Evaluating tissue concentrations in Panamanian golden frogs (Atelopus zeteki) infected with batrachochytrium dendrobatidis following a single 0.01 percent itraconazole immersion treatment

Chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), continues to threaten amphibian biodiversity globally. The Panamanian golden frog (Atelopus zeteki), a species highly susceptible to Bd infection, remains extinct in the wild and dependent on ex situ conservation for survival. Itraconazole, a triazole antifungal, is widely used to treat Bd infections, yet the impact of Bd infection on itraconazole tissue absorption, distribution, and clearance in amphibians is still poorly understood. This study evaluated itraconazole tissue concentrations in Bd-infected (Bd⁺) and uninfected (Bd⁻) A. zeteki following a single 0.01 percent 10-minute immersion. Tissue samples were analyzed at 24, 48, 72, 144, 192, and 240 hours post-treatment, and itraconazole concentrations were measured in the skin, liver, kidney, and gastrointestinal tract using high-performance liquid chromatography (HPLC). Bd⁺ frogs exhibited consistently lower tissue concentrations and more rapid clearance compared to Bd⁻ frogs, likely due to Bd-induced physiological alterations. Tissue concentrations remained above the limit of quantification (LOQ; 0.1 ng/mg) at 240 hours in most tissues of Bd⁻ frogs but fell below the LOQ in most tissues of Bd⁺ frogs by 144–192 hours. These findings suggest that infection status influences itraconazole tissue absorption, distribution, and clearance, supporting the potential for reducing dosing frequency in Bd treatment protocols. Future treatment protocols should consider infection status, tissue-specific distribution, and optimized dosing intervals to improve efficacy and minimize adverse effects in amphibian chytridiomycosis management.