Development of a High-Performance Liquid Chromatographic Method for Determination of Letrozole in Wistar Rat Serum and its Application in Pharmacokinetic Studies

A fast, sensitive, and specific reversed-phase high-performance liquid chromatographic (RP-HPLC) method for the determination of letrozole in Wistar rat serum was developed. In this method, liquid-liquid extraction of letrozole was achieved using diethyl ether as the extracting solvent. The analysis was carried out on a reversed-phase C18 (250 mm × 4.6 mm, 5 μm) column with an isocratic mobile phase of methanol-water (70:30,v/v), at a flow rate of 1.0 mL min(-1). Detection was carried out at 239 nm with a UV-visible spectrophoto-metric detector. The method was shown to be selective and linear over the concentration range of 0.15-100 μg mL(-1). The intra-day and inter-day precision studies showed good reproducibility with coefficients of variation less than 11% for the analyte. The relative errors of intra- and inter-day accuracy were within -11.52 to -2.26%. The limit of quantification was evaluated to be 0.15 μg mL(-1). The method was successfully applied for the pharmacokinetic study of letrozole after oral administration of 10 mg kg(-1) of letrozole in six healthy Wistar rats.