环糊精包合氟苯尼考在猪体内的药代动力学研究

为评价采用新包被工艺生产的氟苯尼考(受试制剂F)与国外同类产品(R1)、国内同类产品(R2)在猪体内的生物等效性并探索其药代动力学特性,本试验采用随机三制剂、三周期自身交叉试验设计,选取6头健康的阉割小公猪(体重15 kg±2 kg),分别灌胃给药3种制剂,给药剂量为20 mg/(kg·BW),采用高效液相色谱法测定血浆中氟苯尼考浓度,利用Kinetica 5.0软件分析药代动力学特性,SAS统计软件进行生物等效性评价。结果显示,受试制剂在猪体内的药时曲线符合带时滞的一级吸收一室开放模型,F、R1、R2的峰浓度(C_(max))分别为16.0845、18.3287和21.1678μg/mL,药物达峰时间(T_(max))分别为5.0、1.9、1.5 h;药-时曲线下面积_((0-∞))(AUC_(0-∞))分别为144.7327、118.2670和123.3715μg/mL·h;受试制剂相比于两种参比制剂的相对生物利用度分别为122.51%(R1)和117.52%(R2)。结果表明,环糊精包被氟苯尼考有更好的缓释作用,具有更好的生物安全性,药效维持时间长,生物利用度有效提高。     

替米考星颗粒在猪体内的药代动力学研究

研究20%树脂包被替米考星颗粒在猪体内的药代动力学特性并评价其(受试制剂T)与国际(R1)国内(R2)两种参比制剂的生物等效性。采用随机三制剂、三周期自身交叉试验设计,选取6头健康的阉割过的小公猪(体重20.7±2.6 kg),分别口灌给药三种制剂(10 mg/kg b.w.),采用高效液相色谱法(HPLC)测定血浆替米考星浓度,利用Kinetica 5.0分析药代动力学特性及生物等效性评价。20%树脂包被替米考星颗粒在猪体内的药时曲线符合带一级吸收的二室开放模型;T、R1、R2的C_(max)分别为(0.2830±0.0292)、(0.2815±0.0291)、(0.4087±0.0421)μg/mL,t_(max)分别为(4±0.9832)、(0.75±0.1581)、(1±0.2458)h,AUC_(0-∞)分别为(10.8715±1.1203)、(9.8715±1.0173)、(10.6441±1.096 9)μg·h·mL~(-1);受试制剂相比于两种参比制剂的相对生物利用度分别为110.13±6.04%(R1)和102.63±9.64%(R2)。结果表明,三种制剂间具备生物等效性;20%树脂包被替米考星颗粒有更好的缓释作用,具有一定的生物安全性,在体内保持药效时间更久。     

盐酸头孢噻呋注射液在猪体内的比较药动学研究

本研究采用肺部支气管灌流技术对盐酸头孢噻呋注射液在健康猪和患巴氏杆菌病的感染猪体内的药动学特征进行了比较,为指导盐酸头孢噻呋注射液治疗猪巴氏杆菌病提供临床数据支持。选取12头健康仔猪,随机均分为健康组和感染组。感染组通过人工感染多杀性巴氏杆菌建立疾病模型。2组动物分别按交叉试验设计,肌内注射盐酸头孢噻呋注射液,在不同时间点采集血液和支气管肺泡灌洗液,用高效液相色谱法（HPLC）检测头孢噻呋含量。健康猪血浆及支气管肺泡灌洗液中的药峰浓度（C_max）分别为22.33和2.49 μg/mL,相差近9倍;消除半衰期（T_1/2）分别为19.51和70.19 h,在肺部的消除非常缓慢,时长是血浆的3.6倍;药-时曲线下面积（AUC_0-∞）分别为372.05和94.59 μg·h/mL;表观分布容积（Vd/F）分别为0.41和5.24 L/kg,头孢噻呋与肺脏呈现高度结合。感染组血浆及支气管肺泡液C_max分别为11.81和5.05 μg/mL,T_1/2分别为11.79和24.65 h,AUC_0-∞分别为162.65和29.73 μg·h/mL,Vd/F分别为0.53和4.65 L/kg,与健康组表现出相同的特点。结果表明,盐酸头孢噻呋注射液在猪体内具有吸收迅速,消除缓慢,生物利用度高的药代动力学特点,且其在血浆和支气管肺泡灌洗液中的药动学参数存在显著差异。     

阿莫西林混悬注射液在猪体内的生物等效性研究

为了研究阿莫西林混悬注射液在猪体内的药代动力学和生物等效性,采用双处理、双周期随机交叉试验设计,将24头健康猪随机分成2组,按15 mg/kg体重肌肉分别单剂量注射受试制剂和参比制剂,采用高效液相色谱法测定血浆中阿莫西林的浓度,利用Win Nonlin6.4软件计算主要药动学参数,并评价两种制剂的生物等效性。结果显示,受试制剂和参比制剂的Tmax分别为(3.45±2.49)h,(1.34±1.74)h;Cmax分别为(6.94±4.73)mg/L,(4.39±2.87)mg/L;AUC0-t分别为(37.00±11.48)mg·h·L-1,(30.02±8.93)mg·h·L-1;AUC0-∞分别为(40.26±13.36)mg·h·L-1,(38.46±15.38)mg·h·L-1。阿莫西林混悬注射液受试制剂和参比制剂的AUC0-t、AUC0-∞、Cmax、Tmax均有显著性差异,双单侧t检验结果显示两种制剂生物不等效,试验为兽医临床给药方案的制定以及合理用药提供参考。     

2种头孢氨苄片在比格犬体内的药代动力学及生物等效性试验

[目的] 研究头孢氨苄片受试制剂和参比制剂在比格犬体内的生物等效性。[方法] 采用双周期和双序列交叉设计,将22只健康比格犬随机分成2组,按30 mg/kg BW分别单剂量口服头孢氨苄片受试制剂Trolevis^®300和参比制剂Rilexine^®300,于给药前（0 h）和给药后0.5、1、1.5、2、2.5、3、4、6、8、12、17和24 h从臂头静脉采血。对超高效液相色谱串联质谱（UPLC-MS/MS）方法进行特异性、线性、检测限、准确度、精密度、稳定性等方法学考察。利用建立好的UPLC-MS/MS方法测定血浆中的药物浓度,并用WinNonlin^TM 8.1软件对药代动力学参数进行分析计算。[结果] 方法学结果显示,在100~5 000 ng/mL浓度范围内相关性良好,相关系数（R²）≥ 0.99,标准曲线方程为y=10.6828x-176.481;高、中、低3个浓度的相对回收率平均值分别为105.63%、104.35%和102.40%;日内和日间变异系数均<15%;检测限为50 ng/mL,定量限为100 ng/mL。药代动力学结果显示,参比制剂组和受试制剂组药代动力学参数如下：T_max分别为（1.77±0.55）和（2.70±4.68）h;C_max分别为（28.09±5.09）和（26.82±7.94）μg/mL;T_1/2分别为（3.39±1.43）和（3.12±1.05）h;AUC_0-t分别为（121.81±25.80）和（116.34±36.30）μg·h/mL。受试制剂与参比制剂药时曲线相似,且受试制剂与参比制剂C_max、AUC_0-t和AUC_0-∞几何均数的比值分别为99.51%、99.27%和99.30%,其90% CI均在80.00%~125.00%之间。[结论] 本试验建立的UPLC-MS/MS方法准确、可靠,可用于头孢氨苄的浓度测定,且头孢氨苄受试制剂与参比制剂是等效的,临床上均可用于相关疾病的治疗。     

硫酸头孢喹肟注射液在猪体内的生物等效性研究

为研究国产和进口硫酸头孢喹肟注射液(7.5%)在猪体内的药代动力学特征和生物等效性,采用双处理、双周期随机交叉试验设计,将20头健康三元杂交猪随机分成2组,按3mg/kg体重分别单剂量肌内注射受试制剂和参比制剂。采用超高效液相色谱-串联质谱法测定血浆中头孢喹肟的浓度,利用Win Nonlin6.3软件计算主要药动学参数,并评价两种制剂的生物等效性。结果显示,受试制剂和参比制剂的Tmax分别为2.30±0.73h和2.25±0.55h;Cmax分别为2.37±0.34μg/mL和2.45±0.36μg/mL;AUC0-t分别为26.38±2.30μg·h·mL^-1和24.86±2.19μg·h·mL^-1;AUC0-∞分别为26.74±2.34μg·h·mL^-1和25.07±2.20μg·h·mL^-1。硫酸头孢喹肟注射液受试制剂和参比制剂的AUC0-t、AUC0-∞、Cmax、Tmax均无显著性差异(P>0.05)。双单侧t检验结果显示两种制剂生物等效,临床上可相互替代。该试验可为兽医临床合理用药提供参考。     

新型兽用纳米乳载药系统在大鼠体内的药代动力学研究

为了解氟苯尼考纳米乳(FFNE)在大鼠体内药代动力学行为,本试验以氟苯尼考溶液(FFSol)为参比制剂,以30 mg/kg剂量给大鼠灌胃和肌内注射给药,分别于给药后0.5、1、2、4、8、12、24、36、48、72 h采血,利用高效液相色谱法测定血浆中氟苯尼考含量,利用DAS 2.0软件计算房室模型与非房室模型条件下药代动力学参数。结果显示,在两种给药方式下,FFNE与FFSol在大鼠体内均符合二室模型。灌胃给药后,FFNE与FFSol在房室模型条件下AUC_(0-∞)分别为1 085.047和2 176.490 mg/L·h,半衰期分别为10.566和13.687 h,FFNE的相对生物利用度为187.4%。肌内注射给药后,FFNE与FFSol在房室模型条件下AUC_(0-∞)分别为1 530.55和3 243.338 mg/L·h,半衰期分别为7.533和13.335 h,FFNE的相对生物利用度为211.9%。结果表明,FFNE通过灌胃和肌内注射给药在大鼠体内分布较广,灌胃相对肌内注射吸收差,消除快。将氟苯尼考制成纳米乳剂后促进了氟苯尼考的吸收,氟苯尼考的生物利用度显著提高。     

两种磷虾油在家兔体内的药动学及生物利用度研究

为了研究两种磷虾油在家兔体内的药动学及生物利用度评价,将18只家兔随机分成3组,分别单剂量灌服南极磷虾油(受试制剂T1),太平洋磷虾油(受试制剂T2),鱼油(参比制剂R)。用GC-MS检测血浆中EPA,DHA的浓度,采用3p97程序计算药动学参数。结果对EPA而言,参比制剂R与受试制剂T1,T2的峰浓度(Cmax)分别为(190.03±4.21μg/m L),(192.79±3.64μg/m L),(218.35±5.47μg/m L);达峰时间(Tmax)分别为(8.02±0.65)、(12.04±0.31)、(12.10±0.24)h;药时曲线下面积(AUC)分别为(23.32±6.72),(20.43±4.58),(19.23±6.24 mg)h/m L。对DHA而言,参比制剂R与受试制剂T1,T2的峰浓度(Cmax)分别为(243.50±3.47μg/m L)、(219.52±2.04μg/m L)、(233.27±2.87μg/m L);达峰时间(Tmax)分别为(7.04±0.52)、(10.06±0.60)、(7.10±0.29)h;药时曲线下面积(AUC)分别为(16.08±4.98)、(23.49±4.84)、(9.70±0.67 mg)h/m L。以鱼油做为对照物,南极磷虾油中EPA和DHA的相对生物利用度(F)分别为(83.27±10.21)%、(134.56±20.51)%。太平洋磷虾油中EPA和DHA的相对生物利用度(F)分别为(84.73±12.03)%,(49.26±8.79)%。结论表明与鱼油相比,南极磷虾油显著提高了DHA的相对生物利用度。     

两种氟苯尼考注射液在鸡体内比较药动学研究

为比较两种氟苯尼考注射液的药物代谢动力学,本研究选择30只健康鸡随机分为两组,分别单剂量20 mg/kg bw肌内注射受试制剂和参比制剂,于给药后0.167、0.33、0.5、0.75、1、1.5、2、4、6、8、12、24、48 h翼下静脉采集血样。用超高效液相色谱法（UPLC-UV）测定血浆中氟苯尼考的含量,并用WinNonlin 8.1非房室模型计算主要药代动力学参数。结果显示,受试制剂和参比制剂的t1/2分别为（3.39±2.65）和（4.47±3.14）h,Tmax分别为（0.66±0.30）和（0.77±0.30）h,Cmax分别为（7.06±2.35）和（8.24±4.54）μg/mL,AUC0→t分别为（19.05±5.79）和（21.76±6.71）（μg/mL）h,AUC0→∞分别为（20.11±6.36）和（23.04±6.91）（μg/mL）h,MRT分别为（3.25±1.25）和（3.55±0.96）h,相对生物利用度为87.55%。结果表明,虽然二者主要药动学参数无显著性差异（p＞0.05）,但受试制剂相对生物利用度较低。     

盐酸贝那普利咀嚼片在犬体内的生物等效性研究

为研究国产和进口盐酸贝那普利片在犬体内的药代动力学和生物等效性,将20只健康比格犬随机分成2组,采用双周期交叉试验设计,按0.5 mg/kg体重分别单剂量口服受试产品和参比产品。采用UPLC-MS/MS法测定血浆中盐酸贝那普利及贝那普利拉的浓度,利用WinNonlin5.2.1软件计算主要药动学参数,并评价两种产品的生物等效性。结果显示,受试产品和参比产品中盐酸贝那普利Tmax分别为（0.85±0.36）h和（0.98±0.40）h;Cmax分别为（65.85±31.14）ng?mL-1和（52.02±25.79）ng?mL-1;AUC0-t分别为（46.98±29.77）h?ng?mL-1和（40.54±20.76）h?ng?mL-1;AUC0-∞分别为（48.28±30.05）h?ng?mL-1和（41.54±20.85）h?ng?mL-1;受试产品和参比产品的贝那普利拉Tmax分别为（1.78±0.55）h和（1.90±0.72）h;Cmax分别为（63.05±28.44）ng?mL-1和（55.29±36.01）ng?mL-1;AUC0-t分别为（249.09±87.90）h?ng?mL-1和（212.50±90.03）h?ng?mL-1;AUC0-∞分别为（274.15±93.86）h?ng?mL-1和（264.42±161.86）h?ng?mL-1。受试产品和参比产品的Tmax、Cmax、AUC0-t和AUC0-∞均无显著性差异（P>0.05）。双单侧t检验及90%置信区间结果均提示两种制剂生物等效,临床上可相互替代。该试验为兽医临床安全使用该药提供科学的依据。     

Evaluation of bioequivalence after oral, intramuscular, and intravenous administration of racemic ketoprofen in pigs

OBJECTIVE: To assess bioequivalence after oral, IM, and IV administration of racemic ketoprofen in pigs and to investigate the bioavailability after oral and IM administration. ANIMALS: 8 crossbred pigs. PROCEDURES: Each pig received 4 treatments in a randomized crossover design, with a 6-day washout period. Ketoprofen was administered at 3 and 6 mg/kg, PO; 3 mg/kg, IM; and 3 mg/kg, IV. Plasma ketoprofen concentrations were measured by use of high-performance liquid chromatography for up to 48 hours. To assess bioequivalence, a 90% confidence interval was calculated for the area under the time-concentration curve (AUC) and maximum plasma concentration (C(max)). RESULTS: Equivalence was not detected in the AUCs among the various routes of administration nor in C(max) between oral and IM administration of 3 mg/kg. The bioavailability of ketoprofen was almost complete after each oral or IM administration. Mean +/- SD C(max) was 5.09 +/- 1.41 microg/mL and 7.62 +/- 1.22 microg/mL after oral and IM doses of 3 mg/kg, respectively. Mean elimination half-life varied from 3.52 +/- 0.90 hours after oral administration of 3 mg/kg to 2.66 +/- 0.50 hours after IV administration. Time to peak C(max) after administration of all treatments was approximately 1 hour. Increases in AUC and C(max) were proportional when the orally administered dose was increased from 3 to 6 mg/kg. Conclusions and Clinical Relevance: Orally administered ketoprofen was absorbed well in pigs, although bioequivalence with IM administration of ketoprofen was not detected. Orally administered ketoprofen may have potential for use in treating pigs.     

Pharmacokinetics of tulathromycin and its metabolite in swine administered with an intravenous bolus injection and a single gavage

Tulathromycin is a macrolide antimicrobial agent proposed for therapeutic use in treatment of porcine and bovine respiratory disease. In this study, the absolute bioavailability of tulathromycin solution was investigated in pigs. Eight pigs, with body weight of 20.5 ± 1.6 kg, were given a single dose of tulathromycin at 2.5 mg/kg oral (p.o.) and intravenous (i.v.) in a crossover design. The plasma concentrations of tulathromycin and its metabolite were determined by LC-MS/MS method, and the pharmacokinetic parameters of tulathromycin were calculated by noncompartmental analysis. After p.o. administration, the maximum plasma concentration (C(max) ) was 0.20 ± 0.05 μg/mL at 3.75 ± 0.71 h. The terminal half-life (t(1/2λz) ) in plasma was 78.7 ± 6.75 h, and plasma clearance (Cl/F) was 1.14 ± 0.28 L/h/kg. After i.v. injection, plasma clearance (Cl) was 0.580 ± 0.170 L/h/kg, the volume of distribution (Vz) was 64.3 ± 21.2 L/kg, and the t(1/2λz) was 76.5 ± 13.4 h. In conclusion, an analytical method for the quantification of tulathromycin and its metabolite in plasma in swine was developed and validated. Following p.o. administration to pigs at 2.5 mg/kg b.w., tulathromycin was rapidly absorbed and the systemic bioavailability was 51.1 ± 10.2.     

Study on Relative Bioavailability of 1α-Hydroxycholecalciferol to 25-Hydroxycholecalciferol in Broiler Chickens

The study was conducted to determine the relative bioavailability (RBV) of 1α-hydroxycholecalciferol (1α-OH-D₃) to 25-hydroxycholecalciferol (25-OH-D₃) in Ross 308 broiler chickens from 1 to 42 days of age.300 one-day-old Ross 308 broilers were randomly assigned into 6 groups with 5 replicates per group and 10 chicks per replicate.The six groups were fed with basal diets in which 2.5,5.0,10.0 μg/kg 25-OH-D₃ and 1.25,2.5,5.0 μg/kg 1α-OH-D₃ were added,respectively.The RBV of 1α-OH-D₃ to 25-OH-D₃ was determined by the slope ratio method.The results showed that average body weight gain (ABWG),feed to gain ratio (F/G),plasma phosphorus (P) were improved with the 1α-OH-D₃ and 25-OH-D₃ addition and the tibia and femur weight,length,and ash weight were linearly increased with the levels of 1α-OH-D₃ or 25-OH-D₃ increasing (P< 0.05).Using ABWG,F/G,and plasma P as the criteria,RBV of 1α-OH-D₃ to 25-OH-D₃ were 2.16,2.56,and 2.77.Using tibia weight,length,width,and ash weight as the criteria,RBV of 1α-OH-D₃ to 25-OH-D₃ were 1.80,1.88,2.42,and 2.04.Using femur weight,length,and ash weight as the criteria,RBV of 1α-OH-D₃ to 25-OH-D₃ were 1.89,1.98,and 2.18.These results indicated that the activity of 1α-OH-D₃ was approximately 2.17 times higher than that of 25-OH-D₃ in promoting growth performance and bone mineralization in broiler chickens from 1 to 42 days of age.     

Comparison of spray-dried blood meal and blood cells in diets for nursery pigs

We used a total of 680 pigs to compare spray-dried blood meal and blood cells in nursery diets. In Exp. 1, 350 barrows (17 +/- 2 d of age at weaning) were used to compare three levels of spray-dried blood meal or blood cells (2.5, 5.0, and 7.5%) in the diet fed from d 5 to 19 postweaning (6.6 to 9.9 kg). Inclusion of either blood product improved ADG (P < 0.005) and G:F (P < 0.001) compared to pigs fed the control diet without added blood products. However, pigs fed spray-dried blood meal had greater ADG (P < 0.001), ADFI (P < 0.04), and G:F (P < 0.001) from d 0 to 7 compared to those fed blood cells. The greatest differences observed between the two blood products occurred at the 5 and 7.5% inclusion levels. No differences (P > 0.05) in growth performance were detected between the two blood products from d 7 to 14. In Exp. 2, 380 barrows (initial BW of 10.7 kg and 41 +/- 2 d of age) were used to determine lysine bioavailability of spray-dried blood meal and blood cells via the slope ratio procedure. With G:F ratio as the response criterion, blood meal and blood cells had similar lysine bioavailability relative to crystalline lysine. These experiments indicate that both blood products had similar lysine bioavailability, and that pigs fed spray-dried blood meal had greater performance during the initial 7 d (d 5 to 12 after weaning). However, as the pigs became heavier, there were no differences observed in performance of pigs fed either blood meal or blood cells.     

Bioavailability of spiramycin and lincomycin after oral administration to fed and fasted pigs

The disposition of spiramycin and lincomycin was measured after intravenous (i.v.) and oral (p.o.) administration to pigs. Twelve healthy pigs (six for each compound) weighing 16–43 kg received a dose of 10 mg/kg intravenously, and 55 mg/kg (spiramycin) or 33 mg/kg (lincomycin) orally in both a fasted and a fed condition in a three-way cross-over design. Spiramycin was detectable in plasma up to 30 h after intravenous and oral administration to both fasted and fed pigs, whereas lincomycin was detected for only 12 h after intravenous administration and up to 15 h after oral administration. The volume of distribution was 5.6 ± 1.5 and 1.1 ± 0.2 L/kg body weight for spiramycin and lincomycin, respectively. For both compounds the bioavailability was strongly dependent on the presence of food in the gastrointestinal tract. For spiramycin the bioavailability was determined to be 60% and 24% in fasted and fed pigs, respectively, whereas the corresponding figures for lincomycin were 73% and 41%. The maximum plasma concentration of spiramycin (C_max) was estimated to be 5 μg/mL in fasted pigs and 1 μg/mL only in fed pigs. It is concluded that an oral dose of 55 mg/kg body weight is not enough to give a therapeutically effective plasma concentration of spiramycin against species of Mycoplasma, Streptoccocus, Staphylococcus and Pasteurella multocida. The maximum plasma concentration of lincomycin was estimated to be 8 μg/mL in fasted pigs and 5 μg/mL in fed pigs, but as the minimum inhibitory concentration for lincomycin against Actinobacillus pleuropneumoniae and P. multocida is higher than 32 μg/mL a therapeutically effective plasma concentration could not be obtained following oral administration of the drug. For Mycoplasma the MIC₉₀ is below 1 μg/mL and a therapeutically effective plasma concentration of lincomycin was thus obtained after oral administration to both fed and fasted pigs.     

半胱胺和酵母铬对生长肥育猪生产性能和胴体品质的影响

试验选择25 kg左右的"杜长大"三元杂交猪96头,采用2×2析因设计分成4组,每组6个重复,每个重复4头。对照组喂基础饲粮,酵母铬(Cr)组在基础饲粮中添加酵母铬(生长期和肥育期分别添加Gr 200、300μg/kg),半胱胺(CS)组在基础饲粮中添加半胱胺(生长期和肥育期分别添加CS 120、170 mg/kg),复合组在基础饲粮中同时添加酵母铬和半胱胺(生长期和肥育期分别添加Gr 200μg+CS 120 mg/kg、Gr300μg+CS 170 mg/kg)。试验分生长期和肥育期两阶段进行,研究半胱胺和酵母铬对生长肥育猪生长性能、胴体和肌肉品质的影响。结果表明,生长肥育猪饲粮中分别添加半胱胺和酵母铬,一定程度上可改善生产性能,提高日增重、降低饲料/增重比;二者同时添加时有提高日增重的趋势,但统计分析差异不显著(P>0.05)。饲粮中分别或同时添加半胱胺和酵母铬对胴体肌肉品质也有一定的改善作用,但统计分析差异不显著(P>0.05)。     

Pharmacokinetics and tissue residues of norfloxacin and its N-desethyl- and oxo-metabolites in healthy pigs

The pharmacokinetic properties of norfloxacin were determined in healthy pigs after single intramuscular (i.m.) and intravenous (i.v.) dosage of 8 mg/kg body weight After i.m. and i.v. administration, the plasma concentration-time graph was characteristic of a two-compartment open model. After single i.m. administration, norfloxacin was absorbed rapidly, with a t _max of 1.46 ± 0.06 h. The elimination half-life ( t _1/2β) and the mean residence time of norfloxacin in plasma were 4.99 ± 0.28 and 6.05 ± 0.22 h, respectively, after i.m. administration and 3.65 ± 0.16 and 3.34 ± 0.16 h, respectively, after i.v. administration. Intramuscular bioavailability was found to be 53.7 ± 4.4%. Plasma concentrations greater than 0.2 μg/mL were achieved at 20 min and persisted up to 8 h post-administration. Maximal plasma concentration was 1.11 ± 0.03 μg/mL. Statistically significant differences between the two routes of administration were found for the half-lives of both distribution and elimination phases ( t _1/2α, t _1/2β) and apparent volume of distribution (V_d(area)). In pigs, norfloxacin was mainly converted to desethylenenorfloxacln and oxonorfloxacin. Considerable tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were found when norfloxacin was administered intramuscularly (8 mg/kg on 4 consecutive days). The concentration of the parent fluoroquinolone in liver and kidney ranged between 0.015 and 0.017 μg/g on day 12 after the end of dosing.     

The pharmacokinetics of oxytetracycline following intravenous administration in healthy and diseased pigs

Pijpers, A., Schoevers, E.J., van Gogh, H., van Leengoed, L.A.M.G., Visser, I.J.R., van Miert, A.S.J.P.A.M. & Verheijden, J.H.M. The pharmacokinetics of oxytetracycline following intravenous administration in healthy and diseased pigs. J. vet. Pharmacol. Therap. 13, 320–326.
The pharmacokinetics of oxytetracycline (OTC) were studied in healthy pigs and in pigs endobronchially inoculated with Actinobacillus pleuropneumoniae toxins. In two groups of seven pigs OTC was administered intravenously in a single dose of 10 or 50 mg/kg, respectively. OTC was administered to clinically healthy pigs and 7 days later at 3 h after a challenge with A. pleuropneumoniae toxins. Pneumonia developed in toxin-treated pigs. In the challenged pigs there was a decreased distribution-rate constant (α) and a significantly increased elimination-rate constant (ß) ( P <0.05). Moreover, the apparent volume of distribution (V_dß) was decreased. The elimination half-lives (t_1/2ß) were approximately 6 h in the healthy pigs and 5 h in the diseased animals. There was no difference in the pharmacokinetic profile of OTC following administration of 50 mg/kg compared to 10 mg/kg.
A. Pijpers, Department of Herd Health and Reproduction, PO Box 80.151, 3508 TD Utrecht, The Netherlands.