II. Causes: Megaloblastic Macrocytic Anemia

  1. Folate Related Changes
    1. Oral Contraceptive Use
    2. Pyrimethamine (Daraprim)
    3. Triamterene
    4. Alcohol
    5. Biguanides
      1. Methotrexate
      2. Cholestyramine (Questran)
    6. Anticonvulsants
      1. Phenytoin (Dilantin)
      2. Primidone (Mysoline)
      3. Phenobarbital
      4. Valproic Acid (Depakote)
    7. Antibiotics
      1. Sulfasalazine (Azulfidine)
      2. Sulfamethoxazole
      3. Trimethoprim (e.g. Bactrim or Septra)
      4. Pentamidine
    8. Reverse transcriptase inhibitors (HIV Medications)
      1. Stavudine (Zerit)
      2. Lamivudine (Epivir)
      3. Zidovudine (Retrovir)
  2. Vitamin B12 Related Changes
    1. Gastric acid-blocking agents
      1. Proton Pump Inhibitors (e.g. Omeprazole)
      2. Histamine H2-receptor blockers (e.g. Ranitidine)
      3. References
        1. Bradford (1999) Pharmacother 33:641-3
    2. Metformin (Glucophage)
    3. Colchicine
    4. Neomycin sulfate
    5. Nitrous oxide
    6. Para-aminosalicylic Acid

III. Causes: Non-megaloblastic Macrocytic Anemia (Marrow Toxins)

  1. Methotrexate
  2. Daunorubicin
  3. Adriamycin
  4. Benzene and derivatives (e.g. trinitrotoluene)
  5. Purine antagonists
    1. 6-Mercaptopurine
    2. Thioguanine
    3. Azathioprine (Imuran)
    4. Acyclovir (Zovirax)
  6. Pyrimidine antagonists
    1. Fluorouracil (Adrucil)
    2. Floxuridine (FUDR)
    3. Azidouridine
    4. Zidovudine (Retrovir)
  7. Ribonucleotide Reduction Inhibitors
    1. Hydroxyurea
    2. Cytosine arabinoside
  8. Alkylating Agents
    1. Cyclophosphamide (Cytoxan)
    2. Busulfan

IV. References

  1. Lee (1999) Wintrobe's Hematology, Lippincott, p. 1453
  2. Brigden (1995) Postgrad Med 97(5):171-86

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