Effect of benzylpenicillin on intravenous pharmacokinetics of acyclovir in red-eared slider turtles (Trachemys scripta elegans)

The aim of this study was to determine the effect of benzylpenicillin on the pharmacokinetics of acyclovir in red-eared slider turtles (Trachemys scripta elegans). Six clinically healthy red-eared slider turtles weighing 400 and 580 g were used for the study. Acyclovir (40 mg/kg) and benzylpenicillin (30 mg/kg) were administered intravenously to turtles. In the study, the cross-pharmacokinetic design (2 x 2) with a 30-day washout period was performed in two periods. Plasma concentrations of acyclovir were assayed using the high-performance liquid chromatography with fluorescence detection. Pharmacokinetic parameters were calculated by two-compartment open pharmacokinetic model. Following the administration of acyclovir alone, elimination half-life (t(1/2)(beta)), area under the plasma concentration-time curve (AUC), total clearance (Cl-T), and volume of distribution at steady-state (V-dss) were 20.12 hr, 1,372 hr * mu g/mL, 0.03 L hr(-1) kg(-1), and 0.84 L/kg, respectively. Benzylpenicillin administration increased t(1/2)(beta), AUC, and V-dss while decreased Cl-T of acyclovir. These results showed that benzylpenicillin changed the pharmacokinetics of acyclovir following simultaneous administration in turtles. However, further research is needed to determine molecular mechanism of interaction in turtle.