Molecular Interaction of Antihypertensive Drug Aliskiren With Cetyltrimethylammonium Bromide and Sodium Dodecyl Sulfate Surfactants in Aqueous Solution

ABSTRACT Microheterogeneous surfactant assemblies have ability to solubilize, encapsulate and protect active drug molecules from adverse environmental conditions and enhance their bioavailability. The aim of the present study is to reveal the molecular interaction of the antihypertensive drug aliskiren (ALI) with ionic surfactants cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) and evaluate the binding properties of drug‐surfactant systems. The quantitative assessment of the drug molecules incorporated in the micellar system provides valuable information about the activities and physicochemical properties required for the design of improved drug delivery system. The extent of molecular interaction of an aqueous solution of ALI was investigated with different concentrations of conventional ionic surfactants CTAB and SDS at 25°C. The effect of ionic surfactants on drug properties was evaluated using UV‐visible spectroscopy and conductivity measurements. Moreover, steady‐state fluorescence (SSF) measurements were performed to investigate drug‐surfactant interaction modes, which were quantified by determining the drug‐surfactant binding constant and partition coefficient of ALI between the aqueous medium and the micellar phase. Moreover, differential spectroscopy technique was used to calculate the Gibbs free energies. The drug‐surfactant binding constant obtained from fluorescence spectroscopy was found to be in good agreement with differential spectroscopic data. Additionally, the results revealed that binding process of drug and surfactant was observed to be spontaneous in nature and ionic surfactants were found to promote dissolution of the ALI interior due to their electrostatic attractive forces and large hydrophobic head groups which may result in controlled release of drug.