Determination of Vardenafil in Pharmaceutical Formulation by HPLC Using Conventional C₁₈ and Monolithic Silica Columns

Abstract

A simple HPLC analysis for the ide.gification and qua.gification of vardenafil in a pharmaceutical tablet formulation was performed on a conventional C₁₈ and Chromolith Performance RP‐18e monolithic columns with acetonitrile–phosphate buffer mixtures as mobile phases. The effects of the proportion of organic solvent (from 20% to 90%), phosphate buffer pH (from 2 to 7.5) and flow rate (from 1 to 5 mL/min) were studied. The best chromatographic conditions were 20:80 (v/v) acetonitrile–10 mM phosphate buffer, pH 3.0, as mobile phase at 1 mL/min flow rate for the C₁₈ column, whereas 30:70 (v/v) acetonitrile–10 mM phosphate buffer, pH 3.0, as mobile phase at 2 mL/min flow rate was best for the monolithic column. Methanol was found to be a suitable solvent for extraction of the active substance from tablets. For the C₁₈ and monolithic column, the calibration plots were linear (R ² = 0.9996 and 0.9997, respectively) in the concentration range 10–1000 µg/mL. Limit of detection (LOD) and limit of qua.gification (LOQ) values were 0.10 and 0.31 µg/mL for the C₁₈ and 0.11 mL and 0.32 µg/mL for the monolithic column. Intra‐assay and inter‐assay precision studies reflected a high level of reliability and reproducibility of the method. The proposed method is selective, precise (RSD = 0.45%), and accurate (recovery = 103–107%) in both columns used.

Keywords:

• Liquid chromatography
• monolithic column
• pharmaceutical preparation
• Vardenafil

Acknowledgment

The authors wish to thank Bayer AG (Leverkusen, Germany) for a sample gift of the vardenafil hydrochloride trihydrate.