Cloudy development and physico-chemical parameters for the triton X-100 and levofloxacin hemihydrate drug mixture: Impacts of the manifestation of several short-chain alcohols and urea

Abstract

Interests on physico-chemical behaviors of surfactant-drug systems in various additives media have increased considerably in recent years owing to their extensive applications in pharmaceuticals and other industrial sectors. LFH is a quinolone-type antibiotic which frequently used to treat a variety of bacterial diseases. Herein, the cloud point (CP) behavior and thermodynamic characteristics of triton X-100 (TX-100) and levofloxacin hemihydrate (LFH) antibiotic drug mixtures in attendance of alcohols and hydrotrope (urea) have been investigated. Different organic additives such as methanol (MeOH), ethanol (EtOH), 1-propanol (1-PrOH), 2-propanol (2-PrOH), 1-butanol (1-BuOH), 2-butanol (2-BuOH), and urea with various concentrations were used to examine their effects on variation of CP in the respective systems. In all experiments, concentrations of TX-100 and LFH were remained the same which were 92.7 mmol kg−1 and 0.5 mmol kg−1 respectively. The magnitudes of CP in TX-100 + LFH mixtures were found to be decreased sharply in the manifestation of alcohols and urea in comparison to those observed with the aqueous system. The CP values in the TX-100 + LFH system were varied with increasing in concentrations of alcohols and urea which followed the order of CPH2O+2-PrOH>CPH2O+EtOH≈CPH2O+MeOH≈CPH2O+Urea>CPH2O+1-PrOH>CPH2O+2-BuOH>CPH2O+1-BuOH. Lower carbon chain alcohols in the structural moieties (MeOH, EtOH, 1-PrOH, 2-PrOH) acted as CP promoter whereas other longer chain alcohols (1-BuOH, 2-BuOH) caused the significant decrease in CP within the respective system. Higher CP values were also noticed in TX-100 + LFH system when aq. hydrotrope urea was used as additive. The Gibbs free energy change (ΔGco) were found to be positive which revealed the nonspontaneous nature of clouding in the studied system. However, the degree of non-spontaneity was reduced by the enhancement of alcohols and urea concentrations. Appearances of positive enthalpy (ΔHco), and entropy (ΔSco) in TX-100 + LFH mixtures with different additives indicated the existence of hydrophobic interactions among the participated constituents whereas the negative magnitudes of ΔHco and ΔSco disclosed the presence of electrostatic interactions among the respective constituents. Entropy-enthalpy compensation parameters were computed and described from logical points.