Sulfadiazine is a white or quasi-white crystalline or powder, odorless, tasteless, gradually darkening when exposed to light. It is almost insoluble in water, boiling water (1:60), slightly soluble in ethanol and acetone, insoluble in chloroform and ether, and soluble in dilute hydrochloric acid, sodium hydroxide solution or ammonia solution. Melting point 252-256 C (simultaneous decomposition). Its sodium salt is white crystalline powder, odorless and slightly bitter. Gradually brown in light. When exposed to moist air for a long time, it slowly absorbs carbon dioxide and releases sulfadiazine. Soluble in water, slightly soluble in ethanol, insoluble in chloroform and ether. The pH of 10% aqueous solution is 9.5-10.5.
Sulfadiazine has stronger antimicrobial effect, better curative effect, faster absorption, slower excretion and higher effective concentration in blood. Clinically, it is used to treat upper respiratory tract infection. Epidemic meningitis, otitis media, boils, puerperal fever, urethral infection and acute bacillary dysentery.
Sulfadiazine can also be used to treat infections caused by hemolytic streptococcus, pneumococcus, meningococcus, gonorrhoea diplococcus and Escherichia coli.