Abstract: The aim of this study was to investigate pharmacokinetics and penetration into the aqueous humor of Long Action Oxytetracycline (OTC-LA) after Intravenous (IV) and Intramuscular (IM) administrations, at a single dose of 20 mg kg-1 b.wt in rabbits. After administrations of the long action formulation, the plasma oxytetracycline concentrations were evaluated using a two-compartmental open model. The study was designed according to a two-period cross-over and the plasma OTC concentration was measured using the ELISA procedure. The elimination half-lives (t1/2β) of the OTC-LA after IV and IM administrations were 12.60±0.92 and 38.67±4.40 h, respectively. After IV administration, the volume of distribution (Vdss) and total body Clearance (Cltot) values of the drug were 3.42±0.21 L kg-1 and 0.19±0.01 L/h/kg, respectively. The maximum concentration of the drug (Cmax) in the plasma (4.23±0.43 μg mL-1) was achieved at 2.0 h (tmax) after IM administration. The Minimum therapeutic plasma Concentration (MIC) of the drug at the amount ≥0.5 μg mL-1 was maintained until 48 h after IV and IM administrations. The intramuscular bioavailability of the drug was 0.79±0.10%. After IV and IM administrations of OTC-LA formulation, the maximum concentrations of the drug in the aqueous humor were 0.1 and 0.068 μg mL-1, respectively. However, the concentrations of the drug in the aqueous humor were below the MIC value (0.5 μg mL-1) during 12-72 and 4-48 h for IM and IV administrations, respectively.
Feride Koc, Ozgur Kaynar, Zafer Okumus, Elif Dogan and Latif Emrah Yanmaz, 2009. Pharmacokinetics and Penetration into the Aqueous Humor of Long Action Oxytetracycline after Single Dose Intravenous and Intramuscular Administrations in Rabbits. Journal of Animal and Veterinary Advances, 8: 1900-1905.