phthalylsulfathiazole

Phthalylsulfathiazole is a synthetic sulfonamide antibiotic and broad-spectrum antimicrobial agent primarily used for the treatment of gastrointestinal infections, including dysentery, colitis, gastroenteritis, and as preoperative prophylaxis in intestinal surgery. It acts locally in the gut due to poor systemic absorption resulting from its phthalic acid substitution. The drug exerts its bacteriostatic effect by competitively inhibiting dihydropteroate synthase—an enzyme involved in bacterial folic acid synthesis—thereby blocking the incorporation of para-aminobenzoic acid (PABA) into folic acid pathways essential for DNA, RNA, and protein production. In the intestine, it may be hydrolyzed to release active sulfathiazole[1][2][3][4][5][6][8]. Phthalylsulfathiazole is now rarely used in human medicine due to more effective alternatives but remains available for certain indications.

Brand names

ENDOTHALYLBL Sulpha Three

Other names

sulfathalidine