bismuth subsalicylate
Brand: Pepto-Bismol
Drug Class: GI protective agent / antidiarrheal
Drug Family: GI agent
Subclass: bismuth salt
Organ Systems: gastrointestinal
Mechanism of Action
Exerts multiple mechanisms: bismuth ions have direct bactericidal activity against H. pylori and inhibit its urease; salicylate component inhibits prostaglandin synthesis, reducing intestinal secretions; bismuth also coats the gastric mucosa, providing a protective barrier.
gastric mucosaHelicobacter pylori (bactericidal)enterotoxin (antisecretory)
Indications
- H. pylori eradication (quadruple therapy)
- traveler's diarrhea (prophylaxis and treatment)
- nausea
- indigestion
- heartburn
Contraindications
- aspirin allergy (salicylate component)
- children/teenagers with viral illness (Reye's syndrome risk)
- renal impairment (bismuth accumulation)
Adverse Effects
Common
- darkening of stools and tongue (harmless)
- constipation
- nausea
Serious
- salicylate toxicity (high doses or renal impairment)
- bismuth encephalopathy (excessive prolonged use)
- Reye's syndrome in children with viral illness
Pharmacokinetics (ADME)
| Absorption | bismuth is minimally absorbed (<1%); salicylate is well absorbed |
| Distribution | bismuth poorly distributed systemically; salicylate distributed widely |
| Metabolism | salicylate metabolized hepatically; bismuth not significantly metabolized |
| Excretion | bismuth excreted in feces; salicylate renally excreted |
| Half-life | salicylate: 2–3 hours; bismuth: 21–72 days (tissue accumulation possible) |
| Onset | 30–60 minutes |
| Peak | variable |
| Duration | 4–6 hours |
| Protein Binding | salicylate ~90% |
| Vd | low (bismuth) |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| aspirin or NSAIDs | additive salicylate toxicity | moderate |
| warfarin | salicylate displaces warfarin from protein binding; antiplatelet effect | major |
| tetracyclines | bismuth chelates tetracyclines, reducing absorption | moderate |
Nursing Considerations
- Warn patients that black/gray stools and dark tongue discoloration are harmless and expected side effects.
- Do not administer to children or teenagers with flu or chickenpox due to Reye's syndrome risk.
- Separate administration from tetracyclines by at least 2 hours as bismuth chelates and reduces their absorption.
- Monitor for salicylate toxicity (tinnitus, dizziness) in patients taking concurrent aspirin, NSAIDs, or anticoagulants.
Clinical Pearls
- A component of bismuth quadruple therapy for H. pylori eradication: bismuth subsalicylate + metronidazole + tetracycline + PPI.
- The dark stool discoloration results from bismuth sulfide formed in the GI tract when bismuth reacts with hydrogen sulfide; this should be distinguished from melena.
Safety Profile
Pregnancy avoid
Lactation avoid
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
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