Subsalicylate

Subsalicylate refers to salts or coordination complexes derived from salicylic acid, in which the salicylate moiety is bound to a metal or other cation. The best-known example is bismuth subsalicylate, a coordination complex of bismuth with salicylate ligands. It is used in medicine as an antidiarrheal and antiemetic.

Bismuth subsalicylate is sold over the counter in liquid suspensions and chewable tablets under brand names such as Pepto-Bismol and Kaopectate in various markets. Indications include acute diarrhea, upset stomach, nausea, indigestion, and relief of gas. In some regimens, it is used as part of broader strategies to address Helicobacter pylori infection when combined with antibiotics and acid-suppressing therapy.

The mechanism of action is multifaceted. The salicylate portion may provide anti-inflammatory effects, while the bismuth component can exert antimicrobial activity and may help coat and protect irritated mucosa. The drug can reduce intestinal secretions and inflammation, contributing to symptom relief.

Safety and interactions are important considerations. Subsalicylates can cause harmless darkening of the tongue and stools. They should be used with caution in children and teenagers with viral illnesses due to concerns about Reye’s syndrome and salicylate exposure. They are not suitable for individuals with aspirin allergy, and excessive or long-term use may increase the risk of salicylate toxicity. Bismuth subsalicylate can interfere with the absorption of tetracyclines; dosing should be separated when both are used.

Regulatory status varies by country, but subsalicylates are commonly available as over-the-counter remedies for gastrointestinal symptoms.