HPLC determination of bezafibrate in human plasma and its application to pharmacokinetics studies

An isocratic high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of bezafibrate in biological fluids. Bezafibrate was separated on a C(18) analytical column (150 x 4.6 mm i.d., 5 microm particle size) with 0.01 M phosphate buffer (pH 3.5)-acetonitrile-methanol (50:40:10) as mobile phase at a flow rate of 1.0 mL/min. The UV detector was set to 230 nm. Bezafibrate was extracted from human plasma using a simple liquid-liquid extraction with tert-butyl methyl ether. Parameters such as linearity, precision, accuracy, recovery, specificity, and stability were evaluated by method validation studies. All the parameters remained within acceptable limits. The validated procedure was linear in the concentration range of 0.2-50 microg/mL. The proposed method used for individual drug determinations is applicable for therapeutic monitoring purposes as well as for use in pharmacokinetic investigations. As an example, the practical quantification limit for bezafibrate in plasma was about 0.05 microg/mL with precision of 10.2% and accuracy of 112.6%. The method was applied in a study of the pharmacokinetics of bezafibrate in six healthy volunteers, who ingested a single oral dose of 200 mg.