Pharmacokinetics of oral ponazuril in kea (Nestor notabilis) support its use as a preventative for sarcocystosis.

OBJECTIVE: To determine the pharmacokinetic profile of ponazuril in kea following administration of a single oral dose and evaluate trough values associated with weekly dosing. The hypothesis was that weekly dosing would maintain plasma ponazuril concentrations above the inhibitory concentration of 5 µg/mL for Sarcocystis organisms. METHODS: 8 adult kea were administered 30 mg/kg of ponazuril via oral gavage. Blood samples were collected at 2, 4, 8, 24, 48, 72, 96, 120, 144, 168, and 192 hours in an incomplete balanced block design. Ponazuril administration was then continued weekly, and blood was collected from all birds immediately prior to the fifth weekly dose. Plasma ponazuril concentrations were determined by reverse-phase HPLC, and results were analyzed by noncompartmental analysis. Trough values were also measured after > 1 year of weekly ponazuril administration for 4 birds. RESULTS: The estimated time to maximum concentration, maximum concentration, and estimated elimination half-life were 23 ± 12 hours, 6.78 ± 1.89 µg/mL, and 128 ± 49 hours, respectively. The mean trough concentration after 4 weekly doses was 5.97 ± 2.15 µg/mL. No adverse effects were observed during the study or following weekly dosing of ponazuril for > 1 year, and long-term trough values were 14.06 ± 4.85 µg/mL. CONCLUSIONS: A single oral 30-mg/kg dose of ponazuril administered weekly maintains plasma concentrations above the known inhibitory concentration for Sarcocystis neurona and should therefore prevent sarcocystosis in kea. CLINICAL RELEVANCE: Weekly administration of ponazuril at 30 mg/kg may prevent mortality associated with Sarcocystis falcatula in kea and other susceptible psittacines where exclusion of host species is not possible.