A new salt of clofazimine to improve leprosy treatment

In this work, a new salt of clofazimine (CFZ) with 4-aminobenzoic acid (PABA is described. CFZ is an antibiotic drug used in the treatment of leprosy. This drug has low absorption when administered orally because of its low water solubility, contributing to the reduction of bioavailability, limiting its application. Towards the augmentation of the bioavailability of CFZ, we propose in this work the development of a salt. The new product CFZ+–PABA– (1:1) was synthesized through liquid assisted grinding method and characterized by powder X-ray diffraction, mid-infrared spectroscopy, and differential scanning calorimetry. The investigations provided evidence of the formation of a new salt. The interaction involves proton transfer between PABA and CFZ forming R21(7) motif in carboxylate region (COO−) of PABA and imines regions (N–H/N+–H) of CFZ. According to the analyses, the stoichiometric ratio of salt formation is 1:1. The salt dissolution profile shows the product is 5.0 folds more soluble than the CFZ free base. [Display omitted] •Salt of Clofazimine with 4-aminobenzoic acid was obtain.•Crystal structure of CFZ+–PABA– (1:1) salt has been reported.•The ionic interaction between compounds is identified.•Studies of solubility show the salt is 5.0 fold more soluble than CFZ.