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ARS Home » Pacific West Area » Pullman, Washington » Animal Disease Research Unit » Research » Publications at this Location » Publication #429978
Research Project: Control Strategies for Theileriosis

Location: Animal Disease Research Unit

Title: Validation of a HPLC method for the quantification of tafenoquine in bovine and equine plasma, red blood cells, and Theileria and Babesia cell culture media

Author
item URSINI, ANDREW - University Of Tennessee
item DUNCAN, MADELINE - University Of Tennessee
item GLIAS, RILEY - University Of Tennessee
item CUTCHIN, JULIA - University Of Tennessee
item Bastos, Reginaldo
item VILLARINO, NICOLAS - Washington State University
item COX, SHERRY - University Of Tennessee

Submitted to: Journal of Chromatography B
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: This study describes a simple and accurate method developed and validated to measure tafenoquine, a drug used to treat blood parasites, in plasma and erythrocytes of horses and cattle, as well as in culture media used for growing in vitro the horse blood parasites Babesia caballi and Theileria equi. To develop the method, samples were precipitated and separated using liquid chromatography. Sample molecules extracted using standard protocols, and fluorescent detection of tafenoquine occurred with an excitation of 262 nm and an emission of 476 nm. The method could detect as little as 1 ng/mL of the drug in all sample types, using just 100 µL of material. Variability between and within tests was under 10%, and recovery rates ranged from 81% to 98%, respectively. This validated method can be applied in pharmacokinetic studies to evaluate the efficacy of tafenoquine in controlling blood parasites responsible for economically important diseases in horses and cattle.

Technical Abstract: A simple and accurate reverse phase high-performance liquid chromatography tafenoquine method was developed and validated for use with Babesia caballi and Theileria equi culture media, bovine and equine plasma, and erythrocytes. After protein precipitation, samples were separated on an X-Bridge C18 column using a mobile phase consisting of 11 mM ammonium acetate (pH 4.0) and acetonitrile (45:55, v/v). The extraction used acetonitrile, zinc sulfate, and hydrochloric acid. Fluorescent detection occurred with an excitation of 262 nm and an emission of 476 nm. The lower limit of quantification (LLOQ) was 1 ng/mL for all matrices with a sample size of 100 µL. Intra and inter-assay variability was less than 10% for all matrices and the average recovery ranged from 81% to 98%, respectively. This validated method can be applied in pharmacokinetic studies to evaluate the efficacy of tafenoquine in controlling hemoparasites responsible for economically important diseases in equines and cattle.