Common term for sulfonamide drug, any member of a class of synthetic antibacterial drugs with a particular chemical structure including both sulfur and nitrogen atoms. Their effectiveness against bacteria was discovered in 1932 by Gerhard Domagk, and they became the first chemical substances systematically used against human bacterial infections. Sulfa drugs inhibit the growth and multiplication of certain bacteria (but do not kill them) by interfering with the synthesis of folic acid. Because of their toxicity and growing bacterial resistance, sulfa drugs are no longer in common use (except for urinary-tract infections, certain forms of malaria, and preventing infection of burns), having been largely superseded by less toxic antibiotics.
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