Association and binding nature of sodium dodecyl sulfate with ofloxacin antibiotic drug in potassium-based electrolyte solutions: a conductometric and UV–Visible spectroscopic investigation

Abstract

The investigation of the impact of different additives on the aggregation behavior of drug-surfactant mixtures is highly important to improve pharmaceutical formulations. This study reveals the micellization characteristics of sodium dodecyl sulfate (NaDS) with ofloxacin (OFC) drug different pH and in the occurrence of different electrolytes (KCl, KNO3, KHSO4, and K2SO4) media at temperatures from 298.15 to 323.15 K. The critical micelle concentration (CMC), the extent of ionization (α), and the degree of counterion binding ( $$\beta$$ ) have been evaluated for the NaDS and OFC system using the conductometric method. The CMC values are found to decline with uprising of salts contents which exposes the favorable micellization in the attendance of employed salts. The CMC values experience an enhancement as the experimental temperatures increased in all electrolyte’s solutions. The Gibbs free energy $${(\Delta G}_{m}^{0})$$ values of NaDS + OFC system in aq. K-based electrolytes media have been appeared as negative indicating a spontaneous association of the system. The changes of enthalpy ( $${\Delta H}_{m}^{0}$$ ), and entropy ( $${\Delta S}_{m}^{0}$$ ) reveal that hydrophobic and electrostatic interactions are the interaction forces between components in aq. electrolytes media. The thermodynamics properties of transfer ( $${\Delta G}_{m,tr}^{0}$$ , $${\Delta H}_{m,tr}^{0}$$ , $${\Delta S}_{m,tr}^{0}$$ ), molar heat capacity $${(\Delta C}_{m}^{0}),$$ compensation temperature (Tc) along with the intrinsic enthalpy gain ( $${\Delta H}_{m}^{0,*}$$ ) were also calculated and the results were discussed accordingly. Moreover, UV–Visible spectroscopic technique was used to determine various significant parameters including binding constant (Kb), partition constant (Kc), partition coefficient (Kx), Gibbs energy of binding (ΔGb), and Gibbs energy of partition (ΔGp) for the mixtures of NaDS and OFC in aqueous and aq. salt solutions, where the corresponding findings were reported rationally. These interesting research findings provide useful tools for understanding the relationships between surfactants and drugs which are crucial for creating effective drugs formulations as well as improving surfactant and drug systems.

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