scholarly journals Pharmacokinetics of the Antiviral Agent β-d-2′,3′-Didehydro-2′,3′-Dideoxy-5-Fluorocytidine in Rhesus Monkeys

1999 ◽  
Vol 43 (2) ◽  
pp. 381-384 ◽  
Author(s):  
Li Ma ◽  
Selwyn J. Hurwitz ◽  
Junxing Shi ◽  
Jeffrey J. McAtee ◽  
Dennis C. Liotta ◽  
...  
Keyword(s):  
Intravenous Administration ◽  
Rhesus Monkeys ◽  
Antiviral Agent ◽  
Compartment Model ◽  
Pharmacokinetic Parameters ◽  
Administration Route ◽  
Two Compartment Model ◽  
Immunodeficiency Virus ◽  
Median Effective Concentration

ABSTRACT The values of the pharmacokinetic parameters of the nucleoside antiretroviral agent β-d-2′,3′-didehydro-2′,3′-dideoxy-5-fluorocytidine (D-D4FC) in rhesus monkeys were determined with a two-compartment model after the administration of a single dose. The average values for the terminal half-life, renal clearance, and total systemic clearance for the intravenous administration route were 3.6 h and 0.31 and 0.43 liter · kg−1 · h−1, respectively. The oral bioavailability of D-D4FC averaged 41%. For the intravenous administration route, 76% of the compound was recovered intact in the urine within 8 h, indicating that D-D4FC was eliminated mainly by renal excretion. D-D4FC was detected in the cerebrospinal fluid (CSF) at similar concentrations after administration by both the intravenous and oral routes. D-D4FC levels in plasma and CSF were higher than the median effective concentration for human immunodeficiency virus type 1 in vitro.

scholarly journals Pharmacology and Pharmacokinetics of the Antiviral Agent β-d-2′,3′-Dideoxy-3′-Oxa-5-Fluorocytidine in Cells and Rhesus Monkeys

2005 ◽  
Vol 49 (7) ◽  
pp. 2589-2597 ◽  
Author(s):  
Brenda I. Hernandez-Santiago ◽  
Huachun Chen ◽  
Ghazia Asif ◽  
Thierry Beltran ◽  
Shuli Mao ◽  
...  
Keyword(s):  
Rhesus Monkeys ◽  
Human Peripheral Blood ◽  
Antiviral Agent ◽  
Pharmacokinetic Studies ◽  
Peripheral Blood Mononuclear ◽  
Cell Extracts ◽  
Human T Cell ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT β-d-2′,3′-Dideoxy-3′-oxa-5-fluorocytidine (d-FDOC) is an effective inhibitor of human immunodeficiency virus 1 (HIV-1) and HIV-2, simian immunodeficiency virus, and hepatitis B virus (HBV) in vitro. The purpose of this study was to evaluate the intracellular metabolism of d-FDOC in human hepatoma (HepG2), human T-cell lymphoma (CEM), and primary human peripheral blood mononuclear (PBM) cells by using tritiated compound. By 24 h, the levels of d-FDOC-triphosphate (d-FDOC-TP) were 2.8 ± 0.4, 6.7 ± 2.3, and 2.0 ± 0.1 pmol/106 cells in HepG2, CEM, and primary human PBM cells, respectively. Intracellular d-FDOC-TP concentrations remained greater than the 50% inhibitory concentration for HIV-1 reverse transcriptase for up to 24 h after removal of the drug from cell cultures. In addition to d-FDOC-monophosphate (d-FDOC-MP), -diphosphate (d-FDOC-DP), and -TP, d-FDOC-DP-ethanolamine and d-FDOC-DP-choline were detected in all cell extracts as major intracellular metabolites. d-FDOC was not a substrate for Escherichia coli thymidine phosphorylase. No toxicity was observed in mice given d-FDOC intraperitoneally for 6 days up to a dose of 100 mg/kg per day. Pharmacokinetic studies in rhesus monkeys indicated that d-FDOC has a t 1/2 of 2.1 h in plasma and an oral bioavailability of 38%. The nucleoside was excreted unchanged primary in the urine, and no metabolites were detected in plasma or urine. These results suggest that further safety and pharmacological studies are warranted to assess the potential of this nucleoside for the treatment of HIV- and HBV-infected individuals.

scholarly journals Pharmacokinetics of the Anti-Human Immunodeficiency Virus Agent 1-(β-d-Dioxolane)Thymine in Rhesus Monkeys

2007 ◽  
Vol 51 (7) ◽  
pp. 2424-2429 ◽  
Author(s):  
Ghazia Asif ◽  
Selwyn J. Hurwitz ◽  
Aleksandr Obikhod ◽  
David Delinsky ◽  
Janarthanan Narayanasamy ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Rhesus Monkeys ◽  
Pharmacokinetic Profile ◽  
Preclinical Development ◽  
Immunodeficiency Virus ◽  
Oral Pharmacokinetics ◽  
Average Serum ◽  
Median Effective Concentration ◽  
Further Development

ABSTRACT β-d-Dioxolane-thymine (D-DOT) has potent and selective in vitro activity against several clinically important resistant human immunodeficiency virus (HIV) mutants and is in advanced preclinical development. Therefore, the single-dose intravenous and oral pharmacokinetics of D-DOT were studied with three rhesus monkeys. The pharmacokinetic profiles of D-DOT in serum and urine were adequately described by a two-compartment open pharmacokinetic model. D-DOT was rapidly and almost completely absorbed (absorption rate constant = 2.7 h−1; fraction of oral dose absorbed = 0.82 to 1.06). The average serum beta half-life was 2.16 h. The average central and steady-state volumes of distributions were 0.52 and 1.02 liter/kg of body weight, respectively, and the average systemic and renal clearance values were 0.36 liter/h/kg and 0.18 liter/h/kg. Four or eight percent of administered D-DOT was eliminated in the urine as glucuronide within 8 h after intravenous or oral administration, respectively. D-DOT reached levels in the cerebrospinal fluid in excess of 10 to 20 times the median effective concentration for wild-type HIV and resistant mutants. The potent antiretroviral activity of D-DOT against a lamivudine- and zidovudine-resistant HIV-1 mutant, together with an excellent pharmacokinetic profile for rhesus monkeys, suggest that further development is warranted.

Perifusion Model for Detoxification of Drugs in a Bioartificial Liver

2003 ◽  
Vol 26 (5) ◽  
pp. 383-394 ◽  
Author(s):  
Y.G. Park ◽  
Y.-S. Son ◽  
H.-W. Ryu
Keyword(s):  
Compartment Model ◽  
Drug Clearance ◽  
Bioartificial Liver ◽  
Pharmacokinetic Parameters ◽  
Quasi Equilibrium ◽  
Elimination Kinetics ◽  
Two Compartment Model ◽  
Quantitative Understanding ◽  
Concentration Behavior

Detoxification of a drug in a bioartificial liver (BAL) during an in vitro experiment was theoretically carried out based on a perifusion model. The detoxification capacity assay, the rates of disappearance of the chemicals such as flow-limited and enzyme-limited drugs in the BAL system could be defined from models of hepatic perfusion-elimination relationships. When the flow-limited drug administrated under a quasi-equilibrium condition, a two-compartment model for the concentration behavior of the drug was introduced and compared with a one-compartment model. For both models, equations involving hepatic drug clearance and various pharmacokinetic parameters were derived under initial bolus loading and constant-rate infusion plus bolus loading conditions. The concentration of enzyme-limited drug in the BAL decreased linearly with time in contrast with the concentration profile of the flow-limited drug followed by exponential functions. The perifusion model offers a quantitative understanding of the elimination kinetics of chemicals such as flow-limited and enzyme-limited drugs in a bioartificial liver and a comparison between the BAL and human liver.

scholarly journals Serum bactericidal activities and comparative pharmacokinetics of meropenem and imipenem-cilastatin.

1996 ◽  
Vol 40 (1) ◽  
pp. 105-109 ◽  
Author(s):  
M Dreetz ◽  
J Hamacher ◽  
J Eller ◽  
K Borner ◽  
P Koeppe ◽  
...  
Keyword(s):  
Compartment Model ◽  
Pharmacokinetic Parameters ◽  
Time Curve ◽  
Dose Administration ◽  
Microdilution Method ◽  
Two Compartment Model ◽  
Elimination Half ◽  
Renal Clearances ◽  
The Mean ◽  
Bactericidal Activities

The pharmacokinetics and serum bactericidal activities (SBAs) of imipenem and meropenem were investigated in a randomized crossover study. Twelve healthy male volunteers received a constant 30-min infusion of either 1 g of imipenem plus 1 g of cilastatin or 1 g of meropenem. The concentrations of the drugs in serum and urine were determined by bioassay and high-pressure liquid chromatography. Pharmacokinetic parameters were based on an open two-compartment model and a noncompartmental technique. At the end of infusion, the mean concentrations of imipenem and meropenem measured in serum were 61.2 +/- 9.8 and 51.6 +/- 6.5 mg/liter, respectively; urinary recoveries were 48.6% +/- 8.2% and 60.0% +/- 6.5% of the dose in 12 h, respectively; and the areas under the concentration-time curve from time zero to infinity were 96.1 +/- 14.4 and 70.5 +/- 10.3 mg.h/liter, respectively (P < or = 0.02). Imipenem had a mean half-life of 66.7 +/- 10.4 min; that of meropenem was 64.4 +/- 6.9 min. The volumes of distribution at steady state of imipenem and meropenem were 15.3 +/- 3.3 and 18.6 +/- 3.0 liters/70 kg, respectively, and the mean renal clearances per 1.73 m2 were 85.6 +/- 17.6 and 144.6 +/- 26.0 ml/min, respectively. Both antibiotics were well tolerated in this single-dose administration study. The SBAs were measured by the microdilution method of Reller and Stratton (L. B. Reller and C. W. Stratton, J. Infect. Dis. 136:196-204, 1977) against 40 clinically isolated strains. Mean reciprocal bactericidal titers were measured 1 and 6 h after administration. After 1 and 6 h the median SBAs for imipenem and meropenem, were 409 and 34.9 and 97.9 and 5.8, respectively, against Staphylococcus aureus, 19.9 and 4.4 and 19.4 and 4.8, respectively, against Pseudomonas aeruginosa, 34.3 and 2.2 and 232 and 15.5, respectively, against Enterobacter cloacae, and 13.4 and 2.25 and 90.7 and 7.9, respectively, against Proteus mirabilis. Both drugs had rather short biological elimination half-lives and a predominantly renal route of elimination. Both carbapenems revealed high SBAs against clinically important pathogens at 1 h; meropenem had a higher SBA against E. cloacae and P. mirabilis, and the SBA of imipenem against S. aureus was greater than the SBA of meropenem.

scholarly journals Pharmacokinetics of lamivudine in human immunodeficiency virus-infected patients with renal dysfunction.

1996 ◽  
Vol 40 (6) ◽  
pp. 1514-1519 ◽  
Author(s):  
A E Heald ◽  
P H Hsyu ◽  
G J Yuen ◽  
P Robinson ◽  
P Mydlow ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Renal Function ◽  
Renal Impairment ◽  
Normal Renal Function ◽  
Severe Renal Impairment ◽  
Moderate Renal Impairment ◽  
Pharmacokinetic Parameters ◽  
Geometric Means ◽  
Immunodeficiency Virus

The purpose of this study was to determine the safety and pharmacokinetics of lamivudine (3TC), a nucleoside analog that has shown potent in vitro and recent in vivo activity against human immunodeficiency virus. Sixteen human immunodeficiency virus-infected patients, six with normal renal function (creatinine clearance [CLCR], > or = 60 ml/min), four with moderate renal impairment (CLCR, 10 to 40 ml/min), and six with severe renal impairment (CLCR, < 10 ml/min), were enrolled in the study. After an overnight fast, patients were administered 300 mg of 3TC orally. Blood was obtained before 3TC administration and 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 16, 24, 32, 40, and 48 h afterward. Timed urine collections were performed for patients able to produce urine. Serum and urine were assayed for 3TC by reverse-phase high-performance liquid chromatography with UV detection. Pharmacokinetic parameters were calculated by using standard noncompartmental techniques. The peak concentration of 3TC increased with decreasing renal function; geometric means were 2,524, 3,538, and 5,684 ng/ml for patients with normal renal function, moderate renal impairment, and severe renal impairment, respectively. The terminal half-life also increased with decreasing renal function; geometric means were 11.5, 14.1, and 20.7 h for patients with normal renal function, moderate renal impairment, and severe renal impairment, respectively. Both oral and renal clearances were linearly correlated with CLCR. A 300-mg dose of 3TC was well tolerated by all three patient groups. The pharmacokinetics of 3TC is profoundly affected by impaired renal function. Dosage adjustment, by either dose reduction or lengthening of the dosing interval, is warranted.

scholarly journals Gag-Specific Cellular Immunity DeterminesIn VitroViral Inhibition andIn VivoVirologic Control following Simian Immunodeficiency Virus Challenges of Vaccinated Rhesus Monkeys

2012 ◽  
Vol 86 (18) ◽  
pp. 9583-9589 ◽  
Author(s):  
Kathryn E. Stephenson ◽  
Hualin Li ◽  
Bruce D. Walker ◽  
Nelson L. Michael ◽  
Dan H. Barouch
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Rhesus Monkeys ◽  
Viral Inhibition ◽  
Viral Loads ◽  
Immunodeficiency Virus ◽  
Virologic Control ◽  
Cellular Immune ◽  
Hiv 1

A comprehensive vaccine for human immunodeficiency virus type 1 (HIV-1) would block HIV-1 acquisition as well as durably control viral replication in breakthrough infections. Recent studies have demonstrated that Env is required for a vaccine to protect against acquisition of simian immunodeficiency virus (SIV) in vaccinated rhesus monkeys, but the antigen requirements for virologic control remain unclear. Here, we investigate whether CD8+T lymphocytes from vaccinated rhesus monkeys mediate viral inhibitionin vitroand whether these responses predict virologic control following SIV challenge. We observed that CD8+lymphocytes from 23 vaccinated rhesus monkeys inhibited replication of SIVin vitro. Moreover, the magnitude of inhibition prior to challenge was inversely correlated with set point SIV plasma viral loads after challenge. In addition, CD8 cell-mediated viral inhibition in vaccinated rhesus monkeys correlated significantly with Gag-specific, but not Pol- or Env-specific, CD4+and CD8+T lymphocyte responses. These findings demonstrate thatin vitroviral inhibition following vaccination largely reflects Gag-specific cellular immune responses and correlates within vivovirologic control following infection. These data suggest the importance of including Gag in an HIV-1 vaccine in which virologic control is desired.

scholarly journals Immunogenicity of Recombinant Fiber-Chimeric Adenovirus Serotype 35 Vector-Based Vaccines in Mice and Rhesus Monkeys

2005 ◽  
Vol 79 (22) ◽  
pp. 14161-14168 ◽  
Author(s):  
Anjali Nanda ◽  
Diana M. Lynch ◽  
Jaap Goudsmit ◽  
Angelique A. C. Lemckert ◽  
Bonnie A. Ewald ◽  
...  
Keyword(s):  
Rhesus Monkeys ◽  
In Vivo Studies ◽  
Preclinical Studies ◽  
Adenovirus Serotype ◽  
Immunodeficiency Virus ◽  
Serotype 5 ◽  
Fiber Proteins ◽  
Hiv 1

ABSTRACT Preexisting immunity to adenovirus serotype 5 (Ad5) has been shown to suppress the immunogenicity of recombinant Ad5 (rAd5) vector-based vaccines for human immunodeficiency virus type 1 (HIV-1) in both preclinical studies and clinical trials. A potential solution to this problem is to utilize rAd vectors derived from rare Ad serotypes, such as Ad35. However, rAd35 vectors have appeared less immunogenic than rAd5 vectors in preclinical studies to date. In this study, we explore the hypothesis that the differences in immunogenicity between rAd5 and rAd35 vectors may be due in part to differences between the fiber proteins of these viruses. We constructed capsid chimeric rAd35 vectors containing the Ad5 fiber knob (rAd35k5) and compared the immunogenicities of rAd5, rAd35k5, and rAd35 vectors expressing simian immunodeficiency virus Gag and HIV-1 Env in mice and rhesus monkeys. In vitro studies demonstrated that rAd35k5 vectors utilized the Ad5 receptor CAR rather than the Ad35 receptor CD46. In vivo studies showed that rAd35k5 vectors were more immunogenic than rAd35 vectors in both mice and rhesus monkeys. These data suggest that the Ad5 fiber knob contributes substantially to the immunogenicity of rAd vectors. Moreover, these studies demonstrate that capsid chimeric rAd vectors can be constructed to combine beneficial immunologic and serologic properties of different Ad serotypes.

Zalcitabine Population Pharmacokinetics: Application of Radioimmunoassay

1998 ◽  
Vol 42 (2) ◽  
pp. 409-413 ◽  
Author(s):  
John M. Adams ◽  
Mark J. Shelton ◽  
Ross G. Hewitt ◽  
Mary DeRemer ◽  
Robin DiFrancesco ◽  
...  
Keyword(s):  
Population Pharmacokinetics ◽  
Information Age ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Pharmacokinetic Studies ◽  
Oral Clearance ◽  
Standard Curve ◽  
Immunodeficiency Virus ◽  
Traditional Approaches

ABSTRACT Zalcitabine population pharmacokinetics were evaluated in 44 human immunodeficiency virus-infected patients (39 males and 5 females) in our immunodeficiency clinic. Eighty-one blood samples were collected during routine clinic visits for the measurement of plasma zalcitabine concentrations by radioimmunoassay (1.84 ± 1.24 samples/patient; range, 1 to 6 samples/patient). These data, along with dosing information, age (38.6 ± 7.13 years), sex, weight (79.1 ± 15.0 kg), and estimated creatinine clearance (89.1 ± 21.5 ml/min), were entered into NONMEM to obtain population estimates for zalcitabine pharmacokinetic parameters (4). The standard curve of the radioimmunoassay ranged from 0.5 to 50.0 ng/ml. The observed concentrations of zalcitabine in plasma ranged from 2.01 to 8.57 ng/ml following the administration of doses of either 0.375 or 0.75 mg. A one-compartment model best fit the data. The addition of patient covariates did not improve the basic fit of the model to the data. Oral clearance was determined to be 14.8 liters/h (0.19 liter/h/kg; coefficient of variation [CV] = 23.8%), while the volume of distribution was estimated to be 87.6 liters (1.18 liters/kg; CV = 54.0%). We were also able to obtain individual estimates of oral clearance (range, 8.05 to 19.8 liters/h; 0.11 to 0.30 liter/h/kg) and volume of distribution (range, 49.2 to 161 liters; 0.43 to 1.92 liters/kg) of zalcitabine in these patients with the POSTHOC option in NONMEM. Our value for oral clearance agrees well with other estimates of oral clearance from traditional pharmacokinetic studies of zalcitabine and suggests that population methods may be a reasonable alternative to these traditional approaches for obtaining information on the disposition of zalcitabine.

Pharmacokinetic Model-driven Infusion of Fentanyl in Children

1996 ◽  
Vol 85 (6) ◽  
pp. 1268-1275. ◽  
Author(s):  
Brian Ginsberg ◽  
Scott Howell ◽  
Peter S. A. Glass ◽  
Judith O. Margolis ◽  
Allison K. Ross ◽  
...  
Keyword(s):  
Continuous Infusion ◽  
Pediatric Population ◽  
Compartment Model ◽  
Pharmacokinetic Parameters ◽  
Context Sensitive ◽  
Model Driven ◽  
Two Compartment Model ◽  
Performance Error ◽  
Adults And Children ◽  
Residual Performance

Background This study determined the accuracy of previously defined adult fentanyl pharmacokinetics in children having surgery; from this population, the pharmacokinetics of fentanyl were characterized in children when administered via a computerized assisted continuous-infusion device. Methods Twenty children between the ages of 2.7 and 11 y scheduled to undergo elective noncardiac surgery were studied. After induction, anesthesia was maintained with 60% nitrous oxide in oxygen supplemented with fentanyl (n = 10) or fentanyl plus isoflurane (n = 10). Fentanyl was administered via computerized assisted continuous-infusion to target concentrations determined by clinical requirements. Plasma fentanyl concentrations were measured and used to evaluate the performance of the fentanyl pharmacokinetics and then to determine a new set of pharmacokinetic parameters and the variance in the context-sensitive half-times simulated for these patients. Results The original adult fentanyl pharmacokinetics resulted in a positive bias (10.4%), indicating that measured concentrations were mostly greater than predicted. A two-compartment model with age and weight as covariates provided the optimal pharmacokinetic parameters. These resulted in a residual performance error of -1.1% and a median absolute performance error of 17.4%. The context-sensitive times determined from this pediatric population were considerably shorter than the context-sensitive times previously published for adults. Conclusions The pharmacokinetics of fentanyl administered by computerized assisted continuous-infusion differ between adults and children. The newly derived parameters are probably more suitable to determine infusion schemes of up to 4 h in children between the ages of 2 and 11 y.

scholarly journals Pharmacokinetics of (-)-beta-D-2-aminopurine dioxolane and (-)-beta-D-2-amino-6-chloropurine dioxolane and their antiviral metabolite (-)-beta-D-dioxolane guanine in rhesus monkeys.

1996 ◽  
Vol 40 (10) ◽  
pp. 2332-2336 ◽  
Author(s):  
H Chen ◽  
F D Boudinot ◽  
C K Chu ◽  
H M Mcclure ◽  
R F Schinazi
Keyword(s):  
Rhesus Monkeys ◽  
Serum Concentrations ◽  
Time Curve ◽  
Preclinical Pharmacokinetics ◽  
Concentration Time ◽  
B Virus ◽  
Immunodeficiency Virus ◽  
Antiviral Nucleoside ◽  
Similar Peak

(-)-beta-D-2-Aminopurine dioxolane (APD) and (-)-beta-D-2-amino-6-chloropurine dioxolane (ACPD) are recently synthesized dioxolanylpurine nucleoside derivatives being developed as potential prodrugs for the antiviral nucleoside analog (-)-beta-D-dioxolane guanine (DXG). In vitro, APD and ACPD are converted to DXG by xanthine oxidase and adenosine deaminase, respectively. The purpose of this study was to evaluate the preclinical pharmacokinetics of APD and ACPD and their potential for generating sustained levels of the parent nucleoside, DXG, in rhesus monkeys following oral administration. Both nucleoside derivatives were rapidly absorbed, with similar peak concentrations achieved within 1 h after administration. However, concentrations of APD were more markedly sustained than those of ACPD. Both prodrugs yielded DXG, but significantly higher serum concentrations of DXG and area under the concentration-time curve values were observed following administration of APD. In addition, APD produced higher concentrations of prodrug and DXG in cerebrospinal fluid than did ACPD. Thus, the results of this pharmacokinetic study suggest that APD is likely to serve as a better prodrug of DXG and should be considered for clinical trials for antiviral therapy against human immunodeficiency virus and hepatitis B virus.

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