Mechano synthesis of co-crystals of Sulfamethoxazole and 8-Hydroxy-7-Iodoquinoline-5-Sulfonic acid based on Green Chemistry principles

Abstract

Co-crystals have been used to produce new drugs and to improve the physical properties of drugs. Some disease causing germs have developed resistance to newer drugs, hence there is a general trend to take ‘old’ but efficacious drugs, improve their properties and use them to treat the conditions. This study used mechano-synthesis to produce a co-crystal of two active pharmaceutical ingredients (API), Sulfamethoxazole and 8-hdroxy-7-iodoquinoline-5-sulfonic acid (Ferron), based on Green Chemistry principles. The two APIs were combined by mixing, grinding and kneading. The resulting co-crystals were characterized using analytical methods such as spectroscopy, thermal analysis and diffractometry. In-Silico techniques based on computer modelling using Gaussian 09 and VEDA 4 software were used to interpret the vibrational spectrum of the co-crystals. The study found that kneading gave the highest yield compared to mixing and grinding. The study also confirmed that a combination of the analytical methods was necessary to characterize a co-crystal. Co-crystals of Sulfamethoxazole and 8-Hydroxy-7-Iodoquinoline- 5-Sulfonic acid can therefore be formed by kneading, implying that the production of the co-crystals can be done using a process that reduces pollution by the minimal use of solvents. Another implication is that Sulfamethoxazole, whose use has been minimised because of problems such as allergic reactions from patients, can be looked at again and used to produce ‘polydrugs’ which can be used to manage conditions at relatively cheaper costs.