Antithrombotic and Hemostatic Drugs Flashcards
What prevents platelet activation and aggregation
Nitric oxide and prostacyclins
When a vessel is damaged, control of bleeding is first initiated by
Vasospasm
What is responsible for creating the reinforcement of a platelet plug
Fibrin
There is usually ___________ balance between clot formation and clot inhibition
homeostatic
Where do deep vein thromboses typically form
Lower extremities
What is Virchow’s triad
- Stasis
- Defect in hemostatic mechanism
- Endothelial injury
What drugs are used to treat venous clots
Anticoagulant drugs, thrombolytics
Are venous or arterial clots more painful
Arterial due to a block of oxygen (ischemia)
What are some examples of why an arterial clot would form
In medium sized arteries (carotid, optical)
Endothelial damage in atherosclerosis (states of low flow)
Emboli in heart in Afib; MI and Stroke
What drug class are you going to use to treat arterial clots or in the prevention of developing clots
antiplatelet drugs, thrombolytics
What is the medication goal of anticoagulants and antithrombotic meds
Prevention of heart attack and stroke, PE, or DVT
Also to prevent complications of Afib, CHF, and genetic and acquired hypercoagulability
How do anticoagulation agents work in slowing down clotting
Interference with fibrin formation
What extrinsic factor is binding with exposed subendothelial components as part of the clotting cascade to aid platelet adhesion to site of injury
Factor VIII
What are the intrinsic factors players of the clotting cascade?
VIII, XI, XI, XII,
After platelet aggregation takes place (and the area of injury is stabilized), the clot is fibrinolyzed by
plasmin
What are antiplatelet agents used for
To prevent platelet activation in arterial system
What are anticoagulant agents used for
To prevent formation of fibrin clot in venous system
What are the “classic” anticoagulants
Heparin and Warfarin
What are fibrinolytic agents used for
To break down existing clot
What are the fibrinolytic agents
Alteplase (tPA)
Anisterplase
Urokinase
Reteplase
COX-1 is a key enzyme involved in the synthesis of
Platelet thromboxane A2 (prostaglandin pathway)
What is the most common indication for daily Asprin
Secondary prevention (after dx with CAD, DM, PVD, CVA, TIA)
Can usually continue ASA 81 peri-operatively except with
Intracranial, intramedullary, or posterior eye surgeries
What is the goal of P2Y12 ADP receptor inhibitors
Prevent further atherosclerotic events in MI, unstable angina, ACS and coronary angioplasty
Generally, how long is a patient on a P2Y12 ADP receptor inhibitor taken after a stent placement and what medication is then used indefinitely?
12 months, Aspirin
Can you use P2Y12 ADP receptor inhibitors during episodes of active bleeding
No
Why should you not prescribe a PPI with a P2Y12 ADP receptor inhibitor
May interfere with antiplatelet properties (co-prescribe with caution)
If a patient is a poor metabolizer what P2Y12 ADP receptor inhibitor would you choose
Ticagrelor (Brilinta)
Why is Tricagrelor not a first line P2Y12 ADP receptor inhibitor?
Interferes with statin medication (increased aches) and is very expensive
What is a severe possible risk factor of Ticlopidine?
Risk of thrombocytopenia, agranulocytosis and TTP (thrombotic thrombocytopenia purpura)
What do you need to monitor when a patient is on Tirofibran?
Monitor aPTT (Partial thromboplastin time- blood coagulation blood test)
When is Cilostazol’s contraindicated?
Heart Failure, only used for intermittent claudication (legs) in PVD
Why is it important to ask patients about supplement use when prescribing antiplatelet drugs?
Some supplements decrease platelet activity creating a high risk for bleeding
Fish oil
Dong quai
Garlic
Ginger
Gincko
Ginseng
Green Tea
What drug class should be avoided with use of Heparins because it can cause bleeding and renal dysfunction when used together
NSAIDs
Do you need to dose adjust Heparins in patients with impaired kidney function?
Yes
What are the side effects of unfractionated Heparin?
Bleeding
Osteoporosis
Hyperkalemia (aldosterone suppression)
Elevation of trasaminases
Heparin induced thromboytopenia
What labs do you need to monitor daily when using unfractionated heparin?
Platelets (CBC) because of risk for heparin induced thrombocytopenia (HIT)
When treating a DVT/PE with Enoxaparin how is it dosed?
Weight-based
What is the onset of action for Warfarin?
3-4 days (although absorption is rapid)
What is an absolute contraindication of Warfarin?
Pregnancy as it crosses the placenta
What is the adverse effect of Warfarin and how can it be reversed?
Bleeding, and can be reversed by vitamin K infusion
What are the drugs that increase bleeding/potentiate Warfarin activity
ASA
Heparin
Antibiotics
What are the drugs that decrease Warfarin activity?
Barbituates, Phenytoin
Vitamin K
Cholestyramine
What are the indications for Warfarin?
DVT/PE Treatment
Prophylaxis of thrombotic event in: Afib, atrial flutter, prosthetic heart valve, recurrant DVT, perioperative (total knee and hip replacements)
It is important to achieve goal of INR levels and prevent bleeding or clottin, what should patients be counseled on to maintain levels?
Missed dose/double dose (what to do)
Changes in OTC/herbals/diet (adjust dose for current therapies and diet)
Changes in meds (abx tx warfarin should be held for 1-2 doses)
What is the MOA of Fonduparinux
Direct Xa Inhibitor - binds to anti-thrombin III, potentiates naturalization Xa 300 to 1000 times, inhibits Xa pathway
How are fibrinolytic therapies delivered?
Intra-arterially
