Population Pharmacokinetics of Enrofloxacin and Its Metabolite Ciprofloxacin in Clinically Diseased and Injured Eastern Box Turtles (Terrapene carolina carolina), Yellow-Bellied Sliders (Trachemys scripta scripta), and River Cooters (Pseudemys concinna)
Enrofloxacin is commonly utilized for antibiotic therapy in turtles in wildlife clinics during rehabilitation. This medication is ideal for treatment due to its antibacterial activity and availability of injectable formulations; however, sufficient pharmacokinetic data to guide dosing are lacking. The objective of this study was to determine pharmacokinetic parameters of enrofloxacin and ciprofloxacin after injection of enrofloxacin in North American chelonians presenting diseased or injured to a wildlife clinic. Thirty-six Eastern box turtles (EBT, Terrapene carolina carolina), 23 yellow-bellied sliders (YBS, Trachemys scripta scripta), and 13 river cooters (RC, Pseudemys concinna) received a single subcutaneous injection of enrofloxacin (Baytril®, 2.27% injectable solution, Bayer HealthCare LLC, Shawnee Mission, KS, USA) at 10 mg/kg. Each animal had blood samples collected three times between 0 and 240 h post-injection. Pharmacokinetic parameters were determined using nonlinear mixed effects modeling (NMLE), an ideal method to allow for sparse sampling due to sampling limitations for each turtle. Results indicate overall elimination half-life (T½) was over 75 h, and varied among species. T½ was 63 h in EBT and 79 h in YBS, longer than previously reported T½ for intracoelomic administration in healthy YBS (47.6 h).1 Variability was high for volume of distribution (steady-state) with a value of 1.4 L/kg across all samples, but 1.9 L/kg for YBS and 0.4 L/kg for RC when evaluating individual species. Antibiotic concentrations were above a minimum inhibitory concentration (MIC) value of 0.5 µg/ml for over 200 h. These results indicate variable pharmacokinetic parameters for enrofloxacin among turtle species, which will help guide appropriate dosing protocols in diseased or injured turtles.
The authors would like to thank Delta Dise, Kent Passingham, and the NC State Turtle Rescue Team for their support and technical assistance with this project. Additionally, John Griffioen is a recipient of the George H. Hitchings New Investigator Award in Health Research, a fund of the Triangle Community Foundation which financially supported this project.
1. Giorgi M, Rota S, Giorgi T, Capasso M, Briganti A. Blood concentrations of enrofloxacin and the metabolite ciprofloxacin in yellow-bellied slider turtles (Trachemys scripta scripta) after a single intracoelomic injection of enrofloxacin. J Exot Pet Med. 2013;22:192–199.