LAUSR

Abstract In this study, we have inspected the interaction amongst ibuprofen sodium salt (NaIB) drug and pharmaceutical excipients TX-45 (nonionic surfactant) using a tensiometric method in an aqueous/electrolyte (NaCl) (50 mmol.kg−1)/urea (UR) (500 mmol.kg−1) medium. Mixed surfactant systems with fairly noticeable improved interfacial characteristics, such as reduced critical micellar concentration and elevated surface activity, contrasted with their singular constituents. A noteworthy change was detected in the diverse evaluated parameters in this investigation. The decrease in critical micelles concentration (cmc) of the system occurs owing to the attendance of NaCl in the solution, whereas the increase in cmc occurs owing to the presence of UR. The TX-45 (nonionic surfactant) has exceptional surface characteristics in conjunction with a great degree of lower cmc value, revealing its scanty toxicity. The cmc values of mixed systems lessening on an enhancement in the mole fraction (α1) of TX-45, which identifies the nonideality of the studied systems, together with the occurrence of mixed micellization. Negative values of β (interaction parameter) are an indication of the attractive force of interaction amid the constituents in solutions. Electrolyte enhances the overall surface activity of studied system, whereas the UR decreases its surface activity. The ∆G0m values for the entire studied system are observed to be negative in all studied media, along other thermodynamic parameters that were evaluated. Furthermore, the excess free energy (∆Gex) of the studied solutions were assessed and proved to be negative. In addition to tensiometry, fluorescence measurements were performed to evaluate various other micellar parameters such as aggregation number (Nagg) and dielectric constant.