Quantification of aesculin in rabbit plasma and ocular tissues by high performance liquid chromatography using fluorescent detection: Application to a pharmacokinetic study

A simple and sensitive high performance liquid chromatography method with fluorescence detection (HPLC-FD) was described for the determination of aesculin (AL) at low concentrations in rabbit plasma and ocular tissues. After deproteinization by methanol using pazufloxacin mesilate (PM) as an internal standard (I.S.), supernatants were evaporated to dryness at 40 °C under a gentle stream of nitrogen. The residue was reconstituted in mobile phase and a volume of 20 μL was injected into the HPLC for analysis. Analytes were separated on an Ultimate XB-C18 column (250 mm × 4.6 mm i.d., 5 μm particle size) and protected by a ODS guard column (10 mm × 4.0 mm i.d., 5 μm particle size), using acetonitrile-0.1% triethylamine in water (adjusted to pH 3.0 using phosphoric acid) (12:88, v/v) as mobile phase with a flow rate of 1.0 mL/min. The wavelengths of fluorescence detector (FD) were set at 344 nm for excitation and 466 nm for emission. The lower limit of quantitation (LOQ) for AL was 0.80 ng/mL for plasma and vitreous body, 1.59 ng/mL for aqueous humor, and 6.55 ng/g for iris and 1.66 ng/g for retina. The method was used in the study of AL concentrations in plasma and ocular tissues after topical administration of AL eye drops.