Pharmacokinetics of ceftazidime in Northern leopard frogs (Lithobates pipiens) at two different doses and administration routes.

Shawna J Hawkins, Sherry K Cox, Kurt K Sladky

American journal of veterinary research 2021 Jul

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To determine an optimal ceftazidime dosing strategy in Northern leopard frogs (Lithobates pipiens) by evaluation of 2 different doses administered SC and 1 dose administered transcutaneously. 44 Northern leopard frogs (including 10 that were replaced). Ceftazidime was administered to frogs SC in a forelimb at 20 mg/kg (n = 10; SC20 group) and 40 mg/kg (10; SC40 group) or transcutaneously on the cranial dorsum at 20 mg/kg (10; TC20 group). Two frogs in each ceftazidime group were euthanized 12, 24, 48, 72, and 96 hours after drug administration. Plasma, renal, and skin concentrations of ceftazidime were measured by means of reversed-phase high-performance liquid chromatography. Four control frogs were used for assay validation. Mean plasma half-life of ceftazidime in the SC20, SC40, and TC20 groups was 9.01 hours, 14.49 hours, and too low to determine, respectively. Mean maximum plasma ceftazidime concentration was 92.9, 96.0, and 1.3 μg/mL, respectively. For 24 hours after drug administration in the SC20 and SC40 groups, plasma ceftazidime concentration exceeded 8 μg/mL. Renal and skin concentrations were detectable at both doses and routes of administration; however, skin concentrations were significantly lower than renal and plasma concentrations. Findings indicated that ceftazidime administration to Northern leopard frogs at 20 mg/kg, SC, every 24 hours would achieve a plasma concentration exceeding the value considered effective against common amphibian pathogens. Transcutaneous administration of the injectable ceftazidime formulation at 20 mg/kg warrants further investigation but is not currently recommended because of a potential lack of efficacy.

Citation

Shawna J Hawkins, Sherry K Cox, Kurt K Sladky. Pharmacokinetics of ceftazidime in Northern leopard frogs (Lithobates pipiens) at two different doses and administration routes. American journal of veterinary research. 2021 Jul;82(7):560-565