skin injury than that irradiated by ${\gamma}$-rays at 1-3 weeks post-exposure; however, while the skin lesions caused by ${\beta}$-rays recovered after 8 weeks, the ${\gamma}$-irradiated skin lesions were not repaired after this time. The observed histopathological changes corresponded with gross appearance scores. Seven days post-irradiation, apoptotic cells in the basal layer were detected more frequently in ${\beta}$-irradiated skin than in ${\gamma}$-irradiated skin. The basal cell density and skin thickness gradually decreased until 4 weeks after ${\gamma}$- and ${\beta}$- irradiation. In ${\beta}$-irradiated skin lesions, and the density and thickness increased sharply back to control levels by 6-9 weeks. However, this was not the case in ${\gamma}$-irradiated skin lesions. In ${\gamma}$-irradiated skin, cyclooxygenase-2 (COX-2) was shown to be expressed in the epidermis, endothelial cells of vessels, and fibroblasts, while ${\beta}$-irradiated lesions exhibited COX-2 expression that was mostly limited to the epidermis. Conclusion: In this study, ${\beta}$-rays were shown to induce more severe skin injury than ${\gamma}$-rays; however, the ${\beta}$-rays-induced injury was largely repaired over time, while the ${\gamma}$-rays-induced injury was not repaired and instead progressed to necrosis. These findings reveal the differential effects of ${\gamma}$- and ${\beta}$-irradiation on skin and demonstrate the use of minipigs as a beneficial experimental model for studying irradiation-induced skin damage.

• Translational and Clinical Pharmacology
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• v.26 no.4
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• pp.160-165
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• 2018

Indobufen ($Ibustrin^{(R)}$), a reversible inhibitor of platelet aggregation, exists in two enantiomeric forms in 1:1 ratio. Here, we characterized the anti-platelet effect of S- and R-indobufen using response surface modeling using $NONMEM^{(R)}$ and predicted the therapeutic doses exerting the maximal efficacy of each enantioselective S- and R-indobufen formulation. S- and R-indobufen were added individually or together to 24 plasma samples from drug-naïve healthy subjects, generating 892 samples containing randomly selected concentrations of the drugs of 0-128 mg/L. Collagen-induced platelet aggregation in platelet-rich plasma was determined using a Chrono-log Lumi-Aggregometer. Inhibitory sigmoid $I_{max}$ model adequately described the anti-platelet effect. The S-form was more potent, whereas the R-form showed less inter-individual variation. No significant interaction was observed between the two enantiomers. The anti-platelet effect of multiple treatments with 200 mg indobufen twice daily doses was predicted in the simulation study, and the effect of S- or R-indobufen alone at various doses was predicted to define optimal dosing regimen for each enantiomer. Simulation study predicted that 200 mg twice daily administration of S-indobufen alone will produce more treatment effect than S-and R-mixture formulation. S-indobufen produced treatment effect at lower concentration than R-indobufen. However, inter-individual variation of the pharmacodynamic response was smaller in R-indobufen. The present study suggests the optimal doses of R-and S-enantioselective indobufen formulations in terms of treatment efficacy for patients with thromboembolic problems. The proposed methodology in this study can be applied to the develop novel enantio-selective drugs more efficiently.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.2
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• pp.267-273
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• 2017

The p53-inducible gene 3 (PIG3), initially identified as a gene downstream of p53, plays an important role in the apoptotic process triggered by p53-mediated reactive oxygen species (ROS) production. Recently, several studies have suggested that PIG3 may play a role in various types of cancer. However, the functional significance of PIG3 in cancer remains unclear. Here, we found that PIG3 was highly expressed in human colon cancer cell lines compared to normal colon-derived fibroblasts. Therefore, we attempted to elucidate the functional role of PIG3 in colon cancer. PIG3 overexpression increases the colony formation, migration and invasion ability of HCT116 colon cancer cells. Conversely, these tumorigenic abilities were significantly decreased in in vitro studies with PIG3 knockdown HCT116 cells. PIG3 knockdown also attenuated the growth of mouse xenograft tumors. These results demonstrate that PIG3 is associated with the tumorigenic potential of cancer cells, both in vitro and in vivo, and could play a key oncogenic role in colon cancer.

• Journal of Oriental Neuropsychiatry
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• v.18 no.3
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• pp.331-340
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• 2007

The etiology of chronic headache is not yet fully explained, the treatment of this symptom is not simple. We show the effect of Qigong therapeutics applied on chronic headache patient, in order to establish a primary data for further studies of new treatments. We treated 2 times a weeks for 3 weeks. The acupoints, (太陽穴)(Ex-HN5), (老龍穴), (大趾甲下穴), and (百會穴)(GV20) were stimulated for 10 seconds by Qigong-Acupuncture, and after that Qigong therapy was performed for 30 minutes The effects were analyzed using VAS scores, PPI(Present Pain Intensity), HI(Headache Index) and HDI(The Henry Ford Headache Disability Inventory). We concluded that Qigong therapeutics applied on chronic headache patient showed effects of relieving pain, improving general activities and changing the mood. Further researches are needed to evaluate the distinct functional mechanism of Qigong therapeutics, hut this study is meaningful in the sense that it will act as a fundamental study to build on.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.3
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• pp.217-223
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• 2014

Plasma ionized calcium ($Ca^{2+}$) concentrations are tightly regulated in the body and maintained within a narrow range; thus it is challenging to quantify calcium absorption under normal physiologic conditions. This study aimed to develop a mechanistic model for the parathyroid hormone (PTH) response after calcium intake and indirectly compare the difference in oral calcium absorption from PTH responses. PTH and $Ca^{2+}$ concentrations were collected from 24 subjects from a clinical trial performed to evaluate the safety and calcium absorption of Geumjin Thermal Water in comparison with calcium carbonate tablets in healthy subjects. Indirect response models (NONMEM Ver. 7.2.0) were fitted to observed $Ca^{2+}$ and PTH data, respectively, in a manner that absorbed but unobserved $Ca^{2+}$ inhibits the secretion of PTH. Without notable changes in $Ca^{2+}$ levels, PTH responses were modeled and used as a marker for the extent of calcium absorption.