Parenteral Anticoagulation Drugs Flashcards
How do anticoagulant drugs work?
They prevent the formation of fibrin which is needed to clot blood
What is another name for an anticoagulant?
Antiothrombotic
Which 3 drugs interrupt the conversion of fibrinogen to fibrin?
-Unfractionated heparin
-Low-molecular weight heparin
-Fondaparinux heparin
How does heparin prevent clots?
-Heparin binds with antithrombin III which inactivates thrombin
-This inhibits the conversion of fibrinogen to fibrin
-Clot is prevented
What are contraindication for heparin therapy?
-Uncontrollable bleeding
-Hemorrhagic cerebrovascular accident
-Thrombocytopenia (low platelet count)
-Before, during, or after surgery involving the eyes, spine, or brain
-Before, during, or after lumbar puncture
What drugs have serious interactions with heparin?
-Other anticoagulants
-Platelet aggregation inhibitors
-NSAIDs
-Thrombolytics
-Antibiotics
What is a normal aPTT value?
25-38 seconds
What is a therapeutic aPTT value for someone taking heparin therapy?
1.5-2xs normal
What is important to remember when administering SQ heparin in the abdominal area?
Don’t administer it within 2 inches of the belly button
What can be administered as an antidote to a patient that has active bleeding during heparin therapy?
Protamine sulfate
What is HIT?
Heparin-induced thrombocytopenia; dangerously low platelet count due to heparin
What are the symptoms of HIT?
-Bleeding gums
-Bruising
-Bloody urine/stool
-Anxiety
When should aPTT be assessed after initiating heparin?
4-6 hours after
Name a Vitamin K Anticoagulant
Warfarin
What is the difference between Warfarin and Heparin?
-They work on different parts of the clotting cascade
-Warfarin doesn’t require strict monitoring
What is the lab test that is performed before Warfarin is adminisitered?
INR; International Normalized Ratio
Describe how Vitamin K Anticoagulants (like Warfarin) work
-Vitamin K is needed in order to make clotting factors
-Warfarin interferes with Vitamin K-dependent clotting factors; it also depletes Vitamin K reserves
How long does it take Warfarin to clear from the body?
4-5 days
What is a good INR for a patient taking Warfarin?
2-3
What is the only Oral Direct Thrombin Inhibitor?
Dabigatran
Name 3 Factor Xa Inhibitors
Rivaroxaban
Apixaban
Edoxaban
How does Dabigatran work?
Directly inhibits thrombin by preventing the conversion of fibrinogen to fibrin
How does the Factor Xa Inhibitors work?
Directly inhibit Xa preventing the conversion of prothrombin to thrombin
What are contraindications of Warfarin?
-Thrombocytopenia
-Lumbar puncture; regional anesthesia; surgery of eye, spine, or brain
-Vitamin K deficiency, liver disease, alcoholism
-Pregnancy
What are some drugs that interfere with Warfarin?
Aspirin
NSAIDs
Sulfonamides
Cimetidine
Allopurinol
Foods high in Vitamin K
What are common side effects of Warfarin?
Bleeding
GI upset
What are adverse drug effects of warfarin?
Intracranial bleeding
Retroperitoneal bleeding
What is the antidote for a Warfarin overdose?
Vitamin K
At what INR value should you hold Warfarin?
Greater than 3
At which age can patients take Dabigatran and Rivaroxaban?
18 and older
What are contraindications for Dabigatran and Rivaroxaban?
Active major bleeding
Mechanical prosthetic heart valve
What are drug interactions of Dabigatran and Rivaroxaban?
-Rifampin can decrease drug concentrations
-Antacids and PPIs and decrease drug effects
-Antiplatelets, NSAIDs, and other anticoags can increase bleed risks
At what dose should you give Rivaroxaban with foods?
10mg+
If a patent is actively bleeding from Warfarin and not responding to Vitamin K, what should we give them?
Fresh-frozen plasma
What is the antidote for Dabigatran?
Idarucizmab
What are antiplatelet drugs?
Drugs that suppress platelet aggregation and used in the prevention of thrombosis. They make platelets less sticky so they don’t form clots
What are antiplatelet drugs used for?
- Prevention of MI
- Prevention of ischemic stroke
What are the 3 classes of Antiplatelet Drugs? Give a drug name for each
-COX Inhibitor; Aspirin
- ADP Receptor Blockers; Clopidogrel
-GP IIb/IIIa Receptor Blockers; Tirofiban
What are contraindications for Clopidogrel?
Active bleeding
What drug interactions are there with Clopidogrel?
-Aspirin, NSAIDs, Warfarin may increase bleed risk
-Grapefruit may lessen effects
What do thrombolytic drugs do?
They disintegrate existing blood clots
Name a thrombolytic drug
Alteplase
Explain how alteplase works
Alteplase binds with plasminogen which activates plasmin. Plasmin is an enzyme that disintegrates the fibrin network of blood clots
What conditions is Alteplase used for?
Acute MI
Acute ischemic stroke
Large, acute PE
Clear clots from central venous catheters
What are absolute contraindications of Alteplase?
Cranial lesions
History of ischemic stroke within 3 months
Active internal bleeding
Suspected aortic dissection
Uncontrolled hypertension
What can be used as an antidote to severe bleeding in a patient taking thrombolytic therapy?
Aminocoproic acid
