Week 5: Anticoagulants Flashcards
Which is the following is the preferred medication to reverse the anticoagulant effects of unfractionated heparin?
a) Vitamin K
b) Protamine Sulfate
c) Platelet transfusion
d) Plasma components
b- protamine sulfate
The onset of anticoagulation effect of warfarin usually occurs how soon after the initiation of therapy?
a) immediately
b) 1 to 2 days
c) 3 to 5 days
d) 5 to 7 days
c - 3 to 5 days
Compared with unfractionated heparin, characteristics of low-molecular-weight heparin (LMWH) include all of the following except:
a) more antiplatelet effect
b) decreased need for monitor of anticoagulant effect
c) longer half-life
d) superior bioavailability
a - more antiplatelet effect
What is the international normalized ratio (INR) range recommended during warfarin therapy as part of the management of a patient with DVT?
a) 1.5 to 2.0
b) 2.0 to 3.0
c) 2.5 to 3.5
d) 3.0 to 4.0
b - 2.0 to 3.0
Which of the following belongs in the direct thrombin inhibitor class?
a) rivaroxaban
b) dabigatran
c) apixaban
d) edoxaban
b - dabigatran
Clotting Cascade
Warfarin MOA and unique indication that it must be given for
- Vitamin K antagonist - depletes functional Vitamin K reserves by competitively inhibiting VKORC1 complex, which reduces the ability of the liver to synthesize (produce) the Vitamin K dependent clotting factors (X, IX, VII, and II) - [2+7= 9 which is one less than 10]
- mechanical heart valve - Warfarin is the only drug FDA approved for this - need INR to be 2.5 to 3.5 (need this INR level if pt has had a previous clot while taking Warfarin)
What enzymes are involved in the metabolism of Warfarin? protein bound?
- CYP2C9 and CYP 1A2
- LOTS of drug interactions
- 99% protein bound so small changes can lead to changes in blood level of warfarin
Warfarin precautions/ contraindications
- severe HTN
- NO in infective endocarditis
- Preg category X
- caution in hepatic impairment (reduces hepatic synthesis of clotting factors)
- hypermetabolic state (avoid)
- safest in patients with kidney disease because of frequent monitoring
The effects of Warfarin may be decreased by:
a) Carbamazepine
b) Vitamin K rich foods
c) Oral contraceptives
d) all of the above
D -all of the above
What can you give if the patient taking warfarin has an seriously elevated INR?
give Vitamin K
Warfarin ADRs
- thrombocytopenia
- hemorrhagic skin necrosis & cyanotic toes
- maculopapular rash eruption
Situations when the NP should consider decreasing the initial dose of Warfarin therapy:
- pt is older than 75 years old
- multiple comorbid conditions
- elevated liver enzymes
- changing thyroid status
Heparin MOA & indication
- DVT/PE; prophylaxis
- increases the action of antithrombin III (a naturally occurring antithrombotic agent) thereby inactivating thrombin and inhibiting the activity of numerous coagulating factors
- prevents the conversion of fibrinogen to fibrin
Heparin cautions/contraindications
- use caution when combining w/ conditions/drugs that may predispose to hyperkalemia
- NO pregnancy
- ok with lacation
- NO in advanced renal or hepatic impairment
Heparin ADRs
- hyperkalemia
- thrombocytopenia
- anemia
Low Molecular Weight Heparin (LMWH) MOA & indication
drug of choice for?
- potentiates the activity of antithrombin III and inactivates factors Xa and IIa (prothrombin)
- DVT/PE, prophylaxis
- great for pregnant women!
LMWH cautions/contraindications
- avoid allergies with pork, sulfites, or benzyl alcohol
- use cautiously in renal impairment, untreated HTN, retinopathy, and severe liver dz.
Dabigatran (Pradaxa) MOA & indication
- Direct thrombin inhibitor (DTI)
- thrombin is required to turn fibrinogen into fibrin
- prodrug
- indication: reduce risk stroke and embolism in afib
dabigatran (Pradaxa) ADRs
- dyspepsia (indigestion)
- gastritis
- hemorrhage
Dibigatran (Pradaxa) caution/ contraindications
antidote
- NO pregnancy/lactation
- black box warning: epidural or spinal hematomas with spinal interventions
- black box warning: discontinuation and increase of thrombotic events
Antidote: Praxbind (Idarucizumab)
Rivaroxaban (Xarelto), Apixaban (Eliquis), Edoxaban (Savaysa), and Betrixaban (Bevyxxa) MOA & indication
“Xa-ban” drugs - direct factor Xa inhibitors
- indication: tx DVT and/or PE and reduce stroke & embolism afib
Rivaroxaban (Xarelto) ADR
back pain, abdominal pain, dyspepsia
Apixaban ADRs
nausea
Edoxaban ADR
Skin rash and GI bleeding, vag lbeeding, dermal bleeding
Edoxaban antidote
andexanet alpha (Andexxa )
Rivaroxaban, Apixaban, Edoxaban, and Betrixaban cautions/ contraindications
- black box warning: discontinuation would cause an increase in thrombotic events, epidural or spinal hematomas with spinal interventions
NO pregnancy or lactation
Rivaroxaban: NO in pts mod-severe liver impairment & CC < 30
Apixaban and edoxaban: NO in < 15 creatinine clearance (caution in moderate, NO in severe liver impairment)
Anticoagulants vs Antiplatelets
Anticoagulants:
- affect the clotting cascade
- makes the blood less able to create clots and thinning the blood
Antiplatelets:
- makes your platelets less sticky and unable to create clots
