scholarly journals Compartmental Pharmacokinetic Analysis of Oral Amprenavir with Secondary Peaks

2007 ◽  
Vol 51 (5) ◽  
pp. 1822-1826 ◽  
Author(s):  
Olanrewaju Okusanya ◽  
Alan Forrest ◽  
Robin DiFrancesco ◽  
Sanela Bilic ◽  
Susan Rosenkranz ◽  
...  
Keyword(s):  
Plasma Concentrations ◽  
Compartment Model ◽  
Central Compartment ◽  
Volume Of Distribution ◽  
Information Criteria ◽  
Secondary Peak ◽  
Pharmacokinetic Analysis ◽  
Therapeutic Drug ◽  
Healthy Human ◽  
Two Compartment Model

ABSTRACT Amprenavir is a protease inhibitor that has been shown to have secondary peaks postulated to be due to enterohepatic recycling. We propose a model to describe the pharmacokinetics of amprenavir which accommodates the secondary peak(s). A total of 82 healthy human immunodeficiency virus (HIV)-seronegative subjects were administered a single 600-mg dose of amprenavir as part of adult AIDS Clinical Trials Group protocol A5043. Serial blood samples were obtained over 24 h. Samples were analyzed for amprenavir and fit to a compartmental model using ADAPT II software, with all relevant parameters conditional with respect to bioavailability. The model accommodated secondary peaks by incorporating clearance out of the central compartment with delayed instantaneous release back into the gut compartment. The data were weighted by the inverse of the estimated measurement error variance; model discrimination was determined using Akaike's Information Criteria. A total of 76 subjects were evaluable in the study analysis. The data were best fit by a two-compartment model, with 98.7% of the subjects demonstrating a secondary peak. Amprenavir had a mean total clearance of 1.163 liters/h/kg of body weight (0.7), a central volume of distribution of 1.208 liters/kg (0.8), a peripheral volume of distribution of 8.2 liters/kg (0.81), and distributional clearance of 0.04 liters/h/kg (0.81). The time to the secondary peak was 7.86 h (0.17), and clearance into a recycling compartment was 0.111 liters/kg/h (0.74). Amprenavir pharmacokinetics has been well described using a two-compartment model with clearance to a recycling compartment and release back into the gut. The nature of the secondary peaks may be an important consideration for the interpretation of amprenavir plasma concentrations during therapeutic drug monitoring.

scholarly journals The intravenous pharmacokinetics of diminazene in healthy dogs

2009 ◽  
Vol 80 (4) ◽  
Author(s):  
V. Naidoo ◽  
M.S.G. Mulders ◽  
G.E. Swan
Keyword(s):  
Plasma Concentrations ◽  
Compartmental Analysis ◽  
Central Compartment ◽  
Volume Of Distribution ◽  
Time Profile ◽  
Secondary Peak ◽  
German Shepherd ◽  
Plasma Pharmacokinetics ◽  
Healthy Dogs ◽  
Over 40 Years

Diminazene remains one of South Africa's most commonly used antiprotozoal agents for the management of babesiosis in dogs . Although the drug has been on the market for over 40 years, its intravenous pharmacokinetics are poorly known. To better understand the pharmacokinetics of the drug Berenil®, it was reconstituted in sterile water and administered intravenously to 6 adult German shepherd dogs. All 6 dogs demonstrated the previously described secondary peak in the plasma concentration versus time profile. The plasma pharmacokinetics for diminazene are described by both non-compartmental and compartmental models. From non-compartmental analysis, the area under curve to the last sample point (AUClast), clearance (CL) and volume of distribution (Vz) were 4.65±1.95 ng/mℓ/h, 0.77±0.18 ℓ/kg/h and 2.28±0.60 ℓ/kg, respectively. For compartmental modelling, the plasma concentrations were fitted to both a 2-compartmental open model and a recirculatory enterohepatic model. From the recirculation model, the rate of release and re-entry into the central compartment varied markedly with the rate of release from the gall bladder (Ttom) being estimated at 27 ± 20.90 h. Once released, drug re-entry into the central compartment was variable at 9.70±5.48 h. With normal biliary excretion time being about 2 h, this indicates that the redistribution cannot be occurring physiologically from the bile. Although it was not possible to identify the site from which sequestration and delayed release is occurring, it is believed that it is most likely from the liver. The study therefore showed that the secondary peak described for the pharmacokinetics of intramuscular administered diminazene in the dog is not related to biphasic absorption.

scholarly journals Population Pharmacokinetics Modelling and Simulation of Mitotane in Patients with Adrenocortical Carcinoma: An Individualized Dose Regimen to Target All Patients at Three Months?

Pharmaceutics ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 566 ◽  
Author(s):  
Yoann Cazaubon ◽  
Yohann Talineau ◽  
Catherine Feliu ◽  
Céline Konecki ◽  
Jennifer Russello ◽  
...  
Keyword(s):  
Adrenocortical Carcinoma ◽  
Plasma Concentrations ◽  
Therapeutic Index ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Pharmacokinetic Analysis ◽  
Concentration Data ◽  
Starting Dose ◽  
Dosing Regimens ◽  
Data Files

Mitotane is the most effective agent in post-operative treatment of adrenocortical carcinoma. In adults, the starting dose is 2–3 g/day and should be slightly increased to reach the therapeutic index of 14–20 mg/L. This study developed a population PK model for mitotane and to simulate recommended/high dosing regimens. We retrospectively analyzed the data files of 38 patients with 503 plasma concentrations for the pharmacokinetic analysis. Monolix version 2019R1 was used for non-linear mixed-effects modelling. Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA ≥ 14 mg/L) at one month and at three months. Mitotane concentration data were best described by a linear one-compartment model. The estimated PK parameters (between-subject variability) were: 8900 L (90.4%) for central volume of distribution (V) and 70 L·h−1 (29.3%) for clearance (Cl). HDL, Triglyceride (Tg) and a latent covariate were found to influence Cl. The PTA at three months for 3, 6, 9, and 12 g per day was 10%, 55%, 76%, and 85%, respectively. For a loading dose of 15 g/day for one month then 5 g/day, the PTA in the first and third months was 57 and 69%, respectively. This is the first PKpop model of mitotane highlighting the effect of HDL and Tg covariates on the clearance as well as a subpopulation of ultrafast metabolizer. The simulations suggest that recommended dose regimens are not enough to target the therapeutic threshold in the third month.

scholarly journals 1573. Population Pharmacokinetic Analyses for Cefepime in Adult and Pediatric Patients

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S574-S575
Author(s):  
Jiajun Liu ◽  
Michael Neely ◽  
Jeffrey Lipman ◽  
Fekade B Sime ◽  
Jason Roberts ◽  
...  
Keyword(s):  
Rate Constant ◽  
Pediatric Patients ◽  
Validation Cohort ◽  
External Validation ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Information Criteria ◽  
Population Pharmacokinetic ◽  
Final Model ◽  
Two Compartment Model

Abstract Background Cefepime (CEF) is commonly used for adult and pediatric infections. Several studies have examined CEF’s pharmacokinetics (PK) in various populations; however, a unifying PK model for adult and pediatric subjects does not yet exist. We developed a combined population model for adult and pediatric patients and validated the model. Methods The initial model includes adult and pediatric patients with a rich cefepime sampling design. All adults received 2 g CEF while pediatric subjects received a mean of 49 (SD 5) mg/kg. One- and two-compartment models were considered as base models and were fit using a non-parametric adaptive grid algorithm within the Pmetrics package 1.5.2 (Los Angeles, CA) for R 3.5.1. Compartmental model selection was based on Akaike information criteria (AIC). Covariate relationships with PK parameters were visually inspected and mathematically assessed. Predictive performance was evaluated using bias and imprecision of the population and individual prediction models. External validation was conducted using a separate adult cohort. Results A total of 45 subjects (n = 9 adults; n = 36 pediatrics) were included in the initial PK model build and 12 subjects in the external validation cohort. Overall, the data were best described using a two-compartment model with volume of distribution (V) normalized to total body weight (TBW/70 kg) and an allometric scaled elimination rate constant (Ke) for pediatric subjects (AIC = 4,138.36). Final model observed vs. predicted plots demonstrated good fit (population R2 = 0.87, individual R2 = 0.97, Figure 1a and b). For the final model, the population median parameter values (95% credibility interval) were V0 (total volume of distribution), 11.7 L (10.2–14.6); Ke for adult, 0.66 hour−1 (0.38–0.78), Ke for pediatrics, 0.82 hour−1 (0.64–0.85), KCP (rate constant from central to peripheral compartment), 1.4 hour−1 (1.3–1.8), KPC (rate constant from peripheral to central compartment), 1.6 hour−1 (1.2–1.8). The validation cohort has 12 subjects, and the final model fit the data well (individual R2 = 0.75). Conclusion In this diverse group of adult and pediatrics, a two-compartment model described CEF PK well and was externally validated with a unique cohort. This model can serve as a population prior for real-time PK software algorithms. Disclosures All authors: No reported disclosures.

Population pharmacokinetics of daptomycin in patients with bone and joint infection: minimal effect of rifampicin co-administration and confirmation of a sex difference

2021 ◽  
Author(s):  
Romain Garreau ◽  
Romain Bricca ◽  
Marie-Claude Gagnieu ◽  
Sandrine Roux ◽  
Anne Conrad ◽  
...  
Keyword(s):  
Joint Infection ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Individual Variability ◽  
Therapeutic Drug ◽  
Marginal Effect ◽  
Bone And Joint Infection ◽  
Two Compartment Model ◽  
Central Volume ◽  
Trough Concentrations

Abstract Background Daptomycin is increasingly used in the treatment of bone and joint infection (BJI), but its pharmacokinetics (PK) and dosage requirements have not been thoroughly investigated in this indication. Daptomycin may be co-administered with rifampicin, which raises questions about a potential drug interaction. Objectives To investigate the population PK and dosage requirements of daptomycin in patients with BJI, and examine the influence of rifampicin co-administration. Methods A population approach was used to analyse PK data from patients who received daptomycin in our regional reference for BJI. We examined the influence of available covariates, including rifampicin co-administration on daptomycin PK. Simulations performed with the final model investigated the influence of dosages and covariates on PTA for both efficacy and safety. Results A total of 1303 daptomycin concentrations from 183 patients were analysed. A two-compartment model best described the data. Significant intra-individual variability was observed. Daptomycin clearance was influenced by renal function and sex, with females having a 26% lower typical clearance than males. Central volume of distribution (V1) was influenced by body weight, age, sex and rifampicin co-administration. Typical V1 was 11% lower in patients who were co-administered rifampicin. In PK/PD simulations, sex influenced the probability of AUC24/MIC target attainment, while rifampicin had a marginal effect. Conclusions A daptomycin dosage of 8 mg/kg/24 h in women and 10 mg/kg/24 h in men should optimize efficacy but may lead to excessive trough concentrations in many patients, especially in women. Therapeutic drug monitoring appears necessary for precision dosing of daptomycin.

scholarly journals Pregnancy-Related Effects on Tenofovir Pharmacokinetics: a Population Study with 186 Women

2011 ◽  
Vol 56 (2) ◽  
pp. 857-862 ◽  
Author(s):  
Sihem Benaboud ◽  
Déborah Hirt ◽  
Odile Launay ◽  
Emmanuelle Pannier ◽  
Ghislaine Firtion ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Therapeutic Drug ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Linear Absorption ◽  
Two Compartment Model ◽  
Apparent Clearance ◽  
Elimination Clearance

ABSTRACTAccording to the European AIDS Clinical Society, tenofovir disoproxil fumarate can be used in HIV-infected pregnant women if started prior to pregnancy, although no data are available on the pharmacokinetics of tenofovir (TFV) during pregnancy. The aim of this study was to describe TFV pharmacokinetics in HIV-infected women and to evaluate the effect of pregnancy on TFV disposition. Samples were collected according to a therapeutic drug monitoring in 186 women, including 46 pregnant women treated with TFV and retrospectively analyzed by a population approach. TFV pharmacokinetics were ascribed to an open two-compartment model with linear absorption and elimination. The mean population parameter estimates (between-subject variability) were as follows: absorption rate constant, 0.56 h−1; elimination clearance, 59.9 liters h−1(0.436); central volume of distribution, 552 liters (1.96); intercompartmental clearance, 172 liters/h; and peripheral volume of distribution, 1,390 liters. Pregnant women had a 39% higher apparent clearance compared to nonpregnant women. Apparent clearance significantly decreased with age. In order to obtain an exposure similar to the known exposure in adults and guarantee similar trough concentrations (Cmin) as observed in adults, an increase in the TFV dose should be considered for women from the second trimester to delivery.

scholarly journals Population Pharmacokinetics of Levetiracetam and Dosing Evaluation in Critically Ill Patients with Normal or Augmented Renal Function

Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1690
Author(s):  
Idoia Bilbao-Meseguer ◽  
Helena Barrasa ◽  
Eduardo Asín-Prieto ◽  
Ana Alarcia-Lacalle ◽  
Alicia Rodríguez-Gascón ◽  
...  
Keyword(s):  
Renal Function ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Plasma Concentrations ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Parameter Estimates ◽  
Population Modelling ◽  
Two Compartment Model ◽  
Relative Standard

Levetiracetam is a broad-spectrum antiepileptic drug commonly used in intensive care units (ICUs). The objective of this study is to evaluate the adequacy of levetiracetam dosing in patients with normal or augmented renal clearance (ARC) admitted to the ICU by population modelling and simulation. A multicentre prospective study including twenty-seven critically ill patients with urinary creatinine clearance (CrCl) > 50 mL/min and treated with levetiracetam was developed. Levetiracetam plasma concentrations were best described by a two-compartment model. The parameter estimates and relative standard errors (%) were clearance (CL) 3.5 L/h (9%), central volume of distribution (V1) 20.7 L (18%), intercompartmental clearance 31.9 L/h (22%), and peripheral volume of distribution 33.5 L (13%). Interindividual variability estimates were, for the CL, 32.7% (21%) and, for V1, 56.1% (29%). The CrCl showed significant influence over CL. Simulations showed that the administration of at least 500 mg every 8 h or 1000 mg every 12 h are needed in patients with normal renal function. Higher doses (1500 or 2000 mg, every 8 h) are needed in patients with ARC. Critically ill patients with normal or ARC treated with levetiracetam could be at high risk of being underdosed.

scholarly journals Pharmacokinetic Profile of Kaurenoic Acid after Oral Administration of Araliae Continentalis Radix Extract Powder to Humans

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 253
Author(s):  
Eun-Jeong Choi ◽  
Go-Wun Choi ◽  
Seung-Jeong Yang ◽  
Yong-Bok Lee ◽  
Hea-Young Cho
Keyword(s):  
Plasma Concentrations ◽  
Compartment Model ◽  
Central Compartment ◽  
Volume Of Distribution ◽  
Efflux Transporters ◽  
Peripheral Compartment ◽  
Simple Liquid ◽  
Usual Dose ◽  
Kaurenoic Acid

The objective of this study was to characterize pharmacokinetics (PKs) of kaurenoic acid (KAU) after administration of the clinical usual dose of Araliae Continentalis Radix extract powder to Korean subjects for the first time and evaluate the mechanism of its absorption in vitro. A simple, sensitive, and selective analytical method was developed for the detection of KAU in human plasma. Concentrations of KAU were quantified by ultra-performance liquid chromatography tandem mass spectrometry after simple liquid–liquid extraction. This pharmacokinetic model of KAU was best described by a two-compartment model with first-order absorption. To identify efflux transporters involved in the absorption of KAU, a Caco-2 monolayer model was used. Estimated PK parameters were: systemic clearance, 23.89 L/h; inter-compartmental clearance, 15.55 L/h; rate constant for absorption, 1.72 h−1; volume of distribution of the central compartment, 24.44 L; and volume of distribution of the peripheral compartment, 64.05 L. Results from Caco-2 bidirectional transport study suggested that KAU was a potential substrate of efflux transporters. In summary, PKs of KAU were successfully characterized after administration of a usual dose of Araliae continentalis Radix extract powder in human with the newly developed bioanalytical method and the mechanism of absorption of KAU was identified clearly.

scholarly journals DOSAGE INDIVIDUALIZATION OF LINEZOLID: PRECISION DOSING OF LINEZOLID TO OPTIMISE EFFICACY AND MINIMISE TOXICITY

2021 ◽  
Author(s):  
S Luque ◽  
W Hope ◽  
L Sorli ◽  
R Muñoz-Bermudez ◽  
N Campillo ◽  
...  
Keyword(s):  
High Performance ◽  
Compartment Model ◽  
Central Compartment ◽  
Pharmacokinetic Analysis ◽  
Therapeutic Drug ◽  
Population Pharmacokinetic ◽  
High Interindividual Variability ◽  
Using Data ◽  
Toxic Concentrations ◽  
High Degree

High interindividual variability in the pharmacokinetics (PK) of linezolid has been described, which results in an unacceptably high proportion of patients with either suboptimal or potentially toxic concentrations following the administration of a fixed regimen. The aim of this study was to develop a population pharmacokinetic model of linezolid and use this to build and validate alogorithms for individualised dosing. A retrospective pharmacokinetic analysis was performed using data from 338 hospitalized patients (65.4% male, 65.5(14.6) years) who underwent routine therapeutic drug monitoring TDM for linezolid. Linezolid concentrations were analysed by using high-performance liquid chromatography. Population pharmacokinetic modelling was performed using a nonparametric methodology with Pmetrics and Monte Carlo simulations were employed to calculate the 100% time >MIC after the administration of a fixed regimen of 600 mg q12h i.v. The dose of linezolid needed to achieve a PTA ≥ 90% for all susceptible isolates classified according to EUCAST was estimated to be as high as 2400mg/12h, which is 4 times higher than the maximum licensed linezolid dose. The final pk model was then used to construct software for dosage individualisation and the performance of the software was assessed using 10 new patients not used to construct the original population PK model. A three-compartment model with an absorptive compartment with zero-order i.v. input and first-order clearance from the central compartment best described the data. The dose optimization software tracked patients with a high degree of accuracy. The software may be a clinically useful tool to adjust linezolid dosages in real-time to achieve prespecified drug exposures targets. A further prospective study is needed to examine the potential clinical utility of individualised therapy.

Procainamide pharmacokinetics during extracorporeal membrane oxygenation

Perfusion ◽  
2021 ◽  
pp. 026765912110506
Author(s):  
Nicholas J Vollmer ◽  
Erica D Wittwer ◽  
Andrew N Rosenbaum ◽  
Patrick M Wieruszewski
Keyword(s):  
Extracorporeal Membrane Oxygenation ◽  
Elevated Serum ◽  
Stable Condition ◽  
Pharmacokinetic Profile ◽  
Volume Of Distribution ◽  
Pharmacokinetic Analysis ◽  
Therapeutic Drug ◽  
Slow Acetylator ◽  
Membrane Oxygenation ◽  
Serum And Urine

Procainamide is a useful agent for management of ventricular arrhythmia, however its disposition and appropriate dosing during extracorporeal membrane oxygenation (ECMO) is unknown. We report experience with continuous procainamide infusion in a critically ill adult requiring venoarterial ECMO for incessant ventricular tachycardia. Pharmacokinetic analysis of procainamide and its metabolite, N-acetylprocainamide (NAPA), was performed using serum and urine specimens. Kidney function was preserved, and sequencing of the N-acetyltransferase 2 gene revealed the patient was a phenotypic slow acetylator. Procainamide volume of distribution and half-life were calculated and found to be similar to healthy individuals. However, despite elevated serum procainamide concentrations, NAPA concentrations remained far lower in the serum and urine. The magnitude of procainamide and NAPA discordance suggested alternative contributors to the deranged pharmacokinetic profile, and we hypothesized NAPA sequestration by the ECMO circuit. Ultimately, the patient received orthotopic cardiac transplantation and was discharged home in stable condition. Procainamide should be used cautiously during ECMO, with close therapeutic drug monitoring of serum procainamide and NAPA concentrations. The achievement of therapeutic NAPA concentrations while maintaining safe serum procainamide concentrations during ECMO support may be challenging.

scholarly journals Population Pharmacokinetic Analysis of Voriconazole and Anidulafungin in Adult Patients with Invasive Aspergillosis

2014 ◽  
Vol 58 (8) ◽  
pp. 4718-4726 ◽  
Author(s):  
Ping Liu ◽  
Diane R. Mould
Keyword(s):  
Invasive Aspergillosis ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Population Pharmacokinetic Analysis ◽  
Institutional Review Boards ◽  
Pharmacokinetic Analysis ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
First Order ◽  
Two Compartment Model

ABSTRACTTo assess the pharmacokinetics (PK) of voriconazole and anidulafungin in patients with invasive aspergillosis (IA) in comparison with other populations, sparse PK data were obtained for 305 adults from a prospective phase 3 study comparing voriconazole and anidulafungin in combination versus voriconazole monotherapy (voriconazole, 6 mg/kg intravenously [IV] every 12 h [q12h] for 24 h followed by 4 mg/kg IV q12h, switched to 300 mg orally q12h as appropriate; with placebo or anidulafungin IV, a 200-mg loading dose followed by 100 mg q24h). Voriconazole PK was described by a two-compartment model with first-order absorption and mixed linear and time-dependent nonlinear (Michaelis-Menten) elimination; anidulafungin PK was described by a two-compartment model with first-order elimination. For voriconazole, the normal inverse Wishart prior approach was implemented to stabilize the model. Compared to previous models, no new covariates were identified for voriconazole or anidulafungin. PK parameter estimates of voriconazole and anidulafungin are in agreement with those reported previously except for voriconazole clearance (the nonlinear clearance component became minimal). At a 4-mg/kg IV dose, voriconazole exposure tended to increase slightly as age, weight, or body mass index increased, but the difference was not considered clinically relevant. Estimated voriconazole exposures in IA patients at 4 mg/kg IV were higher than those reported for healthy adults (e.g., the average area under the curve over a 12-hour dosing interval [AUC0–12] at steady state was 46% higher); while it is not definitive, age and concomitant medications may impact this difference. Estimated anidulafungin exposures in IA patients were comparable to those reported for the general patient population. This study was approved by the appropriate institutional review boards or ethics committees and registered on ClinicalTrials.gov (NCT00531479).

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