Quantitation of tizoxanide in multiple matrices to support cell culture, animal and human research.

Currently nitazoxanide is being assessed as a candidate therapeutic for SARS-CoV-2. Nitazoxanide is rapidly broken down to its active metabolite tizoxanide upon administration. Unlike many other candidates being investigated, tizoxanide plasma concentrations achieve antiviral levels after administration of the approved dose, although higher doses are expected to be needed to maintain these concentrations across the dosing interval in the majority of patients. Here an LC-MS/MS assay is described that has been validated in accordance with Food and Drug Administration (FDA) guidelines. Fundamental parameters have been evaluated, and these included accuracy, precision and sensitivity. The assay was validated for human plasma, mouse plasma and Dulbecco's Modified Eagles Medium (DMEM) containing varying concentrations of Foetal Bovine Serum (FBS). Matrix effects are a well-documented source of concern for chromatographic analysis, with the potential to impact various stages of the analytical process, including suppression or enhancement of ionisation. Herein a validated LC-MS/MS analytical method is presented capable of quantifying tizoxanide in multiple matrices with minimal impact of matrix effects. The validated assay presented here was linear from 15.6 ng/mL to 1000 ng/mL. The presented assay here has applications in both pre-clinical and clinical research and may be used to facilitate further investigations into the application of nitazoxanide against SARS-CoV-2.

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Crown Copyright © 2023. Published by Elsevier B.V. All rights reserved.

Déclaration de conflit d'intérêts

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Andrew Owen reports financial support was provided by UK Research and Innovation. Andrew Owen reports financial support was provided by National Institutes of Health. Andrew Owen reports financial support was provided by Engineering and Physical Sciences Research Council. Andrew Owen reports financial support was provided by European Commission. Andrew Owen reports financial support was provided by Unitaid. Andrew Owen and Steve Rannard reports a relationship with AstraZeneca that includes: funding grants. Andrew Owen and Steve Rannard reports a relationship with Gilead Sciences Inc that includes: consulting or advisory. Andrew Owen reports a relationship with ViiV Healthcare that includes: consulting or advisory and funding grants. Steve Rannard reports a relationship with ViiV Healthcare that includes: funding grants. Andrew Owen reports a relationship with Merck & Co Inc that includes: consulting or advisory and funding grants. Andrew Owen reports a relationship with Janssen Pharmaceuticals Inc that includes: funding grants.