AntiCoag Flashcards
Finely regulated dynamic process of maintaining fluidity of
the blood, repairing vascular injury, and limiting blood loss while avoiding vessel occlusion (thrombosis) and inadequate perfusion of vital organs
Hemostasis
inactived if there are no injuries and because
of the intrinsic presence of anticoagulants
Platelets
Common causes of dysregulated hemostasis
○Hereditary or acquired defects in the clotting
mechanism
○ Secondary effects of infection or cancer
designed to stop bleeding at the site of vascular injury
through complex interactions between the vascular endothelium, platelets, procoagulant proteins, anticoagulant proteins, and fibrinolytic proteins
Coagulation System
THREE LAYERS OF BLOOD VESSELS
Endothelin
Subendothelium
Smooth Muscle
Endothelin produces
Nitric Oxide and Prostacyclin
Layer of the bv that heparin sulfate and thrombomodulin
Endothelin
A Natural coagulant
Heparin sulfate
Once bound, clotting factors II, IX, X will be
inactivated
Heparin sulfate
Heparin sulfate attracts and binds _________
antithrombin III
Composed of fibroblasts with abundant elastic and collagen fibers
Subendothelium
Changes vessel diameter to regulate blood flow and blood pressure
Smooth Muscle
Primary Hemostasis
Vascular constriction
Primary platelet plug formation
Secondary hemostasis
○ Clot propagation through fibrin formation ○ Coagulation cascade
○ Clot retraction/ repair
○ Fibrinolysis
The initial phase of the blood coagulation process is ____________
vascular constriction
T/F: Activation of platelets is absolutely required for hemostasis to proceed.
True
Platelets become activated by ___________
thrombin
Platelets clump by binding to ___________ that becomes exposed following rupture of the endothelial lining of vessels.
collagen
To ensure the stability of the initially loose platelet plug, a _____________ mesh (also called the clot) forms and entraps the plug.
fibrin
_____________ will bind to the smooth muscle and will
cause contraction
Endothelin
Pain is felt because of the
nociceptors
T/F: Nitric oxide and prostacyclin will not be released because of the injury therefore, platelets will be activated
True
Damaged endothelium layer will secrete
Von Willebrand Factor (VWF)
This exposes platelets to collagen thus a change in the shape of collagen can be obserbed
Von Willebrand Factor
activates phospholipase A2 (PLA2) which will be used in the synthesis of arachidonic acid (AA).
Calcium
Arachidonic acid requires ____________ in order to metabolize to form thromboxane.
cyclooxygenase (COX)
The end of the platelet plug will provide a __________ environment that will allow the coagulation cascade to proceed
negative
Intrinsic
12 -> 11 -> 9 -> 8 ->
Extrinsic
3 -> 7
Common Pathway junction
Intrinsic : 8 (with help of 3 and Ca) will activate X
Extrinsic: after 7a, PF4 and Ca will complex and activate X
will attach to Factor X and will activate Prothrombin (II) and Thrombin (Ila)
Factor 5
T/F: Prothrombin III is not too strong so Fibrinogen is needed
True
Activated form of Fibrinogen
Fibrin
activates Fibrinogen (I) to Fibrin (Ia)
Thrombin
insoluble to blood and provides the “jelly” structure of the blood.
Fibrin
In Clot retraction/repair Platelets will release
myosin and actin
contractile proteins that allow
contraction between spaces and connection of both
ends of endothelial tissues
Myosin and Actin
to regenerate cells -> Stimulate the production of endothelial cells and signal mitosis
VEGF (Vascular Endothelial Growth Factor
to regenerate smooth muscle
PDGF (Platelet Derived Growth Factor)
T/F: only VEGF signlas mitosis
False
Irreversible inhibits of Cyclooxygenase
Aspirin
T/F: When taking Aspirin, platelets are permanently inhibited
True
In Aspirin, replacement platelets restore overall function in
3-7 days
T/F: Patient canundergo a surgical procedure within 7 days of aspirin intake
False
dose of aspirin as antiplatelet effect
80 - 160 mg
Aspirin should not be taken with
NSAIDS
T/F: Aspirin should be taken with food
True
Glycoprotein IIb/IIIa Inhibitors
EPTIFIBATIDE, TIROFIBAN
is Glycoprotein IIb/IIIa Inhibition reversible or nonreversible
reversible
Glycoprotein IIb/IIIa Inhibitors can cause
Reduced adhesion
Reduced aggregation
Most commonly used in the Philippines
Abciximab
Inhibits platelet aggregation by reversibly binding to platelet IIb/IIIa receptors, which in turn results in steric hindrance.
Abciximab
ADP Inhibitors drugs
Clopidogrel (PlavixR), Prasugrel (E entR), Ticlopidine(TiclidR) Ticagrelor (BrilantaR, BriliqueR, PossiaR)
Blood thinner
ADP Inhibitors
Used for Ischemic Stroke only
ADP Inhibitors
No ADP → Calcium will be inhibited →
no Thromboxane
Given to Myocardial Infarction, Requires hepatic conversion to be active, Irreversible inhibition
Clopidogrel (PlavixR), Prasugrel (E entR), Ticlopidine(TiclidR)
● Does not require hepatic activation.
● Reversible inhibition of ADP receptor
Ticagrelor (BrilantaR, BriliqueR, PossiaR)
Inhibit phosphodiesterase to reduce cAMP degradation
PDE/Adenosine Uptake Inhibitors
cAMP is an inhibitor of
platelet aggregation and uptake of adenosine
PDE/Adenosine Uptake Inhibitors (drugs)
Dipyridamole, Cilostazol
Antiplatelets
Aspirin
GLYCOPROTEIN IIb/IIIa INHIBITORS
ADP Inhibitors
PDE/Adenosine Uptake Inhibitors
ANTICOAGULANTS
Heparins and Fondaparinux
Direct Thrombin Inhibitors
WARFARIN
NOAC’S FACTOR Xa INHIBITORS
● Prevents coagulation cascade
ANTICOAGULANTS
Highly acidic. Neutralized by a base
Unfractionated Heparin
Binds to antithrombin III to form a complex
Unfractionated Heparin
Unfractionated Heparin targets factors ________
Xa and IIa
Unfractionated Heparin is always given as
IV or SC
Unfractionated Heparin may cause a moderate, transient __________ and
_____________
thrombocytopenia and
thrombosis
● May be linked to osteoporosis in chronic use
Unfractionated Heparin
Do not bind to thrombin but inactivate Xa
Low Molecular Weight Heparins (LMWH)
test used to determine the effectiveness of a drugs, particularly UFHs
Activated partial thromboplastin time
can aPTT be used in LMWH
No, because LMWH only has a minimal effect on Factor II
LWMH is given as
once- or twice- daily SC injections
Synthetic drug, pentasaccharide found in LMWH
Fondaparinux (ArixtraR)
T/F: Fondaparinux does not inhibit thrombin
true; only factor X
Fondaparinux is given as
Daily subcutaneous dose
Direct Thrombin Inhibitors
Bivalirudin
Argatroban
Dabigatran (PradaxaR)
Direct Thrombin Inhibitors are derived from
the medicinal leech Hirudo medicinalis
Often used as an alternative for heparin in patients who
had HITT
Direct Thrombin Inhibitors
Can DTI use aPTT?
Yes
DTI that binds to thrombin active site only
Argatroban, Dabigatran
Administer to patients who are in the cath lab and are
expected to undergo angioplasty and angiogram
Argatroban
Short-acting (4 hours), Twice daily oral medication, Approved for stroke prevention in atrial fibrillation
Dabigatran (PradaxaR)
Also used in deep vein thrombosis (DVT) prevention in post
op hip and knee surgery
Dabigatran (PradaxaR)
Antidote for toxicity of Dabigatran
Idarucizumab (PraxbindR)
Vitamin K reductase inhibitor
WARFARIN
why do we “bridge” a patient with heparin when we start or stop warfarin
because it can cause initial period of hypercoagulability, followed by hypo-coagulability
T/F: Antibiotics may kill off normal gut flora
True
Must not be taken with warfarin as it increase clearance and drop
INR (thrombosis)
CYP450 inducers (carbamazepine, phenytoin,
barbiturates, rifampin)
Must not be taken with warfarin as it reduce
clearance and increase the INR (hemorrhage)
Inhibitors (amiodarone, SSRI’s, cimetidine)
When the INR is too high
there is increased risk of
hemorrhage
When the iNR is too low
there is increase risk for
thrombosis
The most specific antidote for warfarin toxicity is
vitamin K
In case of life-threatening hemorrhage, additional measures need to be taken like
administration of fresh frozen plasma or prothrombin complex concentrate
Novel oral anticoagulants
NOAC’S FACTOR Xa INHIBITORS
RIVAROXABAN, APIXABAN
NOAC’S FACTOR Xa INHIBITORS
Approved for use in stroke prevention in non-valvular atrial
fibrillation
NOAC’S FACTOR Xa INHIBITORS
Also used in post op hip and knee surgeries for DVTP
NOAC’S FACTOR Xa INHIBITORS
a.k.a fibrinolytics, Catalyze conversion of plasminogen → plasmin causing a break down of fibrin
Thrombolytics
Used in acute stroke (after CT confirms no hemorrhage)
Thrombolytics
Can Cause Intracerebral hemorrhage
Thrombolytics
● Does not show affinity for fibrin-bound plasminogen
● Needs to forms complex first with plasminogen
○ The complex will forms plasmin
STREPTOKINASE
● Show affinity for fibrin bound plasminogen
● Will show affinity in the fibrinogen
tPA ANALOGUES
Alteplase
Tenecteplase
Reteplase
tPA ANALOGUES
● Normal human tPA
● will stimulate fibrinogen to plasmin
Alteplase
● Mutated human tPA
● Longer duration of action
Tenecteplase
● Mutated human tPA
● Faster onset, longer duration of action
Reteplase
T/F: Vitamin K oral dosing may be faster than IV dosing
true
for hemophilia A
Factor VIII concentrate
for hemophilia B
Factor IX concentrate
mixture of factors II, VII, IX, X, C, Used in mixed deficiencies, and NOAC overdoes
OctaplexR and BeriplexR
Will not replacement clotting factor but stimulate the deficient clotting factors
VASOPRESSIN AGONISTS
Desmopressin
Vasopressin agonist
V2 agonist
● Increases the concentration of vWF and factor VIII
● Used to prepare hemophilia A or vWD patients for surgery
Desmopressin
ANTIPLASMIN AGENT
Aminocaproic Acid (AmicarR) and Tranexamic Acid
● Prevents the formation of plasmin ● Inhibits the fibrinolysis
ANTIPLASMIN AGENT
Given in heavy bleeding
Tranexamic Acid
Oral agents
● Inhibit fibrinolysis by inhibiting plasminogen activation
● Increases the concentration of vWF and factor VIII
Aminocaproic Acid (AmicarR) and Tranexamic Acid
○ Treat hemophilia
○ Prophylaxis for high risk patients
○ Used in postoperative bleeding
Uses of Aminocaproic Acid (AmicarR) and Tranexamic Acid