Abstract：
The objectives of this study were to compare the serum and seminal plasma pharmacokinetic profiles of florfenicol (FLO) and florfenicol amine (FLA) after the administration of FLO either by IM or SC routes in beef bulls. Four clinically healthy Hereford bulls underwent a comprehensive physical exam, including breeding soundness examination, CBC, and chemistry profile panel. Bulls were healthy and classified satisfactory potential breeders. In one group (n = 2), a single dose of FLO was administered SC in the middle of the neck at a dose of 40 mg/kg of body weight. In the second group (n = 2), a single dose was administered IM in the muscles of the neck at a dose of 20 mg/kg. Concentrations of FLO and FLA in serum and seminal plasma were determined by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Blood and semen samples were collected before the administration of FLO and at 12, 24, 36, 48, 72, 96, 120, 144, and 168 h after injection. The blood was collected from the coccygeal vessels, and semen was collected by electroejaculation. All samples were immediately refrigerated, processed within the first hour after collection, and finally stored at -80 °C. The mean level of total FLO in serum was higher when administered by the SC route (1,415.5 ng/mL) than by the IM route (752.4 ng/mL; P = 0.001). Differences were observed between the percentage of FLA in serum (1.8%; ranging from 1.3 to 2.9) and in seminal plasma (27.5%; ranging from 15.9 to 34.2; P = 0.0001). The mean level (±SD) of FLA was higher in seminal plasma compared to serum (467 ± 466 ng/mL and 18 ± 16 ng/mL, respectively; P = 0.001). The mean level of total FLO in seminal plasma was 1,454.8 ng/mL for the SC route and 1,872.9 ng/mL for the IM route without differences between the two routes (P = 0.51). Differences in the mean level of total FLO between serum and seminal plasma were detected (1,187 ± 2,069 ng/mL and 1,748 ± 1,906 ng/mL, respectively; P = 0.04). From the present investigation, it was concluded that FLO is a suitable antibiotic based on its pharmacokinetic attributes and may be employed for the treatment of bull genital infections when its use is indicated. To study the pharmacokinetics of FLO in seminal plasma, the analysis of FLA should be incorporated.
摘要：
这项研究的目的是比较氟苯尼考（FLO）和氟苯尼考胺（FLA）在牛牛中通过IM或SC途径施用FLO后的血清和精浆药代动力学特征。四只临床健康的赫里福德公牛接受了全面的身体检查，包括繁殖健全性检查，CBC,和化学简介面板。公牛是健康的，被归类为令人满意的潜在育种者。在一组（n=2）中，单剂量的FLO以40mg/kg体重的剂量在颈中SC给药。在第二组（n=2）中，单剂量以20mg/kg的剂量在颈部肌肉中IM给药。采用超高效液相色谱-串联质谱(UHPLC-MS/MS)法测定血清和精浆中FLO和FLA的浓度。在施用FLO之前和在注射后12、24、36、48、72、96、120、144和168小时收集血液和精液样品。血液是从尾骨血管收集的，精液是通过电射精收集的。所有样品立即冷藏,在收集后的第一个小时内处理，最后储存在-80℃。当通过SC途径施用时,血清中总FLO的平均水平(1,415.5ng/mL)高于IM途径(752.4ng/mL;P=0.001)。血清中的FLA百分比（1.8％；范围从1.3到2.9）和精浆中的FLA百分比（27.5％；范围从15.9到34.2；P=0.0001）之间观察到差异。精浆中FLA的平均水平（±SD）高于血清（467±466ng/mL和18±16ng/mL，分别；P=0.001）。SC途径的精浆中总FLO的平均水平为1,454.8ng/mL，IM途径为1,872.9ng/mL，两种途径之间没有差异（P=0.51）。检测到血清和精浆之间总FLO平均水平的差异（1,187±2,069ng/mL和1,748±1,906ng/mL，分别为；P=0.04)。从目前的调查来看,结论是,基于FLO的药代动力学特性,FLO是一种合适的抗生素,在有适应需要时可用于治疗公牛生殖器感染.研究精浆中FLO的药代动力学，应纳入FLA的分析。
