title: Pharmacokinetic disposition of a long-acting oxytetracycline formulation after single-dose intravenous and intramuscular administrations in the American alligator (Alligator mississippiensis).
abstract: The pharmacokinetics of a long-acting oxytetracycline preparation administered i.v. and i.m. to American alligators (Alligator mississippiensis) at 10 mg/kg was determined. Plasma levels of oxytetracycline were measured using high-performance liquid chromatography, and the resulting concentration versus time curve was analyzed using compartmental modeling and noncompartmental modeling techniques for i.v. and i.m. samples, respectively. A two-compartment model best represented the i.v. data. Intravenous administration of oxytetracycline resulted in an extrapolated mean plasma concentration at time zero of 60.63 +/- 28.26 microg/ml, with average plasma drug levels of 2.82 +/- 0.71 microg/ml at the end of the 192-hr sampling period. Plasma volume of distribution for i.v. oxytetracycline was 0.20 +/- 0.09 L/kg, with a harmonic mean elimination half-life of 15.15 hr and mean total body clearance rate of 0.007 +/- 0.002 L/hr/kg. Intramuscular administration of oxytetracycline achieved a mean peak plasma concentration of 6.85 +/- 1.96 microg/ml at 1 hr after administration, with average plasma drug levels of 4.96 +/- 1.97 microg/ml at the end of the 192-hr sampling period. The harmonic mean terminal elimination half-life for i.m. oxytetracycline was 131.23 hr. Based on the results of this study, long-acting preparations of oxytetracycline administered parenterally to American alligators at 10 mg/kg q 5 days is expected to maintain plasma concentrations above the minimum inhibitory concentration of 4.0 microg/ml for susceptible organisms.
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Kelly E
authors.initials: KE
authors.lastname: Helmick
authors.forename: Mark G
authors.initials: MG
authors.lastname: Papich
authors.forename: Kent A
authors.initials: KA
authors.lastname: Vliet
authors.forename: R Avery
authors.initials: RA
authors.lastname: Bennett
authors.forename: Elliott R
authors.initials: ER
authors.lastname: Jacobson
mesh_terms: D000489:Alligators and Crocodiles / Q000097:blood / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D008657:Metabolic Clearance Rate; D010118:Oxytetracycline / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D000900:Anti-Bacterial Agents; D010118:Oxytetracycline