PHARMACOKINETIC DISPOSITION OF A LONG-ACTING OXYTETRACYCLINE FORMULATION AFTER SINGLE-DOSE INTRAVENOUS AND INTRAMUSCULAR ADMINISTRATIONS IN THE AMERICAN ALLIGATOR (ALLIGATOR MISSISSIPPIENSIS)

• Published in: Journal of zoo and wildlife medicine 2004-09, Vol.35 (3), p.341-346
• Main Authors: Helmick, Kelly E, Papich, Mark G, Vliet, Kent A, Bennett, R. Avery, Jacobson, Elliott R
• Format: Article
• Language: English
• Subjects: Alligator mississippiensis; Alligators; Alligators and Crocodiles - blood; Alligators and Crocodiles - metabolism; American alligator; Animals; Anti-Bacterial Agents - blood; Anti-Bacterial Agents - pharmacokinetics; antibiotic; Area Under Curve; Dosage; Drug design; Half lives; Human resources; Injections, Intramuscular - veterinary; Injections, Intravenous - veterinary; Intramuscular injections; Intravenous injections; long-acting oxytetracycline; Medication administration; Metabolic Clearance Rate; Oxytetracycline - administration & dosage; Oxytetracycline - blood; Oxytetracycline - pharmacokinetics; parenteral; Pharmacokinetics; Zoos
• ISSN: 1042-7260; 1937-2825
• DOI: 10.1638/03-001

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 μg/ml, with average plasma drug levels of 2.82 ± 0.71 μg/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 μg/ml at 1 hr after administration, with average plasma drug levels of 4.96 ± 1.97 μg/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 μg/ml for susceptible organisms.