• 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.

• YAKHAK HOEJI
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• v.56 no.1
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• pp.48-54
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• 2012

Enviromental differences in gentamicin pharmacokinetics by using population pharmacokinetic methods were compared with 20 Korean patients and 24 Korean-American appendicitis patients. Two to six blood specimens were collected from all patients at the following times : just before a regularly scheduled infusion and at 0.5 hour after the end of a 0.5 hour infusion. Nonparametric expected maximum (NPEM) algorithm for population modeling was used. The estimated parameters were the elimination rate constant (K), the slope (KS) of the relationship between K versus creatinine clearance ($C_{cr}$), the apparent volume of distribution (V), the slope (VS) of the relationship between V versus weight, gentamicin clearance (CL) and the slope (CS) of the relationship between CL versus $C_{cr}$ and the V. The output includes two marginal probability density function (PDF), means, medians, modes, variance and CV%. The mean K (KS) were $0.402{\pm}0.129\;h^{-1}(0.00486{\pm}0.00197\;[h{\cdot}ml/min/1.73\;m^2]^{-1})$ and $0.411{\pm}0.135\;h^{-1}(0.00475{\pm}0.00180\;[h{\cdot}ml/min/1.73\;m^2]^{-1})$ for Korean and Korean-American populations, respectively. The mean V (VS) were not different at $14.3{\pm}3.6l(0.241{\pm}0.0511l/kg)$ and $15.1{\pm}3.84l(0.239{\pm}0.0492l/kg)$ for Korean and Korean-American populations, respectively (p>0.2). The mean CL (CS) were $5.68{\pm}1.69l/h(0.0714{\pm}0.0222l/kg[h{\cdot}ml/min/1.73\;m^2])$ and $5.70{\pm}1.77l/h(0.0701{\pm}0.0215l/kg[h{\cdot}ml/min/1.73\;m^2])$ for Korean and Korean-American populations, respectively. There were no enviromental differences in gentamicin pharmacokinetics between Korean and Korean-American appendicitis patients.

• Archives of Pharmacal Research
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• v.28 no.8
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• pp.970-976
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• 2005

The purpose of this study was to investigate the effect of morin, a flavonoid, on the pharmacokinetics of diltiazem and one of its metabolites, desacetyldiltiazem in rats. Pharmacokinetic parameters of diltiazem and desacetyldiltiazem were determined after oral administration of diltiazem (15 mg/kg) in rats pretreated with morin (1.5, 7.5, and 15 mg/kg). Compared with the control group (given diltiazem alone), pretreatment of morin significantly increased the absorption rate constant $(K_a)$ and peak concentration $(C_{max})$ of diltiazem (p<0.05, p<0.01). Area under the plasma concentration-time curve (AUC) of diltiazem in rats pretreated with morin were significantly higher than that in the control group (p<0.05, p<0.01), hence the absolute bioavailability $(AB\%)$ of diltiazem was significantly higher than that of the control group (p<0.05, p<0.01). Relative bioavailability $(RB\%)$ of diltiazem in rats pretreated with morin was increased by 1.36- to 2.03-fold. The terminal half-life $(t_{1/2})$ and time to reach the peak concentration $(T_{max})$ of diltiazem were not altered significantly with morin pretreatment. AUC of desacetyldiltiazem was increased significantly (p<0.05) in rats pretreated with morin at doses of 7.5 and 15 mg/kg, but metabolite-parent ratio (MR) of desacetyldiltiazem was decreased significantly (p<0.05), implying that pretreatment of morin could be effective to inhibit the CYP 3A4-mediated metabolism of diltiazem. There were no apparent changes of $T_{max}$ and $t_{1/2}$ of desacetyldiltiazem with morin pretreatment. Collectively, the pretreatment of morin significantly altered pharmacokinetics of diltiazem, which can be attributed to increased intestinal absorption as well as reduced first-pass metabolism. Based on these results, dose modification should be taken into consideration when diltiazem is used concomitantly with morin or morin-containing dietary supplements in clinical setting.

• YAKHAK HOEJI
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• v.39 no.2
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• pp.103-112
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• 1995

Population pharmacokinetics for gentamicin were compared with 24 American patients (16 male and 8 female) and 16 Korean-American appendicitis patients(12 male and 4 female). Two to six blood specimens were collected from all patients at the following times: just before a regularly scheduled infusion and at 1/2 hour after the end of a 1/2 hour infusion. Nonparametric expected maximum(NPEM) algorithm for population modeling was used. The estimated parameters were the elimination rate constant(K), the slope of the relationship between K versus creatinine clearance(KS), the apparent volume of distribution(V), the slope of the relationship between V versus weight(VS), gentamicin clearance(CL) and the slope of the relationship between CL versus creatinine clearance and the VS(CS). The output includes a 3-dimensional plot of the joint probability density function(PDF), two marginal PDF, means, medians, modes, variance, skewness, kurtosis, and CV%. The mean K(KS) were 0.424$\pm$0.139(0.00429$\pm$0.00164) and 0.411$\pm$0.135 hr$^{-1}$ (0.00475$\pm$0.00180[hr.mL/min/1.73m$^{2}]^{-1}$) for American and Korean-American populations, respectively. The mean V(VS) were not different at 15.6$\pm$4.77(0.233$\pm$0.0526) and 15.1$\pm$3.84L(0.239$\pm$0.0492 L/kg) for American and Korean-American populations, respectively (P>0.2). The mean CL (CS) were 6.28$\pm$1.85(0.0634$\pm$0.0191) and 5.70$\pm$1.77 L/hr(0.0701$\pm$0.0215 L/kg[hr.mL/min/1.73m$^{2}$)] for American and Korean-American populations, respectively. There are no differences in gentamicin pharmacokinetics between American and Korean-American Appendicitis patients.

• Biomolecules & Therapeutics
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• v.2 no.4
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• pp.310-315
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• 1994

The pharmacokinetics and tissue distribution of DA-3030 (recombinant human granulocyte colony-stimulating factor, rhG-CSF, recently manufactured by Dong-A research laboratory of Dong-A Pharmaceutical Company) were compared with reported data in the literature. After intravenous(i.v.) administration of DA-3030, at dose of 5, 10 and 100 $\mu\textrm{g}$/kg to rats, some pharmacokinetic parameters, such as terminal half-lives(1.05, 1.19 and 1.83 hr, respectively) and clearance (84.0, 54.8 and 45.5 mι/hr/kg, repectively), were dose-dependent. This could be due to the saturable metabolism of DA-3030 in rats. Similar results were also reported. After subcutaneous(s.c.) and intramuscular(i.m.) administrations of DA-3030, 10 $\mu\textrm{g}$/kg to rats, the extent of bioavailability(absolute bioavailability) were incomplete; the values were 23.3 and 18.2% after s.c. and i.m. injections, respectively, due to the degradation of DA-3030 by protease. After 7-consecutive day i.v. administrations of DA-3030, 10 $\mu\textrm{g}$/kg/day, to rats, the plasma concentrations and pharmacokinetic parameters of DA-3030 were not significantly different from those in single administration. In mice and dogs at DA-3030 dose of 10 $\mu\textrm{g}$/kg, the plasma concentrations of DA-3030 were also declined rapidly with terminal half-lives of 1.31 and 1.15 hr, respectively. DA-3030 was highly concentrated in the kidney after i.v. administration of DA-3030, 10 $\mu\textrm{g}$/kg, to rats, and the results were similar to those obtained using radiolabelled rhG-CSF in the literature. Above data indicate that DA-3030 has similar properties to rhG-CSF manufactured by other companies in view of pharmacokinetics.

• Archives of Pharmacal Research
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• v.26 no.9
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• pp.768-772
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• 2003

Tween 80 (Polysorbate 80) is a hydrophilic nonionic surfactant commonly used as an ingredient in dosing vehicles for pre-clinical in vivo studies (e.g., pharmacokinetic studies, etc.). Tween 80 increased apical to basolateral permeability of digoxin in Caco-2 cells suggesting that Tween 80 is an in vitro inhibitor of P-gp. The overall objective of the present study was to investigate whether an inhibition of P-gp by Tween 80 can potentially influence in vivo absorption of P-gp substrates by evaluating the effect of Tween 80 on the disposition of digoxin (a model P-gp substrate with minimum metabolism) after oral administration in rats. Rats were dosed orally with digoxin (0.2 mg/kg) formulated in ethanol (40％, v/v) and saline mixture with and without Tween 80 (1 or 10％, v/v). Digoxin oral AUC increased 30 and 61％ when dosed in 1 ％ and 10％ Tween 80, respectively, compared to control (P＜0.05). To further examine whether the increase in digoxin AUC after oral administration of Tween 80 is due, in part, to a systemic inhibition of digoxin excretion in addition to an inhibition of P-gp in the GI tract, a separate group of rats received digoxin intravenously (0.2 mg/kg) and Tween 80 (10％ v/v) orally. No significant changes in digoxin IV AUC was noted when Tween 80 was administered orally. In conclusion, Tween 80 significantly increased digoxin AUC and Cmax after oral administration, and the increased AUC is likely to be due to an inhibition of P-gp in the gut (i.e., improved absorption). Therefore, Tween 80 is likely to improve systemic exposure of P-gp substrates after oral administration. Comparing AUC after oral administration with and without Tween 80 may be a viable strategy in evaluating whether oral absorption of P-gp substrates is potentially limited by P-gp in the gut.

• Mass Spectrometry Letters
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• v.12 no.2
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• pp.53-58
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• 2021

Previous in vitro studies have demonstrated that ginsenoside Rc inhibits UGT1A9, but there are no available data to indicate that ginsenoside Rc inhibits UGT1A9 in vivo. The effect of single and repeated intravenous injection of ginsenoside Rc was evaluated on the pharmacokinetics of mycophenolic acid. After injection of ginsenoside Rc (5 mg/kg for one day or 3 mg/kg for five days), 2-mg mycophenolic acid was intravenously injected, and the pharmacokinetics of mycophenolic acid and mycophenolic acid-β-glucuronide were determined. Concentrations of mycophenolic acid and its metabolite from rat plasma were analyzed using a liquid chromatography-triple quadrupole mass spectrometry. Single or repeated pretreatment with ginsenoside Rc had no significant effects on the pharmacokinetics of mycophenolic acid (P > 0.05): The mean difference in maximum plasma concentration (C_max) and area under the concentration-time curve (AUC_inf) were within 0.83- and 0.62-fold, respectively, compared with those in the absence of the ginsenoside Rc. These results indicate that ginsenoside Rc has a negligible effect on the disposition of mycophenolic acid in vivo despite in vitro findings indicating that ginsenoside Rc is a selective UGT1A9 inhibitor. As a result, ginsenoside Rc has little possibility of interacting with drugs that are metabolized by UGT1A9, including mycophenolic acid.

• Journal of Physiology & Pathology in Korean Medicine
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• v.34 no.4
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• pp.201-208
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• 2020

The effects of Gamisoyo-san (GMSYS) co-administration within 5 min on the pharmacokinetics (PK) of tamoxifen were observed. After 50 mg/kg of tamoxifen oral treatment, GMSYS 100 mg/kg was orally administered within 5 min to 7-wk old male SPF.VAF Outbred Crl:CD [Sprague-Dawley (SD)] rats. The plasma were collected at 30 min before administration, 30 min, 1, 2, 3, 4, 6, 8 and 24 hrs after end of GMSYS treatment, and plasma concentrations of tamoxifen were analyzed using LC-MS/MS methods. Tmax, Cmax, AUC, t1/2 and MRTinf of tamoxifen were analysis as compared with tamoxifen single administered rats. Although co-administration with GMSYS did not critically influenced on the pharmacokinetic parameters of oral tamoxifen, they induced increased trends of plasma tamoxifen concentrations, especially significant (p<0.05) increases of plasma tamoxifen concentrations were demonstrated at 0.5 hr after end of co-administration with GMSYS as compared with tamoxifen single formula treated rats, at dosage levels of tamoxifen 10 mg/kg and GMSYS 100 mg/kg within 5 min. It is considered that pharmacokinetic studies should be tested like the effects of GMSYS on the pharmacokinetics of tamoxifen, when they were co-administered with prolonger intervals than Tmax of tamoxifen oral administration (about 2.5 hr-intervals), to achieve the optimal dosing regimen of GMSYS and tamoxifen co-administration.

• Journal of Ginseng Research
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• v.47 no.1
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• pp.74-80
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• 2023

Background: Although many studies have evaluated the efficacy and pharmacokinetics of Korean Red Ginseng (KRG) components (Rg1, Rb1, Rg3, Rd, etc.), few have examined the in vivo pharmacokinetics of the radiolabeled components. This study investigated the pharmacokinetics of ginsenosides and their metabolite compound K (CK), 20(s)-protopanaxadiol (PPD), and 20(s)-protopanaxatriol (PPT) using radioisotopes in rat oral administration. Methods: Sprague-Dawley rats were dosed orally once with 10 mg/kg of the tritium(3H) radiolabeled samples, and then the blood was collected from the tail vein after 0.25, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, 48, 96, and 168 h. Radioactivity in the organs, feces, urine, and carcass was determined using a liquid scintillation counter (LSC) and a bio-imaging analyzer system (BAS). Results and conclusion: After oral administration, as the ³H-labeled ginsenosides were converted to metabolites, C_max and half-life increased, and T_max decreased. Interestingly, Rb1 and CK showed similar values, and after a single oral administration of components, the cumulative excretion ratio of urine and feces was 88.9%-92.4%. Although most KRG components were excreted within 96-168 h of administration, small amounts of components were detected in almost all tissues and mainly distributed to the liver except for the digestive tract when observed through autoradiography. This study demonstrated that KRG components were distributed to various organs in the rats. Further studies could be conducted to prove the bioavailability and transmission of KRG components to confirm the mechanism of KRG efficacy.

• YAKHAK HOEJI
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• v.42 no.3
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• pp.274-274
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• 1998

Aclarubicin(ACL)-entrapped freeze dried liposomes were prepared using Microfludizer to attain a sustained release at targeted organs in a prolonged time so that it can reduce th e side effect and maximize the therapeutic effect. The freeze-dried liposomes were evaluated for pharmacokinetics, antitumor activity against Sarcoma 180, cytotoxicity against L1210 and A549 tumor cells, spleen toxicity and myelosuppressive action. The AUC0->8hr values were 122+/-42, 382+/-140, 419+/-171, 835+/-206 and 443+/-309mcg min/ml for free ACL. ACL-liposome formulation I, II, III and IV, respectively. Cytotoidcity of ACL-entrapped liposomes against L1210 and A549 tumor cells was 2-4 times higher than that of free aclarubicin. ACL-liposome formulation I(PC/CHOL/TA) showed the most potent antitumor activity against Sarcoma 180 in mice. The loss of body weight was much smaller with ACL-entrapped liposomes than free ACL after I.p. injection at a dose of 2 mg/kg/day. Compared to free ACL, ACL-entrapped liposomes expressed a lower and delayed spleen toxicity up to 5th day after I.v. administration. Myelosupperssion seemed to be lower with ACL-entrapped liposome of PC/PC-hydrate/CHOL/TA (formulation III) than free aclarubicin.