Tissue Pharmacokinetic Parameters Research Articles

Translational pharmacokinetics of a novel bispecific antibody against Ebola virus (MBS77E) from animal to human by PBPK modeling & simulation

The goal of this study was to construct a PBPK model to accelerate the translation of MBS77E, a humanized bispecific antibody against the Ebola virus. In-depth nonclinical pharmacokinetic studies in rats, monkeys, wild-type mice and transgenic mice were conducted. The pH-dependent affinities (KD) of MBS77E to recombinant FcRn of different species were determined by surface plasmon resonance analysis. A mechanistic whole-body PBPK model of MBS77E was developed and validated in the assessment of PK profiles and tissue distributions in preclinical models. This PBPK model was finally used to predict human PK behaviors of MBS77E. Simulations from the PBPK model with measured and fitted parameters were able to yield good predictions of the serum and tissue pharmacokinetic parameters of MBS77E within 2-fold errors. The predicted serum concentration in humans was able to maintain a sufficiently high level for more than 14 days after 50 mg/kg i.v. administrating. This achievement unlocks that PBPK modeling is a powerful tool to gain insights into the properties of antibody drugs. It guided experimental efforts to obtain necessary information before entry into humans.

Identification of sensitive biomarker, 3-indoxyl sulfate, to detecting acute kidney injury

Ascending and descending theory is a core principle of traditional Chinese medicine (TCM) theories. It plays an essential role in TCM clinical applications. Some TCM medicine has specific properties, which could alter the inclination and direction of their actions. The properties of the ascending and floating process of one herbal medicine are affected by means of herb processing. Wine-processing, which is sautéing with rice wine, is one of the most popular technologies of herb processing. Wine-processing increases the inclination and direction of its actions, thereby producing or strengthening their efficacy in cleaning the upper-energizer heat.Radix scutellariae, the dried roots of Scutellaria baicalensis Georgi, is a well-known TCM used for the treatment of inflammation, pyrexia, jaundice, etc. Recently, wine-processed Radix scutellariae was normally applied in clinical studies for the treatment of upper-energizer syndrome. In order to investigate the effects of wine-processing on ascending and descending of Radix scutellariae, the comparative study of distribution of flavonoids in rat tissues of triple energizers (SanJiao-upper, middle, lower jiao) after oral administration of crude and wine-processed Radix scutellariae aqueous extracts was carried out.The rats were randomly assigned to two groups and orally administered with crude and wine-processed Radix scutellariae aqueous extracts, respectively. At different pre-determined time points after administration, the concentrations of compounds in rat tissue homogenate were determined, and the main tissue pharmacokinetic parameters were investigated. Tissue pharmacokinetic parameters including AUC0–t, t1/2, Tmax and Cmax were calculated using DAS 2.0. An unpaired Student t-test was used to compare the differences in tissue pharmacokinetic parameters between the two groups. All the results were expressed as arithmetic mean±S.D.The parameters of Cmax and AUC0–t of some flavonoids in wine-processed Radix scutellariae were remarkably increased (p<0.05, p<0.01, p<0.001) in the rat upper-energizer tissues (lung and heart) compared with those of the crude group. However, in the rat middle- and lower-energizer tissues (spleen, liver and kidney), the Cmax and AUC0–t of some flavonoids were significantly decreased (p<0.05, p<0.01) compared with the crude group. The main explanation for these differences seems to the effects of wine-processing on ascending and descending theory.All of these differences in the distribution of triple energizers after oral administration of crude and wine-processed Radix scutellariae aqueous extracts may lead to the increase of efficacy on the upper-energizer tissues and were in compliance with the ascending and descending theory. Therefore, wine-processing was recommended when Radix scutellariae was used for cleaning the upper-energizer heat and humidity. The obtained knowledge can be used to evaluate the impact of these differences on the efficacy of both the drugs in clinical applications and might be helpful in explaining the effects of wine-processing on ascending and descending theory.

First plasma and tissue pharmacokinetic study of the YSNSG cyclopeptide, a new integrin antagonist, using microdialysis

The YSNSG peptide is a synthetic peptide targeting αvβ3 integrin. This peptide exhibits promising activity in vitro and in vivo against melanoma. To determine pharmacokinetic parameters and predictive active doses in the central nervous system (CNS) and subcutaneous tissue (SC), we conducted microdialysis coupled with pharmacokinetic modeling and Monte Carlo simulation. After a recovery period of surgical procedures, a microdialysis probe was inserted in the caudate and in subcutaneous tissue. Plasma samples and dialysates collected 5h after YSNSG intravenous administration (10mg/kg) were analyzed by UPLC-MS/MS. A nonlinear mixed-effect modeling approach implemented in Monolix® 2016R1 was performed. Model selection and evaluation were based on the usual diagnostic plot, precision and information criteria. The primary plasma and tissue pharmacokinetic parameters were comparable with those of other integrin antagonists, such as cilengitide or ATN-161. Tissue/plasma and brain/plasma area under the curve (AUC) ratio were 66.2±21.6% and 3.6±4.7%, respectively. Two models of 2-compartments with an additional microdialysis compartment, parameterized as rate constants (k for elimination, k12/k21 and k13/k31 for distribution) and volumes (central V1 and peripheral microdialysis compartment V3) with zero-order input were selected to describe the dialysate concentrations in CNS and SC. The inter-individual variability (IIV) was described by exponential terms, and residual variability was described by a combined additive and proportional error model. Individual AUC (plasma and tissues) values were derived for each animal using the Empirical-Bayes-Estimates of the individual parameters. The regimens needed to achieve an in vitro predetermined target concentration in tissues were studied by Monte Carlo simulations using Monolix® 2016R1. YSNSG pharmacokinetic parameters show promising results in terms of subcutaneous disposition. Further investigations into such processes as encapsulation and intratumoral disposition are currently being conducted.

Integrating UHPLC-MS/MS quantification and DAS analysis to investigate the effects of wine-processing on the tissue distributions of bioactive constituents of herbs in rats: Exemplarily shown for Dipsacus asper.

Wine-processing, which is sauteing with rice wine, will change the inclination and direction of herbs' actions. After being wine-processed, the effects of nourishing liver and kidney of Dipsacus asper will be strengthened. However, the underlying mechanism remains elusive. The following study is to establish and validate an UHPLC-MS/MS approach to determine six bioactive constituents in tissue samples, including loganin, loganic acid, chlorogenic acid, 3,5-dicaffeoylquinic acid, 4-caffeoylquinic acid and asperosaponin VI and apply the approach to a comparative tissue distribution study of raw and wine-processed Dipsacus asper in rats. A Shimadzu UHPLC system coupled with triple quadrupole mass spectrometer was employed for analysis of the six analytes using multiple reaction monitoring (MRM) mode. A one-step protein precipitation by methanol was employed to extract the six analytes from tissues. Chloramphenicol and glycyrrhetinic acid were selected as internal standards. The proposed approach was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery. Our results revealed that all of the calibration curves displayed good linear regression (r2>0.9991). Intra- and inter-assay variability for all analytes ranged from -4.62 to 4.93% and from -4.98 to 4.92%, respectively. The recovery rates for each analytes were determined to be 88.3-100.1%. All the samples showed satisfactory precision and accuracy after various stability tests, including storage at 25°C for 4h, -80°C for 30days, three-freeze-thaw cycles, and 4°C for 24h. Tissue pharmacokinetic parameters including AUC0-t, t1/2, Tmax and Cmax were calculated. Collectively, the parameters of Cmax and AUC0-t of the six analytes in wine-processed group were remarkably elevated (p<0.05) in the rat liver and kidney as compared with those of the raw group. But in the rat heart and spleen, the Cmax and AUC0-t of asperosaponin VI was decreased as compared with those of the raw group. The accumulation of bioactive constituents in liver and kidney tissues after wine-processing will contribute to the enhancement of liver and kidney nourishing effects.

The effects of wine-processing on ascending and descending: The distribution of flavonoids in rat tissues after oral administration of crude and wine-processed Radix scutellariae

Ethnopharmacological relevanceAscending and descending theory is a core principle of traditional Chinese medicine (TCM) theories. It plays an essential role in TCM clinical applications. Some TCM medicine has specific properties, which could alter the inclination and direction of their actions. The properties of the ascending and floating process of one herbal medicine are affected by means of herb processing. Wine-processing, which is sautéing with rice wine, is one of the most popular technologies of herb processing. Wine-processing increases the inclination and direction of its actions, thereby producing or strengthening their efficacy in cleaning the upper-energizer heat.Radix scutellariae, the dried roots of Scutellaria baicalensis Georgi, is a well-known TCM used for the treatment of inflammation, pyrexia, jaundice, etc. Recently, wine-processed Radix scutellariae was normally applied in clinical studies for the treatment of upper-energizer syndrome. In order to investigate the effects of wine-processing on ascending and descending of Radix scutellariae, the comparative study of distribution of flavonoids in rat tissues of triple energizers (SanJiao-upper, middle, lower jiao) after oral administration of crude and wine-processed Radix scutellariae aqueous extracts was carried out. Materials and methodsThe rats were randomly assigned to two groups and orally administered with crude and wine-processed Radix scutellariae aqueous extracts, respectively. At different pre-determined time points after administration, the concentrations of compounds in rat tissue homogenate were determined, and the main tissue pharmacokinetic parameters were investigated. Tissue pharmacokinetic parameters including AUC0–t, t1/2, Tmax and Cmax were calculated using DAS 2.0. An unpaired Student t-test was used to compare the differences in tissue pharmacokinetic parameters between the two groups. All the results were expressed as arithmetic mean±S.D. ResultsThe parameters of Cmax and AUC0–t of some flavonoids in wine-processed Radix scutellariae were remarkably increased (p<0.05, p<0.01, p<0.001) in the rat upper-energizer tissues (lung and heart) compared with those of the crude group. However, in the rat middle- and lower-energizer tissues (spleen, liver and kidney), the Cmax and AUC0–t of some flavonoids were significantly decreased (p<0.05, p<0.01) compared with the crude group. The main explanation for these differences seems to the effects of wine-processing on ascending and descending theory. ConclusionsAll of these differences in the distribution of triple energizers after oral administration of crude and wine-processed Radix scutellariae aqueous extracts may lead to the increase of efficacy on the upper-energizer tissues and were in compliance with the ascending and descending theory. Therefore, wine-processing was recommended when Radix scutellariae was used for cleaning the upper-energizer heat and humidity. The obtained knowledge can be used to evaluate the impact of these differences on the efficacy of both the drugs in clinical applications and might be helpful in explaining the effects of wine-processing on ascending and descending theory.

419 POSTER A phase I safety and pharmacokinetic (PK) study of 3 and 6 hours (h) intravenously administered belinostat (PXD101) plus carboplatin (C) and paclitaxel (P) in patients (pts) with advanced solid tumours

The YSNSG peptide is a synthetic peptide targeting αvβ3 integrin. This peptide exhibits promising activity in vitro and in vivo against melanoma. To determine pharmacokinetic parameters and predictive active doses in the central nervous system (CNS) and subcutaneous tissue (SC), we conducted microdialysis coupled with pharmacokinetic modeling and Monte Carlo simulation. After a recovery period of surgical procedures, a microdialysis probe was inserted in the caudate and in subcutaneous tissue. Plasma samples and dialysates collected 5 h after YSNSG intravenous administration (10 mg/kg) were analyzed by UPLC-MS/MS. A nonlinear mixed-effect modeling approach implemented in Monolix® 2016R1 was performed. Model selection and evaluation were based on the usual diagnostic plot, precision and information criteria. The primary plasma and tissue pharmacokinetic parameters were comparable with those of other integrin antagonists, such as cilengitide or ATN-161. Tissue/plasma and brain/plasma area under the curve (AUC) ratio were 66.2 ± 21.6% and 3.6 ± 4.7%, respectively. Two models of 2-compartments with an additional microdialysis compartment, parameterized as rate constants (k for elimination, k12/k21 and k13/k31 for distribution) and volumes (central V1 and peripheral microdialysis compartment V3) with zero-order input were selected to describe the dialysate concentrations in CNS and SC. The inter-individual variability (IIV) was described by exponential terms, and residual variability was described by a combined additive and proportional error model. Individual AUC (plasma and tissues) values were derived for each animal using the Empirical-Bayes-Estimates of the individual parameters. The regimens needed to achieve an in vitro predetermined target concentration in tissues were studied by Monte Carlo simulations using Monolix® 2016R1. YSNSG pharmacokinetic parameters show promising results in terms of subcutaneous disposition. Further investigations into such processes as encapsulation and intratumoral disposition are currently being conducted.

420 POSTER A phase I clinical trial of belinostat (PXD101) in combination with doxorubicin (BelDox) in advanced solid tumours, including soft tissue sarcomas (STS)

The YSNSG peptide is a synthetic peptide targeting αvβ3 integrin. This peptide exhibits promising activity in vitro and in vivo against melanoma. To determine pharmacokinetic parameters and predictive active doses in the central nervous system (CNS) and subcutaneous tissue (SC), we conducted microdialysis coupled with pharmacokinetic modeling and Monte Carlo simulation. After a recovery period of surgical procedures, a microdialysis probe was inserted in the caudate and in subcutaneous tissue. Plasma samples and dialysates collected 5 h after YSNSG intravenous administration (10 mg/kg) were analyzed by UPLC-MS/MS. A nonlinear mixed-effect modeling approach implemented in Monolix® 2016R1 was performed. Model selection and evaluation were based on the usual diagnostic plot, precision and information criteria. The primary plasma and tissue pharmacokinetic parameters were comparable with those of other integrin antagonists, such as cilengitide or ATN-161. Tissue/plasma and brain/plasma area under the curve (AUC) ratio were 66.2 ± 21.6% and 3.6 ± 4.7%, respectively. Two models of 2-compartments with an additional microdialysis compartment, parameterized as rate constants (k for elimination, k12/k21 and k13/k31 for distribution) and volumes (central V1 and peripheral microdialysis compartment V3) with zero-order input were selected to describe the dialysate concentrations in CNS and SC. The inter-individual variability (IIV) was described by exponential terms, and residual variability was described by a combined additive and proportional error model. Individual AUC (plasma and tissues) values were derived for each animal using the Empirical-Bayes-Estimates of the individual parameters. The regimens needed to achieve an in vitro predetermined target concentration in tissues were studied by Monte Carlo simulations using Monolix® 2016R1. YSNSG pharmacokinetic parameters show promising results in terms of subcutaneous disposition. Further investigations into such processes as encapsulation and intratumoral disposition are currently being conducted.

Evaluation of the cassette dosing approach for assessing the pharmacokinetics of geldanamycin analogues in mice

There is currently much interest in developing analogues of the benzoquinone ansamycin geldanamycin that may overcome the limitations of 17-(allylamino)-17-demethoxygeldanamycin (17AAG), which is the first known inhibitor of heat shock protein 90 (Hsp90) to enter clinical trials. Studies were performed to assess whether cassette dosing, the coadministration of several compounds to a single animal, is a suitable approach to evaluate the preclinical pharmacokinetics of geldanamycin analogues in high throughput. Five geldanamycin analogues (17AAG, NSC 255110, NSC 682300, NSC 683661, NSC 683663) were administered intravenously to mice in combination at 5 mg/kg each and as single agents at 5 mg/kg and 50 mg/kg, or 12.5 mg/kg for NSC 682300. The compounds were also incubated with mouse liver microsomes individually and in combination at 15 microM each. Quantitative analysis was performed by LC/MS/MS. Plasma and tissue pharmacokinetic parameters were evaluated by non-compartmental analysis. In vitro metabolic stability was assessed by monitoring disappearance of the parent compound. Of the compounds that were detectable following individual administration at 5 mg/kg, 17AAG and NSC 683661 exhibited nonlinear pharmacokinetics. In addition, the plasma area under the curve (AUC) and the half-life of these compounds was greater following cassette dosing at 5 mg/kg compared to single administration at the same dose. When pharmacokinetic parameters were calculated up to the same time point following cassette and individual administration at the higher dose, three of the compounds displayed non-linear increases in AUC and slower clearances following cassette compared to single compound dosing. When all measurable concentrations at the higher dose were included, the half-life of NSC 683663 was nine-fold longer following individual compared to cassette administration. 17AAG displayed the highest AUC following cassette dosing, whereas NSC 683663 displayed the highest AUC following single-compound dosing. Excluding NSC 683663, the rank order from the highest to the lowest AUC was the same; however, NSC 682300, which ranked fifth, was administered at a four-fold lower individual dose than the other compounds. Exposure of the liver and kidneys to the compounds was greater than that of plasma. Despite being administered at a lower dose, NSC 682300 displayed the highest kidney AUC of the five compounds. The same ranking was maintained between cassette and single compound dosing in the kidney. With the exception of NSC 682300, in vitro metabolic stability was predictive of in vivo pharmacokinetics in the plasma and liver. The extent of metabolism of four of the five compounds was lower following microsomal incubation in combination compared to incubation alone, suggestive of likely drug-drug interaction in the cassette. However, for 17AAG this may be partly due to metabolism of NSC 683661 and NSC 683663 to this compound. Whilst cassette dosing has advantages for use in drug discovery, it is probably unsuitable to evaluate the pharmacokinetics of geldanamycin analogues due to non-linear pharmacokinetics and drug-drug interaction. The issues identified for this compound series should also be considered in assessing the suitability of cassette dosing for other chemotypes.

New hybrid technique for accurate and reproducible quantitation of dynamic contrast-enhanced MRI data.

The accuracy and precision of two major approaches for analyzing dynamic MRI data from the first passage of a Gd-DTPA contrast bolus are examined, using a Monte Carlo simulation. Method 1 fits the contrast concentration curve of the first pass to a two-compartment kinetic model to determine the tissue pharmacokinetic parameters. Method 2 decomposes intravascular and interstitial components of the first-pass curve based on a leakage profile (LP) model. Based on the results of these Monte Carlo simulations, a new "hybrid" method is proposed that combines both analytical approaches to optimize accuracy and precision of estimates of K(trans), v(e), and v(p). The new method was evaluated by computer simulation and used on experimental results from a patient with primary brain tumors. The new method has the potential to provide more accurate quantification of tissue plasma volume and vessel permeability.

Tissue pharmacokinetics of florfenicol in pigs experimentally infected with Actinobacillus pleuropneumoniae.

The aim of this study has been to determine the tissue pharmacokinetic parameters of florfenicol in the pigs experimentally infected with Actinobacillus pleuropneumoniae. 21 crossed-bred (Duroc x Landrace x Yorkshire) local species of pigs were infected experimentally with Actinobacillus pleuropneumoniae serotype 1 and confirmed as typical sub-acute pleuropneumonia. A single dose of 20 mg/kg body weight of florfenicol, a novel animal-using antibiotic, was administrated intramuscularly in the pigs and then samples of blood, lung, trachea with bronchi, liver, kidney and muscle were taken at scheduled time points. Drug concentrations were determined by high performance liquid chromatography (HPLC) with an ultraviolet detector via extraction with ethyl acetate under nitrogen flow. The statistic moment theory (SMT) mathematic package was applied to calculate the tissue pharmacokinetic parameters of florfenicol in the infected model. AUC of lung, trachea with bronchi, liver, kidney and muscle were 121.69, 79.37, 81.05, 181.2, and 94.07 mg/l x h, respectively, MRT were from 34.66 to 90.17 h, and t1/2beta from 24.75 to 69.34 h, respectively. Florfenicol was widely distributed in these tissues and maintained the effective therapeutic concentrations especially in the respiratory tract tissues that are the target organs of Actinobacillus pneuropneumoniae. Tissue pharmacokinetic data could be evidence for regime designing of florfenicol in treatment of porcine pleuropneumonia.

Methods determining phosphor imaging limits of quantitation in whole-body autoradiography rodent tissue distribution studies affect predictions of 14C human dosimetry

Introduction: Radioluminography, or phosphor imaging, is often used in rodent quantitative whole-body autoradiography (QWBA) studies to determine the tissue distribution and pharmacokinetic (PK) parameters of new pharmaceutical entities in rodents. The rodent tissue pharmacokinetics information are then used to predict human radiation exposure to 14C or 3H during human radioisotope mass balance studies. The human dosimetry estimation can be biased by the method used to determine the lower limit of quantitation (LOQ) of the phosphor imager. A survey of autoradiographers revealed that at least five different methods are used to determine phosphor imager LOQ. The objective of this study is to compare and evaluate the human dosimetry estimates obtained by applying those five LOQ methods to a single set of WBA data. Methods: Five different phosphor imager LOQ determination methods were applied to a single set of QWBA rodent tissue distribution data to produce five tissue concentration time profiles. Tissue PK parameters were determined for each profile and subsequently used to calculate the 14C exposure for a proposed human 14C mass balance study. Results: A threefold difference was observed among the five predictions of human 14C exposure when the five different phosphor imager LOQ values were applied to the initial data set. Discussion: The method chosen to determine the phosphor imaging LOQ for QWBA rodent tissue distribution study could impact the human 14C exposure estimates. The end result may either under- or overestimate the 14C-tissue exposure in humans during radioisotope studies, depending on the method used to determine LOQ. We recommend two approaches to reduce the variations in the determination of rodent tissue distribution pharmacokinetics: (1) Set more sampling time points to cover the terminal phase to obtain more accurate t 1/2 and (2) use Method 3 or the small sized sampling tool of Method 5 for LOQ determinations because it is a balanced approach for both simplicity and accuracy.