Effect of anionic and nonionic hydrotropes on the clouding behavior and thermodynamic properties of nonionic surfactant and ciprofloxacin hydrochloride drug mixture

Abstract

In the present study, the cloudy development of nonionic triton X-100 (TX-100) and an antibiotic drug ciprofloxacin hydrochloride (CFH) mixture has been conducted by applying the cloud point (CP) measurements method. The CP of TX-100 + CFH mixture was examined in aqueous solutions of hydrotropes (HDTs) (sodium benzoate (NaBenz), sodium salicylate (NaSal), 4-amino benzoic (4-ABA), polyethylene glycol (PGE) and Caffeine (CAF)). The TX-100 and CFH concentration were conserved constant at 50 and 1 mmol kg−1 correspondingly throughout the investigation. The CP values of TX-100 + CFH solution were augmented in the existence of NaBenz, NaSal, CAF along with PEG but diminished in aq. 4-ABA solution; the effects were obtained to be augmented with the enhancing hydrotropes contents. The CP values for TX-100 + CFH mixture in aq. hydrotropes media follow the pattern: CP(aq.4-ABA)<CPaq.CAF≈CPaq.PEG<CPaq.NaBenz<CPaq.NaSal. Therefore, the solubility of TX-100 + CFH mixture is achieved to be decreased in aq. solutions of 4-ABA while the solubility experienced an enhancement in aq. NaSal, NaBenz, PEG and CAF solutions. Among hydrotropes used in the present study, NaSal is the most effective solubility enhancer. The free energy (ΔGc0) were achieved to be positive in all the solvent media used in the study which exposes that the cloudy development process isnot spontaneous. The enthalpy (ΔHc0) and the entropy (ΔSc0) of clouding were obtained to be positive in hydrotropes media. The ΔHc0 and ΔSc0 values imply that the main forces of the cloudy formation in TX-100 and CFH system are hydrophobic interaction, hydrogen bonding, and electrostatic interactions. The compensation temperature (Tc) along with the intrinsic enthalpy gain (ΔHc0,∗) were also calculated and discussed. It is probable that the knowledge gained from these types of studies will be quite helpful in both pharmaceutics formulations and drug delivery system.