scholarly journals Development of a Population Pharmacokinetic Model To Describe Azithromycin Whole-Blood and Plasma Concentrations over Time in Healthy Subjects

2013 ◽  
Vol 57 (7) ◽  
pp. 3194-3201 ◽  
Author(s):  
T. Pene Dumitrescu ◽  
T. Anic-Milic ◽  
K. Oreskovic ◽  
J. Padovan ◽  
K. L. R. Brouwer ◽  
...  
Keyword(s):  
Whole Blood ◽  
Healthy Subjects ◽  
Mononuclear Cells ◽  
Plasma Concentrations ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Population Pharmacokinetic ◽  
Polymorphonuclear Cells ◽  
Peripheral Blood Mononuclear

ABSTRACTAzithromycin (AZI), a broad-spectrum antibiotic, accumulates in polymorphonuclear cells and peripheral blood mononuclear cells. The distribution of AZI in proinflammatory cells may be important to the anti-inflammatory properties. Previous studies have described plasma AZI pharmacokinetics. The objective of this study was to describe the pharmacokinetics of AZI in whole blood (concentration in whole blood [Cb]) and plasma (concentration in plasma [Cp]) of healthy subjects. In this study, 12 subjects received AZI (500 mg once a day for 3 days). AZICbandCpwere quantified in serial samples collected up to 3 weeks after the last dose and analyzed using noncompartmental and compartmental methods. After the last dose,Cbwas greater thanCp. Importantly,Cb, but notCp, was quantifiable in all but one subject at 3 weeks. The blood area under the curve during a 24-h dosing interval (AUC24) was ∼2-fold greater than the plasma AUC24, but simulations suggested thatCbwas not at steady state by day 3. Upon exploration of numerous models, an empirical 3-compartment model adequately describedCpandCb, butCpwas somewhat underestimated. Intercompartmental clearance (CL; likely representing cells) was lower than apparent oral CL (18 versus 118 liters/h). Plasma, peripheral, and cell compartmental volumes were 439 liters, 2,980 liters, and 3,084 liters, respectively. Interindividual variability in CL was low (26.2%), while the volume of distribution variability was high (107%). This is the first report to describe AZICbin healthy subjects, the distribution parameters betweenCpandCb, and AZI retention in blood for up to 3 weeks following 3 daily doses. The model can be used to predictCbfromCpfor AZI under various dosing regimens. (This study has been registered at ClinicalTrials.gov under registration no. NCT01026064.)

scholarly journals Population Pharmacokinetic Modeling of Plasma and Intracellular Ribavirin Concentrations in Patients with Chronic Hepatitis C Virus Infection

2015 ◽  
Vol 59 (4) ◽  
pp. 2179-2188 ◽  
Author(s):  
Liviawati S. Wu ◽  
Joseph E. Rower ◽  
James R. Burton ◽  
Peter L. Anderson ◽  
Kyle P. Hammond ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mononuclear Cells ◽  
Formation Rate ◽  
Plasma Concentrations ◽  
Compartment Model ◽  
Population Pharmacokinetic ◽  
Peripheral Blood Mononuclear ◽  
First Order

ABSTRACTRibavirin, a guanosine analog, is a broad-spectrum antiviral agent. Ribavirin has been a fundamental component of the treatment of hepatitis C virus (HCV) infection for decades, but there is a very limited understanding of the clinical pharmacology of this drug. Furthermore, it is associated with a major dose-limiting toxicity, hemolytic anemia. Ribavirin undergoes intracellular phosphorylation by host enzymes to ribavirin monophosphate (RMP), ribavirin diphosphate (RDP), and ribavirin triphosphate (RTP). The intracellular forms have been associated with antiviral and toxic effectsin vitro, but the kinetics of these phosphorylated moieties have not been fully elucidatedin vivo. We developed a model to characterize the plasma pharmacokinetics of ribavirin and the difference between intracellular phosphorylation kinetics in red cells (nonnucleated) and in peripheral blood mononuclear cells (nucleated). A time-independent two-compartment model with first-order absorption described the plasma data well. The cellular phosphorylation kinetics was described by a one-compartment model for RMP, with the formation rate driven by plasma concentrations and the first-order degradation rate. RDP and RTP rapidly reached equilibrium with RMP. Concomitant telaprevir use, inosine triphosphatase genetics, creatinine clearance, weight, and sex were significant covariates. The terminal ribavirin half-life in plasma and phosphorylated anabolites in cells was approximately 224 h. We found no evidence of time-dependent kinetics. These data provide a foundation for uncovering concentration-effect associations for ribavirin and determining the optimal dose and duration of this drug for use in combination with newer direct-acting HCV agents. (This study has been registered at ClinicalTrials.gov under registration no. NCT01097395.)

scholarly journals Pharmacokinetics of Ceftaroline in Normal Body Weight and Obese (Classes I, II, and III) Healthy Adult Subjects

2015 ◽  
Vol 59 (7) ◽  
pp. 3956-3965 ◽  
Author(s):  
Julie Ann Justo ◽  
Stockton M. Mayer ◽  
Manjunath P. Pai ◽  
Melinda M. Soriano ◽  
Larry H. Danziger ◽  
...  
Keyword(s):  
Body Weight ◽  
Healthy Adult ◽  
Plasma Concentrations ◽  
Area Under The Curve ◽  
Total Body Weight ◽  
Pharmacokinetic Profile ◽  
Volume Of Distribution ◽  
Population Pharmacokinetic ◽  
Ceftaroline Fosamil ◽  
Plasma And Urine Samples

ABSTRACTThe pharmacokinetic profile of ceftaroline has not been well characterized in obese adults. The purpose of this study was to evaluate the pharmacokinetics of ceftaroline in 32 healthy adult volunteers aged 18 to 50 years in the normal, overweight, and obese body size ranges. Subjects were evenly assigned to 1 of 4 groups based on their body mass index (BMI) and total body weight (TBW) (ranges, 22.1 to 63.5 kg/m2and 50.1 to 179.5 kg, respectively). Subjects in the lower-TBW groups were matched by age, sex, race/ethnicity, and serum creatinine to the upper-BMI groups. Serial plasma and urine samples were collected over 12 h after the start of the infusion, and the concentrations of ceftaroline fosamil (prodrug), ceftaroline, and ceftaroline M-1 (inactive metabolite) were assayed. Noncompartmental and population pharmacokinetic analyses were used to evaluate the data. The mean plasma ceftaroline maximum concentration and area under the curve were ca. 30% lower in subjects with a BMI of ≥40 kg/m2compared to those <30 kg/m2. A five-compartment pharmacokinetic model with zero-order infusion and first-order elimination optimally described the plasma concentration-time profiles of the prodrug and ceftaroline. Estimated creatinine clearance (eCLCR) and TBW best explained ceftaroline clearance and volume of distribution, respectively. Although lower ceftaroline plasma concentrations were observed in obese subjects, Monte Carlo simulations suggest the probability of target attainment is ≥90% when the MIC is ≤1 μg/ml irrespective of TBW or eCLCR. No dosage adjustment for ceftaroline appears to be necessary based on TBW alone in adults with comparable eCLCR. Confirmation of these findings in infected obese patients is necessary to validate these findings in healthy volunteers. (This study has been registered at ClinicalTrials.gov under registration no. NCT01648127.)

Pharmacokinetics and metabolism of 4'-iodo-4'-deoxy-doxorubicin in humans.

1992 ◽  
Vol 10 (7) ◽  
pp. 1183-1190 ◽  
Author(s):  
J Robert ◽  
J P Armand ◽  
S Huet ◽  
M Klink-Alakl ◽  
G Recondo ◽  
...  
Keyword(s):  
Blood Cell ◽  
High Performance ◽  
Parent Compound ◽  
Plasma Concentrations ◽  
Area Under The Curve ◽  
Parent Drug ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Hematologic Toxicity ◽  
Cell Counts

PURPOSE 4'-iodo-4'-deoxydoxorubicin is a new anthracycline that currently is under clinical evaluation. To improve the management of future trials, we have determined its pharmacokinetics and metabolism during a phase I/II study and have tried to relate the parameters obtained to the hematologic toxicity of the drug in terms of the survival of blood cells. PATIENTS AND METHODS The pharmacologic study included 19 patients who were entered at dose levels that ranged between 6 and 90 mg/m2; nine patients were treated at 80 mg/m2, which is close to the maximum recommended dose level. Blood sampling was performed from the end of the bolus infusion to 48 hours after treatment. Drug and metabolites were extracted and analyzed by high-performance liquid chromatography (HPLC), and the data were processed by nonlinear fitting to multicompartment models. RESULTS Plasma concentrations were best fitted to a three-compartment model with half-lives of 5.2 minutes, 0.79 hours, and 10.3 hours. The total body clearance and volume of distribution at steady state were high (350 L/h/m2 and 2,065 L/m2). The drug was metabolized extensively to a 13-dihydroderivative, 4'-iodo-4'-deoxy-doxorubicinol; the mean area under the curve (AUC) ratio metabolite/parent drug was the highest observed ever for an anthracycline (12.1 +/- 7.4); the metabolite was cleared from the plasma with an elimination half-life of 15.3 hours. The AUCs of the parent compound and its metabolite were related linearly to the dose administered, and showed no saturation phenomenon. Urinary excretion was studied in nine patients and showed a cumulative elimination of less than 6% of the dose administered, two thirds of which were eliminated in the first 12 hours after injection. Ninety-three percent to 100% of the elimination of fluorescent compounds occurred in the form of the metabolite. Drug concentration in five tumor samples showed a rapid uptake of the drug from plasma and a preferential uptake of the parent drug compared with the metabolite. Blood cell counts after 4'-iodo-4'-deoxydoxorubicin treatment showed significant correlations among the surviving fractions of both granulocytes and platelets and the AUCs of the parent drug and its metabolite; the most significant correlations were obtained for the granulocytes and the metabolite. Significant correlations between AUCs and blood-cell survivals were maintained, even if only the nine patients treated at the dose of 80 mg/m2 were taken into account for the computation. CONCLUSIONS Our results especially show that myelosuppression that is induced by 4'-iodo-4'-deoxydoxorubicin can be well predicted by the measure of the AUC of the drug and its metabolite. This could be used for the further development of the drug toward high-dosage schedules.

scholarly journals Relationship between plasma and intracellular concentrations of bedaquiline and its M2 metabolite in South African patients with rifampin-resistant TB

2021 ◽  
Author(s):  
Precious Ngwalero ◽  
James C.M. Brust ◽  
Stijn W. van Beek ◽  
Sean Wasserman ◽  
Gary Maartens ◽  
...  
Keyword(s):  
High Performance ◽  
Mononuclear Cells ◽  
Plasma Concentrations ◽  
Maximum Effect ◽  
Population Pharmacokinetic ◽  
Primary Metabolite ◽  
Peripheral Blood Mononuclear ◽  
Plasma Ratio ◽  
Intracellular Concentrations

Bedaquiline is recommended for the treatment of all patients with rifampin-resistant tuberculosis (RR-TB). Bedaquiline accumulates within cells, but its intracellular pharmacokinetics have not been characterized, which may have implications for dose optimization. We developed a novel assay using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure the intracellular concentrations of bedaquiline and its primary metabolite M2 in patients with RR-TB in South Africa. Twenty-one participants were enrolled and underwent sparse sampling of plasma and peripheral blood mononuclear cells (PBMCs) at months 1, 2 and 6 of treatment and at 3 and 6 months after bedaquiline treatment completion. Intensive sampling was performed at month 2. We used non-compartmental analysis to describe plasma and intracellular exposures and a population pharmacokinetic model to explore the relationship between plasma and intracellular pharmacokinetics and the effects of key covariates. Bedaquiline concentrations from month 1 to month 6 of treatment ranged from 94.7 – 2540 ng/mL in plasma and 16.2 – 5478 ng/mL in PBMCs and concentrations of M2 over the six-month treatment period ranged from 34.3 – 496 ng/mL in plasma and 109.2 – 16764 ng/mL in PBMCs. Plasma concentrations of bedaquiline were higher than M2, but intracellular concentrations of M2 were considerably higher than bedaquiline. In the pharmacokinetic modeling, we estimated a linear increase in the intracellular-plasma accumulation ratio for bedaquiline and M2, reaching maximum effect after 2 months of treatment. The typical intracellular-plasma ratio 1 and 2 months after start of treatment was 0.61 (95%CI: 0.42-0.92) and 1.10 (95%CI: 0.74-1.63) for bedaquiline and 12.4 (95%CI: 8.8-17.8) and 22.2 (95%CI: 15.6-32.3) for M2. The intracellular-plasma ratio for both bedaquiline and M2 was decreased by 54% (95%CI: 24-72%) in HIV-positive patients compared to HIV-negative patients. Bedaquiline and M2 were detectable in PBMCs 6 months after treatment discontinuation. M2 accumulated at higher concentrations intracellularly than bedaquiline, supporting in vitro evidence that M2 is the main inducer of phospholipidosis.

scholarly journals Population Pharmacokinetic Model Linking Plasma and Peripheral Blood Mononuclear Cell Concentrations of Efavirenz and Its Metabolite, 8-Hydroxy-Efavirenz, in HIV Patients

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Abiy Habtewold ◽  
Eleni Aklillu ◽  
Eyasu Makonnen ◽  
Getnet Yimer ◽  
Leif Bertilsson ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Compartment Model ◽  
Central Compartment ◽  
Peripheral Compartment ◽  
Population Pharmacokinetic ◽  
Concentration Data ◽  
Peripheral Blood Mononuclear ◽  
First Order ◽  
Two Compartment Model

ABSTRACT The objectives of this study were to characterize the population pharmacokinetics (PK) of efavirenz (EFV) and 8-hydroxy-efavirenz (8OHEFV) in plasma and peripheral blood mononuclear cells (PBMCs) and to explore covariates affecting the PK parameters. Fifty-one patients had steady-state 0-to-24-h concentrations of EFV and 8OHEFV in plasma with corresponding concentrations in PBMCs, while 261 patients had one or two sparse concentrations at 16 ± 1 h postdose at weeks 4 and/or 16. The pharmacogenetic markers CYP2B6*6, CYP3A5*3, CYP3A5*6, UGT2B7*2, ABCB1 (3435C→T, 3842A→G), OATP1B1*1B, and OATP1B1*5, the presence of a rifampin-based antituberculosis (anti-TB) regimen, baseline body weight and organ function values, and demographic factors were explored as covariates. EFV concentration data were well described by a two-compartment model with first-order absorption (Ka ) and absorption lag time (A lag) (Ka = 0.2 h−1; A lag = 0.83 h; central compartment clearance [CLc/F] for CYP2B6*1/*1 = 18 liters/h, for CYP2B6*1/*6 = 14 liters/h, and for CYP2B6*6/*6 = 8.6 liters/h) and PBMCs as a peripheral compartment. EFV transfer from plasma to PBMCs was first order (CLp/F = 32 liters/h), followed by capacity-limited return (V max = 4,400 ng/ml/h; Km = 710 ng/ml). Similarly, 8OHEFV displayed a first-order elimination and distribution to PBMCs, with a capacity-limited return to plasma. No covariate relationships resulted in a significant explanation of interindividual variability (IIV) on the estimated PK parameters of EFV and 8OHEFV, except for CYP2B6*6 genotypes, which were consistent with prior evidence. Both EFV and 8OHEFV accumulated to higher concentrations in PBMCs than in plasma and were well described by first-order input and Michaelis-Menten kinetics removal from PBMCs. CYP2B6*6 genotype polymorphisms were associated with decreased EFV and 8OHEFV clearance.

scholarly journals A Population Pharmacokinetic Approach to Describe Cephalexin Disposition in Adult and Aged Dogs

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Ana Paula Prados ◽  
Paula Schaiquevich ◽  
Verónica Kreil ◽  
Agustina Monfrinotti ◽  
Pamela Quaine ◽  
...  
Keyword(s):  
Plasma Concentrations ◽  
Elimination Rate ◽  
Compartment Model ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Population Pharmacokinetic ◽  
Pharmacokinetic Studies ◽  
Mixed Breed ◽  
Pharmacokinetic Approach

This study was conducted in order to characterize the pharmacokinetics of orally administered cephalexin to healthy adult and aged dogs, using a population pharmacokinetic approach. Two hundred and eighty-six cephalexin plasma concentrations obtained from previous pharmacokinetic studies were used. Sex, age, pharmaceutical formulation, and breed were evaluated as covariates. A one-compartment model with an absorption lag-time (Tlag) best described the data. The final model included age (adult; aged) on apparent volume of distribution (Vd/F), apparent elimination rate (ke/F), and Tlag; sex (female; male) on ke/F, and breed (Beagle; mixed-breed) on Vd/F. Addition of the covariates to the model explained 78% of the interindividal variability (IIV) in Vd/F, 36% in ke/F, and 24% in Tlag, respectively. Formulation did not affect the variability of any of the pharmacokinetic parameters. Tlag was longer, whereas Vd/F and ke/F were lower in aged compared to adult animals; in female aged dogs ke/F was lower than in male aged dogs; however, the differences were of low magnitude. Different disposition of cephalexin may be expected in aged dogs.

scholarly journals Expression Profiling of Transcriptome and Its Associated Disease Risk in Yang Deficiency Constitution of Healthy Subjects

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Ruoxi Yu ◽  
Yin Yang ◽  
Yuanyuan Han ◽  
Pengwei Hou ◽  
Yingshuai Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Healthy Subjects ◽  
Mononuclear Cells ◽  
Clinical Medicine ◽  
Disease Risk ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Molecular Evidence ◽  
Chinese Han ◽  
Peripheral Blood Mononuclear

Objectives. Differences among healthy subjects and associated disease risks are of substantial interest in clinical medicine. According to the theory of “constitution-disease correlation” in traditional Chinese medicine, we try to find out if there is any connection between intolerance of cold in Yang deficiency constitution and molecular evidence and if there is any gene expression basis in specific disorders. Methods. Peripheral blood mononuclear cells were collected from Chinese Han individuals with Yang deficiency constitution (n=20) and balanced constitution (n=8) (aged 18–28) and global gene expression profiles were determined between them using the Affymetrix HG-U133 Plus 2.0 array. Results. The results showed that when the fold change was ≥1.2 and q ≤ 0.05, 909 genes were upregulated in the Yang deficiency constitution, while 1189 genes were downregulated. According to our research differential genes found in Yang deficiency constitution were usually related to lower immunity, metabolic disorders, and cancer tendency. Conclusion. Gene expression disturbance exists in Yang deficiency constitution, which corresponds to the concept of constitution and gene classification. It also suggests people with Yang deficiency constitution are susceptible to autoimmune diseases, enteritis, arthritis, metabolism disorders, and cancer, which provides molecular evidence for the theory of “constitution-disease correlation.”

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