• Translational and Clinical Pharmacology
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• v.26 no.4
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• pp.166-171
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• 2018

Although there are many commercially available training software programs for pharmacokinetics, they lack flexibility and convenience. In this study, we develop simulation software to facilitate pharmacokinetics education. General formulas for time courses of drug concentrations after single and multiple dosing were used to build source code that allows users to simulate situations tailored to their learning objectives. A mathematical relationship for a 1-compartment model was implemented in the form of differential equations. The concept of population pharmacokinetics was also taken into consideration for further applications. The source code was written using R. For the convenience of users, two types of software were developed: a web-based simulator and a standalone-type application. The application was built in the JAVA language. We used the JAVA/R Interface library and the 'eval()' method from JAVA for the R/JAVA interface. The final product has an input window that includes fields for parameter values, dosing regimen, and population pharmacokinetics options. When a simulation is performed, the resulting drug concentration time course is shown in the output window. The simulation results are obtained within 1 minute even if the population pharmacokinetics option is selected and many parameters are considered, and the user can therefore quickly learn a variety of situations. Such software is an excellent candidate for development as an open tool intended for wide use in Korea. Pharmacokinetics experts will be able to use this tool to teach various audiences, including undergraduates.

• Korean Journal of Clinical Pharmacy
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• v.2 no.1
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• pp.23-28
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• 1992

This study was attempted to investigate the pharmacokinetics of theophylline(4mg/kg) in the rabbits of carbon tetrachloride induced hepatic Cailure, The plasma concentration and relative bioavailability of theophylline were increased significantly in hepatic railure rabbits compared with those of normal rabbits. There was significant relationship between SGOT value and bioavailability parameters of theophylline. From the results of this experiments, dosage regimen of theophylline is considered to be adjusted in dose size and dosing interval using SGOT values.

• Journal of Ginseng Research
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• v.37 no.4
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• pp.451-456
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• 2013

Compound K is a major metabolite of ginsenoside Rb1, which has various pharmacological activities in vivo and in vitro. However, previous studies have focused on the pharmacokinetics of a single metabolite or the parent compound and have not described the pharmacokinetics of both compounds in humans. To investigate the pharmacokinetics of ginsenoside Rb1 and compound K, we performed an open-label, single-oral dose pharmacokinetic study using Korean Red Ginseng extract. We enrolled 10 healthy Korean male volunteers in this study. Serial blood samples were collected during 36 h after Korean Red Ginseng extract administration to determine plasma concentrations of ginsenoside Rb1 and compound K. The mean maximum plasma concentration of compound K was $8.35{\pm}3.19$ ng/mL, which was significantly higher than that of ginsenoside Rb1 ($3.94{\pm}1.97$ ng/mL). The half-life of compound K was 7 times shorter than that of ginsenoside Rb1. These results suggest that the pharmacokinetics, especially absorption, of compound K are not influenced by the pharmacokinetics of its parent compound, except the time to reach the maximum plasma concentration The delayed absorption of compound K support the evidence that the intestinal microflora play an important role in the transformation of ginsenoside Rb1 to compound K.

• 대한임상약리학회:학술대회논문집
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• 1993.04a
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• pp.10-10
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• 1993

• 한국임상약학회:학술대회논문집
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• 2007.12a
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• pp.168-168
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• 2007

• Korean Journal of Clinical Pharmacy
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• v.9 no.1
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• pp.66-70
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• 1999

The effect of circadian rhythm on cyclosporine pharmacokinetics was studied in rabbits after oral administration of 10 mg/kg dose of cyclosporine at 10:00 a.m. and 10:00 p.m. The blood concentration data were subjected to simultaneous computer nonlinear least squares regression analysis using a 1-compartment pharmacokinetic model. The blood concentrations of cyclosporine at 10:00 a. m. were increased significantly during 2-6 hr compared to those at 10:00 p.m. The area under the blood concentration-time curve (AUC) and peak concentration $(C_{max})$ of cyclosporine at 10:00 a.m. were increased significantly compared to those at 10:00 p.m. The mean total body clearance (CL) of cyclosporine at 10:00 a.m. were decreased significantly compared to those at 10:00 p.m. It is reasonable to consider individual circadian rhythm for effective dosage regimen of cyclosporine in therapeutics.

• Korean Journal of Clinical Pharmacy
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• v.18 no.1
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• pp.60-67
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• 2008

This study aimed to compare a microparticle enzyme immunoassay (MEIA) with a liquid chromatography-tandem mass spectrometry (LC/MS/MS) technique for the measurement of tacrolimus concentrations in adult liver transplant recipients, to investigate how the assay choice influenced the population pharmacokinetics of tacrolimus and to identify patient characteristics that affected pharmacokinetic parameters in each assay. Tacrolimus concentrations from 29 liver (n=52 paired-samples) transplant recipients measured by both MEIA and LC/MS/MS were used to evaluate the performance of these methods in the clinical setting. Tacrolimus pharmacokinetics was studied independently using MEIA and LC/MS/MS data in 70 adult patients using a population approach performed with NONMEM. Patient characteristics which influenced pharmacokinetic parameters in each assay were compared. The relation between LC/MS/MS and MEIA measurements was best described by the regression equation MEIA=1.465*LC/MS/MS-1.336 (r=0.91). Multiple linear regression analysis showed significant inverse relationships between assay difference and hematocrit (Hct) (p<0.025) in liver graft recipients. In MEIA, the population estimate of tacrolimus CL/F and apparent volume of distribution (Vd/F) were found to be 10.1 L/h and 226 L, and in LC/MS/MS, 13 L/h and 305 L respectively. Neither patient's age, weight, gender, grafted hepatic weight, albumin concentration, nor markers of liver function influenced tacrolimus CL/F The final model of CL/F was found to be 10.1+(Hct/Hct mean)$^{12.0}$ in MEIA and 13+(1+Hct/578) in LC/MS/MS indicating that CL/F was influenced by hematocrit.

• Korean Journal of Clinical Pharmacy
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• v.10 no.3
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• pp.125-129
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• 2000

The effect of circadian rhythm on gentamicin pharmacokinetics was studied in rabbits who took a single intravenous 2 mg/kg dose of gentamicin at 09:00 in the morning (a.m.) and 22:00 in the evening (p.m.). A significant circadian rhythm of pharmacokinetic parameters as a function of time of day was noted in rabbits, showing lower total body clearance $CL_t$ and higher serum area under the curve (AUC) when given in the evening. The half-life $t_{1/2}$ was shorter in the morning $(3.88\pm0.62h)$ when compared to the evening $(4.76\pm0.75\;h)$. The AUC was greater in the evening $(25.92\pm3.49\;{\mu}g/ml{\cdot}hr)$ than that in the morning $(22.42\pm3.42\;{\mu}g/ml{\cdot}hr)$, most likely because the CLt was significantly higher when gentamicin was given in the morning $(0.18\pm0.28\;ml/hr)$ versus in the evening $(0.15\pm0.26\;ml/hr)$. The $t_{1/2}$ of gentamicin in the evening was increased significantly(p<0.05) compared to those of gentamicin in the morning. It is reasonable to consider individual circadian rhythm for effective dosage regimen of gentamicin in clinical chronotherapeutics.

• Korean Journal of Clinical Pharmacy
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• v.1 no.1
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• pp.1-7
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• 1991

Folates are involved in a variety of important biosynthesis by way of donating one carbon unit. Since folate metabolism was well understood a number of antifol have been developed. Among these antifols, aminopterin was first used in the treatment of childhood leukemia. However due to its toxicity and purity problems. it was immediately replaced by another antifols. methotrexate (MTX). MTX is shown to be active against various malignancies including leukemia breast cancer, osteogenic sarcoma, and head and neck cancer. Clinically, MTX therapy is divided into 3 categories. depeding on the dose administered; low-dose is defined as doses < $80\;mg/m^2$ intermediate-dose as doses $\geqq\;80\;mg/m^2$ and < $1000\;mg/m^2$ and high-dose as doses $\geqq\;1000\;mg/m^2$. Leucovorin should be administered to minimize MTX toxicities when MTX doses are greater than $80-100\;mg/m^2$. The clinical pharmacokinetics (ADME) of MTX is discussed in this text.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.4
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• pp.249-253
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• 2012

We analyzed the pharmacokinetics of C3G on data from twelve subjects, after 2-week multiple dosing of black bean (Phaseolus vulgaris, Cheongjakong-3-ho) seed coat extract, using the mixed effect analysis method (NONMEM, Ver. 6.2), as well as the conventional non-compartmental method. We also examined the safety and tolerability. The PK analysis used plasma concentrations of the C3G on day 1 and 14. There was no observed accumulation of C3G after 2-week multiple dosing of black bean seed coat extract. The typical point estimates of PK were CL (clearance)=3,420 l/h, V (volume)=7,280 L, Ka (absorption constant)=9.94 $h^{-1}$, ALAG (lag time)=0.217 h. The black bean seed coat extract was well tolerated and there were no serious adverse events. In this study, we confirmed that a significant amount of C3G was absorbed in human after given the black bean seed coat extract.