(623e) Intensified Crystallization of Sulfathiazole and Sulfanilamide By Direct Co-Crystal Assembly

Most of the studies mainly focus on the co-crystallization step rather than on the synthesis and co-crystallization together. Based on the concept of direct co-crystal assembly, we have successfully produced 1:1 co-crystals of sulfathiazole-theophylline (STZ-THE) and 1:1 co-crystals of sulfathiazole-sulfanilamide (STZ-SNM) by integrating the chemical synthesis and co-crystallization. Interestingly, the yields of the integration method were higher than the ones of normal reactive crystallization methods, and the amount of purities were also reduced. For the chemical reaction that suffered from the low yields or had the impurity which was hard to be separated, the formation of co-crystals might be an alternative strategy to improve the efficiency of purification and the value of drugs as well. The modification of loading stoichiometry of reactants to co-formers could lead to the difference of product compositions. Both STZ-THE and STZ-SNM exhibited different pH solubility profiles. In other words, co-crystallization could change the pH effect active pharmaceutical ingredient.