title: Species extrapolation of life-stage physiologically-based pharmacokinetic (PBPK) models to investigate the developmental toxicology of ethanol using in vitro to in vivo (IVIVE) methods.
abstract: To provide useful alternatives to in vivo animal studies, in vitro assays for dose-response assessments of xenobiotic chemicals must use concentrations in media and target tissues that are within biologically-plausible limits. Determining these concentrations is a complex matter, which can be facilitated by applying physiologically-based pharmacokinetic (PBPK) models in an in vitro to in vivo extrapolation (IVIVE) paradigm. We used ethanol (EtOH), a ubiquitous chemical with defined metrics for in vivo and in vitro embryotoxicity, as a model chemical to evaluate this paradigm. A published series of life-stage PBPK models for rats was extended to mice, yielding simulations that adequately predicted in vivo blood EtOH concentrations (BECs) from oral, intraperitoneal, and intravenous routes in nonpregnant and pregnant adult mice. The models were then extrapolated to nonpregnant and pregnant humans, replicating BEC data within a factor of two. The rodent models were then used to conduct IVIVEs for rodent and whole-embryo culture embryotoxicity data (neural tube closure defects, morphological changes). A second IVIVE was conducted for exposure scenarios in pregnant women during critical windows of susceptibility for developmental toxicity, such as the first 6-to-8 weeks (prerecognition period) or mid-to-late pregnancy period, when EtOH consumption is associated with fetal alcohol spectrum disorders. Incorporation of data from human embryonic stem cell studies led to a model-supported linkage of in vitro concentrations with plausible exposure ranges for pregnant women. This effort demonstrates benefits and challenges associated with use of multispecies PBPK models to estimate in vivo tissue concentrations associated with in vitro embryotoxicity studies.
authors.affiliation: *National Health and Environmental Effects Research Laboratory and National Center for Environmental Assessment, United States Environmental Protection Agency sam506@gmail.com.
authors.forename: Sheppard A
authors.initials: SA
authors.lastname: Martin
authors.affiliation: *National Health and Environmental Effects Research Laboratory and National Center for Environmental Assessment, United States Environmental Protection Agency.
authors.forename: Eva D
authors.initials: ED
authors.lastname: McLanahan
authors.affiliation: *National Health and Environmental Effects Research Laboratory and National Center for Environmental Assessment, United States Environmental Protection Agency.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Bushnell
authors.affiliation: *National Health and Environmental Effects Research Laboratory and National Center for Environmental Assessment, United States Environmental Protection Agency.
authors.forename: E Sidney
authors.initials: ES
authors.lastname: Hunter
authors.affiliation: *National Health and Environmental Effects Research Laboratory and National Center for Environmental Assessment, United States Environmental Protection Agency.
authors.forename: Hisham
authors.initials: H
authors.lastname: El-Masri
mesh_terms: D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D004333:Drug Administration Routes; D047108:Embryonic Development / Q000187:drug effects*; D000431:Ethanol / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000633:toxicity*; D005260:Female; D047109:Fetal Development / Q000187:drug effects*; D005865:Gestational Age; D006801:Humans; D018811:Maternal Exposure; D008954:Models, Biological; D011237:Predictive Value of Tests; D011247:Pregnancy; D013045:Species Specificity; D014018:Tissue Distribution
chemical_list: D000431:Ethanol
keywords: Ethanol; Physiologically-based pharmacokinetic model; in vitro to in vivo extrapolation