Evaluating Micellar and Interfacial Properties of Antidepressant Drugs Through Conductometric, Fluorometric, and Tensiometric Approaches

ABSTRACT The micellar and interfacial behavior of amphiphilic antidepressant drugs that is, amitriptyline hydrochloride (AMT), imipramine hydrochloride (IMP), chlorpromazine hydrochloride (CPZ) and desipramine hydrochloride (DSP) were investigated by using surface tension and fluorescence techniques at 300 K. The CMC values of all drugs were determined by conductivity meter at different temperatures (300 K–320 K). The critical micellar concentration (CMC), surface excess concentration (Γ max ), minimum surface area per molecule ( A min ) and surface pressure at CMC (π CMC ), Stern‐Volmer constant ( K sv ), degree of micellar ionization (α), the Gibbs free energy of micellization (Δ G ○ m ), the Gibbs free energy of adsorption (Δ G ○ ads ), Gibbs free energy at the air/water interface (G s min ), standard enthalpy of micellization ) the standard entropy of micellization ) are important interfacial and thermodynamic parameters have also been determined. The result shows that the CMC values of drugs are obtained in increasing order CPZ<AMT<IMP<DSP. Drug‐adsorption at the air‐water interface is indicated by high surface excess concentrations and low minimum areas per molecule, especially for CPZ hence lower CMC values are observed than AMT, IMP and DSP. Aggregation number ( Nagg ) analysis revealed larger, tighter micelles for CPZ, whereas fluorescence analysis verified micelle formation and revealed compact micellar structures. The negative values of of micellization and Gibbs free energy of adsorption are shown the micellization is spontaneous. The negative values of of the systems indicate the process is exothermic. The values of were found to be positive in all cases. The results also provide valuable insights into the self‐assembly and interfacial behavior of amphiphilic antidepressant drugs, which is essential for comprehending their interactions at biological interfaces and bioavailability.