Antithrombotics Flashcards
What are the 3 phases of blood Hemostasis?
Vascular spasm
Platelet plug formation
Coagulation
What are the three major drug classes of antithrombotics?
Antiplatelets
Anticoagulants
Fibrinolytics
What do antiplatelets mainly work on? What is another name for them?
Mainly work on arteries
Blood thinner
What are the 2 routes anticoagulants are given? What vessel do they mainly work on?
Oral
Parenteral
Mainly work on veins
What is the only route that fibrinolytics are given?
Parenteral
What type of receptor is P2Y12?
ADP receptor
What type of receptor is TP?
Thromboxane receptor
What type of receptor is G2b/3a?
Fibrinogen receptor
What type of receptor is GP1B?
vWF receptor on platelets
What activate a platelet?
Thromboxane
ADP
What are the 3 things that platelet activation causes?
- Change in platelet shape
- Express active fibrinogen receptor
- Release thromboxane and ADP
How can an NSAID help fight clotting?
NSAID is COX inhibitor
Inhibits thromboxane
How is an antiplatelet used for MI and strokes?
Prophylactically
Why are antiplatelet drugs used for unstable angina?
Because angina make you more prone to clotting and antiplatelets prevents platelets from being activated and sticking together
Why are antiplatelets used for acute MIs?
To prevent further clot forming
Why are antiplatelets used for precutaneous coronary intervention(ie angioplasty)?
To thin out blood during surgery
What are the 4 indications for antiplatelets?
MI and stroke prevention
Unstable angina
Acute MI
percutaneous coronary intervention
How does the intrinsic pathway start?
Collagen activating factor 12
What starts the extrinsic pathway?
Tissue thromboplastin activates factor 7
What is another name for tissue factor? Where is it released from?
Tissue thromboplastin
Released from subendothelial cells
What is needed to convert prothrombin into thrombin?
Factor 10a
Factor 5a
Ca2+
What turns fibrinogen into fibrin? Which is more soluble in blood?
Thrombin turns fibrinogen into fibrin
Fibrinogen is more soluble in the blood
What are the 4 different types of anticoagulant drugs?
Heparins
Vitamin K antagonists
Direct factor 10a inhibitors
Direct thrombin inhibitors
Where do natural heparins come from?
Liver
What are the 2 different types of heparins?
Unfractionated heparin
Low-molecular weight heparin
What route is heparin given?
IV
SC
What does aPTT stand for? What does it test? What medication is it used to monitor?
Activated partial thromboplastin time
Tests intrinsic pathway and common pathway
Used to monitor Heparin
What is used to prevent blood from clotting for aPTT
Citrated plasma
What is a normal aPTT? What is the aPTT for a pt on heparin?
25-35 seconds
45-70 seconds
What is added to blood in order to measure an aPTT(3)?
Ca2+
Kaolin
Phospholipids
What is the MOA of Heparins?
It enhances antithrombin 3 activity
What does antithrombin do?
Decreases activity of factor 10 and thrombin
What are heparins indicated for? What can heparins be used for the management of?
VTE
Stasis of blood
Endothelial damage
Hypercoagulable conditions
Unstable angina
Coronary angioplasty
Cardiopulmonary bypass tubing
Why can endothelial damage lead to a VTE?
Because these damages are usually caused by surgeries that increase the risk of DVT or PE
What are two conditions that can cause hypercoagulability?
Burn wounds
DIC
How does heparin help unstable angina?
Breaks down clots
How does heparin help w/ coronary angioplasty?
Used during the surgery to prevent clots from forming
How does heparin help when cardiopulmonary bypass tubing is being placed in a body?
Heparin prevents tubing from activating clotting cascade
What percent of unknown deaths are d/t PE?
80%
What does HIT stand for? What does HITT stand for? How is it caused?
Heparin induced thrombocytopenia
Heparin induced thrombocytopenia w/ thrombosis
IgG/PF-4/Heparin complex forms to cause either
- thrombocytopenia…leading to bleeding
- thrombosis…leading to clot forming
If HITT/HIT is suspected in a pt, what should be done w/ the heparin?
Discontinue heparin
What signs can suggest the presence of HIT/HITT?
Skin lesions at injection site
Acute systemic reaction
What type of heparin is used during pregnancy?
LMWH
What are the number of units used for a central line IV catheter lock flush of heparin? What are the units for a full dose of heparin?
1-100 units /mL
1000-40,000units/mL
What is a coumarin?
Vitamin K antagonist
What is a coumarins/vitamin K antagonist MOA?
Inhibits VKOR in the liver which turns vitamin K into active vitamin K which helps makes certain clotting factors
How long does it take for warfarin(Coumadin) to have a full anticoagulant effect? What is given before warfarin kicks in?
2-3 days
Overlapped w/ heparin till warfarin has effect
What are the indications for warfarin(Coumadin)?
- Tx and prevention of VTE
- Tx and prevention of thromboembolism d/t A-Fib or prosthetic heart valves
- prevention of post MI
Why can A-fib cause a thromboembolism?
Blood that is not moving tends to clot
What can prosthetic heart valves cause thromboembolism?
Because they can cause stasis of blood and lead to clots
Why is pregnancy a contraindication for warfarin(Coumadin)?
Because it can cross the placenta and cause hemolytic disease of newborns
What is the antidote for warfarin(Coumadin)? Route?
Vitamin K( phytonadione) Fresh frozen plasma
IM
SC
What is a food that is pro vitamin K?
Leafy greens
Why is warfarin more beneficial then direct oral anticoagulants?
- has antidote
- INR is monitored
- can be used for pt w/ heart valve issues
- costs less
What is PT? What pathway is it used to measure? what is it used to monitor? What units is it measured in?
Prothrombin time (pro time)
Measures time to clot for extrinsic and common pathway
Monitors pt on warfarin
INR
If a pt has a high INR what does that mean for anticoagulant effect?
Higher INR=higher anticoagulant effect
What is the INR for a pt on warfarin?
2-3 INR
What is used to bind up Ca2+ in blood when measuring a PT?
Citrated plasma
What is put into blood to start measuring a PT?
Ca2+
Thromboplastin
If a pt has a too high of an INR what should be done w/ the next warfarin dose?
Hold the warfarin dose
What should be given if a pt has a warfarin-associated major bleed?
PCC
FFP
Vitamin K
What does PCC stand for? What does it do?
Prothrombin complex concentrate
Makes clotting easier
What Sx can becoming present if INR is too high
Hematuria (blood in urine) Melena (blood in stool) Petechia (pinpoint hemorrhage) Ecchymoses (bruising) Purpura (medium hemorrhages)
Where does our vitamin K sources come from?
Food=50%
Bacteria in large intestine=50%
What 3 conditions can affect clotting?
Alcoholism
Kidney disease
Liver disease
What drug can interfere w/ warfarin or heparin?
NSAIDs
What should be done before warfarin is given? What should be done before giving heparin?
Take a PT/INR test
Take aPTT test
Before poking an individual on anticoagulants make sure you know what?
Make sure you know the pts INR
What is a direct factor 10a inhibitor considered?
Direct oral anticoagulants
What is a warning for pts taking direct factor 10a inhibitors?
Epidural catheters w/ these drugs can cause potential spinal hematomas
What is the 3 contraindication for direct factor 10a inhibitors?
Any heart valve issue
Active bleeding
Pts w/ increased risk of bleeding
What are the 2 indications for direct factor 10a inhibitors?
- Tx and prevent VTE
- thromboembolism
What is more beneficial for a pt on direct factor 10a inhibitors than taking an anticoagulant?
No monitoring required (no PT or aPTT taken)
What is direct thrombin inhibitors MOA?
Inhibits thrombin from turning fibrinogen into fibrin
What are two other names for fibrinolytics?
Thrombolytics
Clot busters
What is the MOA of a fibrinolytic? Route?
Increases plasmin production which breaks down fibrin
IV
What are endogenous forms of fibrinolytics?
tPA
Urokinase
What is fibrinolytics indicated for?
Acute MI
PE
Thrombotic strokes
What are contraindications of fibrinolytics?
Hemorrhagic stroke
