Toltrazuril (TZR) is currently the only registered chemotherapeutic drug in the European Union for the treatment of Cystoisospora suis. This study investigated the comparative pharmacokinetics and tissue concentration-time profiles of TZR and its active metabolite, toltrazuril sulfone (TZR-SO₂), after oral (per os, p.o.) and intramuscular (i.m.) administration to suckling piglets. Following a single administration of TZR orally at 50 mg/piglet or intramuscularly at 45 mg/piglet, higher concentrations of TZR and TZR-SO₂ were observed in all three investigated tissues after p.o. administration. The mean TZR concentration in serum peaked at 14 μg/mL (34.03 h) and 5.36 μg/mL (120 h), while TZR-SO₂ peaked at 14.12 μg/mL (246 h) and 9.92 μg/mL (330 h) after p.o. and i.m. administration, respectively. TZR was undetectable in the liver after p.o. administration (18 days) and in the jejunum (24 days) after i.m. injection, while TZR-SO₂ was still detectable in all three tissues after 36 days regardless of administration routes. This study showed that p.o. formulation exhibited faster absorption and higher serum/tissue TZR/TZR-SO₂ concentrations than i.m. formulation. Both formulations generated sufficient therapeutic concentrations in the serum and jejunum, and sustained enough time to protect against Cystoisospora suis infection in the piglets.

中文翻译：

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口服和肌肉注射后托曲珠利及其代谢物托曲珠利砜在哺乳仔猪中的药代动力学

妥曲珠利（TZR）是目前欧盟唯一注册的用于治疗猪等孢子虫的化疗药物。本研究调查了哺乳仔猪口服（口服、口服）和肌肉注射（im）后，TZR 及其活性代谢物妥曲珠利砜（TZR-SO _{2 ）的药代动力学和组织浓度-时间曲线的比较。}单次口服给予 50 mg/仔猪或肌肉注射 45 mg/仔猪后，口服给药后，在所有三个研究组织中均观察到较高浓度的 TZR 和 TZR-SO _{2 。}血清中 TZR 平均浓度峰值为 14 μg/mL（34.03 h）和 5.36 μg/mL（120 h），而 TZR-SO ₂峰值为 14.12 μg/mL（246 h）和 9.92 μg/mL（330 h）分别在 po 和 im 给药后。口服给药后（18天）在肝脏中检测不到TZR，肌内注射后在空肠中（24天）检测不到TZR，而无论给药途径如何，36天后在所有三种组织中仍然可检测到TZR-SO _{2 。}该研究表明，po制剂比im制剂表现出更快的吸收和更高的血清/组织TZR/TZR-SO _2浓度。两种制剂在血清和空肠中产生足够的治疗浓度，并持续足够的时间来防止仔猪感染猪等孢子虫。