Interaction of amphiphilic drug imipramine hydrochloride with gemini surfactants at different temperatures

Aggregation and interfacial phenomenon of amphiphilic drug under the influence of pharmaceutical excipients (green/biocompatible gemini surfactant)

In the current study, we have examined the interaction amongst an antidepressant drug amitriptyline hydrochloride (AMH) and ethane-1, 2-diyl bis(N,N-dimethyl-N-cetylammoniumacetoxy) dichloride (16-E2-16, a green gemini surfactant) through tensiometric and fluorimetric techniques in aqueous/electrolyte/urea solutions. Significant variations are observed in the various evaluated parameters in the present study. Gemini 16-E2-16 has outstanding surface properties along with a much lower cmc value, demonstrating very little toxicity as well as considerable antimicrobial activity. The cmc values of mixtures decrease through increase in mole fraction (α₁) of 16-E2-16, which specifies the nonideality of the solution mixtures, along with demonstrating the occurrence of mixed micellization too. Negative β^Rub values signify on the whole attractive force of interaction between constituents of mixed micelles. Owing to the incidence of electrolyte NaCl (50 mmol.kg^–1), lowering of the micelles’ surface charge happens, resulting in aggregation taking place at lower concentration while the presence of urea (NH₂CONH₂) halts micellization taking place, which means the cmc value increases in the attendance of urea. The ΔGmo values for all systems were negative along with the presence of electrolyte/urea. The excess free energy (G_ex) of studied mixed systems was also estimated and found to be negative for all the systems. Using the fluorescence quenching method, the micelle aggregation number (N_agg) was evaluated and it was found that the contribution of gemini surfactant was always more than that of the AMH and their value enhances in the existence of electrolyte while decreasing in the attendance of NH₂CONH₂ in the system. In addition, other fluorescence parameters such as micropolarity (I₁/I₃), dielectric constant (D_exp) as well as Stern–Volmer binding constants (K_sv) of mixed systems were evaluated and the results showed the synergistic performance of the AMH + 16-E2-16 mixtures. Along with tensiometric and fluorimetric techniques, FT-IR spectroscopy was also engaged to reveal the interaction among constituents.

Study of Mixed Micelles of Promethazine Hydrochloride (PMT) and Nonionic Surfactant (TX-100) Mixtures at Different Temperatures and Compositions

Herein, we have investigated the interaction between a phenothiazine drug promethazine hydrochloride (PMT) and nonionic surfactant t-octylphenoxypolyethoxyethanol (TX-100) in aqueous solutions using a conductometric technique at different temperatures and compositions. The evaluated critical micelle concentration (cmc) values are lower than cmc id values suggesting attractive interactions of mixed micelles components. It is observed that with the increase in temperature, the cmc value increases first and after the value decreases at higher temperature. At 298.15 K, the maximum cmc values were attained in presence or absence of TX-100. The bulk properties of solution were studied by means of different theoretical models reported in the literature such as Clint, Rubingh, Motomura, and Rodenas for explanation and comparison of results of different binary mixtures of the drug and TX-100. The negative values of interaction parameter (β) obtained from the regular solution theory (RST) recommend synergistic interactions. Activity coefficients (f 1 and f 2) calculated by all theoretical models used herein were obtained to be always below unity indicating nonideality in all binary mixtures. Thermodynamic parameters (like standard Gibbs energy (ΔG°m), enthalpy (ΔH°m), and entropy (ΔS°m)) are also evaluated which propose dehydration of hydrophobic portion of the drug at higher temperatures. The above results obtained may be helpful in model drug delivery systems.