title: Tissue distribution of enrofloxacin after intramammary or simulated systemic administration in isolated perfused sheep udders.
abstract: OBJECTIVE
  To determine the tissue distribution of enrofloxacin after intramammary or simulated systemic administration in isolated perfused sheep udders by measuring its concentration at various sample collection sites.
  
  
  METHODS
  26 udders (obtained following euthanasia) from 26 healthy lactating sheep.
  
  
  METHODS
  For each isolated udder, 1 mammary gland was perfused with warmed, gassed Tyrode solution. Enrofloxacin (1 g of enrofloxacin/5 g of ointment) was administered into the perfused gland via the intramammary route or systemically via the perfusion fluid (equivalent to a dose of 5 mg/kg). Samples of the perfusate were obtained every 30 minutes for 180 minutes; glandular tissue samples were obtained at 2, 4, 6, and 8 cm from the teat base after 180 minutes. The enrofloxacin content of the perfusate and tissue samples was analyzed via high-performance liquid chromatography with UV detection.
  
  
  RESULTS
  After intramammary administration, maximun perfusate enrofloxacin concentration was detected at 180 minutes and, at this time, mean tissue enrofloxacin concentration was detected and mean tissue enrofloxacin concentration was 123.80, 54.48, 36.72, and 26.42 μg/g of tissue at 2, 4, 6, and 8 cm from the teat base, respectively. Following systemic administration, perfusate enrofloxacin concentration decreased with time and, at 180 minutes, tissue enrofloxacin concentrations ranged from 40.38 to 35.58 μg/g of tissue.
  
  
  CONCLUSIONS
  By 180 minutes after administration via the intramammary or systemic route in isolated perfused sheep mammary glands, mean tissue concentration of enrofloxacin was greater than the minimum inhibitory concentration required to inhibit growth of 90% of many common mastitis pathogens in sheep. Use of either route of administration (or in combination) appears suitable for the treatment of acute mastitis in sheep.
authors.affiliation: Division of Pharmacology, Department of Biomedical Sciences, Institute of Biomedicine, University of León, Campus de Vegazana s/n, 24071 León, Spain. clopcd@unileon.es
authors.forename: Cristina
authors.initials: C
authors.lastname: López Cadenas
authors.forename: Nélida
authors.initials: N
authors.lastname: Fernández Martínez
authors.forename: Matilde
authors.initials: M
authors.lastname: Sierra Vega
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Diez Liébana
authors.forename: Jose M
authors.initials: JM
authors.lastname: Gonzalo Orden
authors.forename: Ana M
authors.initials: AM
authors.lastname: Sahagún Prieto
authors.forename: Juan J
authors.initials: JJ
authors.lastname: García Vieitez
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D000077422:Enrofloxacin; D005260:Female; D024841:Fluoroquinolones / Q000493:pharmacokinetics*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D010477:Perfusion / Q000662:veterinary; D012756:Sheep; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D000077422:Enrofloxacin