Title: Sulfa drug | medicine | Britannica
Headings: Sulfa drug
Sulfa drug
medicine
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Content: Most bacteria make their own folic acid from simpler starting materials; humans and other higher animals, however, must obtain folic acid in the diet. Thus, sulfa drugs can inhibit the growth of invading microorganisms without harming the host. When trimethoprim (a dihydrofolate reductase inhibitor) is given with sulfamethoxazole, the sequential blockage of the pathway produced by the two drugs achieves markedly greater inhibition of folic acid synthesis. As a result, this combination is valuable in treating urinary tract infections and some systemic infections. The sulfones are related to the sulfonamides 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. This article was most recently revised and updated by Kara Rogers, Senior Editor. Learn More in these related Britannica articles: