title: Pharmacokinetics of enrofloxacin after single intravenous, intramuscular and subcutaneous injections in lactating cows.
abstract: Five Ayrshire cows were given enrofloxacin (5 mg/kg body weight) intravenously (i.v.), intramuscularly (i.m.) and subcutaneously (s.c.). The antimicrobial activity was measured in milk and serum samples using the agar-diffusion technique. High-performance liquid chromatography (HPLC) assay was used to study the extent of metabolism of enrofloxacin to ciprofloxacin. Analysis of the serum concentration-time data was based on statistical moment theory. Mean t1/2 beta of antimicrobial activity in serum was 1.7, 5.9 and 5.6 h after i.v., i.m. and s.c. administration, respectively. Both i.m. and s.c. routes were associated with a marked flip-flop phenomenon. Based on HPLC analysis of serum samples, the half-lives of enrofloxacin and ciprofloxacin were approximately the same. A marked proportion of enrofloxacin was metabolized to ciprofloxacin. The enrofloxacin fraction bound in vitro to serum proteins was 36-45%. About 0.2% of the total enrofloxacin dose was found in milk during the first 24 h and the amount transferred did not depend on the route of administration. Based on the HPLC data, enrofloxacin concentration in milk was parallel to that in serum, while ciprofloxacin was concentrated in milk. After i.v. injection, the peak concentration of enrofloxacin in milk was reached between 0.7 and 1.3 h but occurred much later for ciprofloxacin (tmax 5-8 h). After i.m. and s.c. administration the concentration-time curves for both enrofloxacin and ciprofloxacin in milk were shallow and there were no obvious peaks.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Helsinki, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Kaartinen
authors.forename: M
authors.initials: M
authors.lastname: Salonen
authors.forename: L
authors.initials: L
authors.lastname: Alli
authors.forename: S
authors.initials: S
authors.lastname: Pyörälä
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology; D002417:Cattle / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D002939:Ciprofloxacin / Q000097:blood; D003198:Computer Simulation; D000077422:Enrofloxacin; D004926:Escherichia coli / Q000187:drug effects; D005260:Female; D024841:Fluoroquinolones; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D007279:Injections, Subcutaneous / Q000662:veterinary; D007774:Lactation / Q000378:metabolism; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008892:Milk / Q000737:chemistry / Q000382:microbiology; D011485:Protein Binding / Q000187:drug effects; D015363:Quinolones / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D015363:Quinolones; D000077422:Enrofloxacin; D002939:Ciprofloxacin