Molecular interaction studies of antidepressant drug with aqueous caffeine using volumetric and acoustic methods

Abstract Knowledge of drug interactions and the factors controlling these interactions could be useful to overcome their adverse effects on human health. In this study, the effect of caffeine on the antidepressant action of escitalopram oxalate was investigated to explore the behavior of escitalopram oxalate in the presence of caffeine in terms of molecular interactions in an aqueous system at temperature range 293.15 to 313.15 K and atmospheric pressure. Density (ρ) and ultrasonic velocity (u) of escitalopram oxalate in different concentrations of caffeine solutions were measured at the selected range of temperatures. Experimental data has been used to calculate apparent molar volume (Φv) and apparent molar isentropic compressibility (Φv) and fitted to the Redlich–Mayer equation to obtain limiting parameters. Negative deviations from Debye–Huckel limiting law of apparent molar volume for the drug in the presence of caffeine were observed which can be used as a direct measure of the ion-ion and ion–solvent interactions. Partial molar volumes of transfer (ΔtΦvο) were found to be negative for the studied mixture. The partial molar expansibilities and Hepler's constant (∂2∅V0/∂T2) were found to be positive for the mixture (escitalopram oxalate+ caffeine) in water. Intermolecular free length (Lf) and compressibility hydration number (nH) were also analyzed. Obtained results were explored in terms of molecular interactions prevailing among escitalopram oxalate and caffeine molecules in aqueous solutions.