Determination of bisnafide,a novel bis-naphthalimide anticancer agent,in human plasma by high-performance liquid chromatography with UV detection

A simple, specific, and sensitive high-performance liquid chromatographic (HPLC) assay utilizing ultraviolet (UV) detection for the determination of bisnafide in human plasma was developed, validated, and applied to plasma samples from patients undergoing cancer therapy. Plasma samples, containing an internal standard, XE842, were first deproteinized with 2.0 ml acetonitrile, and subsequently, 1.0 ml of pH 9 boric acid–potassium chloride–sodium hydroxide buffer (0.1 M) was added. To this mixture, 9.0 ml of ethyl ether was added then vortex mixed. Following centrifugation, the ether layer was back-extracted into 250 μl of 0.1 M phosphoric acid, then removed by vacuum aspiration. A portion of the remaining acid layer was directly injected onto the HPLC. Bisnafide was quantified using a Shiseido Capcell Pak C8 HPLC column and ultraviolet detection (274 nm). The lower limit of quantification was 10 ng ml⁻¹ using 1.0 ml plasma. The intraday precision (RSD) ranged from 2.7 to 8.6% over a concentration range of 10–1000 ng ml⁻¹. The interday precision (RSD) ranged from 5.6 to 11.5%. Overall mean accuracy was ±5.2%. The drug was stable in frozen heparinized human plasma stored at −20°C for at least 1 year and stable throughout at least two freeze–thaw cycles. This method was successfully utilized for quantifying plasma concentrations needed to study the clinical pharmacokinetics of bisnafide in patients undergoing cancer therapy.