Comparative pharmacokinetics of minocycline in foals and adult horses.
The objective of this study was to compare the pharmacokinetics of minocycline in foals vs. adult horses. Minocycline was administered to six healthy 6- to 9-week-old foals and six adult horses at a dose of 4 mg/kg intragastrically (IG) and 2 mg/kg intravenously (i.v.) in a cross-over design. Five additional oral doses were administered at 12-h intervals in foals. A microbiologic assay was used to measure minocycline concentration in plasma, urine, synovial fluid, and cerebrospinal fluid (CSF). Liquid chromatography-tandem mass spectrometry was used to measure minocycline concentrations in pulmonary epithelial lining fluid (PELF) and bronchoalveolar (BAL) cells. After i.v. administration to foals, minocycline had a mean (±SD) elimination half-life of 8.5 ± 2.1 h, a systemic clearance of 113.3 ± 26.1 mL/h/kg, and an apparent volume of distribution of 1.24 ± 0.19 L/kg. Pharmacokinetic variables determined after i.v. administration to adult horses were not significantly different from those determined in foals. Bioavailability was significantly higher in foals (57.8 ± 19.3%) than in adult horses (32.0 ± 18.0%). Minocycline concentrations in PELF were higher than in other body fluids. Oral minocycline dosed at 4 mg/kg every 12 h might be adequate for the treatment of susceptible bacterial infections in foals.
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
S
S
Giguère
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
A J
AJ
Burton
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
L J
LJ
Berghaus
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
A D
AD
Haspel
D000818:Animals; D000831:Animals, Newborn; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001826:Body Fluids; D004333:Drug Administration Routes / Q000662:veterinary; D006207:Half-Life; D006736:Horses / Q000378:metabolism*; D007275:Injections, Intravenous / Q000662:veterinary; D008911:Minocycline / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013582:Synovial Fluid
D000900:Anti-Bacterial Agents; D008911:Minocycline