Determination of Simvastatin in Human Plasma by Column‐Switching HPLC with UV Detection

Abstract

The purpose of this study was to develop and validate a sensitive and specific analytical method for determination of simvastatin in human plasma by the column‐switching high performance liquid chromatography (HPLC) system with UV detection. Simvastatin was extracted in diethyl ether from plasma. The residue was dissolved in mobile phase I [acetonitrile–20 mM potassium phosphate buffer (45:55, v/v, pH 5.6)] and the solution was injected into a pre‐column. The analytes fractionated from the pre‐column by a valve switching step were concentrated on the top of an intermediate C₁₈ column. Then, the concentrated simvastatin was separated to the analytical column with a mobile phase II [acetonitrile–20 mM potassium phosphate buffer (65:35, v/v, pH 5.6)], using a UV detector at the wavelength of 238 nm. Simvastatin was eluted at 28.7 min without interference of endogenous material in plasma. The limit of quantification (LOQ) was 0.5 ng/mL of simvastatin. The calibration curve was linear in the concentration range of 0.5–20 ng/mL (r ² = 0.9986). Moreover, the inter‐ and intra‐day precisions of this method were less than 15%. The average recovery of extraction was 89.7% over the concentration. The assay was successful in measuring plasma concentrations of simvastatin in three volunteers after oral administration (80 mg simvastatin).

Keywords:

• Simvastatin
• HPLC
• Human plasma
• Column‐switching

Acknowledgment

This work is supported by the grant from the Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University. The authors would like to acknowledge Mr. Joung‐Hwan Yoo from Young Jin Biochrom Co. Ltd. for his expert technical assistance.