Question

Which of the following drugs causes Vitamin B12 deficiency on long-term use?

• A. Metformin
• B. Omeprazole
• C. Colchicine
• D. All of the above

Hint:

Multiple drugs impair B12 absorption through different mechanisms involving gastric acid, ileal transport, or mucosal function.

Answer 1

The Correct Option is D

Vitamin B12 deficiency from drugs is a frequently tested NEET PG topic. All three listed drugs are implicated:

1. Metformin: Inhibits calcium-dependent IF-B12 complex absorption in the terminal ileum. Incidence ~5-10% of long-term users. Reversible with calcium supplementation. Dose-dependent.

2. Omeprazole (PPIs): Reduces gastric acid, impairing pepsin-dependent release of protein-bound B12 from food. Long-term PPI use causes B12 deficiency especially in elderly patients.

3. Colchicine: Disrupts ileal mucosal cell function, impairing IF-B12 complex absorption in the terminal ileum.

Other drugs causing B12 deficiency: H2 blockers (ranitidine), neomycin, para-aminosalicylic acid (PAS), nitrous oxide (inactivates B12 irreversibly by oxidizing cobalt).

$\text{B12 deficiency}$ presents with megaloblastic anemia, subacute combined degeneration of the spinal cord (SACD), and peripheral neuropathy. SACD is NOT seen in folate deficiency -- this is a key distinguishing feature.

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