LAUSR

Abstract Coccidial disease is significant in tortoises; Testudines intranuclear coccidiosis (TINC), caused by an unnamed coccidia, causes high mortality in diverse tortoise species. There is a lack of information on anticoccidial drugs in tortoises. The drug ponazuril has demonstrated efficacy in treating mammals infected with similar coccidial disease. Previous empirical use of ponazuril in TINC cases suggests that it may be an effective treatment. In this study, 20 mg/kg of ponazuril was orally administered to tortoises with the goal of achieving blood concentrations known to be effective for anticoccidial therapy in mammals. Ponazuril was measured in tortoise plasma, and noncompartmental analyses of pharmacokinetic parameters were attempted. Ponazuril in these tortoises did not achieve the desired concentrations known to be effective for anticoccidial treatment in mammals. Tortoises showed prolonged oral absorption, and despite sampling for 168 hr (1 wk), a terminal elimination rate constant and half-life were not able to be determined. Additional studies are needed to fully characterize ponazuril pharmacokinetics in red-footed tortoises. The optimal dose for treating TINC remains to be determined.