scholarly journals Pharmacokinetics of Telbivudine in Healthy Subjects and Absence of Drug Interaction with Lamivudine or Adefovir Dipivoxil

2006 ◽  
Vol 50 (7) ◽  
pp. 2309-2315 ◽  
Author(s):  
Xiao-Jian Zhou ◽  
Barbara A. Fielman ◽  
Deborah M. Lloyd ◽  
George C. Chao ◽  
Nathaniel A. Brown
Keyword(s):  
Single Dose ◽  
Steady State ◽  
Plasma Concentration ◽  
Healthy Subjects ◽  
Adefovir Dipivoxil ◽  
Geometric Mean ◽  
Time Curve ◽  
Concentration Time ◽  
Plasma Pharmacokinetics ◽  
Plasma Concentration Time Curve

ABSTRACT Two phase I studies were conducted to assess the plasma pharmacokinetics of telbivudine and potential drug-drug interactions between telbivudine (200 or 600 mg/day) and lamivudine (100 mg/day) or adefovir dipivoxil (10 mg/day) in healthy subjects. Study drugs were administered orally. The pharmacokinetics of telbivudine were characterized by rapid absorption with biphasic disposition. The maximum concentrations in plasma (C max) were reached at median times ranging from 2.5 to 3.0 h after dosing. Mean single-dose C max and area under the plasma concentration-time curve from time zero to infinity (AUC0-∞) were 1.1 and 2.9 μg/ml and 7.4 and 21.8 μg · h/ml for the 200- and 600-mg telbivudine doses, respectively. Steady state was reached after daily dosing for 5 to 7 days. The mean steady-state C max and area under the plasma concentration-time curve over the dosing interval (AUCτ) were 1.2 and 3.4 μg/ml and 8.9 and 27.5 μg · h/ml for the 200- and 600-mg telbivudine repeat doses, respectively. The steady-state AUCτ of telbivudine was 23 to 57% higher than the single-dose values. Concomitant lamivudine or adefovir dipivoxil did not appear to significantly alter the steady-state plasma pharmacokinetics of telbivudine; the geometric mean ratios and associated 90% confidence interval (CI) for the AUCτ of telbivudine alone versus in combination were 106.3% (92.0 to 122.8%) and 98.6% (86.4 to 112.5%) when coadministered with lamivudine and adefovir dipivoxil, respectively. Similarly, the steady-state plasma pharmacokinetics of lamivudine or adefovir were not markedly affected by the coadministration of telbivudine; the geometric mean ratios and associated 90% CI, alone versus in combination with telbivudine, were 99.0% (87.1 to 112.4%) and 92.2% (84.0 to 101.1%), respectively, for the lamivudine and adefovir AUCτ values. Moreover, the combination regimens studied were well tolerated in all subjects. The results from these studies provide pharmacologic support for combination therapy or therapy switching involving telbivudine, lamivudine, and adefovir dipivoxil for the treatment of chronic hepatitis B virus infection.

Methotrexate pharmacokinetics following administration of recombinant carboxypeptidase-G2 in rhesus monkeys.

1992 ◽  
Vol 10 (8) ◽  
pp. 1359-1364 ◽  
Author(s):  
P C Adamson ◽  
F M Balis ◽  
C L McCully ◽  
K S Godwin ◽  
D G Poplack
Keyword(s):  
Plasma Concentration ◽  
Rhesus Monkeys ◽  
Alternative Form ◽  
High Dose ◽  
Time Curve ◽  
Carboxypeptidase G2 ◽  
Concentration Time ◽  
Bacterial Enzyme ◽  
Plasma Pharmacokinetics ◽  
Plasma Concentration Time Curve

PURPOSE Carboxypeptidase-G2 (CPDG2) is a bacterial enzyme that rapidly hydrolyzes methotrexate (MTX) into inactive metabolites. As an alternative form of rescue after high-dose MTX (HDMTX), CPDG2 has more potential advantages than standard leucovorin (LV) rescue. In this study, the plasma pharmacokinetics of MTX with and without CPDG2 were evaluated in adult rhesus monkeys. MATERIALS AND METHODS The plasma pharmacokinetics of MTX were determined in groups of animals that had received a 300-mg/m2 loading dose of MTX followed by a 60-mg/m2/h infusion during an 18-hour period. One group received CPDG2 at the end of the infusion, and the other group served as a control. Two additional animals with high titers of anti-CPDG2 antibody also were studied. RESULTS During infusion, the steady-state MTX plasma concentration was 11.3 +/- 4.8 mumol/L. Without CPDG2, the postinfusion plasma MTX concentration remained above 0.1 mumol/L for more than 6 hours. After the administration of 50 U/kg of CPDG2, plasma MTX concentrations decreased to nontoxic levels (less than 0.05 mumol/L) within 30 minutes. The initial half-life (t1/2 alpha) of MTX decreased from 5.8 +/- 2.1 minutes to 0.7 +/- 0.02 minutes after enzyme administration. The postinfusion area under the plasma concentration time curve of MTX was 301 +/- 171 mumol/L/min without CPDG2 compared with 19.6 +/- 6.1 mumol/L/min with CPDG2. The immunogenicity studies performed indicated that although animals developed anti-CPDG2 antibodies, none of them manifested allergic symptoms. The effectiveness of CPDG2 was diminished but not eliminated in animals with high titers of anti-CPDG2 antibody. CONCLUSIONS CPDG2 is capable of rapidly decreasing plasma MTX concentrations to nontoxic levels. The administration of CPDG2 seems safe, well tolerated, and it may be useful as an alternative to LV rescue.

scholarly journals Switch from Enfuvirtide to Raltegravir Lowers Plasma Concentrations of Darunavir and Tipranavir: a Pharmacokinetic Substudy of the EASIER-ANRS 138 Trial

2011 ◽  
Vol 55 (7) ◽  
pp. 3613-3615 ◽  
Author(s):  
Lauriane Goldwirt ◽  
Joséphine Braun ◽  
Nathalie de Castro ◽  
Isabelle Charreau ◽  
Aurélie Barrail-Tran ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Human Immunodeficiency Virus ◽  
Steady State ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Time Curve ◽  
Concentration Time ◽  
Background Regimen ◽  
Immunodeficiency Virus ◽  
Plasma Concentration Time Curve

ABSTRACTWe compared tipranavir and darunavir concentrations measured at steady state in 20 human immunodeficiency virus (HIV)-infected patients enrolled in the EASIER-ANRS 138 clinical trial who switched from enfuvirtide to raltegravir while maintaining the same background regimen. The geometric mean ratios of the observed predose concentration (Ctrough), maximum concentration of drug observed in plasma (Cmax), and area under the plasma concentration-time curve (AUC) before (day 0) and after (week 24) the switch were 0.49, 0.76, and 0.67 and 0.82, 0.68, and 0.64 for tipranavir and darunavir, respectively. The virologic consequences of these drug interactions have yet to be determined.

scholarly journals Differential Effects of Tipranavir plus Ritonavir on Atorvastatin or Rosuvastatin Pharmacokinetics in Healthy Volunteers

2009 ◽  
Vol 53 (10) ◽  
pp. 4385-4392 ◽  
Author(s):  
P. A. Pham ◽  
C. J. L. la Porte ◽  
L. S. Lee ◽  
R. van Heeswijk ◽  
J. P. Sabo ◽  
...  
Keyword(s):  
Single Dose ◽  
Steady State ◽  
Adverse Events ◽  
Confidence Interval ◽  
Geometric Mean ◽  
Drug Reactions ◽  
Open Label ◽  
Time Curve ◽  
Concentration Time ◽  
Gastrointestinal Intolerance

ABSTRACT To identify pharmacokinetic (PK) drug-drug interactions between tipranavir-ritonavir (TPV/r) and rosuvastatin and atorvastatin, we conducted two prospective, open-label, single-arm, two-period studies. The geometric mean (GM) ratio was 1.37 (90% confidence interval [CI], 1.15 to 1.62) for the area under the concentration-time curve (AUC) for rosuvastatin and 2.23 (90% CI, 1.83 to 2.72) for the maximum concentration of drug in serum (C max) for rosuvastatin with TPV/r at steady state versus alone. The GM ratio was 9.36 (90% CI, 8.02 to 10.94) for the AUC of atorvastatin and 8.61 (90% CI, 7.25 to 10.21) for the C max of atorvastatin with TPV/r at steady state versus alone. Tipranavir PK parameters were not affected by single-dose rosuvastatin or atorvastatin. Mild gastrointestinal intolerance, headache, and mild reversible liver enzyme elevations (grade 1 and 2) were the most commonly reported adverse drug reactions. Based on these interactions, we recommend low initial doses of rosuvastatin (5 mg) and atorvastatin (10 mg), with careful clinical monitoring of rosuvastatin- or atorvastatin-related adverse events when combined with TPV/r.

Charcoal and Isoniazid Pharmacokinetics

1986 ◽  
Vol 5 (4) ◽  
pp. 285-286 ◽  
Author(s):  
N. Scolding ◽  
M.J. Ward ◽  
A. Hutchings ◽  
P.A. Routledge
Keyword(s):  
Plasma Concentration ◽  
Oral Dose ◽  
Activated Charcoal ◽  
Healthy Subjects ◽  
Time Curve ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

Activated charcoal (10 g) administered 1 h after a 600 mg oral dose of isoniazid to six healthy subjects did not reduce the area under the plasma concentration-time curve for isoniazid significantly. Charcoal administration is unlikely to be of value in isoniazid poisoning if delayed by an hour or more after the overdose.

scholarly journals Pharmacokinetics and Bioequivalence Study of Two Ciprofloxacin Hydrochloride Tablets in Chinese Healthy Volunteers Under Fasting and Fed Conditions: A Randomized, Open-Label, Two-Formulation, Two-Sequence, Two-Period, Single-Dose Crossover Study.

2020 ◽  
Author(s):  
Fei Qin ◽  
Gan-Mi Wang ◽  
Jin-Ying Huang ◽  
Jia-Rong Wu ◽  
Wen-Jie Song ◽  
...  
Keyword(s):  
Single Dose ◽  
Plasma Concentration ◽  
Oral Dose ◽  
Single Oral Dose ◽  
Pharmacokinetic Parameters ◽  
Open Label ◽  
Time Curve ◽  
Ciprofloxacin Hydrochloride ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

Abstract BackgroundCiprofloxacin is a broad-spectrum fluoroquinolone antibiotic which is active against a wide range of Gram-positive and Gram-negative bacteria. The study mainly aimed to determine the bioequivalence of two branded ciprofloxacin hydrochloride tablets (250 mg) under the fasting and fed conditions.MethodsThe study was carried out in 48 healthy Chinese subjects under fasting and fed conditions with a randomized, open-label, two-formulation, two-sequence, two-period, single-dose crossover design. In each period of the study, the subjects were assigned to receive a single oral dose of 250 mg of ciprofloxacin hydrochloride. Blood samples were collected from an hour before dosing to 36 h after administration with 16 time points in total. The bioequivalence analysis was performed after ln-transformation of the ciprofloxacin pharmacokinetic parameters including maximum concentration (Cmax), area under the plasma concentration–time curve from time 0 to time t (AUC0-t), area under the plasma concentration-time curve from time 0 to infinity (AUC0-∞). Two formulations are considered bioequivalent if the 90% confidence intervals (CIs) for the test/reference geometric mean ratios (GMRs) for the ln-transformed pharmacokinetic parameters fall within the standard acceptance range of 80% – 125%. ResultsIn total of 48 subjects were enrolled in the fasting and fed studies, and one of the subjects was excluded before the administration. In the fasting study, the 90% CIs for the test/reference GMRs of the ln-transformed data for Cmax, AUC0–t, and AUC0–∞ were 85.41% to 100.97%, 95.40% to 100.27%, and 95.48% to 100.30%, respectively. For the fed study, the 90% CIs for the test/reference GMRs of the ln-transformed data for Cmax, AUC0–t, and AUC0–∞ were 90.15% to 113.75%, 99.10% to 103.77% and 99.11% to 103.80%, respectively. A total of 8 of 47 subjects experienced AEs in the fasting and fed studies.ConclusionsIn the study, the generic (test) product of ciprofloxacin hydrochloride 250 mg was bioequivalent to the innovator (reference) product after a single oral dose administration under the fasting and fed conditions. Both two brands of ciprofloxacin tablets were safe and well tolerated.Trial registrationThe clinical trial was registered at Center for the Drug Evaluation of the National Medical Products Administration (registration number: CTR20171152; date of registration：September 25, 2017; http://www.chinadrugtrials.org.cn/clinicaltrials.searchlistdetail.dhtml).

scholarly journals Fosamprenavir plus Ritonavir Increases Plasma Ketoconazole and Ritonavir Exposure, while Amprenavir Exposure Remains Unchanged

2007 ◽  
Vol 51 (8) ◽  
pp. 2982-2984 ◽  
Author(s):  
Mary B. Wire ◽  
Charles H. Ballow ◽  
Julie Borland ◽  
Mark J. Shelton ◽  
Yu Lou ◽  
...  
Keyword(s):  
Steady State ◽  
Healthy Subjects ◽  
Open Label ◽  
Time Curve ◽  
Once Daily ◽  
Open Label Study ◽  
Label Study ◽  
Concentration Time

ABSTRACT Plasma ketoconazole (KETO), amprenavir (APV), and ritonavir (RTV) pharmacokinetics were evaluated in 15 healthy subjects after being treated with KETO at 200 mg once daily (QD), fosamprenavir (FPV)/RTV at 700/100 mg twice daily (BID), and then KETO at 200 mg QD plus FPV/RTV at 700/100 mg BID in this open-label study. The KETO area under the concentration-time curve at steady state was increased 2.69-fold with FPV/RTV. APV exposure was unchanged, and RTV exposure was slightly increased.

Exposure to Retinoic Acids in Non-Pregnant Women Following High Vitamin A Intake with a Liver Meal

2005 ◽  
Vol 75 (3) ◽  
pp. 187-194 ◽  
Author(s):  
Hartmann ◽  
Brørs ◽  
Bock ◽  
Blomhoff ◽  
Bausch ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Vitamin A ◽  
Safety Concern ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Pregnant Female ◽  
Time Curve ◽  
High Vitamin ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

Animal liver is a rich source of vitamin A. Due to retinoic acid (RA) metabolites, vitamin A has a teratogenic potential and women are generally advised to avoid or to limit the consumption of liver during pregnancy. In a recent study in non-pregnant female volunteers following single and repeated doses of up to 30,000 IU/day of vitamin A as a supplement, the plasma concentration time curve of all-trans RA acid showed a diurnal-like profile. But, the overall exposure (AUC24h) remained essentially unaltered whereas AUC24h increased linearly with dose for 13-cis and 13-cis-4-oxo RA. The current study in non-pregnant female volunteers showed that a single high vitamin A intake with a liver meal (up to 120,000 IU) exhibited a similar diurnal-like plasma concentration time curve for all-trans RA and its overall exposure remained also unaltered, despite a temporary two-fold increase in peak plasma concentration. Concentrations of 13-cis and 13-cis-4-oxo RA increased several-fold after a liver meal, and exposure (AUC24h) increased three- to five-fold. Pooling our results with data in the literature revealed a linear relation between the mean AUC24h of 13-cis and 13-cis-4-oxo RA and vitamin A intake with liver. Metabolism to all-trans RA of vitamin A with liver seems not to be of safety concern. However, the observed increase of plasma concentrations and the dose-dependent increase in exposure to 13-cis and 13-cis-4-oxo RA support the current safety recommendations on vitamin A intake and suggest that women should be cautious regarding their consumption of liver-containing meals during pregnancy.

scholarly journals Lack of Effect of Zafirlukast on the Pharmacokinetics of Azithromycin, Clarithromycin, and 14-Hydroxyclarithromycin in Healthy Volunteers

1999 ◽  
Vol 43 (5) ◽  
pp. 1152-1155 ◽  
Author(s):  
Kevin W. Garey ◽  
Charles A. Peloquin ◽  
Paul G. Godo ◽  
Anne N. Nafziger ◽  
Guy W. Amsden
Keyword(s):  
Steady State ◽  
Healthy Subjects ◽  
High Performance ◽  
Pharmacokinetic Parameters ◽  
Steady State Concentration ◽  
Open Label ◽  
Time Curve ◽  
Data Analyses ◽  
Concentration Time ◽  
State Concentration

ABSTRACT This randomized, open-label, crossover study was conducted to investigate whether the coadministration of zafirlukast would affect the pharmacokinetics of azithromycin, clarithromycin, or 14-hydroxyclarithromycin (14-OHC). Twelve healthy subjects (six males and six females) received single 500-mg doses of azithromycin and clarithromycin with and without zafirlukast given to a steady-state concentration. Blood was collected prior to all macrolide doses and for 3 and 10 days after each clarithromycin and azithromycin dose, respectively. Serum was assayed for azithromycin, clarithromycin, and 14-OHC concentrations by validated high-performance liquid chromatography assay systems. Data analyses were done by noncompartmental and nonparametric methods. Analysis of the patients indicated that the addition of steady-state concentrations of zafirlukast did not significantly alter the pharmacokinetic parameters of or overall exposure (based on the area under the concentration-time curve) to azithromycin, clarithromycin, and 14-OHC. While zafirlukast is a known inhibitor of CYP3A4, it does not appear to exert a clinically or statistically significant pharmacokinetic effect on azithromycin, clarithromycin, or 14-OHC.

Pharmacokinetics of an immunomodulating dose of levamisole in weaned pigs

2013 ◽  
Vol 61 (3) ◽  
pp. 376-382
Author(s):  
Jelena Šuran ◽  
Dubravka Flajs ◽  
Maja Peraica ◽  
Andreja Prevendar Crnić ◽  
Marcela Šperanda ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Area Under The Curve ◽  
Maximum Plasma ◽  
Weaned Pigs ◽  
Time Curve ◽  
Treatment Groups ◽  
Parallel Design ◽  
Concentration Time ◽  
Plasma Concentration Time Curve ◽  
Crossbred Pigs

Levamisole has been shown to stimulate the immune response in immunocompromised humans and animals. However, its use as an adjuvant in immunocompromised weaned pigs prone to colibacillosis has only been experimentally tested but not yet officially approved. Therefore, the aim of these studies was to study the pharmacokinetics (PK) of an immunomodulating dose of levamisole in weaned pigs. For that purpose, 20 weaned crossbred pigs were divided into two treatment groups. In this parallel-design study, a single dose of levamisole (2.5 mg/kg body weight) was administered by the intramuscular (i.m.) or oral (p.o.) route. Statistically significant differences between the i.m. and p.o. routes in terminal beta rate constant (β), maximum plasma concentration (Cmax), area under the curve (AUC) for plasma concentration-time curve from time zero to infinity (AUC0-inf), area under the plasma concentration-time curve from time 0 to the last quantifiable time point (AUC0-t) were determined. Further research is needed to establish a relationship between the PK and the immunomodulating effect of levamisole in pigs.

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