This study was conducted to re-establish the withdrawal time (WT) for ivermectin (IVM) in pigs as part of the introduction of the positive list system (PLS) program. Forty-two healthy pigs were orally administered IVM at doses of 2.4 mg/kg feed (IVM-1, n = 20) and 4.8 mg/kg feed (IVM-2, n = 20) once daily for 7 days. After treatment, tissue samples were collected from four pigs at 1, 3, 5, 7, and 14 days post-administration. Based on a previously established analytical method, residual IVM concentrations in pig tissues were determined using LC-MS/MS. In the IVM-1 group, IVM levels in muscle, liver, kidney, and fat were below the limit of quantification (LOQ) on days 7, 7, 7, and 14 after the final administration, respectively. In the IVM-2 group, IVM levels in muscle, liver, kidney, and fat were below the LOQ on days 7, 14, 7, and 14 after the final administration, respectively. According to the European Medicines Agency guideline on the determination of withdrawal times, the WTs for IVM-1 and IVM-2 in edible pig tissues were established as 8 and 11 days, respectively. In conclusion, the estimated WT of IVM in swine edible tissues was shorter than the currently recommended WT of 14 days for IVM.

• Yeung Bae Jin(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Chang-Soo Cho(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Woo H. Kim(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Kwang Il Park(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Suk Kim(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Hu-Jang Lee(College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea) Corresponding author
• Jin-Kyung Kim(Department of Dental Hygiene, Daegu Health College, Daegu 41453, Korea) Corresponding author