HPLC determination and pharmacokinetic study of valdecoxib in human plasma

A sensitive, simple, and accurate high-performance liquid chromatographic method has been developed for determination of valdecoxib and the internal standard rofecoxib in human plasma. Protein was precipitated from plasma samples by addition of perchloric acid (HClO4); the drug was then extracted with diethyl ether. Separation was performed on a Cosmosil C-18 column (150 mm x 4.6 mm i.d., 5 mum particles) with ammonium acetate buffer-acetonitrile, 60:40 (v/v), containing 0.1 % TEA, pH 6.5, as mobile phase. Detection and quantification were performed by UV-visible detection at 239 nm. Detection and quantification limits were 3 and 5 ng mL(-1), respectively. The linear concentration range for valdecoxib was 5-400 ng mL(-1). The validated RP HPLC method was used for determination of the pharmacokinetic data for the drug in humans.