Bismuth Subsalicylate and Black Tongue 

  • Bismuth subsalicylate is a compound containing Bismuth element and Salicylic acid.
  • Upon ingestion it gets rapidly dissociated into bismuth and salicylate in stomach.
    • Bismuth forms bismuth thiolate complexes with the proteins on the base of gastric ulcers and hence forms a coating over them.
    • Salicylate on the other hand has anti-inflammatory properties (aspirin also is a salicylic acid structure)
  • MOA : Bismuth reacts with sulphur present in saliva and gastrointestinal tract (sulphides are produced by intestinal bacteria) to form a black coloured compound Bismuth sulphide which causes the colour of tongue and stool to blacken temporarily.

Sucralfate and Gastric Bezoars 

  • Sucralfate is a salt of sucrose complexed with aluminium hydroxide.
  • This negatively charged structure binds to the positively charged proteins at the base of ulcer. 
  • Bezoars (stones) are any mass of undigested material that gets collected in gut lumen.
  • Hence at pH < 4 Sucralfate polymerizes into viscid gel which traps the food particles, forming bezoars.
Chemical Structure of Sucralfate
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