Bismuth subsalicylate
Also Known As: Bismuth subsalicylate, pink bismuth, Pepto-Bismol, Kaopectate
Bismuth subsalicylate, with a nominal chemical formula of C7H5BiO4, It is a colloidal substance obtained by hydrolysis of bismuth salicylate (Bi{C6H3(OH)CO2}3). The actual structure is unknown and the formulation is only approximate. Recent evidence indicates that it is composed of a bismuth oxide core structure with salicylate ions attached to the surface. A model structure has recently been published having the composition Bi38O44{C6H3(OH)CO2}26. It is a drug used to treat temporary discomforts of the stomach and gastrointestinal tract, such as diarrhea, heartburn and nausea. Commonly known as pink bismuth, it is the active ingredient in popular medications such as Pepto-Bismol and, since 2003, in Kaopectate.
There are some adverse effects. It can cause a black tongue and black stools in some users of the drug, when it combines with trace amounts of sulfur in saliva and the colon to form bismuth sulfide.[4] Bismuth sulfide is a highly insoluble black salt, and the discoloration seen is temporary and harmless.
Some of the risks of salicylism can apply to the use of bismuth subsalicylate.[5][6][7]
Children should not take medication with bismuth subsalicylate while recovering from influenza or chicken pox, as epidemiologic evidence points to an association between the use of salicylate-containing medications during certain viral infections and the onset of Reye's syndrome.[8] For the same reason, it is typically recommended that nursing mothers not use medication containing bismuth subsalicylate (such as Pepto-Bismol) because small amounts of the medication are excreted in breast milk and pose a theoretical risk of Reye's syndrome to nursing children.[9]
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