HPLC法测定氨苄西林钠可溶性粉中氨苄西林的含量

采用HPLC法测定氨苄西林钠可溶性粉中氨苄西林的含量.色谱柱为WaterssphericalC18(3.9mm×150mm,5μm),流动相为水-乙腈-1mol/L磷酸二氢钾溶液-1mol/L醋酸溶液(909∶80∶10∶1,V/V),检测波长254nm,流速1.0mL/min,柱温30℃,保留时间约4.5min.氨苄西林在0.25～2.0mg/mL范围内具有良好的线性关系(r=0.9999),平均回收率99.6%,RSD为0.3%.     

高效液相色谱法测定抗病毒颗粒中黄芩苷的含量

采用高效液相色谱法测定抗病毒颗粒中黄芩苷的含量.用C18色谱柱(150 mm×3.9 mm,5 μm),以甲醇-磷酸二氢钠缓冲液(0.2 mol/L,pH 2.7)(42∶58,V/V)为流动相,流速为1 mL*min-1,检测波长为275 nm.黄芩苷在0.02～0.1 mg/mL的浓度范围内,峰面积与浓度呈良好线性关系,r=0.999 9,回收率为98.7%.     

对中国兽药典中黄芩含量测定方法的改进

采用反相高效液相色谱法测定黄芩中黄芩苷的含量.色谱柱为luna C18柱(5μm,250mm×4.60 mm);流动相为乙腈-水-磷酸(30:70:0.1,V/V);流速为1.0 mL/min;检测波长为280 nm;柱温为35℃.黄芩苷浓度在29.4～102.9μg/mL范围内,峰面积与浓度间有良好的线性关系(r=0.999 7),平均回收率为98.6%,RSD为0.60%.     

小柴胡散中黄芩苷含量测定HPLC法研究

建立了测定小柴胡散中黄芩苷含量的高效液相色谱法.采用Hypersil BDS C18柱(5 μm,4.6 mm×200 mm),以甲醇-0.025%磷酸溶液(55∶ 45,V/V)为流动相,紫外检测器检测波长为280 nm.对照品在0.038 6～0.617 0 μg/mL的浓度范围内呈现良好的线性关系(R2=0.998 5),黄芩苷加样平均回收率为 98.61%,RSD为 2.64%.该方法简便、准确、快速,适合于小柴胡散的质量控制检测.     

HPLC法测定鸡蛋中土霉素和金霉素的残留量

采用RP-HPLC方法同时测定了鸡蛋中土霉素和金霉素的残留量.用0.01 mol/L的乙二胺四乙酸二钠溶液和0.3%磷酸溶液为提取液,三氯乙酸(1 1)溶液为蛋白沉淀剂,离心后上清液经C18固相萃取柱净化、浓缩.色谱柱为Waters Symmetry ShieldTM RP18柱,250 mm×4.6 mm (i.d.),粒径5 μm;检测波长353 nm;以0.02 mol/L草酸∶乙腈∶ 0.01 mol/L磷酸二氢钠(45∶ 19∶ 36,V/V/V)为流动相.土霉素和金霉素标准曲线的线性范围分别为0.05～1.0 μg/mL和0.1～2.0 μg/mL.经过3种不同浓度回收率的测定,其回收率在50.6%～85.6%之间,RSD%小于8.60%(n＝5).     

高效液相色谱法测定饲料中三聚氰胺

采用高效液相色谱法测定饲料中三聚氰胺含量。色谱柱为Waters Xterra柱(4.6mm×150mm,5μm);流动相为乙腈:10mmol/L辛烷磺酸钠-柠檬酸缓冲液(10∶90,V∶V),检测波长为240nm,流速1.0mL/min,进样量20μL,保留时间约6.23min。三聚氰胺在1.0～50μg/mL范围内具有良好的线性关系(R2=0.99996),在添加浓度为20～100mg/kg范围内,三聚氰胺添加回收率在90%～95%,RSD小于5%。     

高效液相色谱法检测鸡粪便中洛克沙胂

建立了用固相萃取-高效液相色谱法(HPLC)测定鸡粪便中洛克沙胂(ROX)的方法。鸡粪便采用0.05 mol/L磷酸氢二钾∶甲醇=90∶10(V/V)溶液作提取液,用Waters Oasis(MAX固相萃取小柱净化;色谱条件为:Agilent C18色谱柱(4.6×250 mm,5μm),流动相为0.05 mol/L磷酸二氢钾∶100 mL/L乙酸∶甲醇=90∶7∶3(V/V/V),流速1.0 mL/min,柱温30℃,进样量20μL,紫外检测波长266 nm。ROX的浓度在10.0μg/mL范围内,线性相关系数为0.999 9,方法的回收率为80.09%～81.5%,变异系数为2.09%～5.87%,检出限为1.0 mg/kg。该方法精确度和灵敏度很高,适用于鸡粪便中ROX含量的测定。从某鸡场随机采集8个粪样,调查鸡粪中的ROX含量,其ROX的平均浓度为21.49 mg/kg。     

RP-HPLC法检测安替比林血药浓度

建立了安替比林血药浓度检测的反相高效液相色谱法(RP-HPLC).血浆经乙腈提取后进样测定,色谱柱为Kromasil C18(250 mm×4.6 mm,5μm),柱温为30℃,流动相为0.025 mol/L醋酸钠溶液-乙腈(74:26,V/V),流速为0.8 mL/min,检测波长为254 nm,进样量20μL.安替比林血药浓度在0.1～30μg/mL范围内线性关系良好(r=0.999 5),平均回收率为93.44%～97.21%,日内和日间变异系数小于4.26%.     

HPLC法测定喹乙醇预混剂中喹乙醇的含量

建立并验证了喹乙醇预混剂中喹乙醇含量的高效液相色谱测定法。试验采用十八烷基硅烷键合硅胶色谱柱(250 mm×4.6 mm,5μm),以0.02 mol/L磷酸二氢钾溶液(用三乙胺调节pH值为6.0)-乙腈(92∶8,V∶V)为流动相,流速为1.0 mL/min,柱温为30℃,检测波长为262 nm。试验结果表明喹乙醇在5~100μg/mL范围内线性良好,R~2=1.0000,平均回收率100.2%(n=6),RSD为0.2%。建立的方法简便、准确、可靠,可更好地控制喹乙醇预混剂的质量。     

HPLC法检测磺胺间甲氧嘧啶钠和甲氧苄啶方法的研究

采用HPLC法同时测定复方磺胺间甲氧嘧啶钠蜂胶溶液中磺胺间甲氧嘧啶钠和甲氧苄啶的含量.色谱柱为Kromasil C18柱(250×4.6 mm,粒径5 μm),流动相为0.02 mol/L磷酸溶液-甲醇(80∶20,V/V),检测波长270 nm,流速1.0 mL/min,柱温30 ℃.在10～500 μg/mL浓度范围内,磺胺间甲氧嘧啶钠和甲氧苄啶均呈线性关系.平均回收率分别为99.3%和99.4%.该法准确可行,适用于同时检测复方磺胺间甲氧嘧啶钠蜂胶溶液中磺胺间甲氧嘧啶钠和甲氧苄啶的含量.     

Clinical pharmacokinetics of flumequine in calves

The minimal inhibitory concentration (MIC) of flumequine for 249 Salmonella, 126 Escherichia coli, and 22 Pasteurella multocida isolates recovered from clinical cases of neonatal calf diarrhoea, pneumonia and sudden death was less than or equal to 0.78 microgram/ml. The pharmacokinetics of flumequine in calves was investigated after intravenous (i.v.), intramuscular (i.m.) and oral administration. The two-compartment open model was used for the analysis of serum drug concentrations measured after rapid i.v. ('bolus') injection. The distribution half-life (t1/2 alpha) was 13 min, elimination half-life (t1/2 beta) was 2.25 h, the apparent area volume of distribution (Vd(area)), and the volume of distribution at steady state (Vd(ss)) were 1.48 and 1.43 l/kg, respectively. Flumequine was quickly and completely absorbed into the systemic circulation after i.m. administration of a soluble drug formulation; a mean peak serum drug concentration (Cmax) of 6.2 micrograms/ml was attained 30 min after treatment at 10 mg/kg and was similar to the concentration measured 30 min after an equal dose of the drug was injected i.v. On the other hand, the i.m. bioavailability of two injectable oily suspensions of the drug was 44%; both formulations failed to produce serum drug concentrations of potential clinical significance after administration at 20 mg/kg. The drug was rapidly absorbed after oral administration; the oral bioavailability ranged between 55.7% for the 5 mg/kg dose and 92.5% for the 20 mg/kg dose. Concomitant i.m. or oral administration of probenecid at 40 mg/kg did not change the Cmax of the flumequine but slightly decreased its elimination rate. Flumequine was 74.5% bound in serum. Kinetic data generated from single dose i.v., i.m. and oral drug administration were used to calculate practical dosage recommendations. Calculations showed that the soluble drug formulation should be administered i.m. at 25 mg/kg every 12 h, or alternatively at 50 mg/kg every 24 h. The drug should be administered orally at 30 and 60 mg/kg every 12 and 24 h, respectively. Very large, and in our opinion impractical, doses of flumequine formulated as oily suspension are required to produce serum drug concentrations of potential clinical value.     

Oral absorption and bioavailability of flumequine in veal calves

Summary

The oral absorption and bioavailability of flumequine was studied in 1‐, 5‐ and 18‐week‐old calves following intravenous and oral administration of different formulations of flumequine (Flumix^®, Flumix C^® and pure flumequine). Increasing age had a negative influence on the C_max after the administration of Flumix^®, based on a larger V_D in the older calves. The C_max decreased from 5.02 ± 1.46 μg/ml in the first week to 3.28 ± 0.42 μg/ml in the 18th week. Adding colistin sulfate to the flumequine formulation and administring pure flumequine mixed with milk replacer had a negative effect on the C_max of flumequine after oral administration of 5 and 10 mg/kg body weight. The bioavailability of the orally administered flumequine formulations was 100% in all cases except after the administration of Flumix C^®, for which it was 75.9 ± 18.2%. The urinary recovery of flumequine after intravenous injection of a 10% solution varied from 35.2 ± 2.3% for Group B. to 41.2 ± 6.3% for Group C.

The dosage of 5 mg/kg body weight Flumix^® twice daily in 1‐week‐old veal calves is sufficient to reach therapeutic plasma concentrations, based on a MIC value of 0.8 μg/ml of the target bacteria.

In older calves it is advisable to increase the dosage 7.5 or 10 mg/kg body weight every 12 hours. In combination with colistin sulfate it is also advisable to increase the dosage slightly because of the negative effect of the colistin sulfate on the C_max of flumequine.     

Oral absorption and bioavailability of flumequine in veal calves

The oral absorption and bioavailability of flumequine was studied in 1-, 5- and 18-week-old calves following intravenous and oral administration of different formulations of flumequine (Flumix, Flumix C and pure flumequine). Increasing age had a negative influence on the Cmax after the administration of Flumix, based on a larger VD in the older calves. The Cmax decreased from 5.02 +/- 1.46 micrograms/ml in the first week to 3.28 +/- 0.42 micrograms/ml in the 18th week. Adding colistin sulfate to the flumequine formulation and administring pure flumequine mixed with milk replacer had a negative effect on the Cmax of flumequine after oral administration of 5 and 10 mg/kg body weight. The bioavailability of the orally administered flumequine formulations was 100% in all cases except after the administration of Flumix C, for which it was 75.9 +/- 18.2%. The urinary recovery of flumequine after intravenous injection of a 10% solution varied from 35.2 +/- 2.3% for Group B, to 41.2 +/- 6.3% for Group C. The dosage of 5 mg/kg body weight Flumix twice daily in 1-week-old veal calves is sufficient to reach therapeutic plasma concentrations, based on a MIC value of 0.8 micrograms/ml of the target bacteria. In older calves it is advisable to increase the dosage 7.5 or 10 mg/kg body weight every 12 hours. In combination with colistin sulfate it is also advisable to increase the dosage slightly because of the negative effect of the colistin sulfate on the Cmax of flumequine.     

Pharmacokinetics, metabolism and renal clearance of flumequine in veal calves

The pharmacokinetics of flumequine was studied in 1-, 5- and 18-week-old veal calves. A two-compartment model was used to fit the plasma concentration-time curve of flumequine after the intravenous injection of 10 mg/kg of a 10% solution. The elimination half-life (t1/2 beta) of the drug ranged from 6 to 7 h. The Vd beta and ClB of 1-week-old calves (1.07 l/kg, 1.78 ml/min/kg) were significantly lower than those of 5-week-old (1.89 l/kg, 3.23 ml/min/kg) and 18-week-old calves (1.57 l/kg, 3.10 ml/min/kg). After the oral administration of 10 mg/kg of a 2% flumequine formulation mixed with milk replacer, the Cmax was highest in 1-week-old (9.27 micrograms/ml) and lowest in 18-week-old calves (4.47 micrograms/ml). The absorption was rapid (Tmax of approximately 3 h) and complete. When flumequine itself and a formulation containing 2% flumequine and 20 X 10(6) iu of colistin sulphate were mixed with milk replacer and administered at the same dose rate, absorption was incomplete and Cmax was lower. The main urinary metabolite of flumequine was the glucuronide conjugate (approximately 40% recovery within 48 h of intravenous injection) and the second most important metabolite was 7-hydroxy-flumequine (approximately 3% recovery within 12 h of intravenous injection). Only 3.2-6.5% was excreted in the urine unchanged. After oral administration a 'first-pass' effect was observed, with a significant increase in the excretion of conjugated drug. For 1-week-old calves it is recommended that the 2% formulation should be administered at a dose rate of 8 mg/kg every 24 h or 4 mg/kg every 12 h; for calves over 6 weeks old, the dose should be increased to 15 mg/kg every 24 h or 7.5 mg/kg every 12 h. The formulation containing colistin sulphate should be administered to 1-week-old calves at a flumequine dose of 12 mg/kg every 24 h or 6 mg/kg every 12 h.     

Pharmacodynamics and pharmacokinetics of flumequine in pigs after single intravenous and intramuscular administration

The pharmacokinetics and intramuscular (IM) bioavailability of flumequine (15 mgkg(-1)) were investigated in healthy pigs and the findings related to published minimal inhibitory concentrations (MICs) for susceptible bacteria of animal origin, and to experimentally determined MICs for susceptible strains of porcine origin. We found MICs for Escherichia coli, Salmonella spp., Pasteurella spp. and Bordetella spp. in the range 0.5 to >64 microg mL(-1) isolated from infected pigs in the Forli area of Italy; only the Pasteurella multocida strains were sensitive (MIC(90)=0.5 microg mL(-1)). After intravenous (IV) injection, flumequine was slowly distributed and eliminated (t(1/2lambda(1))1.40+/-0.16 h and t(1/2lambda(2))6.35+/-1.69 h). The distribution volume at steady state (V(dss)) was 752.59+/-84.03 mL kg(-1) and clearance (Cl(B)) was 237.19+/-17.88 mL kg(-1)h(-1). After IM administration, peak serum concentration (4.99+/-0.92 microg mL(-1)) was reached between the 2nd and the 3rd hour. The results on MIC of isolated bacteria, although only indicative, suggest that the efficacy of flumequine on Gram-negative bacteria may be impaired by the emergence of less sensitive or resistant strains.     

Effects of experimentally induced Pasteurella haemolytica infection in dairy calves on the pharmacokinetics of flumequine

The effect of experimental Pasteurella haemolytica infection on the intravenous and intramuscular pharmacokinetics of flumequine was studied in dairy calves. The plasma concentration-time curve of flumequine after intravenous injection of 5 mg/kg bodyweight flumequine of a 10% solution before and after experimental infection, was best described by a three-compartment open model. After intramuscular injection of the same dosage rate of a 3% flumequine suspension is was best described by the one-compartment open model with first-order absorption. The experimental infection by intratracheal administration of infectious bovine rhinotracheitis (IBR)-virus and 5 days later intrapulmonary administration of Pasteurella haemolytica produced a clear temperature rise and signs of disease expressed as Average Health Status. Subsequently, plasma Fe and Zn concentration decreased after infection. The distribution volumes Vc, Vd(area) and Vd(ss) after infection (0.07 +/- 0.04, 1.38 +/- 0.36 and 0.50 +/- 0.11 l/kg, respectively) were smaller than those before infection, but the differences were not significant (P less than or equal to 0.1). The intravenous AUC infinity was significantly increased (21.86 +/- 3.51 to 33.85 +/- 2.97 mg.h/l, P less than or equal to 0.01) and the total body clearance (ClB) significantly decreased (0.24 +/- 0.02 to 0.15 +/- 0.01, P less than or equal to 0.01) after infection. After intramuscular injection of flumequine at 5 mg/kg as a 3% suspension, only the bioavailability, F, was significantly decreased after infection (78.5 +/- 14.3 to 59.7 +/- 21.2%, P less than or equal to 0.02). However, this had no consequences for the dosage regimen used. The urine concentration ratio flumequine:7-hydroxy-flumequine:conjugated flumequine changed from 2:1:10 before infection to 6:1:15 after infection, which indicates that hydroxylation and glucuronidation as metabolic pathways for flumequine were decreased after Pasteurella sp. infection.     

Study of enrofloxacin and flumequine residues depletion in eggs of laying hens after oral administration

Two groups of laying hens (each n=12) were administered 10 mg/kg enrofloxacin (ENRO) (group A) or 26.6 mg/kg flumequine (FLU) (group B) by gastric catheter daily for five consecutive days. A third group (n=6) was untreated controls. Eggs were collected from day one of treatment and up to 30 days after withdrawal of the drug. Egg white and yolk from each egg were separated, and ENRO, its metabolite ciprofloxacin (CIP) and FLU residues were analysed by a high-performance liquid chromatography method with fluorescence detection. The sum of ENRO and CIP was detectable in egg white on the first day of treatment in high-level concentrations (2007.7 μg/kg) and remained steady during administration. In egg yolk, residues were detectable at day one in lower concentrations (324.4 μg/kg), increasing to the end of treatment. After treatment, these residues decreased and were detectable up to day 8 in egg white, and day 10 in yolk. FLU residues during drug administration in white were detectable in high concentrations from day one to five (6788.4-6525.9 μg/kg), and in yolk, concentrations were lower during administration (629.6-853.9 μg/kg). After drug withdrawal, FLU residues remained longer in egg white (30 days) than in yolk (26 days). For both drugs, differences of concentrations between matrices were significant.