Clouding of TX-100 and promethazine hydrochloride mixture: Impacts of Na salts on the physicochemical parameters and interaction forces linked with studied components

Abstract

Interest in the phase separation behaviors and interactions between non-ionic surfactants and various drug species in aqueous salt solutions have grown significantly in recent years due to their extensive applications in industry and medicine. This study explored the clouding characteristics of a triton X-100 (TX-100) and promethazine hydrochloride (PMH) mixture in various aqueous sodium salt (such as NaOAc, NaOxal, Na2CO3, NaHCO3, and NaNO3) solutions. The physicochemical variables and interaction forces between TX-100 and PMH species in different sodium salt media were successfully determined by measuring the cloud point (CP). Different electrolyte solutions have been found to alter the clouding behavior of TX-100 + PMH. The CP magnitudes for TX-100 + PMH combinations decreased as the Na salt concentrations were increased, and the respective CPs decreased in the order: Na2CO3 > NaOxal > NaHCO3 > NaOAc > NaNO3. The salting-out effect played a significant role in decreased CP, possibly due to the reduction in water solubility of solutes in the presence of other soluble ions within the mixtures. The ΔGc0 of TX-100 and the employed drug mixture in aqueous salt media was positive, demonstrating the non-spontaneous nature of the clouding process. However, the non-spontaneity of phase separation in the corresponding mixtures decreased as the electrolyte content of the solution increased. The ΔHc0 and ΔSc0 were negative, suggesting that the clouding progression in the studied mixtures was exothermic and driven by enthalpy change. The evaluation of the intrinsic enthalpy gain (ΔHco,∗) and the compensation temperature (Tc) provided evidence of the interactions between TX-100 and PMH species. This research is significant and may be useful in different industries, including for formulating various drugs in the pharmaceutical industry.