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PK Data (pk + data)
Selected AbstractsPopulation pharmacokinetics of intravenous itraconazole in patients with persistent neutropenic feverJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 3 2009D.-G. Lee MD Summary Purpose:, Empirical use of intravenous (IV) itraconazole (ITZ) for febrile neutropenic patients has recently been introduced in Korea. This study was designed to investigate the population pharmacokinetics (PK) of IV-ITZ. Methods:, Sparse PK data were collected from febrile neutropenic patients undergoing empirical ITZ therapy at 200 mg/day after loading doses. NONMEM (Version. 5·1·1) was used to estimate population PK parameters. Results:, Forty-two patients were enrolled in the study. Mean population CL and V of IV-ITZ were 10 L/h and 1050 L, respectively. Body weight was the only contributing covariate of CL. The median simulated trough concentration of ITZ after 10 days was predicted to be about 700 ng/mL. Conclusions:, In this study, we explored the population PK profile of ITZ given in IV formulation. We found that the current dosage regimen of IV-ITZ (200 mg/day) was appropriate to obtain therapeutic trough concentrations for neutropenic patients in Korea. [source] Clinical Pharmacokinetics of the PDT Photosensitizers Porfimer Sodium (Photofrin), 2-[1-Hexyloxyethyl]-2-Devinyl Pyropheophorbide-a (Photochlor) and 5-ALA-Induced Protoporphyrin IXLASERS IN SURGERY AND MEDICINE, Issue 5 2006David A. Bellnier PhD Abstract Background and Objectives Photodynamic therapy (PDT) uses a photosensitizer activated by light, in an oxygen-rich environment, to destroy malignant tumors. Clinical trials of PDT at Roswell Park Cancer Institute (RPCI) use the photosensitizers Photofrin, Photochlor, and 5-ALA-induced protoporphyrin IX (PpIX). In some studies the concentrations of photosensitizer in blood, and occasionally in tumor tissue, were obtained. Pharmacokinetic (PK) data from these individual studies were pooled and analyzed. This is the first published review to compare head-to-head the PK of Photofrin and Photochlor. Study Design/Materials and Methods Blood and tissue specimens were obtained from patients undergoing PDT at RPCI. Concentrations of Photofrin, Photochlor, and PpIX were measured using fluorescence analysis. A non-linear mixed effects modeling approach was used to analyze the PK data for Photochlor (up to 4 days post-infusion; two-compartment model) and a simpler multipatient-data-pooling approach was used to model PK data for both Photofrin and Photochlor (at least 150 days post-infusion; three-compartment models). Physiological parameters were standardized to correspond to a standard (70 kg; 1.818 m2 surface area) man to facilitate comparisons between Photofrin and Photochlor. Results Serum concentration-time profiles obtained for Photofrin and Photochlor showed long circulating half-lives, where both sensitizers could be found more than 3 months after intravenous infusion; however, estimated plasma clearances (standard man) were markedly smaller for Photofrin (25.8 ml/hour) than for Photochlor (84.2 ml/hour). Volumes of distribution of the central compartment (standard man) for both Photofrin and Photochlor were about the size (3.14 L, 4.29 L, respectively) of plasma volume, implying that both photosensitizers are almost 100% bound to serum components. Circulating levels of PpIX were generally quite low, falling below the level of instrument sensitivity within a few days after topical application of 5-ALA. Conclusion We have modeled the PK of Photochlor and Photofrin. PK parameter estimates may, in part, explain the relatively long skin photosensitivity attributed to Photofrin but not Photochlor. Due to the potential impact and limited experimental PK data in the PDT field further clinical studies of photosensitizer kinetics in tumor and normal tissues are warranted. Lasers Surg. Med. © 2006 Wiley-Liss, Inc. [source] The prediction of human response to ONO-4641, a sphingosine 1-phosphate receptor modulator, from preclinical data based on pharmacokinetic,pharmacodynamic modelingBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2010Tomoya Ohno Abstract The pharmacokinetic (PK) and pharmacodynamic (PD) parameters of ONO-4641 in humans were estimated using preclinical data in order to provide essential information to better design future clinical studies. The characterization of PK/PD was measured in terms of decreased lymphocyte counts in blood after administration of ONO-4641, a sphingosine 1-phosphate receptor modulator. Using a two-compartment model, human PK parameters were estimated from preclinical PK data of cynomolgus monkey and in vitro human metabolism data. To estimate human PD parameters, the relationship between lymphocyte counts and plasma concentrations of ONO-4641 in cynomolgus monkeys was determined. The relationship between lymphocyte counts and plasma concentrations of ONO-4641 was described by an indirect-response model. The indirect-response model had an Imax value of 0.828 and an IC50 value of 1.29,ng/ml based on the cynomolgus monkey data. These parameters were used to represent human PD parameters for the simulation of lymphocyte counts. Other human PD parameters such as input and output rate constants for lymphocytes were obtained from the literature. Based on these estimated human PK and PD parameters, human lymphocyte counts after administration of ONO-4641 were simulated. In conclusion, the simulation of human lymphocyte counts based on preclinical data led to the acquisition of useful information for designing future clinical studies. Copyright © 2010 John Wiley & Sons, Ltd. [source] Population pharmacokinetics of intravenously and orally administered docetaxel with or without co-administration of ritonavir in patients with advanced cancerBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 5 2010Stijn L. W. Koolen WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , Docetaxel is an approved drug for the treatment of cancer of various primary origins. , An oral docetaxel regimen is warranted because of patient convenience and the opportunity to investigate more schedule intensive treatment regimens. , Co-administration of ritonavir significantly enhanced the apparent oral bioavailability of docetaxel. WHAT THIS STUDY ADDS , This study demonstrates that ritonavir increased the absorption of docetaxel after oral administration. , Furthermore, we showed that the clearance of docetaxel was inhibited in a concentration dependent manner. , The developed model will be used for further development of an oral docetaxel regimen. AIM Docetaxel has a low oral bioavailability due to affinity for P-glycoprotein and cytochrome P450 (CYP) 3A4 enzymes. Inhibition of the CYP3A4 enzymes by ritonavir resulted in increased oral bioavailability. The aim of this study was to develop a population pharmacokinetic (PK) model and to evaluate and quantify the influence of ritonavir on the PK of docetaxel. METHODS Data from two clinical trials were included in the data analysis, in which docetaxel (75 mg m,2 or 100 mg) had been administered intravenously or orally (10 mg or 100 mg) with or without co-administration of oral ritonavir (100 mg). Population modelling was performed using non-linear mixed effects modelling. A three-compartment model was used to describe the i.v. data. PK data after oral administration, with or without co-administration of ritonavir, were incorporated into the model. RESULTS Gut bioavailability of docetaxel increased approximately two-fold from 19 to 39% (CV 13%) with ritonavir co-administration. The hepatic extraction ratio and the elimination rate of docetaxel were best described by estimating the intrinsic clearance. Ritonavir was found to inhibit in a concentration dependent manner the intrinsic clearance of docetaxel, which was described by an inhibition constant of 0.028 µg ml,1 (CV 36%). A maximum inhibition of docetaxel clearance of more then 90% was reached. CONCLUSIONS A PK model describing both the PK of orally and intravenously administered docetaxel in combination with ritonavir, was successfully developed. Co-administration of ritonavir lead to increased oral absorption and reduced elimination rate of docetaxel. [source] | ||||||||||