Dorzolamide is a sulfonamide and topical carbonic anhydrase II inhibitor. Sulfanilamide (also spelled sulphanilamide) is a sulfonamide antibacterial drug. A primary amine will form a soluble sulfonamide salt. Antibiotic therapy with a sulfonamide, most commonly trimethoprim-sulfamethoxazole, is the treatment of choice. A tertiary amine will not react with the sulfonamide but is insoluble. Acidification of this salt then precipitates the sulfonamide of the primary amine. Approximately 3% of the general population have adverse reactions when treated with sulfonamide antimicrobials. The concurrent use of potentiated sulfonamide antibiotics is considered particularly dangerous. Chemically, it is an organic compound consisting of an aniline derivatized with a sulfonamide group. The discovery and development of this sulfonamide drug opened the era of antibacterials. Torasemide is a sulfonamide and loop diuretic. The first sulfonamide, trade-named Prontosil, was a prodrug. The "ortho" isomer is separated and converted to the sulfonamide with ammonia. This makes it a useful target for sulfonamide antibiotics, which compete with the PABA precursor. Reaction with sulfuryl chloride followed by oxidation of the sulfonamide give diethyldiazene, EtN=NEt.