Comparison of Enrofloxacin concentration residue in milk of healthy and clinical mastitis quarters following intramascular administration by HPLC

Pharmacokinetic studies of drugs from the body are done in healthy animals. Regarding the pathological changes in the permeability of drugs to the anatomical spaces, the knowledge about the rate of permeability of antibiotic to infected mammary glands can be effective in the selection of antibiotics. The aim of this study is to evaluate the amount of enrofloxacin in milk of healthy and clinical mastitis quarters after single dose intramasular injection in dairy cows. To do this research, from six Holstein lactating cattle with clinical grade 2 mastitis infected by E. coli, using aseptic method milk were taken and cultured in a blood Agar and McConkey environment. Finally, 6 isolates sent to the reference laboratory for approval. After confirming the cause of mastitis, Enrofloxacin 5% (hipralona) was injected intramuscularly at dose of 5 mg/kg B.W. Then, milk samples were taken at different times from healthy and clinical mastitis quarters and transferred to the laboratory to analyze. Enrofloxacin and its metabolite, Ciprofloxacin, were extracted by standard protocols. Then drug concentrations were measured using a high-performance liquid chromatographic (HPLC) method. Chromatographic conditions included a mobile phase as methanol-acetonitril solution (76:24 v/v) using an isocratic method with a flow rate of 1.0 ml/min and UV detection at 280nm. The results of our study showed that the amount of enrofloxacin in milk samples between two groups was not significantly different in hours of measurement. However, for ciprofloxacin at 12 h, it was significantly higher in milk of clinical mastitis quarters than in healthy ones. Based on the HPLC data, it can be concluded that the penetration pattern of enrofloxacin in healthy and clinical mastitis quarters had no significant difference.