Solubility of 5-aminosalicylic acid in N-methyl-2-pyrrolidone + water mixtures at various temperatures

Abstract

Drug solubility studies in solvent mixtures have great importance in the pharmaceutical sciences especially in pharmaceutical technology. Advancements in thermodynamic modeling enable a better mechanistic understanding and can provide guidance in the development of promising solvent mixtures for a given drug. This work studied equilibrium solubility of 5-aminosalicylic acid (mesalazine) in mixed solvents using N-methyl-2-pyrrolidone (NMP) and water at T = (293.2 to 313.2) K. The obtained solubility data were described mathematically by the van't Hoff, Jouyban-Acree, Jouyban-Acree-van't Hoff, UNIQUAC and NRTL models. To discuss the solute-solvent interactions, the activity coefficients of mesalazine were determined in the investigated mixtures. Calculation of the apparent thermodynamic properties of dissolution and mixing for mesalazine, as well as, the preferential solvation parameters in the studied mixtures provided valuable molecular insights into the studied model system and the results are of practical relevance in case of mesalazine.