Anticoagulants/Antiplatelets Flashcards
What is the most commonly used anticoagulant?
Heparin
What is the mechanism of action of heparin?
Promotes antithrombin to inhibit Factor Xa and thrombin which suppresses fibrin formation to decrease clots
What are adverse effects of heparin?
Bleeding, HIT
How is heparin monitored?
aPTT levels, needs close monitoring and titration, not often used outpatient
When is heparin contraindicated?
Patients with current bleeds, recent spinal surgeries/anesthesias
How do heparin and low-molecular weight heparins differ?
LMW heparin is shorter so it does not effect thrombin making it safer for outpatient use and does not require as close monitoring or titrations
What is the mechanism of action of LMW heparins?
Promotes antithrombin to inhibit Factor Xa to suppress fibrin formation
What are adverse effects of LMW heparins?
Bleeding, thrombocytopenia
When are LMW heparins contrainidacted?
Patients with current bleeds, recent spinal surgeries/anesthesias
What is the antidote for heparin?
Protamine sulfate
What do the LMW heparins end in?
-parin
What is the most commonly used LMW heparin?
Enoxaparin (Lovenox)
What is a barrier with heparin/LMW heparin use?
They must be given subcutaneously making them not easy to use
What is the oldest oral anticoagulant?
Warfarin
Why has Warfarin fallen out of favor in anticoagulation therapy?
It has many drug interactions and requires very close monitoring as well as frequent titrations. The newer oral anticoagulants do not require as close monitoring or have as many drug interactions so they have taken the place of warfarin in anticoagulation therapy
What is the mechanism of action of warfarin?
It decreases the production of Factors VII, IX, X, and prothrombin by preventing the activation of Vitamin K
What are adverse effects of warfarin?
Bleeding, hemorrhage
Can warfarin be used in pregnacy?
No, it is associated with fetal hemorrhage making it a Category X risk for pregnancy
What is the antidote for warfarin?
Vitamin K
What is an prominent education piece for patients on warfarin?
Dietary modifications to limit Vitamin K intake, need to educate on foods that contain Vitamin K
How are warfarin levels monitored?
PT/INR
What is the INR goal for most patients on warfarin?
2-3
How often is INR monitored for patients on warfarin?
Daily for the first 5 days of initiation
2 times a week for the next 1-2 weeks
Weekly for the next 1-2 months
Every 2-4 weeks for the duration of therapy
What is the half-life of warfarin?
2-5 days
What is the mechanism of action of dabigatran etexilate?
Directly inhibits thrombin thus preventing clots, it can also bind to thrombin in already formed clots to help break the clots down
How is dabigatran etexilate activated?
It is a prodrug and needs to be metabolized to form it’s active state of dabigatran to produce its effects
What are benefits of dabigatran?
PO administration, same dose for all patients, no frequent monitoring
What are adverse effects of dabigatran?
Bleeding, dyspepsia, ulcers, GERD, esophagitis
What are the two Factor Xa inhibitors?
Rivaroxaban (Xarelto) and Apixaban (Eliquis)
What is the mechanism of action of the Factor Xa inhibitors?
Inhibit Factor Xa from producing clots.
Rivaroxaban binds directly to Factor Xa to prevent it from activating
Apixaban inhibits and binds to free and clot bound Factor Xa
What are adverse effects for the Factor Xa inhibitors?
bleeding, hematoma with spinal surgeries/anesthesias
Which Factor Xa inhibitor is safer with pregnancy?
Apixaban, it is a Category B
When are the Factor Xa inhibitors contraindicated?
Patients with severe renal impairment as they both carry risk of renal impairment
What is the most commonly used antiplatelet?
Aspirin
What is the mechanism of action of aspirin?
It inhibits COX to prevent platelet aggregation
What are the adverse effects of aspirin?
GI upset (ulcers), bleeding
What can help reduce the risk of GI ulcers when prescribing aspirin?
Enteric-coated medication as it is a less acidic coating and takes longer to break down
How long is aspirin effective for?
Aspirin is effective in the body for the life of the platelet, thus its duration is about 7-10 days
What is the mechanism of action of clopidogrel?
Inhibit ADP receptors thus decreasing ADP stimulated platelet aggregation
What are the adverse effects of clopidogrel?
GI upset/ulcers, bleeding
Who should be on clopidogrel and aspirin therapy?
Patients with acute coronary syndrome
