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Updated: Oct 14, 2025

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids
Published on: April 25, 2016
Pharmacokinetics of fluoxetine in horses following oral administration
Laura H Waitt Wolker1, Charles A Veltri2, Krista Pearman3
1Department of Equine Medicine and Surgery, College of Veterinary Medicine, Midwestern University, Glendale, Arizona, USA.
Abstract:
This study aimed to investigate pharmacokinetics of fluoxetine in horses and validate a method for liquid chromatography mass spectrometry analysis of serum levels. Fluoxetine pharmacokinetics were determined using 10 healthy, adult horses. Fluoxetine pharmacokinetics following a single oral dose (0.25 mg/kg) were determined using blood samples collected prior to and at several time points over 7 days following administration. Serum concentrations of fluoxetine and its bioactive metabolite norfluoxetine were measured using liquid chromatography coupled to an accurate mass/high-resolution mass spectrometer. Pharmacokinetic parameters were estimated using a noncompartmental model. Time to maximum serum concentration and serum half-life of fluoxetine was 1.5 and 15.6 h, respectively. Steady-state serum concentrations were evaluated using five horses each receiving fluoxetine (0.25 mg/kg, PO, q24hrs) for 8 weeks and were found to be 62.9 ± 25.5 ng/ml on average. Norfluoxetine was not detected in any sample.
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