SOLVATION BEHAVIOUR OF KETOROLACTROMETHAMINE IN AQUEOUS KCl ANDα-LACTOSEMONOHYDRATE SYSTEMS: A VOLUMETRICINVESTIGATION

Abstract

Density measurements of ketorolac tromethamine (KT), a non-steroidal anti-inflammatory drug, were carriedout over the molality range 0.02–0.10 mol·kg⁻¹ in water and in aqueous 0.06 mol·kg⁻¹ KCl and 0.06 mol·kg⁻¹ α-lactosemonohydrate solutions at temperatures from 288.15 to 318.15 K and atmospheric pressure. Fromthe experimental density data, apparent molar volume (�� ), limiting apparent molar volume (�� 0 ), limiting apparent molar volumeof transfer ( Δ푡�� 0 ), and Hepler’s constant were evaluated to characterize solute–solvent and solute–soluteinteractions. The positive transfer volumes indicate favourable interactions of KT with the co-solutes, whilecomparatively higher limiting apparent molar volumes in α-lactose monohydrate medium reveal its stronger influence on the solvation environment of KT than KCl. The temperature dependence of the volumetric parametersfurther indicates changes in hydration and electrostriction around the solute species. The positive Hepler’s constantssuggest structure-making behaviour of KT in the investigated media. These results provide molecular-level physicochemical information on the behaviour of KT in electrolyte and non-electrolyte aqueous environments andmay provide a basis for further investigations of drug–excipient and drug–solvent interactions. The study is relevant to United Nations Sustainable Development Goal 3 (SDG-3): Good Health and Well-Being, through its contributionto the fundamental physicochemical understanding of a therapeutically important drug.