Which of the following best describes the mechanism of action of oral zinc acetate as maintenance therapy in Wilson's disease?
- A Chelates copper and increases urinary excretion
- B Induces intestinal metallothionein, blocking copper absorption ✓
- C Increases incorporation of copper into ceruloplasmin
- D Blocks lysosomal copper transport in hepatocytes
Correct answer: B. Induces intestinal metallothionein, blocking copper absorption
Explanation
Zinc induces metallothionein synthesis in duodenal enterocytes; metallothionein binds dietary copper in the cell and prevents its transfer into the portal circulation, so absorbed copper is lost when enterocytes slough. This makes zinc ideal for long-term maintenance after initial chelation and for presymptomatic siblings. Chelation with increased urinary copper loss is the mechanism of penicillamine and trientine, which are reserved for de-coppering rather than maintenance.
Reference: Sherlock's Diseases of the Liver and Biliary System, 13th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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