Antithrombotics and Anemia

Question 1

Components of hemostasis

Answer 1

Question 2

Anticoagulants vs Antiplatelets

Answer 2

Anticoagulants

• Can be used for prevention and treatment of thrombosis in venous and arterial systems

Antiplatelets

• Only used for arterial or intracardiac thrombosis

Question 3

Components of thrombus

Answer 3

Platelets

Thrombin

Fibrin

Question 4

Intrinsic vs Extrinsic Coagulation Pathways

Answer 4

Question 5

Clopidogrel (Plavix)

Mechanism of Action

Answer 5

ADP antagonist: ADP is needed to activate platelets

Question 6

NSAID antiplatelet activity

Answer 6

Has a weaker antiplatelet effect than other agents and is therefor not indicated for prevention of thrombosis

Question 7

Tissue Plasminogen Activator (TPA)

Mechanism of Action and Indications

Answer 7

Activates plasminogen into plasmin which dissolves blood clots

Used for embolic stroke and MI

Must be given within 3 hours

Question 8

Warfarin

Mechanism of Action and Indications

Answer 8

Vitamin K antagonist

Indicated for atrial fibrillation, recurrent stroke, DVT, pulmonary embolism, heart valve prosthesis

Question 9

Warfarin

Adverse Effects

Answer 9

Major risk for frequent and severe bleeding

Contraindicated in pregnancy

MANY drug interactions

Question 10

Goals of Warfarin Therapy

Answer 10

Goal INR for A Fib, DVT and PE is 2.0-3.0

Goal INR for prosthetic heart valve is 2.5-3.5

Remember that dose response is non-linear. This means that small changes in dose can have big impacts on INR.

Question 11

Warfarin Dose Adjustments

Answer 11

If INR consistently high, lower weekly dose by 10%

If INR consistently los, increase weekly dose by 10%

Remember to calculate the weekly dose, adjust by 10% and then divide back to get daily dose

Question 12

Direct oral anticoagulants (DOACs)

Examples and Indications

Answer 12

Aka Target Specific Oral Anticoagulants (TSOACs) or Non-vit. K oral anticoagulants (NOACs)

Examples include dabigatrin (Pradaxa), rivaroxiban (Xarelto), apixaban (Eliquis)

Indicated for atrial fibrillation, PE, and DVT

Question 13

Direct Oral Anticoagulants (DOACs)

Adverse Effects

Answer 13

Risk for bleeding

No method for monitoring

Use caution in renal failure patients

Question 14

Antidote for Thrombin Inhibitors

Answer 14

Idarucizumab (Praxbind)

Question 15

Antidote for Factor Xa inhibitors

Answer 15

Andexxa

Parenteral for apixaban and rivaroxaban

Question 16

Enoxaparin (Lovenox)

Indications and precautions

Answer 16

Initial treatment of venous thromboembolism, DVT prevention, unstable angina, NSTEMI, STEMI, PCI after MI

Use caution with renal insuffiency

Question 17

Antidote for warfarin

Answer 17

Vitamin K

Question 18

Which DOAC is a direct thrombin inhibitor?

Answer 18

Dabigatran

Question 19

Which DOAC are factor Xa inhibtors

Answer 19

• Rivaroxaban
• Apixaban
• Endoxaban
• Betrixaban (not available in US)

Question 20

Characteristics of iron defiency anemia

Answer 20

Microcytic, hypochromic anemia

Low serum iron

Total iron binding capacity increased

Decreased serum ferratin

Question 21

Iron supplementation side effects

Answer 21

Constipation, darkened stool, nausea, vomiting

Try increasing dose interval, taking with food, or switching to liquid if unable to tolerate side effects

Question 22

Drugs and food that inhibit iron absorption

Answer 22

Taking with food reduces absorption

Caffeinated drinks

Calcium containing foods/drinks/supplements

Antacids (some contain calcium)

H2 Receptor blockers

PPIs

Question 23

Macrocytic anemia causes

Answer 23

Folate and B12 deficiency