sul·fon·amide or chiefly Brit sul·phon·amide .səl-'fän-ə-.mīd, -məd; -'fō-nə-.mīd n any of various amides (as sulfanilamide) of a sulfonic acid also SULFA DRUG
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sul·fon·a·mide (səl-fonґə-mīd) 1. an organic compound containing the
SO2NH2 group. 2. any of a class of drugs, the sulfa drugs, which are derivatives of sulfanilamide, competitively inhibiting folic acid synthesis in microorganisms and formerly bacteriostatic against gram-positive cocci (streptococci and pneumococci), gram-negative cocci (meningococci and gonococci), gram-negative bacilli (Escherichia coli and shigellae), a wide variety of other bacteria, and some protozoa. Because many strains of bacteria have developed resistance to sulfonamides, particularly to agents used singly, they have largely been supplanted by more effective and less toxic antibiotics, and when used are generally combined with another sulfonamide or other antimicrobial agent.
Medical dictionary. 2011.