Megaloblastic anemia is caused by all EXCEPT:
Methorexate can induce folate deficiency. Prolonged N2O anesthesia has the potential to depress bone marrow and cause peripheral neuropathy. Primidone is similar to phenytoin that is induces folate deficiency. From medical pharmacology padmaja 4th edition Page no 331 and Essential of medical pharmacology K D Tripati 7th edition page no 378
Aspirin
primidone
Methotrexate
N2O
Hematology