Bismuth subsalicylate is the active ingredient in the popular medication Pepto-Bismol that is used to treat nausea, heartburn, indigestion, upset stomach, diarrhea, and other temporary discomforts of the stomach and gastrointestinal tract. It is also the main ingredient of Kaopectate. It displays anti-inflammatory action (due to salicylic acid) and also acts as an antacid and mild antibiotic.

Indication

Used to treat nausea, heartburn, indigestion, upset stomach, diarrhea, and other temporary discomforts of the stomach and gastrointestinal tract.

Associated Conditions

Contraindications & Blackbox Warnings

Pharmacodynamics

Bismuth subsalicylate displays anti-inflammatory action (due to salicylic acid) and also acts as an antacid and mild antibiotic. It can also cause a black tongue and black stools in some users of the drug, when it combines with trace amounts of sulfur in their saliva and gastrointestinal tract. This discoloration is temporary and harmless.

Mechanism of action

As an antidiarrheal, the exact mechanism has not been determined. Bismuth subsalicylate may exert its antidiarrheal action not only by stimulating absorption of fluid and electrolytes across the intestinal wall (antisecretory action) but also, when hydrolyzed to salicylic acid, by inhibiting synthesis of a prostaglandin responsible for intestinal inflammation and hypermotility. In addition, bismuth subsalicylate binds toxins produced by Escherichia coli. Both bismuth subsalicylate and the intestinal reaction products, bismuth oxychloride and bismuth hydroxide, are believed to have bactericidal action. As an antacid, bismuth has weak antacid properties.

Absorption

Following oral administration, absorption of the salicylate component from the small intestine is generally rapid and complete (>90%).

Volume of distribution

Not Available

Protein binding

Not Available

Metabolism

Based on in vitro dissociation data and in vivo animal data, bismuth subsalicylate is believed to be largely hydrolyzed in the stomach to bismuth oxychloride and salicylic acid. In the small intestine, nondissociated bismuth subsalicylate reacts with other anions (bicarbonate and phosphate) to form insoluble bismuth salts. In the colon, nondissociated bismuth subsalicylate and other bismuth salts react with hydrogen sulfide to produce bismuth sulfide, a highly insoluble black salt responsible for the darkening of the stools.

Route of elimination

Not Available

Half-life

Not Available

Clearance

Not Available

Adverse Effects

Toxicity

Not Available

Affected organisms

Not Available

Pathways

Not Available

Pharmacogenomic Effects/ADRs