Sulphonamides

Sulphonamides

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  SULPHONAMIDES
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  Sulphonamides (sulphonamides) area group of man-made (synthetic) medicines that contain the sulphonamide chemical group. They may also be called sulpha drugs. Many people use the term sulphonamide imprecisely to refer only to antibiotics that have a sulphonamide functional group in their chemical structure. However, there are several non-antibiotic sulphonamides that have been developed by exploiting observations made during the clinical evaluation of the antibiotic sulphonamides. These are used for a range of conditions such as diabetes and pain relief. Sulphanilamide was the first sulphonamide developed in 1906, although it was not used as an antimicrobial agent until the late 1930s.
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  Sulphonamide antimicrobials arebacteriostatic (stop bacteria from reproducing but don't necessarily kill them) and work by interfering with the synthesis of folic acid in bacteria, which is essential for nucleic acid formation and ultimately DNA and RNA.  Humans obtain folic acid from their diet, but bacteria need to synthesize it. Sulphonamide antimicrobials may be combined with trimethoprim to make them bactericidal (kill bacteria), because trimethoprim acts on a different enzyme in the folic acid synthesis pathway. Sulpha drug, also called sulphonamide, any member of a group of synthetic antibiotics containing the sulphanilamide molecular structure. Sulpha drugs were the first chemical substances systematically used to treat and prevent bacterial infections in humans.
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  Their use hasdiminished because of the availability of antibiotics that are more effective and safer and because of increased instances of drug resistance. Sulphonamides are still used, but largely for treating urinary tract infections and preventing infection of burns. They are also used in the treatment of certain forms of malaria. The antibacterial effects of sulphonamides were first observed in 1932, when German bacteriologist and pathologistGerhard Domagk noted the effects of the red dye Prontosil on Streptococcus infections in mice. It was later proved by French researchers that the active agent of Prontosil was sulphanilamide, or para-amino benzene sulphonamide, a product of the body’s metabolism of Prontosil. By the 1940s sulphanilamide was a widely used drug.
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  During WorldWar IIwhite sulphanilamide powders became standard in first-aid kits for the treatment of open wounds, and sulphanilamide tablets were taken to fight intestinal infections. Though the medicine was relatively safe, allergic reactions such as skin rashes, fever, nausea, vomiting, and even mental confusion were common. With the introduction of less-toxic derivatives and especially with the mass production of penicillin, its use declined. Sulpha drugs are bacteriostatic; i.e., they inhibit the growth and multiplication of bacteria but do not kill them. They act by interfering with the synthesis of folic acid (folate), a member of the vitamin B complex present in all living cells. Most bacteria make their own folic acid from simpler starting materials; humans and other higher animals, however, must obtain folic acid in the diet. Sulpha drugs can inhibit the growth of invading microorganisms without harming the host.
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  The sulfones arerelated to the sulphonamides and are inhibitors of folic acid synthesis. They tend to accumulate in skin and inflamed tissue and are retained in the tissue for long periods. Thus, sulfones such as dapsone are useful in treatment of leprosy.