单次肌注亚硒酸钠硒在犊牛体内的药代动力学研究

实验研究了单次肌注(OAmg/kg)亚硒酸钠注射液后,不同时间采血,用荧光分光光度计测定血硒浓度。经微机处理获得出血硒浓度理论值及药动学参数。血硒浓度—时间曲线符合—室开放模型,最佳药时方程:Ci=0.8688×(e-0.0023t-e-15.8967t)。主要动力学参数:T_(1/2) Ka=0.05±0.01(hrε);T_(1/2) Kel=322.62±45.86(hrs);Tp=0.58±0.12(hrs);Cmax=0.8665±0.1031(μg/ml);AUC=387.26±45.51(mg/L·hrs)。按单剂量给药参数,用多剂量给药模型公式计算出多剂量给药参数。     

Pharmacokinetic Disposition of Subcutaneously Administered Enrofloxacin in Goats

The pharmacokinetic disposition of enrofloxacin was studied in goats after subcutaneous (s.c.) administration at a single dose of 7.5 mg/kg body weight. Blood samples were drawn from a jugular vein into heparinized tubes at predetermined time intervals after administration of the drug and the plasma was separated by centrifugation. The concentrations of enrofloxacin in the plasma were determined by a microbiological assay using Escherichia coli as the test organism. The plasma concentration–time data were analysed by non-compartmental methods. Enrofloxacin was rapidly absorbed, an appreciable concentration of the drug (0.30±0.13 g/ml) being present in the plasma by 5 min after s.c. administration. The maximum plasma concentration of enrofloxacin and the time to reach that maximum were 2.91±0.39 g/ml and 2.9±0.51 h, respectively. A detectable concentration of enrofloxacin persisted in the plasma for 12 h. The elimination half-life and mean residence time of enrofloxacin were 2.84±0.57 and 5.74±0.28 h, respectively. It is suggested that enrofloxacin given subcutaneously may be useful in the treatment of susceptible bacterial infections in goats.     

吡喹酮脂质体在山羊体内的代谢动力学研究

本试验对吡喹酮脂质体在山羊体内的代谢动力学进行了研究.给山羊一次静脉推注吡喹酮脂质体3mg/kg·bw,取24h内不同间隔时间血样,血药浓度测定按文献操作[1].4只山羊的血药浓度测定结果,血药浓度--时间曲线符合无吸收因素一室开放模型.其药代动力学参数,消除半衰期(T1/2β)为10.00+0.59h);消除速率常数(ke)为0.0690±0.040h-1;初始浓度(B)为18.81±0.64(ug/100m1);维持有效血药浓度时间(TCP)为20.01±1.28h;表现分布容积(vd)O 2.85±0.37(100ml/ky);廓清率(CL)为0.139±0.029(100ml/ky·h)药时曲试下面积(AUC)为271.67士21.07(μg/100m1).     

丙硫苯咪唑在猪体内的药代动力学研究

本文建立了用反相高效液相色谱法测定丙硫苯咪唑及其代谢物丙硫苯咪唑亚砜、丙硫苯咪唑砜的血药浓度的方法,并测定了6头健康猪口服丙硫苯咪唑(25mg/kg)后亚砜和砜的血药浓度及有关药代动力学参数。结果:给药后20min采血,6头猪血中,丙硫苯咪唑原形药均未检出,而以丙硫苯咪唑亚砜和丙硫苯咪唑砜的形式出现。以NaVa pack C18 4μm 0.39×15cm为固定相,紫外检测器波长为290nm,甲苯咪唑为内标物,测定丙硫苯咪唑亚砜和砜.本法测得血清中亚砜的最低含量为23.56ng/mL,砜为16.54ng/mL。亚砜平均回收率为93.73±6.75％,砜为90.044±5.33％,不同浓度水平测定结果的日内和日间变动系数均在10％以下。丙硫苯咪唑亚砜和砜的药代动力学符合有吸收因素二室模型,健康猪口服丙硫苯咪唑后,亚砜半衰期(t1/B)为12.6466±1.8491h;血浆清除率(CL_B)为0.1364±0.0921L/(kg·h);血药浓度达峰时间(Tmax)为10h,峰浓度(Cmax)为11.919±1.382μg/mL血清;药时曲线下面积(AUC)为1156.69±742.52μg/(mL·h)。     

Comparative pharmacokinetics of an injectable cephalexin suspension in beef cattle

This study describes and compares the pharmacokinetics of a single 7.5 mg/kg dose of cephalexin monohydrate oil-based 20% suspension after its administrations to six cows by the intramuscular (i.m.) and subcutaneous (s.c.) routes, and to five calves by the i.m. route. Significantly (P < 0.05) higher peak plasma concentrations (5.6 ± 0.79 μg/ml versus 3.93 ± 1.24 μg/ml) and lower half-life (1.81 ± 0.56 h versus 4.21 ± 0.82 h) and mean residence time (4.12 ± 1.07 h versus 6.63 ± 0.85 h) were obtained after i.m. administration when compared to the s.c. administration to cows. No differences were found between pharmacokinetic parameters calculated for cows and calves. Cephalexin plasma concentrations remained above 0.5–0.75 μg/ml for 11–14 h and 8–9 h after the s.c. and i.m. administrations, respectively. Thus, route of administration may be an important issue to be considered when calculating dosage schedules for successful treatments and safe withdrawal times for veterinary medicines.     

氟苯尼考在鸡体内的药动学及其体内抗菌后效应研究

为探讨氟苯尼考的药动学特征及抗菌后效应(PAE),制订临床给药方案,用微生物法测定鸡血清中氟苯尼考浓度。建立鸡组织笼感染模型,以菌落计数法测定氟苯尼考的体内PAE。结果显示内服给药后药-时数据符合一级吸收一室开放式模型,其药动学方程为C=4.7804(e-0.1096t-e-2.5858t),主要药动学参数:t1/2Ke=(6.42±0.83)h、Cmax=(3.96±0.42)μg/mL、AUC=(42.41±7.50)(μg/mL).h-1、Vd=(6.63±0.68)L/kg;氟苯尼考浓度在2MIC、4MIC和8MIC时,作用1h的体内PAE分别为0.35、1.20和1.48h,同时测定的体外PAE为0.23、0.93和1.17h。鸡内服氟苯尼考的给药方案为1日1次,维持剂量30mg/kg体重。     

单诺沙星在鲫鱼体内的药物代谢动力学研究

以15 mg/kg的剂量肌肉注射单诺沙星,研究其在鲫鱼体内的药物动力学代谢规律。取给药后不同时间的鲫鱼血浆,采用反相高效液相色谱法测定血浆中单诺沙星的质量浓度,用MPTCP软件进行数据处理和分析。结果表明,健康鲫鱼肌注给药的药时数据符合二室开放模型,主要药物动力学参数为:表观分布容积(V)为5.099 0 L±0.061 5 L,分布半衰期(t1/2α)为0.527 5 h±0.008 1 h,消除半衰期(t1/2β)为286.944 0 h±18.595 0 h,药时曲线下面积(AUC)为387.767 7/(mg/L).h±23.779 3/(mg/L).h。单诺沙星在鲫鱼体内的主要药物动力学特征为分布快且完全,消除缓慢,作用时间长。     

Increased bioavailability of tylosin phosphate as in-feed medication formulated for long-action pellets in broiler chickens

Circadian variation of serum concentrations of tylosin in broiler chickens after in-feed medication prompted a comparison study of the serum profiles of this drug after in-feed medication with standard tylosin phosphate (Tprf reference formulation group), and after in-feed medication with a sustained-release pellet formulation (Tpsr group), based on Patent No.MX/a/2012/013222 and PCT/MX2013/000137, in broiler chickens. Six hundred 4-week-old Ross broiler chickens were in-feed medicated with tylosin phosphate at an approximate dose of 25.2 mg/kg/d, based on daily feed consumption values and a final concentration of tylosin in feed of 200 mg/kg of feed. Approximately 2 to 3 mL of blood were obtained per 5 chickens every 2 h, avoiding the sampling of a bird more than once and during 72 h after making medicated feed available for the first time. Serum concentrations of tylosin were determined by HPLC. Gaussian multi-peak regressions were then fitted to serum concentration vs. time profiles. Day by d areas under the serum concentration vs. time profiles (AUC_0–24), as well as overall AUC_0–72, were statistically higher for the Tpsr group (P < 0.001). Also, maximum serum concentrations obtained and relative bioavailability for the Tpsr formulation were statistically higher (382.8%) as compared to the Tprf group (P < 0.01). Considering the referred improved values of AUC observed in the Tpsr formulation, as well as the fact that tylosin is a time-dependent antibacterial drug, better clinical responses are postulated with this pharmaceutical preparation intended for chickens. Tissue deposition studies for this new formulation of tylosin are required.     

PHARMACOKINETICS OF SINGLE-DOSE BUPRENORPHINE,BUTORPHANOL, AND HYDROMORPHONE IN THE DOMESTIC FERRET (MUSTELA PUTORIUS FURO)

The objective of this study was to establish the clinical pharmacokinetic profile of 4 different opioid drugs (buprenorphine, butorphanol, hydromorphone, and morphine) in the domestic ferret (Mustela putorius furo). Twenty-four, approximately 1-year-old, male neutered purpose-bred domestic ferrets were used for this study. The ferrets were divided into 4 groups of 6, with a different opioid drug used for each group. A preopioid venous blood sample was obtained via cranial vena cava venipuncture. Following the initial blood collection, a single injection of opioid (hydromorphone 0.1 mg/kg, buprenorphine 0.04 mg/kg, butorphanol 0.3 mg/kg, and morphine 1 mg/kg) was given to each ferret, dependent on assigned drug group, intramuscularly (buprenorphine) or subcutaneously (hydromorphone, butorphanol, and morphine). Intramuscular injections were administered in the semimembranosis and semitendinosis muscles, whereas the subcutaneous injections were delivered in the intrascapular subcutaneous space. A venous blood sample was obtained at 5, 15, 30, 60, 120, 240, 360, 480, and 720 minutes postinjection from the ferrets in the buprenorphine, butorphanol, and hydromorphone groups. Mass spectrometry and liquid chromatography was performed to obtain plasma concentrations of the administered drugs. The mean maximum concentration of buprenorphine was 6.96 ng/mL, butorphanol was 48.6 ng/mL, and hydromorphone was 17.3 ng/mL. Maximum concentrations were achieved at a mean of 9 minutes after administration for buprenorphine, 13.3 minutes for butorphanol, and 8.33 minutes for hydromorphone. The mean half-life of buprenorphine was 219.1 minutes, butorphanol was 91.1 minutes, and hydromorphone was 24.7 minutes. Owing to severe complications arising within the morphine group, including hypersalivation and vomiting, the morphine study was discontinued prior to blood sample collection. Intramuscular injections of buprenorphine and subcutaneous injections of butorphanol or hydromorphone appeared to be well tolerated by all ferrets. The pharmacokinetics of buprenorphine, butorphanol, and hydromorphone of a single equipotent dose of each drug have been established through this research investigation and may be useful for further studies.