Validated HPLC method for the quantitative determination of CoQ10 in dog plasma and its application to a pharmacokinetic study.

Coenzyme Q₁₀ (CoQ₁₀) is a naturally occurring compound located in all membranes throughout the cell. A rapid and sensitive HPLC method was developed to determine the concentration of CoQ₁₀ in dog plasma using a surrogate matrix. Chromatographic separation was carried out on a Diamonsil C₁₈ column with the UV detector set at 275 nm. Methanol-2-propanol (40:60, v/v) was used as a mobile phase delivered at a flow rate of 1.0 mL/min. Calibrators were prepared using blank plasma-K₂HPO₄ buffer (50 m m, pH 8.0)-saline (1:3:6, v/v/v) as surrogate matrix. It was shown that the surrogate matrix had similar properties to dog plasma for CoQ₁₀ in extraction, freeze-thaw and stability. The assay was linear over the concentration range of 0.10-100 µg/mL. The intra- and inter-day precisions were within 13.3% in terms of relative standard deviation (RSD%) and the accuracy was within ±7.5% in terms of relative error. This simple and reproducible HPLC method with less plasma volume (0.4 mL) and adequate sensitivity was successfully applied to pharmacokinetic studies of CoQ₁₀ in dogs and an investigation of the effect of CoQ₁₀ formulation on CoQ₁₀ baseline levels. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]