Chemical Component Summary

FormulaC10 H11 N3 O3 S
Molecular Weight253.28
Isomeric SMILESCc1cc(NS(=O)(=O)c2ccc(N)cc2)no1

Chemical Details

Formal Charge0
Atom Count28
Chiral Atom Count0
Chiral Atomsn/a
Bond Count29
Aromatic Bond Count11
Leaving Atomsn/a

Drug Info: DrugBank

DrugBank IDDB01015 Different stereochemistry
DescriptionA bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p208)
  • 3-(p-Aminophenylsulfonamido)-5-methylisoxazole
  • 3-Sulfanilamido-5-methylisoxazole
  • 4-Amino-N-(5-methyl-3-isoxazolyl)benzenesulfonamide
  • Gantanol (tn)
  • SMX
Brand Names
  • Apo Sulfamethoxazole Tab 500mg
  • Apo Sulfatrim DS Tab
  • Apo Sulfatrim Pediatric
  • Apo Sulfatrim Tab
  • Apo-su
Affected Organism
  • Gram negative and gram positive bacteria
  • Listeria monocytogenes
  • Escherichia coli
IndicationFor the treatment bacterial infections causing bronchitis, prostatitis and urinary tract infections.
PharmacologySulfamethoxazole is a sulfonamide drug that inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA) for binding to dihydropteroate synthetase (dihydrofolate synthetase). Sulfamethoxazole is bacteriostatic in nature. Inhibition of dihydrofolic acid synthesis decreases the synthesis of bacterial nucleotides and DNA. Sulfamethoxazole is normally given in combination with Trimethoprim, a dihydrofolate reductase inhibitor, which inhibits the reduction of dihydrofolic acid to tetrahydrofolic acid. Studies have shown that bacterial resistance develops more slowly with the combination of the two drugs than with either Trimethoprim or Sulfamethoxazole alone.
Mechanism of actionSulfonamides inhibit the enzymatic conversion of pteridine and p-aminobenzoic acid (PABA) to dihydropteroic acid by competing with PABA for binding to dihydrofolate synthetase, an intermediate of tetrahydrofolic acid (THF) synthesis. THF is required for the synthesis of purines and dTMP and inhibition of its synthesis inhibits bacterial growth. Pyrimethamine and trimethoprim inhibit dihydrofolate reductase, another step in THF synthesis, and therefore act synergistically with the sulfonamides.
Route of administration
  • Intravenous
  • Oral
  • Amides
  • Amines
  • Aniline Compounds
  • Anti-Infective Agents
  • Antibacterials for Systemic Use
  • J01EE01
  • J01EC01
CAS number723-46-6
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS. Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682