Sulfalene (INN, USAN) or Sulfametopyrazine (BAN) is a long-acting sulfonamide antibiotic used for the treatment of chronic bronchitis, urinary tract infections, and malaria. Sulfametopyrazine, by virtue of a long half-life, achieves peak blood levels of 120 mkg/ml or more which fall to around 30-50 mkg/ml one week after a single oral dose of 2 g. Long-term administration of this drug in the treatment of leprosy for up to 3 years has been accomplished without serious unwanted effects

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.

Sulfamethoxypyridazine is a sulfonamide antibacterial with a broad spector of activity. It acts by inhibiting the enzyme dihydropteroate synthetase (DHPS), required for the synthesis of nucleic acids and microbial cells.

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).

Sulfanilamide is an anibiotic drug, which has been used for decades for the treatment of vulvovaginal candidiasis. The drug blocks folic acid synthesis in bacterias by inhibitin the enzyme dihydropteroate synthase.