HPLC AND SPECTROPHOTOMETRIC STABILITY – INDICATING STUDY OF RALOXIFENE IN PURE FORM AND TABLETS

Document Type : Original Article

Author

Analytical Chemistry Department, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.

Abstract

Five simple, sensitive, accurate and precise methods were developed for determination of raloxifene (RLX) in pure form as well as in its pharmaceutical preparation. Method [A] is HPLC stability–indicatingmethod, where the intact drug (RLX), the internal standard (methocarbamol) and RLX degradation products were separated using a YMC-pack ODS-AQ C18 column (150 mm X 4.6 mm ID, 3µm particle size ) using acetonitrile–0.05 M KH2PO4 adjusted to pH 2.5 using H3PO4 (50 : 50 v/v ) as a mobile phase  at a flow rate 1 ml/min. and UV detection at 280 nm, where a good linearity was obtained in the range of  0.5 – 8 µgml-1.The LOD was 0.077 µg ml-1 and the LOQ was 0.258 µgml-1. Method [B] depended on measurement of the difference absorbance (ΔA) of the drug in the presence of its degradate between solutions in methanolic 0.1 M HCl and 0.1 M NaOH at 285 nm. Beer’s low was obeyed in the range of 3 – 27 µgml-1. LOD and LOQ were found to be 0.233 and 0.778 µg ml-1,respectively. Method [C] is stability – indicating First-Derivative (1D) for the determination of intact RLX in presence of its degradation product at 268 nm in the range of 3 – 18 µg ml-1 with LOD of 0.254 µg ml- and LOQ of 0.849 µg ml-1. Method [D] depended on ion pairing of RLX with eosin-Y dye at pH 3.5 to produce red coloured complex measured at 545 nm. Beer’s low was obeyed in the range of 2 – 20 µgml-1. LOD and LOQ were found to be 0.276 and 0.920 µg ml-1,respectively. Method [E] depended on ion pairing of RLX with bromothymol blue (BTB) dye at pH 2.6 to form a chloroform-soluble coloured ion association complex. The formed complex could be extracted and measured at 420 nm. Good agreement with Beer’s low was found in the range of 4 – 28 µgml-1. LOD and LOQ were found to be 0.633 and 2.110 µg ml-1,respectively. The percent recoveries ± RSD% of these methods were 100.83±0.920, 100.24±0.724, 100.15±0.586, 100.26±0.383 and 99.98±0.261, respectively. The obtained results were compared with those of the reported method and no significant difference was observed regarding accuracy and precision.