{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T16:36:57Z","timestamp":1753893417906,"version":"3.41.2"},"reference-count":25,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2024,7,31]],"date-time":"2024-07-31T00:00:00Z","timestamp":1722384000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Vet. Sci."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>Prescribing fenbendazole medicated feed for pheasants in the USA is considered extra-label drug use under CPG Sec 615.115, and a safe estimated withdrawal interval (WDI) must be applied following administration to this minor food-producing species. This study sought to determine the pharmacokinetic and residue depletion profile for fenbendazole and its major metabolites to estimate a WDI for pheasants following fenbendazole administration as an oral medicated feed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Method<\/jats:title><jats:p>Pheasants (<jats:italic>n<\/jats:italic> = 32) were administered fenbendazole as an oral medicated feed (100 ppm) for 7 days. Fenbendazole, fenbendazole sulfoxide, and fenbendazole sulfone (FBZ-SO<jats:sub>2<\/jats:sub>) in liver and muscle samples were analyzed using HPLC-UV. Tissue WDIs were estimated using FDA, European Medicines Agency (EMA), and half-life multiplication methods for US poultry tolerances, EMA maximum residue limits, and the analytical limit of detection (LOD; 0.004 ppm). Terminal tissue elimination half-lives (T<jats:sub>1\/2<\/jats:sub>) were estimated by non-compartmental analysis using a na\u00efve pooled data approach.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The tissue T<jats:sub>1\/2<\/jats:sub> was 14.4 h for liver, 13.2 h for thigh muscle, and 14.1 h for pectoral muscle. The maximum estimated withdrawal interval was 153 h (7 days) for FBZ-SO<jats:sub>2<\/jats:sub> in pectoral muscle using the FDA tolerance method (95% confidence interval for the 99<jats:sup>th<\/jats:sup> percentile of the population), and the LOD as the residue limit.<\/jats:p><\/jats:sec><jats:sec><jats:title>Discussion<\/jats:title><jats:p>The results from this study support the use of FBZ-SO<jats:sub>2<\/jats:sub> as the marker residue in the liver of pheasants and the provision of evidence based WDIs following the extra-label administration of fenbendazole medicated feed (100 ppm) for 7 days.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fvets.2024.1444009","type":"journal-article","created":{"date-parts":[[2024,7,31]],"date-time":"2024-07-31T10:19:36Z","timestamp":1722421176000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Estimation of withdrawal interval recommendations following administration of fenbendazole medicated feed to ring-necked pheasants (Phasianus colchicus)"],"prefix":"10.3389","volume":"11","author":[{"given":"Marta","family":"Carre\u00f1o G\u00fatiez","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Melissa A.","family":"Mercer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Beatriz","family":"Mart\u00ednez-L\u00f3pez","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ronald W.","family":"Griffith","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Scott","family":"Wetzlich","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lisa A.","family":"Tell","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2024,7,31]]},"reference":[{"key":"B1","unstructured":"Minor Use\/Minor Species2021"},{"key":"B2","unstructured":"Poultry - Inventory and Number Sold: 2017 and 20122017"},{"key":"B3","unstructured":"Animal Drugs @ FDA2024"},{"key":"B4","unstructured":"Electronic Code of Federal Regulations. Title 21: Food and Drugs. PART 530\u2014Extralabel drug use in animals1991"},{"key":"B5","first-page":"1054","article-title":"Anti-nematodal drugs","author":"Lanusse","year":"2009","journal-title":"Veterinary Pharmacology and Therapeutics"},{"key":"B6","doi-asserted-by":"publisher","first-page":"393","DOI":"10.2298\/AVB0306393P","article-title":"Most frequent nematode parasites of artificially raised pheasants (Phasianus colchicus L","volume":"53","author":"Pavlovic","year":"2003","journal-title":"Acta Veterinaria."},{"key":"B7","first-page":"1047","article-title":"Syngamus trachea","author":"Yazwinski","year":"2008","journal-title":"Diseases of Poultry."},{"key":"B8","doi-asserted-by":"publisher","first-page":"311","DOI":"10.2307\/1590337","article-title":"Treatment of nematodiasis in poultry and game birds with fenbendazole","volume":"28","author":"Kirsch","year":"1984","journal-title":"Avian Dis."},{"key":"B9","doi-asserted-by":"publisher","first-page":"50","DOI":"10.1111\/j.1365-2885.1988.tb00120.x","article-title":"The oxidative metabolism of fenbendazole: a comparative study","volume":"11","author":"Short","year":"1988","journal-title":"J Vet Pharmacol Ther."},{"key":"B10","unstructured":"CPG Sec 615.115 Extralabel Use of Medicated Feeds for Minor Species2016"},{"key":"B11","unstructured":"General Principles for Evaluating the Human Food Safety of New Animal Drugs Used in Food-Producing Animals2022"},{"key":"B12","doi-asserted-by":"publisher","first-page":"147","DOI":"10.1016\/j.chemolab.2007.03.002","article-title":"Using the correct intervals for prediction: a tutorial on tolerance intervals for ordinary least-squares regression","volume":"87","author":"De Gryze","year":"2007","journal-title":"Chemom Intell Lab Syst."},{"key":"B13","unstructured":"Guideline on determination of withdrawal periods for edible tissues2022"},{"key":"B14","first-page":"1474","article-title":"Chapter 61-chemical residues in the tissues of food animals","volume-title":"Veterinary Pharmacology and Therapeutics.","author":"Riviere","year":"2018"},{"key":"B15","doi-asserted-by":"publisher","first-page":"2559","DOI":"10.1039\/a805363d","article-title":"Determination of fenbendazole and its metabolites in trout by a high-performance liquid chromatographic method","volume":"123","author":"S\u00f8rensen","year":"1998","journal-title":"Analyst."},{"key":"B16","unstructured":"Validation of analytical procedures: Methodology. 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