Anticoagulants, Antiplatelets, ASA, DOACS

Question 1

Warfarin: Anticoagulant MOA

Answer 1

Inhibits vitamin K dependent coagulation factors II, VII, IX, X proteins C&S
Interferes with the conversion of vitamin K from its inactive form to active vitamin K

Question 2

Warfarin (Anticoagulant): Considerations

Answer 2

Least expensive
Inconvenient laboratory monitoring, multiple CYP interactions, and varied dosing for patients
No effect on existing clotting factors or existing thrombus

Question 3

Warfarin (Anticoagulant): SE’s

Answer 3

Hematuria
GI bleeding, Hemoptysis

Question 4

Warfarin (Anticoagulant): Interactions

Answer 4

Metabolized by CYP2C9, use in caution with drugs that inhibit or are substrates or that isoenzyme
Fluconazole
Amiodarone
Sulfamethoxazole-trimethoprim
Metronidazole

Question 5

Low-Molecular Weight Heparins (Enoxaparin (! Lovenox ®) and Fondaparinux (Arixtra): Anticoagulants, MOA

Answer 5

Binds to antithrombin III and accelerates activity inhibiting thrombin and factor Xa (low-molecular weight heparin)
Fondaparinux: Synthetic specific inhibitor of factor Xa

Question 6

Low-Molecular Weight Heparins (Enoxaparin (! Lovenox ®) and Fondaparinux (Arixtra): Anticoagulants, SE’s

Answer 6

Hematuria
GI bleeding
HIT: 4T’s: Thrombocytopenia, Timing, Thrombosis, and oTher

Question 7

Unfractionated Heparin (UFH): Anticoagulant, MOA

Answer 7

Inhibits reactions that lead to clotting, does not alter the concentration of the normal clotting factors of the blood.
Inactivates thrombin and preventing the conversion of fibrinogen to fibrin

Question 8

Warfarin (Anticoagulant): Reversal

Answer 8

Vitamin K

Question 9

LMWH (Anticoagulant): Reversal

Answer 9

Nothing specific, maybe use protamine

Question 10

UFH (Anticoagulant): Reversal

Answer 10

IV protamine sulfate

Question 11

NOACs / DOACs (Direct acting oral anticoagulants): Rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa) and dabigatran (Pradaxa) MOA

Answer 11

Bind directly to factor Xa and do not require antithrombin like LMWHs do

Pradaxa: Binds to and inhibits thrombin that prevents the conversion of fibrinogen to fibrin.

Question 12

NOACs / DOACs (Direct acting oral anticoagulants): Rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa) and dabigatran (Pradaxa) Interactions

Answer 12

Avoid use with P-gp inhibitors: Ketoconazole, ritonavir
Avoid P-gp Inducers: rifampin, carbamazepine, phenytoin, St. John’s wort

Question 13

NOACs / DOACs (Direct acting oral anticoagulants): Rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa) and dabigatran (Pradaxa) Reversal

Answer 13

No antidotes for Endoxaban

Andexanet: Xa decoy protein that binds to factor Xa
Reverses apixaban, edoxaban, rivaroxaban, betrixaban, LMWH’s

Question 14

Clopidogrel (Antiplatelet): MOA

Answer 14

Irreversibly bind to P2Y12 adenosine diphosphate receptors
Must be activated / bio-transformed to inhibit platelet aggregation

Question 15

Clopidogrel (Antiplatelet) Interactions

Answer 15

CYP450 dependent -CYP2C19 alleles nonfunction=poor metabolizers

Inhibitors: Fluconazole, fluvoxamine, and fluoxetine (decrease antiplatelet effects)

Question 16

ASA (Bayer, Antiplatelet): MOA

Answer 16

Non-selectively and irreversibly inhibits cyclooxygenase reducing prostaglandin and thromboxane A2 synthesis, producing platelet aggregation, analgesia, anti-inflammatory + antipyretic effects

Prevents prostaglandin synthesis in Plts and other tissues by irreversibly modifying and inhibiting the enzyme cyclooxygenase (COX)

Every 24 hours, platelets are replaced. At 5 days, 50% of platelets are functional.