Sulfamethoxazole is a synthetic antibacterial drug,which is used in combination with trimethoprim (Bactrim, Septra) for the treatment or prevention of infections that are proven or strongly suspected to be caused by bacteria. Sulfamethoxazole acts by inhibiting folic acid synthesis via enzyme called dihydropteroate synthase.

Dapsone was synthesized in 1908 by Fromm and Wittmann. The drug was approved by FDA for the treatment of such conditions as acne vulgaris, leprosy and dermatitis herpetiformis, also the drug is used off-label for many skin diseases. Although the exact mechanism of dapsone action is unknown, it is speculated that it acts as both anti-inflammatory and antimicrobial agent. It was demonstrated that dapsone suppresses ROS generation, inhibits neutrophil myeloperoxidase and eosinophil peroxidase and also inhibits bacterial dihydropteroate synthase.

Sulfacetamide is a synthetic sulfonamide antibiotic, which exerts its effect through inhibition of bacterial dihydrofolate synthetase, an enzyme responsible for the conversion of p-aminobenzoic acid into folic acid in bacterias. The topical formulation of the drug is prescribed for the treatment of acne vulgaris and the ophtalmic formulation is used in patients with eye infections.

Sulfadiazine is a sulfonamide antibiotic. The sulfonamides are synthetic bacteriostatic antibiotics with a wide spectrum against most gram-positive and many gram-negative organisms. However, many strains of an individual species may be resistant. Sulfonamides inhibit multiplication of bacteria by acting as competitive inhibitors of p-aminobenzoic acid in the folic acid metabolism cycle. Bacterial sensitivity is the same for the various sulfonamides, and resistance to one sulfonamide indicates resistance to all. Most sulfonamides are readily absorbed orally. However, parenteral administration is difficult, since the soluble sulfonamide salts are highly alkaline and irritating to the tissues. The sulfonamides are widely distributed throughout all tissues. High levels are achieved in pleural, peritoneal, synovial, and ocular fluids. Although these drugs are no longer used to treat meningitis, CSF levels are high in meningeal infections. Their antibacterial action is inhibited by pus. Sulfadiazine is a competitive inhibitor of the bacterial enzyme dihydropteroate synthetase. This enzyme is needed for the proper processing of para-aminobenzoic acid (PABA) which is essential for folic acid synthesis. The inhibited reaction is necessary in these organisms for the synthesis of folic acid. Used for the treatment of rheumatic fever and meningococcal meningitis.

Sulfametoxydiazine (INN) or sulfamethoxydiazine (USAN: sulfameter) is a long-acting sulfonamide antibacterial, shows bacteriostatic effects against Gram positive and Gram negative bacteria in vivo. It is used as a leprostatic agent and in the treatment of urinary tract infections. Orally active. Sulfonamides block the synthesis of dihydrofolic acid by inhibiting the enzyme dihydropteroate synthase. Sulfonamides are competitive inhibitors of bacterial para-aminobenzoic acid (PABA), which is required for bacterial synthesis of folic acid. Sulfameter is a dihydrofolate reductase (DHFR) inhibitor. Mode of resistance is via the alteration of dihydropteroate synthase or alternative pathway for folic acid synthesis.

Sulfaphenazole is an oral antibiotic, which was used for the treatment of bacterial infections under the name Sulfabid. The drug was found to block folate synthesis in bacterias by inhibiting the enzyme dihydropteroate synthase. Sulfaphenazole is also known to inhibit CYP2C9 with high potency and specificity. Sulfabid is no longer marketed in the USA.

Sulfachlorpyridazine is a broad spectrum antibacterial compound which is effective in the treatment of infections caused by gram-positive and gram-negative organisms that are commonly susceptible to sulfonamide therapy and which has been proven by laboratory and field experiments to be highly effective against diseases caused by Escherichia coli. Sulfachlorpyridazine has a rapid onset of action in several species of animals following both oral and parenteral administration. Sulfachlorpyridazine (brand name Vetisulid) is especially indicated for the treatment of diarrhea caused or complicated by E. coli (colibacillosis) in calves under 1 month of age: Vetisulid powder is also indicated for the treatment of colibacillosis in swine. Sulfachlorpyridazine is a dihydropteroate synthase inhibitor.

Sulfamethizole is an oral antiobiotic, which was used against urinary tract infections under the name Thiosulfil. Sulfamethizole blocks bacterial growth by inhibiting folic acid synthesis via enzyme called dihydropteroate synthase. The drug is no longer marketed in the USA.

Sulfisoxazole is a sulfonamide antibacterial antibiotic. The sulfonamides are synthetic bacteriostatic antibiotics with a wide spectrum against most gram-positive and many gram-negative organisms. However, many strains of an individual species may be resistant. Sulfisoxazole acetyl in combination with erythromycin ethylsuccinate is used for treatment of ACUTE OTITIS MEDIA in children that is caused by susceptible strains of Haemophilus influenzae. Sulfisoxazole acetyl is a prodrug of sulfisoxazole. Acetyl group is added to make the drug poorly water soluble, and is hydrolyzed in vivo to the active drug. Sulfisoxazole and its acetylated metabolites are excreted primarily by the kidneys through glomerular filtration. Sulfisoxazole is a competitive inhibitor of the enzyme dihydropteroate synthetase. It inhibits bacterial synthesis of dihydrofolic acid by preventing the condensation of the pteridine with para-aminobenzoic acid (PABA), a substrate of the enzyme dihydropteroate synthetase. The inhibited reaction is necessary in these organisms for the synthesis of folic acid

Sulfamethazine is a sulfonamide used to treat a variety of bacterial diseases in animals. It inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA) for binding to dihydropteroate synthetase (dihydrofolate synthetase).