after 10 min incubation, followed by the cell lysate samplings. The amount of compounds in the collected samples were quantitated by LC-MS/MS analyses, which were used to calculate the respective disposition end- points. Gene expression levels of conjugation enzymes and efflux trans- porters in SCPC were evaluated by Real-time RT-PCR on Day 1 and 8. Results & Discussion: The majority of the related enzymes and trans- porters were upregulated in SCPC compared to the freshly isolated hepa- tocytes. In terms of acetaminophen (APAP), the metabolism seemed to follow the uptake of APAP, which saturated after 60 min incubation. The proportion of the major metabolites of glucuronide (APAP-Gluc) and sul- fate (APAPeSulf) corresponded to the known human metabolism proper- ties 2 . In addition, these compounds mostly transported to basolateral efflux than biliary excretion, which represented the tendency of urinary elimination. Further, in terms of basolateral efflux, APAP showed relatively higher passive diffusion portion than that of transporter-mediated, whereas APAP-Gluc and eSulf represented opposite trend, suggested the hydrophilic property of the conjugates mediated by the transporters. Conclusion: D-PREX can be used for the simultaneous evaluation of total disposition profiles not only the parent compounds but also their metab- olites, resulted from the complex interplay of the hepatic metabolism and transport. Further evaluations using probes regarding active-metabolites and human-specific metabolites are under examination. References: 1. Takahashi R, Ichikawa H, and Kanda K (2016) Novel multiple assessment of hepatocellular drug disposition in a single packaged procedure. Drug Metab Pharmacokinet 31(2): 167-171. 2. Bertolini A, Ferrari A, Ottani A, Guerzoni S, Tacchi R, and Leone S (2006) Paracetamol: New vistas of an old drug. CNS Drug Reviews 12(3-4): 250- 275. P108 IN VITRO ASSESSMENT OF THE RELATIVE TOXICITY OF A SERIES OF PYRROLIZIDINE ALKALOIDS: TAKING ACCOUNT OF METABOLIC ACTIVATION AND TOXICOKINETICS Cindy Obringer , Cathy Lester, John Troutman, Mike Karb, Catherine Mahony, Beatrice Nyagode, Amy Roe, Peter Stoffolano, Ken Wehmeyer. The Procter & Gamble Company, USA 1, 2-unsaturated pyrrolizidine alkaloids (PAs) are hepatotoxic compounds produced in some flowering weeds that can contaminate crops used for food or herbal medicines. The liver is the primary organ of toxicity making PAs a concern for safety assessment. PAs display a strong structure toxicity relationship with relative potencies spanning two orders of magnitude across structural classes. Current regulatory approaches to risk assessment take a precautionary approach and assume all PAs display the same toxicity as the most potent PA lasiocarpine. Here we outline an in vitro metabolism approach to support the assessment of the relative potencies of a structurally diverse group of PAs. Metabolic activation is catalyzed by P450 isozymes and results in the formation of a pyrrolizine reactive in- termediate known to bind proteins, glutathione and DNA. Because all hepatotoxic PAs exhibit the same mode of action, in vitro measurement of metabolic clearance and DNA adduct formation may be used to determine and rank relative PA potency. Here we present data for substrate depletion of lasiocarpine and heliotrine and their N-oxides. Effects of oxygen tension on oxidative and reductive metabolism by pooled male Sprague-Dawley rat liver microsomes is considered. Intrinsic clearance values are calculated using the t 1/2 method providing information on intracellular biotransfor- mation kinetics. Under ambient oxygen levels, the intrinsic clearance for 1 mM lasiocarpine and 1 uM heliotrine is 355 and 33.4 mL/min/mg protein, respectively, while no substrate loss was detected for their corresponding N-oxides. Under hypoxic conditions (2% O 2 ), intrinsic clearance values for lasiocarpine and lasiocarpine N-oxide are 170 mL/min/mg protein and 11 mL/min/mg protein, respectively. DNA adduct formation has been associ- ated with the incidence of tumor formation in vivo and is often studied in vitro in liver microsomal preparations in the presence of calf thymus DNA. We demonstrate enhanced sensitivity and simplification of this mea- surement by replacing calf thymus DNA with deoxyguanosine and deox- yadenosine in the microsomal incubation. The application of the tools presented here are being used to inform a strategy to assess the relative potencies of PAs and their N-oxides in vitro. P109 HIGH-THROUGHPUT, PERFUSED INTESTINAL TUBULES FOR REAL-TIME ASSESSMENT OF DRUG-INDUCED BARRIER DISRUPTION John Lowman 1 , Remko van Vught 2 , Sebastiaan Trietsch 2 , Elena Naumovska 2 , Dorota Kurek 2 , Karlijn Wilschut 2 , Henriette Lanz 2 , Arnaud Nicolas 2 , Stefan Kustermann 3 , Adrian Roth 3 , Paul Vulto 2 , Annie Moisan 3 . 1 Mimetas Inc, USA; 2 Mimetas BV, USA; 3 Roche Innovation Center Basel, Switzerland In vitro models that better reflect in vivo epithelial barrier (patho-) phys- iology are urgently required to better predict adverse drug effects ahead of clinical trials. Here, we describe extracellular matrix-supported intestinal tubules, continuously-perfused in a high-throughput microfluidic system (Mimetas’ OrganoPlate®). These tubules exhibit key tissue polarization markers (ErB1, ErBb2, Ezrin, ZO-1), relevant transporters (Glut-2, MRP2), and crypt-like morphology. Leak-tight polarization of these gut-on-a-chip barrier tubules was achieved after just 4 days in culture, and high-content characterization of the tubules was possible due to the absence of a filter membrane in the microfluidics. Functional drug-induced toxicity was assessed by apical exposure of model compounds to these in vitro intestinal barriers. Within each OrganoPlate®, forty leak-tight intestinal tubules were cultured in parallel, and their response to pharmacological stimuli was recorded over 125 hours of exposure. Overall, a study comprising 357 gut-on-a-chip tubes is per- formed, of which 93% are leak tight before exposure. EC50-time curves could be extracted that provide insight in both concentration and exposure time response. Full compatibility with standard equipment and user-friendly operation make this Organ-on-a-Chip platform readily applicable in routine labo- ratories. P110 BBB-ON-A-CHIP: A 3D IN VITRO MODEL OF THE HUMAN BLOOD-BRAIN BARRIER John Lowman 1 , Nienke Wevers 2 , Xandor Spijkers 2 , Karlijn Wilschut 2 , Remko van Vught 2 , Sebastiaan Trietsch 2 , Paul Vulto 2 . 1 Mimetas Inc, USA; 2 Mimetas BV, USA The BBB ensures a homeostatic environment for the brain and is made up of specialized endothelial cells and supporting astrocytes and pericytes. The BBB protects the brain from harmful substances. It also prevents large lipophilic compounds, including most therapeutic drugs, from entering the brain. This makes it difficult to treat brain diseases. While recent developments in microfluidic engineering have resulted in promising in vitro models of the BBB, the throughput and ease of use of these systems is low. This makes these models not suited for regular ac- ademic research and drug development. Here we present a novel BBB model using the 3-lane OrganoPlate®. This platform is based on a 384-well microtiter plate and allows for parallel culture of 40 perfused miniaturized tissues, making it fully compatible with standard lab procedures and equipment. The BBB-on-a-chip model comprises a perfused 3D microvessel of human brain microvascular endothelial cells. Perfusion through the lumen of the vessel is induced without pumps and can be controlled to model me- chanical cues. In addition, the microvessel is supported by human astro- cytes and pericytes that interact and support the endothelial vessel. The phenotype of the BBB-on-a-chip was characterized using immunofluo- rescent staining and showed presence of junctional markers VE-cadherin, PECAM-1, Claudin-5, and ZO-1. In addition, we have confirmed barrier function and adopted transporter assays to show functionality of two major BBB transporters, Pgp and GLUT1. In conclusion, we present a novel human BBB model in an easy to use microfluidic platform. This model can be used for fundamental BBB research, drug development or studying neurological disorders. Abstracts / Drug Metabolism and Pharmacokinetics 34 (2019) S20eS79 S54