LIQUID-CHROMATOGRAPHIC DETERMINATION OF FLUNARIZINE DIHYDROCHLORIDE IN THE PRESENCE OF ITS DEGRADATION PRODUCT

A simple, stability-indicating liquid chromatographic method has been developed for the assay of flunarizine dihydrochloride in the presence of its acid-induced degradation product. A Bondapak-C-18 column was u sed with a mobile phase consisting of methanol-water (75:25, v/v) cont aining 0.5% w/v sodium chloride and 0.2% v/v triethanolamine adjusted to pH 6.6 with 30% hydrochloric acid at a flow rate 2 ml min(-1). Quan titation was achieved with UV detection at 254 nm based on peak area o r peak height ratios. The proposed method was successfully applied to the determination of the drug in laboratory-prepared mixtures in the p resence of its degradation product and in capsules. Moreover, the meth od was utilized to investigate the kinetics of the degradation process at different temperatures and the apparent first-order rate constant, half-life and activation energy calculated.