Test 1: Wk1: 5 Coagulation and Anticoagulants - Valentovic Flashcards
Anticoagulants (6)
Heparin LMW Heparin Warfarin Argatroban Dabagatran XaInhibitors
Anticoagulants work by
inhibiting fibrin formation
Antiplatelets (5)
Aspirin, Dipyridamole, Clopidogrel, Abciximab & Eptifibatide
Antiplatelets work by
inhibit platelet aggregation
Thrombolytics/ Fibrinolytics (4)
Streptokinase, Alteplase, Anistreplase& Tenecteplase
Thrombolytics/ Fibrinolytics work by
dissolve formed fibrin clots
Heparin Natural Product
Porcine MW 5-30 kDa
Heparin accelerates the reaction of — with —
AT-III (antithrombin 3) with coagulation factors
Heparin — binds AT-III and induces —
irreversibly
conformational change
Heparin binds AT-III — times faster with what coagulation factors
1000x
II, X, XI and XII
Heparin - active coagulation factors bind — to AT-III at the — site. This prevents — generation
irreversibly
Arg-Ser
Fibrin
AT-III is a — substrate
suicide; it binds and doesnt let go
Heparin is an anticoagulant in
vitro
Heparin use in vivo
Tx of Venous Thrombosis
Tx of Pulmonary thromboembolism
Is Heparin approved in pregnant women
yes - it does not cross placenta
Heparin Administration
What administration is contraindicated
SC or IV
IM contraindicated - induce hematoma
how is Heparin montored
aPTT
How much does heparin increase aPTT
1.5 - 2.5 x
Heparin has a lipid clearing effect that
increase lipoprotein lipase activity
What does aPTT asses
intrinsic pathway and factors I, II and X
Heparin Adverse Effects
- bleeding
- Thrombocytopenia Type 1 and 2
Thrombocytopenia Type I
non-immune medicated platelet heparin interaction
Thrombocytopenia Type II
immune mediated; begins 4-10 days after tx
ab form to heparin-platelet factor 4 complex which binds to platelet surface causing aggregation
What should be monitored in long term use of unfractionated heparin
platelet count
Reverse Heparin with
Protamine
plasma or whole blood
Protamine MOA
binds heparin disabling anticoagulant activity
Protamine Allergy
diabetics
Fish allergy
Heparin Contrindications
Bleeding disorder
pre-existing bleeding site
low molecular weight Heparin (3)
Enoxaparin
Dalteparin
Tinzaparin
low molecular weight Heparin weight
4500 daltons
low molecular weight Heparin is too small to do what
simultaneously bind ATIII and thrombin
low molecular weight Heparin MOA
enhance ATIII inactivation of factor Xa
low affinity for thrombin
low molecular weight Heparin uses (4)
prophylaxis
acute venous thrombosis
DVT
Unstable angina or non Q-wave MI
low molecular weight Heparin administration
SC 1/day
low molecular weight Heparin monitoring
anti Xa activity
is low molecular weight Heparin approved in pregnant women
yes
LMW Enoxaparin vs Heparin
longer half life
outptx
lower thrombocytopenia
Predictable
Fondaparinux is a
Synthetic Pentasaccharide
Fondaparinux MOA
Specific for ATIII inactivation of Factor Xa
Fondaparinux adminstration
IV, SC
Fondaparinux uses
Prophylaxis and acute deep vein thrombosis
can Fondaparinux be used in pregnant women
yes
Fondaparinux contraindications
Contraindicated in bleeding or severe renal impairment
Warfarin is an anticoagulant where
only in vivo
Warfarin does not inhibit clotting when directly added to blood
Warfarin MOA
inhibits synthesis of biologically active VitK dependent clotting factors
Warfarin inhibits what enzyme
Vit K epoxide reductase
Vit K is stuck in epoxide form
Warfarin inhibits biologically active factors
II, VII, IX, X
how long for warfarin to work
actively after <24hrs but takes 5-7 days for generation of coagulation factors incapable of binding Calcium
Warfarin administration
oral anticoagulant of choice
Warfarin Uses (3)
Prophylaxis for DVT & pulmonary embolism
Prosthetic Heart valves
Arterial thromboembolism prophylaxis in atrial fibrillation
Warfarin monitoring
INR VALUES Standardization of Prothrombin time
Warfarin Adverse Effects
Bleeding
Warfarin adverse rxns occur with (4)
Change in absorption and/or metabolism of Warfarin
Change in synthesis and/or catabolism of Vitamin K or coagulation factors (decreased hepatic function)
Changes in platelet function
Alteration in fibrin degradation
Warfarin genetic varients
CYP2C9 and VKORC genes
reduce warfarin dose by 30% in
Hetero or homozygotes for CYP2C9*2
heterozygous for CYP2C9*3
reduce warfarin dose by 90% in
Homozygote CYP2C9*3
VKORC1 G allele
A allele synthesize less VKORC1
less protein for warfarin to bind
Drugs that increase warfarin effects (6)
Aspirin Ketoconazole & erythromycin Cimetidine Ibuprofen Cephalosporins Sulfamethoxazole/trimethoprim
Drugs that decrease warfarin effects (4)
Cholestyramine
Rifampin
Phenobarbital
Cigarette smoking
Warfarin contraindications
Presence of bleeding disorder or active bleeding site
can warfarin be given to pregnant women
no
Warfarin 1st trimester
nasal hypoplasia
Warfarin 2nd and 3rd trimester
CNS, increased fetal death
Tx of excessive bleeding
Whole blood or plasma
VitK - takes 24 hrs
Direct Thrombin Inhibitors (2)
ARGATROBAN (iv)
DABIGATRAN (ora)
Argatroban MOA
directly block site on thrombin
Argatroban adminstration
IV
Argatroban use (2)
pts at risk of heparin induce thrombocytopenia
coronary artery thrombosis
Dabigatran Etexilate Mesylate (DEM) is a
Anticoagulant –direct thrombin inhibitor
DEM MOA
affinity for free and fibrin bound thrombin
DEM administration
oral
DEM is converted to — by plasma esterases
Dabigatran
DEM uses (2)
prophylaxis DVT and thromboembolism
DEM metabolites
4 Glucuronide metabolites (active)
is DEM a p450 substrate
no - less drug interactions
DEM is a substrate for
P-glycoprotein
DEM is excreted in
urine - must have good kidney function
Antidote for DEM associated excess bleeding
Idarucizumab
Idarucizumab MOA
Humanized monoclonal antibody binds to dabigatrin
350x higher affinity dabigatrin> thrombin
Direct factor Xa inhibitors (2)
Rivaroxaban and Apixaban
Rivaroxaban and Apixaban MOA
bind directly to factor Xa
prevent Xa cleaving prothrombin to thrombin
Rivaroxaban and Apixaban administration
oral
Rivaroxaban and Apixaban substrates for
CYP3A4
P-glycoprotein
Rivaroxaban and Apixaban uses (3)
Tx DVT and embolism
Prevent DVT after hip/knee replacement
Decrease risk of stroke in nonvalvular atrial fibrillation
Rivaroxaban and Apixaban side effects
BLACK BOX WARNING:
Bleeding can be life threatening
Bruising
Rivaroxaban and Apixaban antidote
Andexanet
recombinant factor Xa
Rivaroxaban and Apixabanc contraindications
active bleeding site
antiplatelet drugs (7)
Aspirin
Dipyridamole
Clopidogrel
Abciximab
Eptifibatide
Cangrelor
Tirofiban
Aspirin MOA
irreversible inhibitor of COX-1 and 2
Acetylates enzyme - thromboxane
Aspirin goal
inhibit platelet prostaglandin formation
Aspirin use
reduce risk of 2nd heart attack
Aspirin adverse effects
bleeding, GI irritation, GI ulcers
Dipyridamole MOA
inhibits phosphodiesterase increases platelet cAMP levels
Dipyridamole use
combination with other agents, very little benefit when used alone
Combined with warfarin
Clopidogrel is a platelet —
Platelet ADP Aggregation Inhibitors
irreversible inhibitor
Clopidogrel is a prodrug that is metabolized to
thiol metabolite
Clopidogrel MOA
Bind Irreversibly to ADP P2Y12 receptor on platelets
Inhibits ADP activation of IIb/IIIa complex needed for platelet aggregation
Clopidogrel uses
prophylaxis for thrombosis
reverse Clopidogrel
must generate new plataletes
Clopidogrel side effects
bleeding
Thrombocytopenia purpura risk
Clopidogrel monitoring
Monitor WBC and platelets
Cangrelor MOA
reversible P2Y12 platelet receptor inhibitor
Cangrelor administration
IV
Cangrelor half life
6 minutes - effect reverse within 1 hr
Platelet glycoprotein IIb/IIIa receptor antagonists (2)
Abciximab
Eptifibatide
Abciximab MOA
monoclonal antibody Fab fragment) construct of receptor
Ab binds to IIb/IIIa receptor
Eptifibatide is a
peptide derivative
what is more effective Abciximab or Eptifibatide
Abciximab
Abciximab and Eptifibatide administration
IV
Abciximab and Eptifibatide uses
Prevent thrombotic occurrence in patients with unstable angina or undergoing angioplasty
Tirofiban is a
PLATELET GLYCOPROTEIN IIb/IIIa RECEPTOR ANTAGONISTS
non peptide
Tirofiban administered
IV
Platelet glycoprotein IIb/IIIa receptor antagonists MOA
Competitive reversible inhibitor of interaction of Von Willebrand factor and fibrinogen with glycoprotein IIb/IIIa receptor
prevent cross linking of fibrinogen with platalets
Platelet glycoprotein IIb/IIIa receptor antagonists adverse effects
high incidence of bleeding
History of hemorrhagic stroke
Surgery, trauma past 6 weeks
Thrombocytopenia
Cannot use with warfarin
Abciximab and Eptifibatide time of action
Abciximab (>24 h) action longer than Eptifibatide (4-6 h) and Tirofiban (8 h)
Fibrinolytic system is responsible for degrading — during wound healing.
Fibrinolytic system is responsible for degrading fibrin during wound healing.
what degrades fibrin, clotting factors, and fibrinogen
Plasmin
Plasminogen is converted to PLASMIN by — which is released by — cells
Plasminogen is converted to PLASMIN by t-plasminogen activator (t-PA) which is released by endothelial cells
Streptokinase MOA
streptokinase combines with 1 molecule of Plasminogen to form a complex
Complex then converts a second molecule of Plasminogen to plasmin
Streptokinase use
reperfusion of occluded coronaries following an MI, works best if used within 4-6 hr of chest pain
Pulmonary embolism
Deep vein Thromboembolism
Arterial thrombosis
Streptokinase adverse effects
33% of people develop fever
BLEEDING
LYTIC STATE excessive bleeding, circulating plasmin exceeds capacity of α2-antiplasmin
Highly antigenic
Streptokinase contraindications
Surgery or trauma in past 10 days
Pre-existing bleeding disorder (GI ulcer, retinal bleeding)
Diastolic pressure >110 mm Hg
Intracranial trauma
Anistreplase
Combination of streptokinase and plasminogen with catalytic site acylated
Acyl removed by plasma enzymes
Designed to provide more specific binding to fibrin
Less lytic state
Anistreplase t-plasminogen activator (rt-PA)
high affinity for fibrin, more rapid binding to fibrin and activation of fibrin bound plasminogen
Low activity for circulating plasminogen
t-PA directly activates — to —
t-PA directly activates plasminogen to plasmin
Anistreplase t-plasminogen activator (rt-PA) uses
• Reperfusion of coronary arteries following an MI • Pulmonary embolism • Thrombotic stroke, use within 3 hrs
Tenecteplase
Genetically engineered derivative of alteplase
Tenecteplase Vs alteplase
More specific binding to fibrin
More resistant to PAI-1
Longer half-life
Higher incidence of reperfusion and functional outcome than alteplase for ischemic stroke treated
Thrombolytics adverse rxns
- inducing a hypocoagulable state
- patients bruise very easily
- any bleeding is difficult to stop
Aminocaproic Acid
Inhibitor of fibrinolysis
Lysine analog competes for lysine binding sites on plasminogen and plasmin
Inhibits interaction of plasmin and fibrin