Comparative Pharmacokinetics of Intravenous Enrofloxacin in One- Six- And Twelve-Month-Old Sheep

Abstract

Background: Enrofloxacin (ENR) is a fluoroquinolone antibiotic approved for use in sheep of all ages. The body composition and metabolic capability change with age. These changes may alter the pharmacokinetics of drugs and thus their effect. Therefore, the pharmacokinetics of drugs need to be established in target- age animals Objective: To determine the pharmacokinetics of ENR and its active metabolite, ciprofloxacin (CIP), following a single intravenous administration of ENR at a dose of 10 mg/kg in different ages of sheep. Methods: The study was carried out in the one-, six- and twelve-month age period of the sheep. A single dose of 10 mg/kg ENR was administered intravenously through the jugular vein to sheep in all age periods. ENR and CIP plasma concentrations were determined using HPLC–UV and analyzed using a non-compartmental method. Results: ENR was detected in the plasma until 36 h in one-month-old and up to 24 h in other ages. CIP was detected in the plasma up to 24 h in all age groups. The t1/2ʎz and Vdss were significantly higher in one-month-old sheep than in six and twelve-months old sheep. There was no difference in ClT and AUC values in different age groups. AUC0-∞CIP/AUC0-∞ENR ratios were higher in one-month-old than in six- and twelve-months sheep. Conclusion: The most important pharmacokinetic changes associated with aging in sheep are decreased Vdss and t1/2ʎz of ENR and the low ratio metabolizing of ENR to CIP. Pharmacokinetic/pharmacodynamic data showed that ENR after IV administration of 10 mg/kg dose provided the optimal AUC0–24/MIC90 ratios for E. coli, P. multocida and Mycoplasma spp. (>125) with MIC of 0.37 μg/mL and for S. aureus (>30) with MIC of 0.5 μg/mL in all ages of sheep.

Biosafety assessment of laying hens fed different treatments of black soldier flies (Hermetia illucens) under doxycycline stress

“…The trend that fecal residue levels remained unchanged during the first 5 d of feeding was consistent with previous study, but compared with the residue levels in previous study (48.99–75.28%), the residue rate of doxycycline in our study was lower ( Peng et al, 2016 ). This may be because the metabolic digestion rate of the 120-day-old young laying hens we used in our study was greater than that of the 525-day-old laying hens used previously ( Coskun et al, 2023 ). The residual content of doxycycline increased to a certain extent on the 7th and 21st d of feeding, reaching 10.78 ± 0.85 mg/kg and 13.38 ± 2.13 mg/kg, respectively.…”