Development and application of a simple and robust liquid chromatography-mass spectrometry method for determination of diclazuril concentration in kiwi ( <i>Apteryx</i> spp.) faeces

AIMS: spp.) faeces using liquid chromatography-mass spectrometry (LC-MS), to non-invasively determine drug disposition. METHODS: ) chicks (n = 6) following a single dose of 5 mg/kg bodyweight of the anticoccidial drug diclazuril for a period of 5 days. Daily pooled samples from each bird were prepared for LC-MS using dispersive solid phase extraction to isolate the drug for analysis. The LC-MS assay was validated using linear regression, inter-day and intra-day variation, and recovery analysis. Pharmacokinetic parameters were calculated using non-compartmental analysis. RESULTS: , consistent with the previously reported rate in kiwi plasma. CONCLUSIONS: This study establishes that the quantification of diclazuril in kiwi faeces by LC-MS is robust and reliable. Diclazuril exhibits a prolonged elimination half-life in kiwi faeces, supporting its potential for sustained coccidiostatic activity. CLINICAL RELEVANCE: The methods developed here have the potential to be modified to analyse other target drugs from faeces of birds and can assist in the evaluation of efficacy of drug treatment regimes, in particular for drugs that target infection in the gastrointestinal tract, such as anticoccidials. This non-invasive approach will be especially valuable in wildlife species where establishing plasma pharmacokinetics for drug treatments is challenging and can have significant animal welfare consequences.