Synthesis, characterization, and determination of metabolite of verapamil hydrochloride by reversed-phase high performance liquid chromatography

Abstract

Aims: A suitable reversed-phase high performance liquid chromatography (RP-HPLC) method for detection and determination of laboratory synthesized metabolite norverapamil (NVER) present in the pharmaceutical formulations is the prime purpose of this study. The present study deals with synthesis, characterization, and development of simple, selective, rapid, and sensitive RP-HPLC method for simultaneous determination of verapamil (VER) and its synthetic metabolite NVER. Materials and Methods: A HIQ sil ODS C-18 column having 250 mm × 4.6 mm i.d. in isocratic mode with a mobile phase consisting methanol: Water (70:30 v/v, pH adjusted to 7.4 with dilute orthophosphoric acid (OPA) and triethylamine used as an organic modifier to avoid tailing effect). The flow rate was 1.0 ml/min and effluents were monitored at 222 nm. Results: The retention time of synthesized metabolite NVER and its parent drug VER were found to be 3.44 and 5.67 min, respectively. Valsartan (VAL) was used as the internal standard. The limit of detection were found to be 0.30 μg/ml for VER and 1.21μg/ml for NVER from physical mixture, and limit of quantitation 1.06 μg/ml for VER and 4.14 μg/ml for NVER. Conclusions: The method can be used for quantitation of synthesized metabolite NVER, in presence of the parent drug VER which could be useful in detection and determination of some impurities, such as NVER, described in European Pharmacopeia and others which can be toxic and often present in the pharma ceutical formulations.