Pharmacokinetics of ceftiofur sodium after intramuscular or subcutaneous administration in green iguanas (Iguana iguana)

Objective - To determine the pharmacokinetics of ceftiofur sodium after IM and SC administration in green iguanas. Animals - 6 male and 4 female adult green iguanas. Procedure - In a crossover design, 5 iguanas received a single dose of ceftiofur sodium (5 mg/kg) IM, and 5 iguanas received the same dose SC. Blood samples were taken at 0, 20, and 40 minutes and 1, 2, 4, 8, 24, 48, and 72 hours after administration. After a 10-week washout period, each iguana was given the same dose via the reciprocal administration route, and blood was collected in the same fashion. Ceftiofur free-acid equivalents were measured via high-performance liquid chromatography. Results - The first phase intercepts were significantly different between the 2 administration routes. Mean maximum plasma concentration was significantly higher with the IM (28.6 ± 8.0 μg/mL) than the SC (18.6 ± 8.3 μg/mL) administration route. There were no significant differences between terminal half-lives (harmonic mean via IM route, 15.7 ± 4.7 hours; harmonic mean via SC route, 19.7 ± 6.7 hours) and mean areas under the curve measured to the last time point (IM route, 11,722 ± 7,907 μg·h/mL; SC route, 12,143 ± 9,633 μg·h/mL). Ceftiofur free-acid equivalent concentrations were maintained ≥ 2 μg/mL for > 24 hours via both routes. Conclusions and Clinical Relevance - A suggested dosing schedule for ceftiofur sodium in green iguanas for microbes susceptible at > 2 μg/mL would be 5 mg/kg, IM or SC, every 24 hours.