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Anemia Drugs: Vitamin B12 and Folic Acid

Terms in this set (21)

What is the main source of vitamin B12?
Microbial synthesis.
How long can vitamin B12 be stored?
Can be stored in the liver for up to five years.
What are the symptoms of B12 deficiency (4)?
-Anemia
-Red tongue or bleeding gums
-GI symptoms
-Neurological abnormalities (e.g. numbness, tingling in the feet or hands)
What are the common causes of B12 deficiency (5)?
-Pernicious anemia
-Partial or total gastrectomy
-Malabsorption syndrome, inflammatory bowel syndrome --Bacterial overgrowth of the small bowel, chronic pancreatitis, and thyroid disease
-Congenital deficiency of intrinsic factor or congenital selective Vit B12 malabsorption due to defects of the receptor sites in the distal ileum
Why can B12 deficiency be diagnosed years after a patient has started a vegan diet?
B12 can be stored for up to five years and therefore it takes many years to deplete the body's storage.
Why do strict vegans and vegetarians develop B12 deficiency?
B12 is microbially derived mostly in meat, eggs and dairy.
What is the clinical use of B12 (2)?
-Megaloblastic anemia
-Neurological abnormalities
What are the B12 drugs?
-Cyanocobalamin
-Hydroxocobalamin
What is important to note about B12 therapy?
Most Vitamin B12 deficiency (especially those due to malabsorption syndrome or inflammatory bowel syndrome) should be treated with life-long intramuscular Vit B12 injections.
What are the important B12 drug interactions (3)?
-Proton pump inhibitors
-H2 antagonists
-Metformin (used to treat diabetes)
How do PPIs and H2 antagonists interact with B12?
PPIs and H2 receptor antagonists can interfere with vitamin B12 absorption from food by slowing the release of hydrochloric acid into the stomach. This is a concern because acid is needed to release vitamin B12 from food prior to absorption.
How does metformin interact with B12?
Metformin may interfere with calcium metabolism. This may indirectly reduce vitamin B12 absorption because vitamin B12 absorption requires calcium.
What are the consequences of folic acid deficiency?
-Megaloblastic anemia
-Fetal neural tube defects (spina bifida)
What are the signs/symptoms of folate deficiency (4)?
-Pregnant women may give birth to low birth weight, premature, and/or infants with neural tube defects
-Infants and children may exhibit slow overall growth rate
-Anemia
-Other signs
What is the most important "other sign" of folic acid deficiency?
Elevated level of homocysteine (a risk factor for cardiovascular disease).
What are the causes of folic acid deficiency (4)?
-Inadequate dietary intake of folates
-Increased requirement of folates
-Malabsorption syndrome (Celiac disease aka sprue)
-Drugs
What causes an increased requirement of folates (2)?
-Pregnancy
-Patients with hemolytic anemia
What drugs cause folic acid deficiency (4)?
-Methotrexate
-Trimethoprim
-Pyrimethamine
-Long therapy with phenytoin
What is the advantage of folic acid supplementation?
Partially or totally corrects the anemia caused by B12 deficiency (e.g., megaloblastic anemia).
What is a disadvantage of folic acid supplementation?
Does not prevent the neurological damage caused by B12 deficiency.
Why is it important to combine folic acid supplementation with B12 supplementation?
Folate supplementation may mask B12 deficiency and increase the prevalence of neurologic disease in elderly populations
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