Start practicing

Pharmacology · single question

Which patient must be CAUTIONED when using nitrous oxide sedation?

  1. Patient with vitamin B12 deficiency
  2. Patient with vitamin C deficiency
  3. Patient taking beta-blockers
  4. Pregnant patient in 3rd trimester
Show answer and explanation

Correct answer: A. Patient with vitamin B12 deficiency

Nitrous oxide irreversibly oxidizes cobalt in vitamin B12 (cobalamin), inactivating methionine synthase → impairs DNA synthesis → megaloblastic anemia and neurologic damage (subacute combined degeneration). Patients with B12 deficiency are at serious risk with N2O exposure. This is an absolute caution. Vitamin C deficiency is unrelated.

Practice Pharmacology questions Pharmacology study notes

More Pharmacology practice questions