Thermodynamics and solute-solvent interactions of lovastatin in an aqueous arginine solution

Lovastatin (LVS) is an effective therapeutic and prophylactic agent in several cardiovascular disorders. However, it has low bioavailability. This study investigated solute-solvent and solute-cosolute interactions and assessed thermodynamic parameters that contributed to LVS solubility enhancement in the presence of arginine (ARG) as a hydrotropic agent. The electrolytic conductance of LVS-ARG binary system was measured at temperatures from 298.15 K to 313.15 K. Conductometric parameters such as limiting molar conductance was evaluated. Additionally, thermodynamic parameters (ΔG0, ΔH0, ΔS0 and ES) involved in the association process of the solute in the aqueous solution of ARG solution were determined systematically. Solubility markedly improved 43-fold in the LVS-ARG complex compared to LVS alone. The analysed data from values of molar conductance and activation energy suggested favourable solubilisation, with a stronger solute-solvent interaction between LVS-ARG in water at higher temperatures. ARG and LVS complexation caused by strong molecular interactions was confirmed by spectral results. Hence, the addition of ARG as a co-solute was proven to enhance LVS solubility in water. The obtained data will ultimately enable the development of desired highly soluble, more efficient and safer LVS preparations.