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Clinical data
AHFS/Drugs.comInternational Drug Names
ATC code
  • 2-[({4-[(1,3-Thiazol-2-ylamino)sulfonyl]phenyl}amino)carbonyl]benzoic acid
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.001.480 Edit this at Wikidata
Chemical and physical data
Molar mass403.43 g·mol−1
3D model (JSmol)
  • OC(=O)c1ccccc1C(=O)Nc2ccc(cc2)S(=O)(=O)Nc3nccs3 C1=CC=C(C(=C1)C(=O)NC2=CC=C(C=C2)S(=O)(=O)/N=C\3/NC=CS3)C(=O)O
  • InChI=1S/C17H13N3O5S2/c21-15(13-3-1-2-4-14(13)16(22)23)19-11-5-7-12(8-6-11)27(24,25)20-17-18-9-10-26-17/h1-10H,(H,18,20)(H,19,21)(H,22,23) ☒N
 ☒NcheckY (what is this?)  (verify)

Phthalylsulfathiazole (also known as sulfathalidine) belongs to the group of drugs called sulfonamides. The drug is a broad-spectrum antimicrobial that can treat different types of infections including intestinal. The mechanism of action depends on competitive antagonism with para-aminobenzoic acid and inhibition of dihydropteroate synthetase activity, which in turn leads to impaired synthesis of dihydrofolic acid and as a result its active metabolite necessary for the synthesis of purine and pyrimidine.

The drug is indicated in the treatment of dysentery, colitis, gastroenteritis and intestinal surgery. It is not absorbed into the blood stream from the gut due to extra n⁴ substitute. Adverse effects may include allergic reactions, vitamin B insufficiency, agranulocytosis and aplastic anemia.