Enhanced spectrophotometric determination of Losartan potassium based on its physicochemical interaction with cationic surfactant

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2015-02, Vol.136, p.178-184
• Main Authors: Abdel-Fattah, Laila, Abdel-Aziz, Lobna, Gaied, Mariam
• Format: Article
• Language: English
• Subjects: Binding; CTAB; Losartan potassium; Partition coefficient; Spectrophotometric determination
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2014.09.007

The absorbance spectrum of 43.38μm LST (20μgml−1) in absence and in presence of increasing concentrations of CTAB (0.01–0.6mM). [Display omitted] •Calculation of the degree of drug/micelle interaction is reported.•Understand the interactions with biomembranes and structure–activity relationship of drugs.•Describing the effect of cationic micelles on the spectroscopic and acid–base properties of LST K. In this study, a simple and sensitive spectrophotometric method was developed for determination of Losartan potassium (LST K), an angiotensin-II receptor (type AT1) antagonist, in presence of cationic surfactant cetyltrimethylammonium bromide (CTAB). The physicochemical interaction of LST K with CTAB was investigated. The effect of cationic micelles on the spectroscopic and acid–base properties of LST K was studied at pH 7.4. The binding constant (Kb) and the partition coefficient (Kx) of LST K-CTAB were 1.62×105M−1 and 1.38×105; respectively. The binding of LST K to CTAB micelles implied a shift in drug acidity constant (ΔpKa=0.422). The developed method is linear over the range 0.5–28μgmL−1. The accuracy was evaluated and was found to be 99.79±0.509% and the relative standard deviation for intraday and interday precision was 0.821 and 0.963; respectively. The method was successfully applied to determine LST K in pharmaceutical formulations.