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The regional center at NCSU will continue to support the essential tasks of the national FARAD program outlined below, providepharmacokinetic services to all FARAD sites, and continue developing pharmacokinetic model tools that allow FARAD responders to fully utilize published studies to avoid meat, egg, and milk violative residues in food animals. The primary focusareas of the NC FARAD component for 2019 - 2020 are as follows: (1) collaborate with KSU, UC Davis, Virginia Tech, andUniversity of Florida, to validate (via in vivo studies) many of our computational estimates of a safe withdrawal time; (2)strengthen the response team by recruiting graduate students at NCSU-CVM and working closely Dr. Jennifer Davis' team atVirginia Tech. and Dr. Lisa Tell's team at UC Davis to provide drug and chemical residue management expertise to veterinariansby answering telephone and internet inquiries; (3) continue to implement an interface between developed PopPK models andresidue cases for those PopPK models already developed by FARAD over the last 17 years. The latter will continue to betasked to Dr. Jason Chitterden, Principal Consultant with Modelytica, LLC and Dr. Rob DeWoskin (Ph.D, DABT) to provideQA/QC of all FARAD models. Dr. Kristin Messenger will continue to provide her expertise in PopPk and develop PK/PD modelsin livestock with her graduate student.Pharmacokinetic Trials: One specific focus area for 2020-2021 will be to continue our work with Dr. Derek Foster (DVM,DACVIM), as he has brought his expertise in antimicrobial resistance (AMR) and attempting to understand drug residuedeposition in various tissue compartments and how it is related to AMR. There is the question of whether drug residuewithdrawal times have any effect on emerging AMR. Our team will continue to assess drug residues in laying hens as backyardpoultry continues to be about a 30% of calls that FARAD receives and we have very limited data to help poultry farmers andveterinarians. Our ruminant team will also be completing our goat residue trials with flunixin for which there is no data andstarting other ruminant projects related to Dr. Foster's antimicrobials and Dr. Smith's work with gabapentin in cattle. Our teamwill be conducting at least animal trials; these will be mostly cows but include some goat and swine and to validatephysiologically-based PK (PBPK) models and mixed effect (PopPK) models developed by our team and one poultry trial.Respond to drug and chemical residue cases: The NCSU FARAD Regional Access Center will continue in collaboration withUC-Davis FARAD Regional Access Center and response center at Virginia Tech to answer residue avoidance. This service atNC FARAD will be led by Dr. Jennifer Halleran (DVM, DACVIM). Dr. Halleran in addition to her PhD work will be responsible fordaily management of cases at NC FARAD and will be working very closely with Dr. Baynes and the other regional responsecenters. The strengthening of the response team at NCSU will greatly facilitate literature retrieval and the accuracy andtimeliness of NCSU's response to as many as 70 cases a week. We will continue to collaborate on writing timely FARADDigests that focus on the management of the more common drug residue scenarios facing food animal veterinarians. We willcontinue to collaborate in outreach programs to producer groups and veterinary specialty groups such as AVMA, AABP,AAVPT, and US Codex. Dr. Baynes represents FARAD and AAVPT in bimonthly US Codex delegation discussions. Dr. Smith isan active member of AABP and has provided key feedback to FARAD from bovine veterinarians regarding the quality of FARADservice provided to veterinarians.Implementation of a PopPK Responders Interface: FARAD has developed numerous PopPK models over the last 17 years.Several of these models have part been validated for the most part and therefore robust enough to be implemented to helpanswer drug residue questions fielded by our FARAD responders. We intend to continue building an interface between thesemodels and questions presented to our responders so that our recommended withdrawal intervals are population-based andmore reliable than using traditional PK parameters and methods that are based on average parameter values and does not takeinto account population variance. Dr. Jason Chitterden will be tasked to improve delivery of this interface in 2020-2021. In termsof developing pharmacokinetic model tools, our long-term goal is to develop a web-based interactive tool that allows FARADresponders to easily calculate drug withdrawal intervals after extralabel use of different drugs in different food animal species.To achieve this long-term goal and build upon our earlier work we plan to develop popPK models describing withdrawal intervalsfor common drugs in common species.

Baynes, Ronald E; Foster, Derek
North Carolina State University
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