A Simple Colorimetric Method for the Determination of Raloxifene Hydrochloride in Pharmaceuticals Using Modified Romini’s Reagent

Abstract

An analytical method has been developed based on a colorimetric assay for the estimation of raloxifene hydrochloride, followed by validation of the optimized method by using the ICH guidelines. The new method, aromatic ring derivatization technique, is based on a coupling reaction using modified Romini’s reagent in which sodium nitroprusside is used as a chromogenic derivatizing reagent. Raloxifene contains a phenolic hydroxyl group, containing reactive hydrogen. This reactive proton reacts with sodium nitroprusside and reduces it to sodium meta-hydrogen ferrocyano nitrate, which is a colored product. Optimization studies revealed that the coupling reaction was very rapid and completed in less than 1 minute. A 1 : 1 drug-to-reagent stoichiometric ratio was obtained for the azo dye formed. The azo adduct formed exhibits a bathochromic shift with absorption maximum λmax at 440 nm, which was selected as the analytical wavelength. The drug seems to be linear, which was established via the regression analysis from 20 to 120μg/ml. LOD and LOQ of the developed method were found to be 1.807μg/ml and 5.47μg/ml, respectively. Interday and intraday precision was studied, and %RSD was less than 2. Since the stability of the drug and the reagent was found to be predominantly massive, this method can be used for the formulation of raloxifene hydrochloride . The method can be extended for the routine assay of raloxifene formulations.

Development and validation of ultra‐high‐performance liquid chromatography–mass spectrometry method for the determination of raloxifene and its phase II metabolites in plasma: Application to pharmacokinetic studies in rats

“…Our one‐step protein precipitation with combined solvent is more simple and rapid than previously published assay which involved solid phase extraction procedure or Thermo Scientific™ SOLAµ™ SCX 96‐well plate [17–20]. In addition, our method can simultaneously quantify both raloxifene glucuronide and sulfate in plasma.…”

“…For example, Trontelj et al reported an LC-MS method to quantify Ral, Ral-6-G, and Ral-4′-G, but sulfate was not quantified. In addition, the extraction recovery of sample processing was only about 71% [17][18][19][20]. We report a sensitive, reliable ultra-high performance liquid chromatography (UHPLC)-MS/MS method that can simultaneously determine Ral and its three conjugates (Ral-6-G, Ral-4′-G, and Ral-6-S) in plasma sample with excellent extraction recovery.…”

Quality by design‐steered development and validation of analytical and bioanalytical methods for raloxifene: Application of Monte Carlo simulations and variance inflation factor

“…The drug molecule belongs to class II of Biopharmaceutical Classification System, as it is characterized by low aqueous solubility and high intestinal permeability (Snyder et al, 2000). Various analytical methodologies reported for estimation of RLX include colorimetric, spectrophotometric, densitometric, and liquid chromatographic techniques (Kumar et al, 2019; Merey et al, 2013; Shirkhedkar et al, 2012; Suneetha & Rao, 2010; Teeter & Meyerhoff, 2002). The HPLC method for the analysis of RLX, as per the European Pharmacopoeia (2010), uses a solvent system of 50 mM phosphate buffer and acetonitrile (66:37).…”