Investigating the solubilization effect of oxcarbazepine by forming cocrystals

Abstract

Oxcarbazepine (OXCBZ) is a poorly soluble drug that can't form a salt. It has an amide functional group and a carbonyl group in its structure, which can be used to form cocrystals. Three cocrystals of OXCBZ were successfully synthesized through liquid-assisted grinding and reaction crystallization. Since OXCBZ has an amide group and a keto group, oxalic acid (OA), 2,5-dihydroxybenzoic acid (2,5-DHBA), and salicylic acid (SA) were selected as coformers which can form a hydrogen bond with an amide group or a keto group. The formation of OXCBZ cocrystals was confirmed by characterization via powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and solid state nuclear magnetic resonance spectroscopy. Effects of different conditions on the preparation of the cocrystal were investigated to optimize the cocrystal preparation process. The apparent solubility and dissolution rate of the cocrystals were investigated too. The apparent solubility of the OXCBZ–OA and OXCBZ–2,5-DHBA cocrystals increased approximately 2.6 and 4.7 times that of the pure drug.