Bismuth+subsalicylate

Chemical Formula: C7H5BiO4

It is a colloidal substance obtained by hydrolysis of bismuth salicylate (Bi{C6H4(OH)CO2}3). The actual structure is unknown, and therefore the formulation is only approximate. It is more than likely composed of a bismuth oxide core structure with salicylate ions attached to the surface. Bismuth subsalicyte is used as a drug to temporarily treat temporary pain and discomfort in the stomach and gastrointestinal tract, such as diarrhea, heartburn and nausea. It is the active ingredient in popular medications such as Pepto-Bismol and, since 2003, in Kaopectate.

The term "sub" refers to the high oxygen content in the molecule and the presence of Bi-O moieties. Characterization of the properties of bismuth subsalicylate has been difficult due to its insolubility and its partial hydrolysis. The crystal structure of the molecule is available here, which shows an octahedral cluster. Two crystal structures are observed, them being: • [Bi38O44(HSal)26(Me2CO)16(H2O)2] with a Bi38O44 core • [Bi9O7(HSal)13(Me2CO)5] with a Bi9O7 core It is believed that the latter cluster gives rise to the former, leading researchers to believe that they may be extrapolated to form larger clusters. This may be the basis for bismuth subsalicylate's extreme insolubility. Other bismuth carboxylates have typically been trapped using chelating amines such as Bipyridine. Attempts to do so with bismuth subsalicylate have typically led to a loss of the "sub" portion of the molecule.

Bismuth subsalicylate is used as an antidiarrheal and to treat some other gastro-intestinal diseases (oligodynamic effect). It is the active ingredient in various stomach-settling medications, including pepto-bismol. The means by which this occurs is still not well documented. It is thought to be some combination of the following:[2] • Retarding the expulsion of fluids into the digestive system by irritated tissues, by "coating" them. • Stimulation of absorption of fluids and electrolytes by the intestinal wall (antisecretory action) • Reducing inflammation/irritation of stomach and intestinal lining through inhibition of prostaglandin G/H Synthase 1/2 • Reduction in hypermotility of the stomach • Binding of toxins produced by E. coli • Bactericidal action • Weak antacid properties In vitro and in vivo data has shown that bismuth subsalicylate hydrolyzes in the gut to bismuth oxychloride and salicylic acid. In the stomach, this is likely an acid-catalyzed hydrolysis.

Bismuth subsalicylate is the only active ingredient in an over the counter medication that will leave a shiny metal oxide slag behind after being completely burnt with a blow torch.