Simple and sensitive HPLC-UV method for determination of bexarotene in rat plasma

Bexarotene is currently marketed for treatment of cutaneous T-cell lymphoma and there has been growing interest in its therapeutic effectiveness for other cancers. Neuroprotective effects of bexarotene have also been reported. In this study, a simple, sensitive and cost-efficient bioanalytical method for determination of bexarotene in rat plasma was developed and fully validated. The method utilises protein precipitation with acetonitrile and liquid-liquid extraction with n-hexane-ethyl acetate (10:1, v/v). An HPLC-UV system with a Waters Atlantis C18 column and a mobile phase of acetonitrile-ammonium acetate buffer (10mM, pH 4.1) at a ratio of 75:25 (v/v), flow rate 0.2mL/min was used. Chromatograms were observed by a UV detector with wavelength set to 259nm. Intra- and inter-day validations were performed and sample stability tests were conducted at various conditions. The applicability of the method was demonstrated by a pharmacokinetic study in rats. Intravenous bolus dose of 2.5mg/kg was administered to rats and samples were obtained at predetermined time points. As a result, pharmacokinetic parameters of AUC_inf (4668±452hng/mL), C₀ (6219±1068ng/mL) and t_1/2 (1.15±0.02h) were obtained. In addition, the developed method was further applied to human and mouse plasma to assess the suitability of the method for samples from other species.