盐酸多西环素片在羔羊体内残留消除规律及休药期分析

旨在确定盐酸多西环素片按照给药说明给药后在羔羊体内的残留消除规律及休药期。将盐酸多西环素片根据体重以5 mg·kg^-1内服给药，间隔24 h，连续给药5次。在最后1次给药后，分别在第0（12小时）、1、2、3、5、7和9天时间点采集羔羊脂肪、肌肉、肝和肾，采用建立并验证的HPLC-VWD方法测定组织中多西环素的含量。结果显示：方法学考察结果表明，在50~5 000 ng·mL^-1添加的线性方程和相关系数为y=0.044x-0.414，R²=0.999。试验结果表明，多西环素在羔羊组织中代谢快速，最后1次给药后第9天，在肌肉、肝、肾和脂肪中均未检测到多西环素。本试验以5 mg·kg^-1体重内服给予羔羊盐酸多西环素片后，根据欧洲药品评估机构法规《EMEA/CVMP/036/95》，建议盐酸多西环素片在羔羊组织中的休药期为2 d。     

氟苯尼考注射液中非法添加多西环素检查方法的建立

为建立氟苯尼考注射液中非法添加多西环素高效液相检查方法,研究使用C18(4.6 mm×150 mm,5μm)色谱柱,以醋酸盐缓冲液[0.25 mol/L醋酸铵溶液-0.1 mol/L乙二胺四醋酸二钠-三乙胺(100∶10∶1),调节p H值至8.8]-乙腈(85∶15)为流动相,采用二极管阵列检测器,波长采集范围为200~400 nm,记录色谱图波长为269 nm,流速为1 m L/min,进样量为10μL。结果表明,多西环素进样浓度在0.015~0.96 mg/m L范围内与峰面积呈良好的线性关系(r=1.0000);平均回收率为99.4%(n=9),RSD为0.3%。本方法简便、准确、可行,适用于氟苯尼考注射液中非法添加多西环素的检测。     

高效液相色谱法测定盐酸多西环素可溶性粉的含量

采用高效液相色谱法（HPLC）测定盐酸多西环素可溶性粉中多西环素的含量,并对检验方法[1]进行复核验证。色谱柱W aters Nova.pakR○C18（3.9 mm×150 mm,4μm）;以0.05 mol/L草酸铵溶液-二甲基甲酰胺-0.2 mol/L磷酸氢二铵溶液（65∶30∶5）（用氨试液调节pH值为8.0）为流动相;柱温35℃;检测波长280 nm;流速1.0 mL/min;进样量20μL。多西环素进样浓度在4.0-144.0μg/mL的范围内与峰面积呈良好的线性关系（r=1.000）;样品的平均加样回收率（n=9）为98.5%,RSD为2.0%;完成了185批次样品的检验,检验结果准确可靠。该方法准确度高,重复性好,结果可靠,能够有效地检测盐酸多西环素可溶性粉的含量。     

HPLC-PDA法测定17种兽药中非法添加多西环素

建立了17种兽药中非法添加多西环素的HPLC-PDA法。采用十八烷基键合硅胶为填充剂,以醋酸盐缓冲液-乙腈(80:20)为流动相,二极管阵列检测器进行全波长(200~400 inia)扫描,检测波长为280 nm,并通过液相色谱保留时间、紫外光谱信息和峰纯度检查,对非法添加物质进行定性鉴别和定量测定。结果表明,该色谱条件下,多西环素与其他物质峰分离良好。多西环素在5~500μg/mL浓度范围内线性良好,回收率在86.5%~118.1%之间,RSD为0.2%~4.5%,检测限为0.5 mg/g。本方法准确、可靠、重现性好,可用于兽药制剂中多西环素的定性和定量检测。     

Integration of pharmacokinetic–pharmacodynamic for dose optimization of doxycycline against Haemophilus parasuis in pigs

The aims of this study were to establish optimal doses of doxycycline (dox) against Haemophilus parasuis on the basis of pharmacokinetic–pharmacodynamic (PK‐PD) integration modeling. The infected model was established by intranasal inoculation of organism in pigs and confirmed by clinical signs, blood biochemistry, and microscopic examinations. The recommended dose (20 mg/kg b.w.) was administered in pigs through intramuscular routes for PK studies. The area under the concentration 0‐ to 24‐hr curve (AUC_0–24), elimination half‐life (T_½ke), and mean residence time (MRT) of dox in healthy and H. parasuis‐infected pigs were 55.51 ± 5.72 versus 57.10 ± 4.89 μg·hr/ml, 8.28 ± 0.91 versus 9.80 ± 2.38 hr, and 8.43 ± 0.27 versus 8.79 ± 0.18 hr, respectively. The minimal inhibitory concentration (MIC) of dox against 40 H. parasuis isolates was conducted through broth microdilution method, the corresponding MIC₅₀ and MIC₉₀ were 0.25 and 1 μg/ml, respectively. The Ex vivo growth inhibition data suggested that dox exhibited a concentration‐dependent killing mechanism. Based on the observed AUC_24 hr/MIC values by modeling PK‐PD data in H. parasuis‐infected pigs, the doses predicted to obtain bacteriostatic, bactericidal, and elimination effects for H. parasuis over 24 hr were 5.25, 8.55, and 10.37 mg/kg for the 50% target attainment rate (TAR), and 7.26, 13.82, and 18.17 mg/kg for 90% TAR, respectively. This study provided a more optimized alternative for clinical use and demonstrated that the dosage 20 mg/kg of dox by intramuscular administration could have an effective bactericidal activity against H. parasuis.     

Differential susceptibility to tetracycline,oxytetracycline and doxycycline of the calf pathogens Mannheimia haemolytica and Pasteurella multocida in three growth media

For clinical isolates of bovine Mannheimia haemolytica and Pasteurella multocida, this study reports minimum inhibitory concentration (MIC) differences for tetracycline, oxytetracycline and doxycycline between cation‐adjusted Mueller‐Hinton broth (CAMHB), foetal bovine serum (FBS) and Roswell Park Memorial Institute (RPMI) medium. MICs were determined according to CLSI standards and additionally using five overlapping sets of twofold dilutions. Matrix effect: (a) free drug MICs and minimum bactericidal concentrations (MBC) for all drugs were significantly higher in FBS than in CAMHB for both pathogens (p < 0.001); (b) MICs and MBCs were higher for CAMHB and FBS compared to RPMI for P. multocida only. Net growth rate for P. multocida in CAMHB was significantly slower than in FBS and higher than in RPMI, correlating to MIC and MBC ranking. Drug effect: doxycycline MICs and MBCs were significantly lower (p < 0.001) in both CAMHB and FBS than tetracycline and oxytetracycline for both pathogens. Only for M. haemolytica were oxytetracycline MIC and MBC significantly lower than tetracycline, precluding the use of tetracycline to predict oxytetracycline susceptibility in this species. Determining potencies of tetracyclines in a physiological medium, such as FBS, is proposed, when the objective is correlation with pharmacokinetic data for dosage determination.     

双波长紫外分光光度法测定复方恩诺沙星可溶性粉中恩诺沙星和盐酸多西环素的含量

建立了复方恩诺沙星可溶性粉中恩诺沙星和盐酸多西环素含量的检测方法.采用双波长紫外分光光度法,直接测定两组分的含量.结果显示可同时测出复方恩诺沙星可溶性粉中恩诺沙星和盐酸多西环素的各自含量,且吸收度与各自的浓度成良好线性关系.恩诺沙星平均回收率为100.1%,RSD为0.04%(n=5).盐酸多西环素平均回收率为100.2%,RSD为0.14%(n=5).本方法简便、快速、可靠,可用于复方恩诺沙星可溶性粉的含量测定.     

固相萃取-高效液相色谱-紫外检测土壤中多西环素

为了了解多西环素（DOX）在土壤中的污染现状,降低检测成本,本研究建立了固相萃取-高效液相色谱-紫外（HPLC-UV）检测3种土壤中DOX的分析方法。土壤样品通过采用乙腈和Na₂EDTA-Mcllvaine（1：1,V/V,pH 4.88）的混合溶液作为提取试剂,HLB固相萃取小柱进行富集净化,Agilent ZORBAX SB-C18（4.6 mm×250 mm×5 μm）色谱柱分离,以0.01 mol/L草酸（A）、乙腈（B）和甲醇（C）为流动相系统,在355 nm波长下进行高效液相色谱检测时提取效果最佳。以3倍信噪比确定方法检测限,以10倍信噪比确定方法定量限。结果表明,DOX在10 min出峰,在0.1~10 μg/mL范围内,DOX的峰面积与浓度线性关系良好,回归方程为y=22 747x+3.3256,相关系数是0.9999。本方法DOX的检测限为0.05 mg/kg,定量限为0.1 mg/kg。当土壤添加浓度为0.1 μg/g时,DOX在壤土、砂壤土及砂土中的回收率分别为58.96%、75.84%和83.06%,变异系数为1.00%~9.54%;当土壤添加浓度为0.2 μg/g时,DOX在壤土、砂壤土及砂土中的回收率分别为63.89%、70.48%和81.07%,变异系数为2.40%~8.83%;当土壤添加浓度为0.4 μg/g时,DOX在壤土、砂壤土及砂土中的回收率分别为59.02%、76.16%和81.29%,变异系数为1.52%~5.89%。本检测方法高效、稳定、特异性好,可以用于不同类型土壤中DOX的检测与定量,有助于环境中DOX检测方法的建立。     

Septic osteitis of the axial border of the proximal sesamoid bones in two foals

This case report describes the history, clinical findings, clinical pathology and diagnostic imaging of 2 cases of septic osteitis of the proximal sesamoid bones in foals. Treatment with doxycycline (10 mg/kg bwt per os b.i.d.) was successful in treating both of these cases.     

盐酸多西环素黄芪多糖可溶性粉对人工感染鸡传染性喉气管炎的疗效试验

用盐酸多西环素黄芪多糖可溶性粉以1.5、1.0、0.5 g/L对人工感染鸡传染性喉气管炎鸡群混饮治疗,同时设立病毒灵对照组。试验结果表明,用药5 d后,盐酸多西环素黄芪多糖可溶性粉高、中剂量组有效率皆为98%,治愈率皆为90%,效果优于对照药物病毒灵。