Cobalamin sequestrant
- B₁₂ absorption blocked or its cobalt core inactivated
- Prolonged exposure → macrocytic anemia and subacute combined degeneration
- Check a B₁₂ level
Drugs with this mechanism (3)
- Metformin — First-line diabetes drug; weight-neutral, sometimes used for antipsychotic weight gain.
- Metformin ER — Extended-release biguanide; often rescues GI intolerance to immediate-release therapy.
- Nitrous oxide — Rapid inhaled NMDA-antagonist analgesic and anesthetic; repeated exposure depletes vitamin B12.
Self-check
- What anemia can prolonged B12 impairment cause?
Macrocytic anemia. - What spinal-cord disorder can prolonged B12 impairment cause?
Subacute combined degeneration.
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