RESUMO
A sensitive, specific and cost-effective HPLC method was developed for quantitative determination of carbinoxamine in human plasma using liquid chromatography with ultraviolet detection. A simple liquid-liquid extraction by ethyl acetate was used to extract carbinoxamine from human plasma. Satisfactory separation was achieved by a mobile phase consisting of 20 mM ammonium dihydrogen orthophosphate containing 0.01% triethyl amine (pH adjusted to 3 by using phosphoric acid) and acetonitrile in ratio of (75:25, v/v) at a flow rate of 0.9 mL/min on Hypersil® BDS C18 column (250×4.6 mm, 5 µm) column. The UV detector was set at 260 nm. The developed method was validated in human plasma with a lower limit of quantitation of 5 ng/mL for carbinoxamine. Linearity was demonstrated over the concentration range 5-200 ng/mL. The observed within- and between-day assay precision ranged from 1.902 to 14.90%; accuracy varied between 98.87 and 108.0%. This method can be used suitably for pharmacokinetic studies and in therapeutic drug monitoring in patients treated with carbinoxamine.