title: Comparative pharmacokinetics of enrofloxacin in mice, rats, rabbits, sheep, and cows.
abstract: OBJECTIVE
  To compare pharmacokinetic variables of enrofloxacin (ENR) after IV administration in mice, rats, rabbits, sheep, and cows and to perform allometric analysis of ENR.
  
  
  METHODS
  47 mice, 5 rats, 5 rabbits, 5 sheep, and 5 cows.
  
  
  METHODS
  Serially obtained plasma samples were assayed for ENR concentration, using high-performance liquid chromatography. In vitro plasma protein binding was determined by ultrafiltration. Plasma ENR concentration versus time curves were fitted by use of nonlinear least-squared regression analysis. Pharmacokinetic variables were correlated further with body weight.
  
  
  RESULTS
  In all species studied, the best fit was obtained for a two-compartment open model; ENR half-life ranged from 89 minutes in mice to 169 minutes in cows. Volume of distribution was large in all species studied, with values ranging from 10.5 L/kg in mice to 1.5 L/kg in sheep. Body clearance ranged from 68.1 ml/min/kg for mice to 4.6 ml/min/kg for sheep. Unbound ENR was found to be (mean +/- SD) 58+/-2, 50+/-6, 50+/-2, 31+/-2, and 40+/-3% in plasma of mice, rats, rabbits, sheep, and cows, respectively. The only pharmacokinetic variables that could be correlated with body weight were elimination half-life, clearance, and volume of distribution. Allometric exponents denoting proportionality of half-life, body clearance, and volume of distribution with body weight were 0.06, 0.82, and 0.90, respectively.
  
  
  CONCLUSIONS
  An allometric approach could provide a suitable method for determining a scale for ENR pharmacokinetics among various mammalian species. This would faciliatate the administration of appropriate doses of ENR to all animals.
authors.affiliation: Department of Pharmacology and Physiology, School of Veterinary Science, University of Zaragoza, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Bregante
authors.forename: P
authors.initials: P
authors.lastname: Saez
authors.forename: J J
authors.initials: JJ
authors.lastname: Aramayona
authors.forename: L
authors.initials: L
authors.lastname: Fraile
authors.forename: M A
authors.initials: MA
authors.lastname: Garcia
authors.forename: C
authors.initials: C
authors.lastname: Solans
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000097:blood / Q000493:pharmacokinetics*; D000970:Antineoplastic Agents / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001835:Body Weight; D002417:Cattle / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D000077422:Enrofloxacin; D024841:Fluoroquinolones; D006207:Half-Life; D007275:Injections, Intravenous / Q000662:veterinary; D016018:Least-Squares Analysis; D051379:Mice / Q000378:metabolism*; D015363:Quinolones / Q000097:blood / Q000493:pharmacokinetics*; D011817:Rabbits / Q000378:metabolism*; D051381:Rats / Q000378:metabolism*; D012044:Regression Analysis; D012756:Sheep / Q000378:metabolism*; D014462:Ultrafiltration
chemical_list: D000890:Anti-Infective Agents; D000970:Antineoplastic Agents; D024841:Fluoroquinolones; D015363:Quinolones; D000077422:Enrofloxacin