Assay validation and determination of in vitro binding of mefloquine to plasma proteins from clinically normal and FIP-affected cats

• Published in: PloS one 2020-08, Vol.15 (8), p.e0236754-e0236754
• Main Authors: Izes, Aaron M, Kimble, Benjamin, Norris, Jacqueline M, Govendir, Merran
• Format: Article
• Language: English
• Subjects: Accuracy; Antiviral drugs; Assaying; Binding; Biochemical assays; Biology and Life Sciences; Blood plasma; Cat diseases; Chromatography; Clinical trials; Coefficient of variation; Composition; Coronaviridae; Coronaviruses; Dialysis; Drug dosages; Drug therapy; Equilibrium dialysis; Feline infectious peritonitis; High performance liquid chromatography; High pressure; In vitro methods and tests; Liquid chromatography; Medicine and Health Sciences; Mefloquine; Metabolism; Peritonitis; Plasma; Plasma proteins; Protein binding; Proteins; Quality control; Research and Analysis Methods; Software; Supervision; Testing; Validation studies; Veterinary research; Virulence
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0236754

The antimalarial agent mefloquine is currently being investigated for its potential to inhibit feline coronavirus and feline calicivirus infections. A simple, high pressure liquid chromatography assay was developed to detect mefloquine plasma concentrations in feline plasma. The assay's lower limit of quantification was 250 ng/mL. The mean ± standard deviation intra- and inter-day precision expressed as coefficients of variation were 6.83 ± 1.75 and 5.33 ± 1.37%, respectively, whereas intra- and inter-day accuracy expressed as a percentage of the bias were 11.40 ± 3.73 and 10.59 ± 3.88%, respectively. Accordingly, this validated assay should prove valuable for future in vivo clinical trials of mefloquine as an antiviral agent against feline coronavirus and feline calicivirus. However, the proportion of mefloquine binding to feline plasma proteins has not been reported. The proportion of drug bound to plasma protein binding is an important concept when developing drug dosing regimens. As cats with feline infectious peritonitis (FIP) demonstrate altered concentrations of plasma proteins, the proportion of mefloquine binding to plasma proteins in both clinically normal cats and FIP-affected cats was also investigated. An in vitro method using rapid equilibrium dialysis demonstrated that mefloquine was highly plasma protein bound in both populations (on average > 99%).