title: Influence of age on the disposition kinetics of chloramphenicol in equine neonates.
abstract: The effect of age on the pharmacokinetics of chloramphenicol was determined after IV administration of chloramphenicol sodium succinate (25 mg/kg of body weight) to 6 foals at 1 day and 3, 7, 14, and 42 days of age. The disposition of chloramphenicol was best described, using a two-compartment open model in all foals at all ages evaluated. Significant age-related changes were observed in values for the major kinetic terms describing the disposition of chloramphenicol in foals; the greatest changes were observed between 1 day and 3 days of age. The mean +/- SD value for elimination rate constant (beta) for chloramphenicol in 1-day-old foals (0.131 +/- 0.06 h-1) was significantly (P less than 0.005) lower than the value in 3-day-old foals (0.514 +/- 0.156 h-1), and both values were significantly (P less than 0.05) lower than values for beta in 7-, 14-, and 42-day-old foals. With increasing age, the increase in the mean value for beta resulted in decrease in the harmonic mean elimination half-time (t1/2 beta) for chloramphenicol, from 5.29 hours in 1-day-old foals to: 1.35 hours in 3-day-old foals; 0.61 hour in 7-day-old foals; 0.51 hour in 14-day-old foals; and 0.34 hour in 42-day-old foals. At 1, 3, and 7 days of age, values for t1/2 beta of chloramphenicol in a premature foal born after parturition was induced with oxytocin, were considerably longer than comparable t1/2 beta values for term foals born naturally.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, School of Veterinary Medicine, University of California, Davis 95616.
authors.forename: P J
authors.initials: PJ
authors.lastname: Adamson
authors.forename: W D
authors.initials: WD
authors.lastname: Wilson
authors.forename: J D
authors.initials: JD
authors.lastname: Baggot
authors.forename: S K
authors.initials: SK
authors.lastname: Hietala
authors.forename: J E
authors.initials: JE
authors.lastname: Mihalyi
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002701:Chloramphenicol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D006736:Horses / Q000378:metabolism*; D007262:Infusions, Intravenous / Q000662:veterinary; D007751:Labor, Induced / Q000662:veterinary; D008297:Male; D011247:Pregnancy; D012016:Reference Values
chemical_list: D002701:Chloramphenicol