Microemulsion Liquid Chromatographic Determination of Nicardipine Hydrochloride in Pharmaceutical Preparations and Biological Fluids. Application to Stability Studies

Abstract

A simple, stability indicating, reversed phase high performance liquid chromatographic method has been developed for the determination of nicardipine hydrochloride (NC) in the presence of its degradation products. Reversed phase chromatography was conducted using a Hibar‐C18 (150×4.6 mm i.d.) stainless steel column at ambient temperature with UV‐detection at 238 nm. Microemulsion mobile phase consisting of 0.175 M sodium dodecyl sulphate, 10% n‐propanol, 0.3% triethylamine in 0.02 M phosphoric acid of pH 6.5, has been used for the separation of nicardipine hydrochloride and its two degradation products at a flow rate of 1 mL min−1. The calibration curve was rectilinear over the concentration range 1‐40 µg mL−1 with a detection limit of 0.024 µg mL−1 (4.65×10−8 mol/L) and quantification limit of 0.08 µg mL−1 (1.55×10−7 mol/L). The proposed method was successfully applied for the analysis of nicardipine in pure form and commercial capsules, with the mean % recoveries of 100.12±0.28 and 100.87±0.41, respectively. The results obtained were favorably compared to those obtained by a reference method. The method was extended to the in‐vitro determination of NC in spiked human plasma samples with the mean % recovery of 100.33±3.06 (n=3). Moreover, the method was utilized to investigate the kinetics of both alkaline induced degradation and photo degradation of the drug. The apparent first‐order rate constant, half‐life time, and activation energy of the degradation product were calculated.