Pharmaceutical cocrystal consisting of ascorbic acid with p-aminobenzoic acid and paracetamol

Abstract

Abstract As small molecule drugs become harder to develop and less cost effective for patient use, efficient strategies for their property improvement become increasingly important for global health initiatives. As a new crystal engineering strategy, cocrystals have opened a new way to modify the physicochemical properties of pharmaceutical solids. Improvements in the physical properties of Active Pharmaceutical Ingredients (APIs) without changes in the covalent chemistry have been possible through the application of binary component solids. In this work, a pharmaceutical cocrystal of ascorbic acid (A) + para-aminobenzoic acid (B) and ascorbic acid (A) + paracetamol (P) cocrystal are synthesized and characterized by PXRD, DSC, and FT-IR. FT-IR indicates the kind of interactions occurring between API and coformer. The DSC thermogram for (A–B) cocrystal showed a single endothermic peak attributed to the melting temperature at 155 °C. The thermal behavior of the cocrystal was distinct with different melting temperatures from that seen with either of the individual components; this suggests the formation of a new phase. As molecular modeling is presented as a support to the experiment, a computational study using density functional theory (DFT) at the level of the WB97XD functional and 6-311 + G (d, p) basis set was carried out using the Gaussian 09 program. This theoretical study made it possible to calculate the energetic properties, the intramolecular hydrogen bonds as well as the thermodynamic properties for the two cocrystals.