Sulfadiazine is a sulfonamide consisting of pyrimidine with a 4-aminobenzenesulfonamido group at the 2-position. It has a role as an antimicrobial agent, an antiinfective agent, a coccidiostat, an antiprotozoal drug, an EC 2.5.1.15 (dihydropteroate synthase) inhibitor, an EC 1.1.1.153 [sepiapterin reductase (L-erythro-7,8-dihydrobiopterin forming)] inhibitor, a xenobiotic, an environmental contaminant and a drug allergen. It is a member of pyrimidines, a sulfonamide, a substituted aniline and a sulfonamide antibiotic. It is functionally related to a sulfanilamide. It is a conjugate acid of a sulfadiazinate.