Drug metabolism and disposition : the biological fate of chemicals
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Drug Metab. Dispos. · Apr 2017
Application of Physiologically Based Pharmacokinetic Modeling to the Understanding of Bosutinib Pharmacokinetics: Prediction of Drug-Drug and Drug-Disease Interactions.
Bosutinib is an orally available Src/Abl tyrosine kinase inhibitor indicated for the treatment of patients with Philadelphia chromosome-positive chronic myelogenous leukemia. Bosutinib is predominantly metabolized by CYP3A4 as the primary clearance mechanism. The main objectives of this study were to 1) develop physiologically based pharmacokinetic (PBPK) models of bosutinib; 2) verify and refine the PBPK models based on clinical study results of bosutinib single-dose drug-drug interaction (DDI) with ketoconazole and rifampin, as well as single-dose drug-disease interaction (DDZI) in patients with renal and hepatic impairment; 3) apply the PBPK models to predict DDI outcomes in patients with weak and moderate CYP3A inhibitors; and 4) apply the PBPK models to predict DDZI outcomes in renally and hepatically impaired patients after multiple-dose administration. ⋯ The PBPK models also reasonably predicted changes in bosutinib exposures in the single-dose DDI and DDZI results, suggesting that the PBPK models were sufficiently developed and verified based on the currently available data. Finally, the PBPK models predicted 2- to 4-fold increases in bosutinib exposures by moderate CYP3A inhibitors, as well as comparable increases in bosutinib exposures in renally and hepatically impaired patients between single- and multiple-dose administrations. Given the challenges in conducting numerous DDI and DDZI studies of anticancer drugs in patients, we believe that the PBPK models verified in our study would be valuable to reasonably predict bosutinib exposures under various scenarios that have not been tested clinically.
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Drug Metab. Dispos. · Mar 2017
Metabolism and Disposition of a Novel B-Cell Lymphoma-2 Inhibitor Venetoclax in Humans and Characterization of Its Unusual Metabolites.
Venetoclax (ABT-199), a B-cell lymphoma-2 (Bcl-2) protein inhibitor, is currently in clinical development for the treatment of hematologic malignancies. We characterized the absorption, metabolism, and excretion of venetoclax in humans. After a single oral dose of [14C]venetoclax to healthy volunteers, the recovery of total radioactive dose was 100%, with feces being the major route of elimination of the administered dose, whereas urinary excretion was minimal (<0.1%). ⋯ M27 was primarily formed by cytochrome P450 isoform 3A4 (CYP3A4). Steady-state plasma concentrations of M27 in human and preclinical species used for safety testing suggested that M27 is a disproportionate human metabolite. M27 is not expected to have clinically relevant on- or off-target pharmacologic activities.
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Drug Metab. Dispos. · Oct 2016
Randomized Controlled TrialMorbid Obesity Alters Both Pharmacokinetics and Pharmacodynamics of Propofol: Dosing Recommendation for Anesthesia Induction.
The prevalence of obesity has markedly increased worldwide. Obese patients pose significant challenges to anesthesiologists with regard to accurate dosing of anesthetics due to potentially altered pharmacokinetics (PK). Here we determined the PK and pharmacodynamics (PD) of propofol for anesthesia induction in morbidly obese (MO) subjects (body mass index >35 kg/m(2)) at two dosing regimens: dosing based on total body weight and lean body weight (LBW), respectively. ⋯ Moreover, dose reduction (i.e., dosing based on LBW) generated identical anesthetic effects in MO subjects compared with controls. In conclusion, morbid obesity significantly altered both PK and PD of propofol. LBW was a better weight-based dosing scalar for anesthesia induction with propofol in MO subjects.
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Drug Metab. Dispos. · Oct 2016
The Use of In Vitro Data and Physiologically-Based Pharmacokinetic Modeling to Predict Drug Metabolite Exposure: Desipramine Exposure in Cytochrome P4502D6 Extensive and Poor Metabolizers Following Administration of Imipramine.
Major circulating drug metabolites can be as important as the drugs themselves in efficacy and safety, so establishing methods whereby exposure to major metabolites following administration of parent drug can be predicted is important. In this study, imipramine, a tricyclic antidepressant, and its major metabolite desipramine were selected as a model system to develop metabolite prediction methods. Imipramine undergoes N-demethylation to form the active metabolite desipramine, and both imipramine and desipramine are converted to hydroxylated metabolites by the polymorphic enzyme CYP2D6. ⋯ The predicted area under the curve (AUCm/AUCp) of desipramine/imipramine was 12- to 20-fold higher in PM compared with EM subjects following i.v. or oral doses of imipramine using the static model. Moreover, the PBPK model was able to recover simultaneously plasma profiles of imipramine and desipramine in populations with different phenotypes of CYP2D6. This example suggested that mechanistic PBPK modeling combined with information obtained from in vitro studies can provide quantitative solutions to predict in vivo pharmacokinetics of drugs and major metabolites in a target human population.
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Drug Metab. Dispos. · Aug 2016
Metabolism and Disposition of Hepatitis C Polymerase Inhibitor Dasabuvir in Humans.
Dasabuvir [also known as ABT-333 or N-(6-(3-(tert-butyl)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2-methoxyphenyl)naphthalen-2-yl)methanesulfonamide] is a potent non-nucleoside NS protein 5B polymerase inhibitor of the hepatitis C virus (HCV) and is being developed in combination with paritaprevir/ritonavir and ombitasvir in an oral regimen with three direct-acting antivirals for the treatment of patients infected with HCV genotype 1. This article describes the mass balance, metabolism, and disposition of dasabuvir in humans. After administration of a single oral dose of 400-mg [(14)C]dasabuvir (without coadministration of paritaprevir/ritonavir and ombitasvir) to four healthy male volunteers, the mean total percentage of the administered radioactive dose recovered was 96.6%. ⋯ Subsequent oxidation of M1 to the tert-butyl acid, followed by formation of the corresponding glucuronide conjugate, plays a secondary role in elimination. Cytochrome P450 profiling indicated that dasabuvir was mainly metabolized by CYP2C8, followed by CYP3A4. In summary, the biotransformation pathway and clearance routes of dasabuvir were characterized, and the structures of metabolites in circulation and excreta were elucidated.