• 한국임상약학회지
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• 제16권1호
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• pp.57-62
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• 2006

The purpose of this study was to investigate the effect of naringenin, one of flavonoids, on the pharmacokinetics and bioavailability of diltiazem (15 mg/kg) after oral administration of diltiazem with or without naringenin (2.0, 10 and 20 mg/kg) in rabbits. Coadministration of naringenin increased the absorption rate constant $(K_a)$, the area under the plasma concentration-time curve (AUC) and peak concentration $(C_{max})$ of diltiazem compared to the control group, but only significantly (p<0.05) by 10mg/kg of naringenin coadministration. The absolute bioavailability (AB%) of diltiazem by coadministration ranges from 7.8% to 10.3%, increased more than control (7.2%), and relative bioavailability (RB%) of diltiazem is increased from 1.08- to 1.43-fold. Coadministration caused on significant changes in the terminal half-lives $(t_{1/2})$ and the time to reach the peak concentration $(T_{max})$ of diltiazem. On the other hand, coadministration of naringenin increased the AUC desacetyldiltiazem, significantly at the dose of 10mg/kg. But the metabolite ratio (MR) was decreased, significantly at 10mg/kg of naringenin. Based on these results, we can make a conclusion that the increased bioavailability and the significant changes of these pharmacokinetic parameters might be due to naringenin, which possess the potency to inhibit the metabolizing enzyme (CYP3A4) in the liver and intestinal mucosa, and also inhibit the P-glycoprotein efflux pump in the intestinal mucosa.

• Journal of Pharmaceutical Investigation
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• 제17권3호
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• pp.135-139
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• 1987

This study was attempted to investigate the dissolution rate and the bioavailability of commercially available sulfamethoxazole and trimethoprim (SMX-TM) tablets in rabbits. The dissolution test was conducted in artificial gastric juice by basket method with eight SMX-TM tablets which were chemically equivalent. According to the dissolution rate, SMX-TM tablets were divided into four groups, such as rapid, intermediate, slow and very slow groups for the bioavailability test in rabbits. The results were as follows: 1) The dissolution rate of brand A was most rapid but brand H was most slow in artificial gastric juice. 2) Area under the blood concentration curve was larger in the order of brand A > C > E > H in rabbits. 3) There was a little difference in pharmacokinetic parameters such as biological half life, absorption rate constant and $t_{max}$. 4) The relationship between the dissolution rate and relative bioavailability was significant in brand A, C, E and H. From the results of this experiment, the bioavailability of SMX-TM tablets in rabbits may be predicted from the results of dissolution rate studies.

• 약학회지
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• 제55권4호
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• pp.332-337
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• 2011

The purpose of this study was to investigate the effect of epigallocatechin gallate (EGCG) on the pharmacokinetics of nimodipine in rats. Pharmacokinetic parameters of nimodipine were determined in rats after oral and iv administration of nimodipine with or without EGCG and also the effect of EGCG on the cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp) activity were evaluated. EGCG inhibited CYP3A4 and P-gp activity. EGCG significantly increased the area under the plasma concentration-time curve (AUC) and peak plasma concentration ($C_{max}$) of nimodipine. The absolute bioavailability (AB%) and relative bioavailability (RB%) of nimodipine by EGCG were increased by 16% and by 48%, respectively, compared to the control. In contrast, EGCG did not affect the intravenous pharmacokinetics of nimodipine. Based on these results, the increased bioavailability of nimodipine might be due to inhibition of CYP3A4 in the small intestine and/or in the liver and inhibition of P-gp in the small intestine by EGCG.

• Journal of Pharmaceutical Investigation
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• 제40권5호
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• pp.291-296
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• 2010

This study was to investigate the effect of baicalein, an antioxidant, on the bioavailability of nicardipine after orally or intravenously administered nicardipine in rats. Nicardipine was administered orally (12 mg/kg) or intravenously (4 mg/kg) with or without orally administered baicalein (0.4, 2 or 10 mg/kg) to rats. In the inhibitory effect of baicalein on CYP3A4 activity, baicalein inhibited CYP3A4 activity with $IC_{50}$ values of 9.2 ${\mu}M$. The cell-based P-gp activity test using rhodamine-123 also showed that baicalein (30-10 ${\mu}M$, p<0.01) significantly inhibited P-gp activity. Compared with the control group (given nicardipine alone), the area under the plasma concentration-time curve (AUC) was significantly (2 mg/kg, P<0.05; 10 mg/kg, P<0.01) increased by 25.9-60.0%, and the peak concentration ($C_{max}$) was significantly (10 mg/kg, P<0.01) increased by 40.0% in the presence of baicalein after orally administration of nicardipine. Consequently, the relative bioavailability (R.B.) of nicardipine was increased by 1.26- to 1.60-fold and the absolute bioavailability (A.B.) was significantly (2 mg/kg, P<0.05; 10 mg/kg, P<0.01) increased by 26.0-59.9%. Compared to the i.v. control, baicalein did not significantly change pharmacokinetic parameters of nicardipine in i.v. administration. Accordingly, the enhanced oral bioavailability of nicardipine might be mainly due to increased intestinal absorption caused by P-gp inhibition rather than to reduced elimination of nicardipine by baicalein. The increase in the oral bioavailability might be mainly attributed to enhanced absorption in the small intestine via the inhibition of P-gp and reduced first-pass metabolism of nicardipine via the inhibition of the CYP3A subfamily in the small intestine and/or in the liver by baicalein. Based on these results, nicardipine dosage should be adjusted when given concomitantly with baicalein.

• Archives of Pharmacal Research
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• 제17권2호
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• pp.80-86
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• 1994

The bioavailability of digoxin generic tablets manufactures in Korea (formulations A & B) wwere compared to a standard (formulation C; Lanoxin brand digoxin, Burroughs Wellcome, USA) in 12 healthy Korean male volunteers (mean age 31.4 years) in a single dose, randomized, complete block crossover study. Using a latin square design, each of the subjects was randomized to the order number and allocated to each of the three treatments of 0.5mg oral digoxin. Digoxin conc4ntrations in serum and urine samples collected for 48 hours after dosing were measured by fluoprescence polarization immunoassy and radioimmunoassy, respectively. Treatments were compared by using nonlinear least squares regession analysis to evaluate the following pharmacokinetic parameters : maximum serum concentation $(C_{max})$; time of maximum serum concentation $(T_{max})$; area under the serum concentration-time curve $AUC_{0-12}$, $C_{max}$\;and\;(AUC_{0-12})$; and cummulative urinary excretion for 0-48 hours $(CLE_{0-48}.\;Mean\;AUC_{0-12},\;C_{max},\;and\;CUE_{0-48}$ values for formulations B and C were significantly different from formulation A (P<0.001), but not significantly diffeerent form each other. Basede on $AUL_{0-12}\;and\;CUE_{0-48}$ respectively, the relative availability of formulation B was 87.5% and 89.6% and the relative availability of formultation A was 43% and 35% when compared to formulation C(the standard).

• Journal of Pharmaceutical Investigation
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• 제27권3호
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• pp.225-231
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• 1997

For the effective administration of naloxone, we attempted to investigate the naloxone sustained-release implants. Using the biodegradable polymer, poly[(diethyl glutamate)-co-(ethyl glycinate)phosphazenes](PGGP), the implantable devices containing naloxone hydrochloride(NLX HCl) and naloxone base(NLX) were prepared. The release rates of NLX and NLX HCl were compared. Influences of NLX contents on release rates were examined. For pharmacokinetic studies, NLX and NLX HCl loaded devices were implanted subcutaneously in rabbits and then the plasma concentrations of NLX were determined by HPLC(ECD). NLX-containing devices were implanted with various doses and pharmacokinetic parameters according to dose were calculated. The relative bioavailabilities were evaluated and compared. Incorporation of NLX in the polymer leaded to a slow release. There were no differences of release rates based on drug contents. In pharmacokinetic parameters determined in 216 hours, NLX loaded devices resulted in enhanced bioavailability with the higher AUC (p<0.01) than NLX HCl loaded devices and MRT was significantly (p<0.05) increased. This result demonstrates that NLX is more suitable for sustained release devices than NLX HCl. Therefore it is anticipated that the effective concentrations of naloxone could be maintained for longer periods and bioavailabilities could be improved by naloxone sustained-release implants, with varying drug base/hydrochloride.

• 한국임상약학회지
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• 제2권1호
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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 Pharmaceutical Investigation
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• 제20권4호
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• pp.199-203
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• 1990

The pharmacokinetics of propranolol administered orally (10 me/kg) was investgated in the rabbits of carbon tetrachloride induced hepatic failure. The plasma concentration and relative bioavailability of propranolol were increased significantly in hepatic failure rabbits, compared with those of normal rabbits. There were significant relationship between GOT, GPT value and bioavailability parameters of propranolol. In short, dosage regimen of propranolol is considered to be adjusted in dose size and dosing interval using GOT or GPT an index.

• 약학회지
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• 제49권3호
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• pp.212-216
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• 2005

A rapid, sensitive and selective electrospray tandem mass spectrometric (ESI-LC/MS/MS) method for the quantitation of gliquidone in human plasma was developed. A bioavailability study of gliquidone tablet (30 mg gliquidone, Boehringer Ingelheim Korea Co.) was performed using the validated ESI-LC/MS/MS method. The dose of 30 mg of gliquidone (1 tablet) was orally administered to 9 healthy Korean subjects. After administration, blood was taken at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 7, 9, 12, 24, and 33 hour. The validation data were as follows; the standard curve was linear ($r^2$=0.999) over the concentration range of $10\~1000 ng/ml$. The coefficient of variation for intra- and inter-day assay were $8.30\~18.86$, and $2.19\~12.92\%$, respectively. The lower limit of quantification for gliquidone was 10 ng/ml. The pharmacokinetic parameters obtained were as follows; $AUC_t$ was 3861.17$\pm$1328.61 ng-hr/ml, $C_{max}$ was 831.02$\pm$227.99 ng/ml, $T_{max}$ was $2.94{\pm}0.77 hr,\;K_e$, was 0.19$\pm$0.06 1/hr, and $t_{l/2}$ was 4.47$\pm$3.52 hr. Based on the validated analytical method and pharmacokinetic parameters, a standard guideline of the bioavailability test of gliquidone dosage forms was prepared successfully and could be used for the bioequivalence test of gliquidone preparation.

• 약학회지
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• 제49권3호
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• pp.225-229
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• 2005

A rapid, sensitive and selective tandem mass spectrometric method (LC-MS/MS) for the quantitation of nicorandil in human plasma was developed. A bioavailability study of Sigmat tablet (5 mg nicorandil, Choongwae Co.) was per-formed using the validated LC-MS/MS method. The dose of 5 fig of nicorandil (1 tablet) was orally administered to 9 healthy Korean subjects. After administration, blood was taken at 0.25, 0.5, 1, 2, 3, 4, 5, 6, 9, 12, and 24 hour. The validation data were as follows; the standard curve was linear ($r^2$=0.999) over the concentration range of $0.5\~200.0 ng/ml$. The coefficient of variation for intra- and inter-day assay were $3.55\~7.44$, and $2.17\~9.102\%$, respectively. The lower limit of quantification for nicorandil was 0.5 ng/ml. The pharmacokinetic parameters obtained were as follows; $AUC_t$ was 145.9$\pm$83.0 ng-hr/ml, Cmax was 83.8$\pm$32.2 ng/ml, $C_{max}$ was 0.42$\pm$0.13 hr, $K_e$ was 0.56$\pm$0.23 l/hr, and $t_{l/2}$ was 1.42$\pm$0.52 hr. Based on the validated analytical method and pharmacokinetic parameters, a standard guideline of the bioavailability test of nicorandil dos-age forms was prepared successfully and could be used for the bioequivalence test of nicorandil preparation.