Apo-Sulfamethoxazole;Azo Gantanol;Azo-Gantanol;Bactrimel;Gamazole;Gantanol;Gantanol-DS;Metoxal;Radonil;Septran;SIM;Simsinomin;Sinomin;Sulfamethalazole;Sulfamethoxazol;Sulfamethoxizole;Sulfamethylisoxazole;Sulfisomezole;Sulpha-Methoxizole;Sulphamethalazole;Sulphamethoxazol;Sulphamethoxazole;Sulphamethoxazole BP 98;Sulphamethylisoxazole;Sulphisomezole;Trib;Urobak;

A 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)

• Ascot hosp pharmaceuticals inc div travenol laboratories inc
• Barr laboratories inc
• Heather drug co inc
• Hoffmann la roche inc
• Sandoz inc
• Shionogi usa inc
• Watson laboratories inc

• Medisca Inc.

Synthesis Reference	Not Available
General Reference	Not Available

Type	small molecule

Classes

Benzenesulfonamides Sulfanilamides

Substructures

Sulfonyls Aliphatic and Aryl Amines Benzene and Derivatives Isoxazoles Benzenesulfonamides Heterocyclic compounds Aromatic compounds Oxazoles Sulfanilamides Sulfonamides Anilines

antibacterials 抗细菌;

Indication	For the treatment bacterial infections causing bronchitis, prostatitis and urinary tract infections.
Pharmacodynamics	Sulfamethoxazole 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 action	Sulfonamides 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.
Absorption	Rapidly absorbed following oral administration. Also well-absorbed topically.
Volume of distribution	Not Available
Protein binding	70%
Metabolism	Hepatic. The metabolism of sulfamethoxazole occurs predominately by N4-acetylation, although the glucuronide conjugate has been identified. Important The metabolism module of DrugBank is currently in beta. Questions or suggestions? Please contact us. Substrate Enzymes Product Sulfamethoxazole Cytochrome P450 2C9 Sulfamethoxazole N4-hydroxylamine Details Sulfamethoxazole Prostaglandin G/H synthase 1 5-Hydroxysulfamethoxazole Details Sulfamethoxazole Arylamine N-acetyltransferase 1 Arylamine N-acetyltransferase 2 N4-Acetylsulfamethoxazole Details Sulfamethoxazole UDP-glucuronosyltransferase 1-9 Sulfamethoxazole N1-glucuronide Details Sulfamethoxazole Cytochrome P450 2C9 sulfamethoxazole hydroxylamine Details
Route of elimination	Not Available
Half life	10 hours
Clearance	Not Available
Toxicity	Sulfamethoxazole may cause nausea, vomiting, diarrhea and hypersensitivity reactions. Hematologic effects such as anemia, agranulocytosis, thrombocytopenia and hemolytic anemia in patients with glucose-6-phosphate dehydrogenase deficiency may also occur. Sulfamethoxazole may displace bilirubin from albumin binding sites causing jaundice or kernicterus in newborns.
Affected organisms	Gram negative and gram positive bacteria
Pathways	Not Available

Properties
State	solid
Experimental Properties	Property Value Source melting point 167 °C PhysProp water solubility 610 mg/L (at 37 °C) YALKOWSKY,SH & DANNENFELSER,RM (1992) logP 0.89 HANSCH,C ET AL. (1995) logS -2.62 ADME Research, USCD
Predicted Properties	Property Value Source water solubility 4.59e-01 g/l ALOGPS logP 0.79 ALOGPS logP 0.79 ChemAxon logS -2.7 ALOGPS pKa (strongest acidic) 6.16 ChemAxon pKa (strongest basic) 1.97 ChemAxon physiological charge -1 ChemAxon hydrogen acceptor count 4 ChemAxon hydrogen donor count 2 ChemAxon polar surface area 98.22 ChemAxon rotatable bond count 2 ChemAxon refractivity 64.5 ChemAxon polarizability 24.99 ChemAxon

Drug	Interaction
Chlorpropamide	Sulfonamide/sulfonylurea: possible hypoglycemia
Cyclosporine	The sulfonamide decreases the effect of cyclosporine
Methotrexate	The sulfamide increases the toxicity of methotrexate
Pralatrexate	Decreases renal clearance of pralatrexate thus increasing exposure. Monitor for adverse effects.
Tobramycin	Increased risk of nephrotoxicity
Tolbutamide	Tolbutamide, a strong CYP2C9 inhibitor, may decrease the metabolism and clearance of Sulfamethoxazole. Consider alternate therapy or monitor for changes in Sulfamethoxazole therapeutic and adverse effects if Tolbutamide is initiated, discontinued or dose changed.
Warfarin	Sulfamethoxazole may increase the anticoagulant effect of warfarin by decreasing its metabolism. Consider alternate therapy or monitor for changes in prothrombin time if sulfamethoxazole is initiated, discontinued or dose changed.

• Do not take calcium, aluminium, magnesium or iron supplements within 2 hours of taking this medication.
• Take on empty stomach: 1 hour before or 2 hours after meals.
• Take with a full glass of water.