Antiplatelets, Iron, Folic Acid, and Vitamin B12

Question 1

Aspirin MOA

Answer 1

• inhibits thromboxane A2 in the cyclooxygenase pathway thus interfering with platelet aggregation
• COX 1 and COX 2 inhibitor
• salicylated NSAIDs
• inhibits prostaglandins

Question 2

Aspirin ADRs

Answer 2

• GI ulcer
• angioedema
• Steven Johnson syndrome
• Reye’s syndrome

Question 3

Aspirin cautions/contraindications

Answer 3

• do not use in pediatrics w/ influenza or chickenpox
• low dose used to prevent preeclampsia in pregnancy
• low dose is safe in lactation

Question 4

Aspirin pharmacokinetics

Answer 4

• well absorbed with oral intake
• is affected by food
• metabolized in the liver
• renally excreted (pH affects excretion)

Question 5

Clopidogrel (Plavix) MOA

Answer 5

• reduces platelet aggregation by inhibiting adenosine diphosphate pathway
• blocks the ADP receptor so that platelets cannot adhere to one another at that receptor

Question 6

Plavix Pharmacokinectics

Answer 6

• Prodrug
• metabolized by CYP2C19
• Excreted in urine and feces

Question 7

Clopidogrel (Plavix) Cautions/precautions

Answer 7

• avoid in pts with GI ulcers (anti-prostaglandin- prostaglandins are GI protective
• severe hepatic dysfuction - unable to metabolize into active form
• use with PPIs can attenuate (weaken) the antiplatelet effect of Plavix

Question 8

Clopidogrel (Plavix) ADRs

Answer 8

• bleeding
• Steven Johnson syndrome (rare)

Question 9

What is the most common iron preparation given because it contains the highest amount of elemental iron?

Answer 9

Ferrous sulfate (20% elemental iron) - 65mg of elemental iron in a 325mg tablet - dosing is based on the amount of elemental iron

Ferrous Gluconate - 32mg of elemental iron in a 324mg tablet

Question 10

Iron preparations pharmacokinetics

Answer 10

• food affects absorption
• take on an empty stomach
• take with vitamin C to help with absorption
• avoid taking with dairy products, eggs, antacids, calcium which may inhibit absorption

Question 11

Iron preparations ADRs

Answer 11

• GI symptoms - constipation, GI upset
• acute iron toxicity with overdose
• keep away from children

Question 12

Iron preparations - monitoring

Answer 12

• check reticulocyte count (immature RBCs) 7 to 10 days after starting iron therapy - if this is not back to normal, there is something else wrong
• check and Hgb and Hct at 2 weeks then Hgb, Hct , and ferritin at 3 months

Question 13

Folic acid deficiency - causes

Answer 13

• poor dietary intake - absorption issues - increased demand - impaired utilization

Question 14

Folic acid pharmacokinetics

Answer 14

• oral, IM, SC are well absorbed
• metabolized by the liver
• excreted in urine and feces

Question 15

Folic acid supplementation indications

Answer 15

• treatment of megaloblastic anemia
• prevention of folic acid deficiency
• increased demand during pregnancy, ETOH abuse, hypothyroidism, hemolytic anemia, or malignancy

Question 16

Vitamin B12 deficiency causes/indications

Answer 16

• decreased absorption due to lack on intrinsic factor (made from parietal cells in the stomach)
• can be caused by GI surgery, diseases of the ilium, constipation - pernicious anemia d/t malabsorption issues
• Vitamin B12 is needed for the final steps of folate metabolism

Question 17

Vitamin B12 ADRs

Answer 17

hypokalemia

headache

pain @ injection site

transient diarrhea

urticaria

pruritis