恩诺沙星及其活性代谢物在传染性鼻炎鸡体的药动学

为建立鸡传染性鼻炎的药动学模型,研究了恩诺沙星及其活性代谢物在传染性鼻炎鸡体内的药动学特征.用反向高效液相色谱法测定血浆中的药物浓度,所得恩诺沙星的ci-ti数据用MCPKP程序处理,代谢物环丙沙星的ci-ti数据用代谢物动力学方法处理.结果表明,鸡静注恩诺沙星后的ci-ti数据符合二室开放模型,其主要动力学参数如下:t1/2α(0.25±0.04) h、t1/2β(5.46±0.71) h、Vd(4.21±1.09) L/kg、CLB(0.54±0.11) L/(kg.h)、AUC(19.68±3.50) mg/(L.h).鸡内服恩诺沙星的ci-ti数据,符合有吸收因素二室模型,其主要动力学参数如下:t1/2ka(0.44±0.11) h、t1/2α(1.17±0.40) h、t1/2β(9.24±2.07) h、AUC(12.23±3.68) mg/(L.h)、tmax(1.50±0.29) h、Cmax(1.34±0.44) mg/L、F 62.26%.恩诺沙星在感染鸡体内的动力学特征是吸收迅速、分布广泛、消除缓慢;感染鸡静注与内服恩诺沙星后,代谢物环丙沙星的动力学特征是生成及消除缓慢、分布广泛.鸡传染性鼻炎可使恩诺沙星内服的生物利用度下降,但对恩诺沙星的分布、消除及代谢物的动力学过程无显著影响.     

三聚氰胺在鸡体内的药动学研究

40日龄岭南三黄肉鸡30只,随机分为2组,分别进行了静注和口服三聚氰胺(20 mg/kg)的药动学研究。用反相高效液相色谱法测定鸡血浆中三聚氰胺的浓度,WinNonlin计算机程序软件处理静注和口服的血浆药物浓度-时间数据。健康鸡静注给药的药时数据适合二室开放模型,主要药物动力学参数为:t1/2α(1.95±0.34)h;t1/2β(9.71±4.28)h;Vc(1.54±0.11)L/kg;Vd(area)(4.10±0.33)L/kg;ClB(0.42±0.08)L.kg-1.h;AUC(49.28±9.97)mg.L-1.h。健康鸡内服三聚氰胺的药时数据适合一级吸收二室开放模型,主要药动学参数为:t1/2α(1.98±0.24)h;t1/2β(12.05±5.66)h;tmax(2.05±0.74)h;Cm ax(5.87±0.94)mg/L;AUC(40.76±6.33)mg.L-1.h。三聚氰胺在健康鸡体内的主要药动学特征为,口服吸收较完全,分布广泛,消除缓慢。     

甲砜霉素在感染多杀性巴氏杆菌鸡体内的药物动力学

30只健康杂交肉鸡随机分成3组,每组10只,雌雄各半,分别进行健康鸡静脉注射、健康和巴氏杆菌感染鸡口服给药的药动学研究。静注和口服的给药剂量按体质量分别为15mg/kg和30mg/kg。以反相HPLC测定血浆中甲砜霉素的质量浓度,药物浓度-时间数据用3P97药动学程序软件处理。健康鸡单剂量静注给药后,血药浓度-时间数据符合无吸收二室开放模型,其主要动力学参数分别为:V(c)为(0.58±0.09)L/kg,t1/2α(0.11±0.03)h,t1/2β(0.95±0.18)h,AUC为(11.99±0.90)mg/(L.h),CL(s)为(1.26±0.10)L/(kg.h)。健康鸡和巴氏杆菌感染鸡单剂量口服给药血药浓度-时间数据均符合一级吸收一室开放模型。健康鸡口服给药的主要动力学参数分别为:Lagtime(0.04±0.02)h,t1/2ka(0.16±0.08)h,t1/2ke(1.64±0.22)h,T(peak)(0.57±0.18)h,C(max)(6.34±0.56)mg/L,AUC为(19.02±1.48)mg/(L.h),F为79.32%。巴氏杆菌感染鸡口服给药的主要动力学参数分别为:Lagtime(0.07±0.02)h,t1/2ka(0.54±0.26)h,t1/2ke(1.74±0.27)h,T(peak)(1.31±0.39)h,C(max)(5.28±0.73)mg/L,AUC为(21.75±1.03)mg/(L.h),F90.70%。与健康鸡相比,甲砜霉素在感染鸡的t1/2(ka)、T(peak)和Lag-time显著延长(P0.05或P0.01),且比健康鸡具有更高的生物利用度。但甲砜霉素在巴氏杆菌感染鸡体内的消除速度未受影响。     

恩诺沙星在鸡体内的生物利用度试验

将40日龄肉鸡12只,随机分为2组,分别进行了静脉注射、肌肉注射恩诺沙星(10mg/kg)进行药动学研究。血浆样品经甲醇沉淀血浆蛋白,高速离心,用反相高效液相色谱法测定鸡血浆中恩诺沙星的浓度,3P97计算机程序处理静注及肌注的血浆药物浓度-时间数据。健康鸡静注给药的药时数据适合二室开放模型,主要药物动力学参数为:t1/2α (0.45±0.56) h;t1/2β (7.02±1.42) h;C LB (0.38±0.10) L/(kg·h);A U C (23.69±5.56) (mg·h)/L。健康鸡肌注给药的药时数据适合一级吸收二室模型,主要药物动力学参数为:t1/2α (0.60±0.00) h;t1/2β (8.25±1.73) h;tmax (2.44±0.17)h;Cmax (1.44±0.30) m g/L;A U C(20.74±3.80) (mg·h)/L;F为87.54%。恩诺沙星在健康鸡体内的吸收迅速,达到峰值时间短,消除缓慢。     

硫酸头孢喹肟在鸡体内的药动学和生物利用度研究

为了解硫酸头孢喹肟口服和静注给药在鸡体内的动力学特征,用高效液相色谱法测定鸡血浆中的药物质量浓度,所得硫酸头孢喹肟血药浓度数据用3p97计算机软件处理。结果显示:硫酸头孢喹肟以每公斤体重10 mg单剂量静注给药,药物浓度-时间数据经药动学程序拟合符合无吸收二室开放动力学模型,主要药动学参数分别为:中央室分布容积V(c)(1.16±0.02)L·kg-1,分布半衰期T1/2α(0.29±0.03)h,消除半衰期T1/2β(1.69±0.24)h,曲线下面积AUC(6.57±0.18)mg·L-1·h,清除率CL/f(s)(1.53±0.04)mg·L-1·h。硫酸头孢喹肟以每公斤体重20 mg口服给药的血药浓度时间数据,符合一级吸收一室开放模型,主要动力学参数:吸收半衰期T1/2 ka(0.52±0.04)h,消除半衰期T1/2 ke(0.88±0.05)h,峰时Tmax(1.07±0.02)h,最高血药浓度Cmax(3.63±0.25)μg·mL-1,曲线下面积AUC(9.84±0.68)mg·L-1·h,表观分布容积V/f(c)(3.85±0.30)L·kg-1·h-1,生物利用度F(74.9±0.06)%。结果表明:硫酸头孢喹肟静注给药能迅速从血液分布进入组织中,在体液中具有良好的渗透和分布性能,体内分布广泛,能迅速从血液中消除。口服给药吸收迅速,达峰时间短。口服给药在鸡体内生物利用度稍低,可能由于硫酸头孢喹肟的脂溶性低,其在消化道吸收率低所致。但在8 h内能保持有效血药浓度范围(0.09⁵.74μg·mL-1),可以有效控制常见细菌感染。     

单诺沙星在支原体一大肠杆菌感染鸡体内的药动学与生物利用度的研究

以高效液相色谱法为定量手段研究了单诺沙星内服给药在支原体与大肠杆菌合并感染鸡体内的药动学特征及生物利用度。 12 0只合并感染雏鸡静注或内服单诺沙星 (5mg/kg)后 ,血药浓度时间数据分别符合无吸收二室模型和一级吸收二室模型。静注给药的主要动力学参数为t1/ 2α0 .5 0 34h,t1/ 2 β为 6 .8485h,VB 为 12 .16 0 3L/kg,AUC为 40 6 33mg/L·h ,Tcp为 2 5 .2 43h。内服给药的主要动力学参数如下 :t1/ 2ka为 0 .3182h ,t1/ 2α为 1.5 5 0 2h ,t1/ 2 β为 12 .6 2 0 0h ,Tp 为 1.110 7h ,Cmax为 0 .5 10 6 μg/mL ,AUC为 3.6 6 2mg/Lh ,Tcp为 39.18h。内服生物利用度为 90 .0 8%。     

单诺沙星在雏鸡体内的药动学特征及生物利用度研究

以高效液相色谱法为定量手段研究了单诺沙星内服给药在雏鸡体内的药动学特征及生物利用度。 12 0只雏鸡静注或内服单诺沙星 (5mg/kg)后 ,血药浓度时间数据分别符合无吸收二室模型和一级吸收二室模型。静注给药的主要动力学参数为t1/ 2α0 .34h ,t1/ 2 β为 7.3184h ,VB 为 16 .0 6 31L/kg ,AUC为 3.2 872mg/L·h ,Tcp为 2 5 .0 1h。内服给药的主要动力学参数如下 :t1/ 2ka为 0 .2 42 8h ,t1/ 2α为 0 .8917h ,t1/ 2 β为 8.7936h ,Tp 为 0 .9377h ,Cmax为 0 .5 487μg/mL ,AUC为3 .0 5 2 3mg/L·h ,Tcp为 31.115h。内服生物利用度为 92 .85 %。     

20%吡喹酮注射剂在水牛体内的药代动力学研究

4头成年健康水牛采用随机交叉实验设计,分别进行吡喹酮注射剂肌注和吡喹酮片内服给药的药动学试验.吡喹酮注射剂按10 mg/kg的剂量单次肌注,吡喹酮片按20 mg/kg的剂量单次内服给药.采用高效液相色谱法测定血浆中吡喹酮的质量浓度,方法最低检测限和定量限分别为0.01 mg/L和0.062 5 mg/L.吡喹酮注射剂单剂量肌注给药,血药浓度-时间数据符合一级吸收一室开放模型,其主要动力学参数分别为:t1/2(ka)(0.45±0.029)h,t1/2(ke)(5.04±0.1 0)h,T(peak)(1.72±0.029)h,C(max)(0.87±0.006)mg/L,V(c)(8.58±0.010)L/kg,AUC(7.99±0.005)mg·L-1·h-1.吡喹酮片单剂量口服给药血药浓度-时间数据符合有吸收-室开放模型,其主要动力学参数分别为:Lagtime(0.13±0.010)h,t1/2(ka)(0.76±0.11)h,t1/2(ke),(1.31±0.076)h,T(peak)(3.84±0.026)h,C(max)(0.51±0.006)mg/L,V(c)(26.07±1.221)L/kg,AUC(7.99±0.005)mg·L-11·h-1.肌注相对生物利用度为(232±12.9)%.研究结果表明,20%吡喹酮注射剂肌注给药吸收迅速且完全,具有较高的生物利用度;吡喹酮吸收后在体内广泛分布.     

环丙沙星和磺胺间甲氧嘧啶联合用药在猪体内的血浆药动学

采用高剂量CIP(20mg/kg体质量)和SMM(100mg/kg体质量)联合肌注给药,同步检测试验猪各采血点的血药浓度,通过DAS药物动力学程序软件分析血药浓度—时间数据。结果显示:CIP和SMM在联用时药时数据均符合一级吸收二室开放模型,CIP主要的药动学参数:t1/2为(4.98±0.60)h,Vd为(6.61±0.81)L/kg,AUC为(21.79±1.01)(mg/L)·h,Cmax为(7.56±0.26)mg/L,t1/2Ka为(0.93±1.86)h;SMM主要的药动学参数:t1/2为(4.98±0.92)h,Vd为(1.06±0.19)L/kg,AUC为(679.99±13.17)(mg/L)·h,Cmax为(72.75±3.26)mg/L,t1/2Ka为(0.72±0.36)h。联合用药符合生产中多种药共用的情况,为以后多类属药物残留消除规律研究提供参考。     

甲砜霉素在鸡体内的药动学

20只健康杂交肉鸡,随机分成2组,每组10只,雌雄各半,分别进行静脉注射和口服甲砜霉素给药的药动学研究。静注和口服的给药剂量分别为15、30 mg/kg。以反相HPLC测定血浆中甲砜霉素的浓度,药物浓度-时间数据用3P97药动学程序软件处理。鸡单剂量静注给药后,血药浓度-时间数据符合无吸收二室开放模型,其主要动力学参数分别为:V(c)(0.92±0.01)L/kg,t1/2α(0.27±0.02)h,t1/2β(3.46±0.74)h,AUC(11.67±0.57)mg/(L.h),CL(s)1.29 L/(kg.h)。鸡单剂量口服给药血药浓度-时间数据符合一级吸收一室开放模型,其主要动力学参数分别为:Lagtime(0.04±0.01)h,t1/2ka(0.76±0.11)h,t1/2ke(2.16±0.58)h,T(peak)(1.73±0.11)h,C(max)(6.03±0.92)mg/L,AUC(32.43±0.75)mg/(L.h),F(138.58±0.07)%。甲砜霉素在鸡体内的药动学特征表现为分布广泛,消除迅速;口服给药吸收迅速且完全,生物利用度高。     

硫酸头孢喹肟在鸭体内的药动学及生物利用度研究

试验将20只2月龄健康番鸭,随机分为2组,每组10只,雌雄各半,分别进行静脉注射和口服硫酸头孢喹肟给药的药动学研究。静脉注射和口服的给药剂量分别为10和20 mg/kg。以反相HPLC测定血浆中硫酸头孢喹肟的浓度,血药浓度—时间数据用3P97药动学程序软件处理。鸭单剂量静脉注射给药后,血药浓度—时间数据符合无吸收二室开放模型,其主要动力学参数分别为:V（c）,（1.146±0.02） L/kg;t_1/2α,（0.290±0.02）h;t_1/2β,（1.691±0.15）h;AUC （6.635±0.18）（mg·h）/L;CL（s）,（1.508±0.04）L/（kg·h）。鸭口服硫酸头孢喹肟的血药浓度—时间数据符合一级吸收一室开放模型,主要动力学参数分别为:t_1/2（ka）,（0.45±0.05）h;t_1/2（ke）,（0.96±0.29）h;T_（peak）,（0.91±0.09）h;C_（max）,（3.14±0.64）mg/L;AUC,（8.29±1.26）（mg·h）/L;F,（62.55±0.10）%。硫酸头孢喹肟在体内的药动学特征表现为吸收迅速、分布广泛、消除迅速。但口服给药在鸭体内生物利用度低,可能由于硫酸头孢喹肟的脂溶性低,其在消化道吸收率低所致。但8 h内能保持有效血药浓度范围（（0.14±0.03）~（3.14±0.64）μg/mL）,可抑制鸭疫里默氏杆菌及其他细菌感染。     

Comparative study of the plasma pharmacokinetics and tissue concentrations of danofloxacin and enrofloxacin in broiler chickens

The plasma pharmacokinetics of danofloxacin and enrofloxacin in broiler chickens was investigated following single intravenous (i.v.) or oral administration (p.o.) and the steady-state plasma and tissue concentrations of both drugs were investigated after continuous administration via the drinking water. The following dosages approved for the treatment of chickens were used: danofloxacin 5 mg/kg and enrofloxacin 10 mg/kg of body weight. Concentrations of danofloxacin and enrofloxacin including its metabolite ciprofloxacin were determined in plasma and eight tissues by specific and sensitive high performance liquid chromatography methods. Pharmacokinetic parameter values for both application routes calculated by noncompartmental methods were similar for danofloxacin compared to enrofloxacin with respect to elimination half-life (t1/2: approximately 6-7 h), mean residence time (MRT; 6-9 h) and mean absorption time (MAT; 1.44 vs. 1.20 h). However, values were twofold higher for body clearance (ClB; 24 vs. 10 mL/min. kg) and volume of distribution at steady state (VdSS; 10 vs. 4 L/kg). Maximum plasma concentration (Cmax) after oral administration was 0.5 and 1.9 micrograms/mL for danofloxacin and enrofloxacin, respectively, occurring at 1.5 h for both drugs. Bioavailability (F) was high: 99% for danofloxacin and 89% for enrofloxacin. Steady-state plasma concentrations (mean +/- SD) following administration via the drinking water were fourfold higher for enrofloxacin (0.52 +/- 0.16 microgram/mL) compared to danofloxacin (0.12 +/- 0.01 microgram/mL). The steady-state AUC0-24 h values of 12.48 and 2.88 micrograms.h/mL, respectively, derived from these plasma concentrations are comparable with corresponding area under the plasma concentration-time curve (AUC) values after single oral administration. For both drugs, tissue concentrations markedly exceeded plasma concentrations, e.g. in the target lung, tissue concentrations of 0.31 +/- 0.07 microgram/g for danofloxacin and 0.88 +/- 0.24 microgram/g for enrofloxacin were detected. Taking into account the similar in vitro activity of danofloxacin and enrofloxacin against important pathogens in chickens, a higher therapeutic efficacy of water medication for enrofloxacin compared to danofloxacin can be expected when given at the approved dosages.     

Bioavailability and pharmacokinetics of florfenicol in broiler chickens

The bioavailability and pharmacokinetic disposition of florfenicol in broiler chickens were investigated after intravenous (i.v.), intramuscular (i.m.) and oral administrations of 15 and 30 mg/kg body weight (b.w.). Plasma concentrations of florfenicol were determined by a high performance liquid chromatographic method in which plasma samples were spiked with chloramphenicol as internal standard. Plasma concentration-time data after i.v. administration were best described by a two-compartment open model. The elimination half-lives were 168 +/- 43 and 181 +/- 71 min, total body clearance 1.02 +/- 0.17 and 1.02 +/- 0.16 L x kg/h, the volume of distribution at steady-state 4.99 +/- 1.11 and 3.50 +/- 1.01 L/kg after i.v. injections of 15 and 30 mg/kg b.w., respectively. Plasma concentration-time data after i.m. and oral administrations were adequately described by a one-compartment model. The i.m. bioavailability and the oral bioavailability of florfenicol were 95, 98 and 96, 94%, respectively, indicating that florfenicol was almost absorbed completely after i.m. and oral administrations of 15 and 30 mg/kg b.w.     

Pharmacokinetics of enrofloxacin in Korean catfish (Silurus asotus)

The objective of this study was to evaluate the pharmacokinetic profile of enrofloxacin and its active metabolite, ciprofloxacin, in Korean catfish after intravenous and oral administrations. Enrofloxacin was administered to Korean catfish by a single intravenous and oral administrations at the dose of 10 mg/kg body weight. The plasma concentrations from intravenous and oral administrations of enrofloxacin were determined by LC/MS. Pharmacokinetic parameters from both routes were described to have a two-compartmental model. After intravenous and oral administrations of enrofloxacin, the elimination half-lives (t(1/2,beta)), area under the drug concentration-time curves (AUC), oral bioavailability (F) were 17.44 +/- 4.66 h and 34.13 +/- 11.50 h, 48.1 +/- 15.7 microgxh/mL and 27.3 +/- 12.4 microgxh/mL, and 64.59 +/- 4.58% respectively. The 3.44 +/- 0.81 h maximum concentration (C(max)) of 1.2 +/- 0.2 microg/mL. Ciprofloxacin, an active metabolite of enrofloxacin, was detected at all the determined time-points from 0.25 to 72 h, with the C(max) of 0.17 +/- 0.08 microg/mL for intravenous dose. After oral administration, ciprofloxacin was detected at all the time-points except 0.25 h, with the C(max) of 0.03 +/- 0.01 microg/mL at 6.67 +/- 2.31 h. Ciprofloxacin was eliminated with terminal half-life t(1/2,beta) of 52.08 +/- 17.34 h for intravenous administration and 52.43 +/- 22.37 h for oral administration.     

口服不同剂型替米考星在鸡体内相对生物等效性研究

本试验按单剂量口服的方法对健康蛋鸡进行替米考星可溶性粉和替米考星溶液中主要组分替米考星的生物利用度和药代动力学研究。利用HPLC方法分析不同时间点试验鸡血浆中的药物浓度。药物的药动学参数结果显示,替米考星可溶性粉和替米考星溶液的平均血药浓度-时间曲线下面积(AUC0-48)分别为(16.947±0.624)μg/mL.h和(16.020±0.631)μg/mL.h,没有显著差异;二者AUC0-48比值为1.058,Cmax分别为(0.759±0.012)μg/mL和(0.764±0.012)μg/mL,比值为0.993;替米考星可溶性粉和替米考星溶液的t1/2β、C l(s)、t1/2 Ka和V/F(c)均没有显著差异;二者的tmax分别为(1.211±0.036)h和(1.030±0.063)h虽然有显著差异,但并不能以此说明二者生物学的非等效性。试验结果说明,单剂量口服替米考星可溶性粉和替米考星溶液后,替米考星被迅速吸收,消退缓慢,依据生物等效性的重要评判指标,得出替米考星可溶性粉和替米考星溶液在治疗中可以相互替代。     

仔猪脾虚状态下单剂量口服左旋氧氟沙星的药动学研究

10头健康仔猪随机均分为健康组、脾虚组 ,按 2 0mg/kg的剂量进行内服左旋氧氟沙星的药动学研究。高效液相色谱法测定血浆中药物浓度 ,3P97药代动力学程序处理药时数据。健康组和脾虚组药动学数据适合一级吸收一室模型。健康组主要药动学数据为 :吸收半衰期 (t1 / 2ka)(0 42± 0 0 8)h ,消除半衰期 (t1 / 2ke) (7 62± 0 38)h ,达峰时间 (tmax) (1 85± 0 2 5)h ,达峰浓度 (Cmax) (6 99± 0 92 )mg/L ,药时曲线下面积 (AUC) (90 7± 1 0 0 7)mg·L- 1 ·h ,表观分布容积 (V/ F(s) ) (2 45± 0 2 8)L·kg,平均滞留时间 (MRT) (1 1 92± 0 94)h。脾虚组 :t1 / 2ka(1 1 7± 0 38)h ,t1 / 2ke (9 0 2± 1 1 8)h ,tmax (3 93± 1 0 5)h ,Cmax (4 2 8± 1 45)mg/L ,AUC (72 2 1± 1 6 0 7)mg·L- 1 ·h ,V/ F(s) (3 95±1 2 8)L·kg,MRT (1 3 74± 1 2 1 )h。结果表明 :仔猪脾虚状态下明显影响左旋氧氟沙星内服给药的药动学特征     

加丽素红中角黄素在鸡体内的药代动力学研究

本试验旨在探讨加丽素红中角黄素在鸡体内的药代动力学特征.选取19周龄的海兰蛋鸡12只,单次灌胃口服加丽素红9.6 mg/kg BW,在72 h内不同时间段分10次采集静脉血,用高效液相色谱法测定鸡血清中角黄素的质量浓度,并利用3P97药代动力学程序软件处理血药浓度-时间数据.结果如下:加丽素红经口服给药后,角黄素在鸡体内的血药浓度-时间数据符合一级吸收一室模型,其理论方程为C=0.471(e-0.036-e-0.190),主要药代动力学参数为:吸收半衰期t1/2(Ka)=(3.643±0.205)h,消除半衰期t1/2(Ke)=(19.263±1.312)h,达峰时间Tmax=(10.795±1.007)h,达峰浓度Cmax=(0.259±0.048)μg/mL,血药浓度-时间曲线下面积AUC=(10.607±1.029)μg/(mL·h),总体清除率CLB=(0.905±0.076)L/(kg·h),表观分布容积Vd=(2.515±0.133)L/kg.上述结果表明,角黄素在鸡体内血药浓度的变化表征了加丽素红在鸡体内代谢的变化规律,具有吸收分布较迅速、达峰快、体内分布广泛、消除速度较慢等特点.     

Pharmacokinetics of enrofloxacin in allogynogenetic silver crucian carp, Carassius auratus gibelio

The pharmacokinetics of enrofloxacin (EF) was investigated after single intravenous (i.v.) and oral (p.o.) administration of 10 mg/kg body weight (b.w.) in 300 healthy allogynogenetic silver crucian carp at 24-26°C. The plasma concentrations of EF and its metabolite ciprofloxacin (CF) were determined by high-performance liquid chromatography. After i.v. administration, the plasma concentration-time data were described by an open two-compartment model. The elimination half-life (T(1/2β)), area under the concentration-time curve (AUC) and total body clearance of EF were 63.5 h, 239.6 μg·h/mL and 0.04 L/h/kg, respectively. Following p.o. administration, the plasma concentration-time data showed a double peak-shaped curve, indicating the possibility of enterohepatic recirculation of EF in allogynogenetic silver crucian carp. The maximum plasma concentration (C(max)), T(1/2β) and AUC of EF were 4.5 μg/mL, 62.7 h and 205.9 μg·h/mL, respectively. Absorption of EF was very good with a bioavailability (F) of 86%, which could be correlated with the unique structure of the alimentary canal in allogynogenetic silver crucian. CF, an active metabolite of EF, was not detected in this study.     

Pharmacokinetics of enrofloxacin following intravenous and intramuscular administration in Angora rabbits

The pharmacokinetic behaviour and bioavailability of enrofloxacin (ENR) were determined after single intravenous (iv) and intramuscular (im) administrations of 5mg/kg bw to six healthy adult Angora rabbits. Plasma ENR concentrations were measured by high performance liquid chromatography. The pharmacokinetic data were best described by a two-compartment open model. ENR pharmacokinetic parameters were similar (p>0.05) for iv and im administrations in terms of AUC0-infinity, t1/2beta and MRT. ENR was rapidly (t1/2a, 0.05 h) and almost completely (F, 87%) absorbed after im injection. In conclusion, the pharmacokinetic properties of ENR following iv and im administration in Angora rabbits are similar to other rabbit breeds, and once or twice daily iv and im administrations of ENR at the dose of 5mg/kg bw, depending upon the causative pathogen and/or severity of disorders, may be useful in treatment of infectious diseases caused by sensitive pathogens in Angora rabbits.     

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in goats given enrofloxacin alone and in combination with probenecid.

The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats given enrofloxacin alone or in combination with probenecid. Enrofloxacin was administered i.m. at a dosage of 5 mg x kg(-1) alone or in conjunction with probenecid (40 mg x kg(-1), i.v.). Blood samples were drawn from the jugular vein at predetermined time intervals after drug injection. Plasma was separated and analysed simultaneously for enrofloxacin and ciprofloxacin by reverse-phase high performance liquid chromatography. The plasma concentration-time data for both enrofloxacin and ciprofloxacin were best described by a one-compartment open pharmacokinetic model. The elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), volume of distribution (V(d(area))), mean residence time (MRT) and total systemic clearance (Cl(B)) were 1.39 h, 7.82 microg x h x mL, 1.52 L x kg(-1), 2.37 h and 802.9 mL x h(-1) x kg(-1), respectively. Enrofloxacin was metabolized to ciprofloxacin in goats and the ratio between the AUCs of ciprofloxacin and enrofloxacin was 0.34. The t(1/2beta), AUC and MRT of ciprofloxacin were 1.82 h, 2.55 microg x h x mL and 3.59 h, respectively. Following combined administration of probenecid and enrofloxacin in goats, the sum of concentrations of enrofloxacin and ciprofloxacin levels > or = 0.1 microg x mL(-1) persisted in plasma up to 12 h.Co-administration of probenecid did not affect the t(1/2beta), AUC, V(d (area)) and Cl(B) of enrofloxacin, whereas the values of t(1/2beta) (3.85 h), AUC (6.29 microg x h x mL), MRT (7.34 h) and metabolite ratio (0.86) of ciprofloxacin were significantly increased. The sum of both enrofloxacin and ciprofloxacin levels was > or = 0.1 microg x mL(-1) and was maintained in plasma up to 8 h in goats after i.m. administration of enrofloxacin alone. These data indicate that a 12 h dosing regime may be appropriate for use in goats.