NEIL H. SHEAR, M.D.; STEPHEN P. SPIELBERG, M.D., Ph.D.; DENIS M. GRANT, Ph.D.; BING K. TANG, Ph.D.; WERNER KALOW, M.D.
Individual differences in metabolism of the sulfonamides may predispose patients to idiosyncratic reactions. Sulfonamides are metabolized by N-acetylation (mediated by a genetically polymorphic enzyme) and oxidation to potentially toxic metabolites. We examined 6 patients who had severe reactions to sulfonamides and compared them with 20 controls. Acetylator phenotype was determined with caffeine, a safe in-vivo probe of enzyme activity. All 6 patients were slow acetylators (expected, 55%; p < 0.05). Detoxification of oxidative metabolites was studied in vitro with a lymphocyte assay evaluating cell death from metabolites generated by a murine hepatic microsomal system. Cells from each patient showed increased toxicity from sulfonamide metabolites but not from the drugs themselves. Cells from parents of 3 patients had intermediate toxicity from sulfonamide metabolites, whereas cells from a sibling of 1 patient had a normal response. Susceptibility to sulfonamide reactions may be due to interaction of metabolic pathways, possibly under genetic control, regulating N-acetylation and specific detoxification of toxic metabolites of the drugs.
SHEAR NH, SPIELBERG SP, GRANT DM, TANG BK, KALOW W. Differences in Metabolism of Sulfonamides Predisposing to Idiosyncratic Toxicity. Ann Intern Med. 1986;105:179–184. doi: 10.7326/0003-4819-105-2-179
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Published: Ann Intern Med. 1986;105(2):179-184.
Emergency Medicine, Hospital Medicine.
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