Therapeutic dosing and monitoring of warfarin (Coumadin) & Types of anticoagulants- mechanisms of action and indications for use
Blood coagulation
... [Show More] mechanisms:
1. injury exposes subendothelial matrix proteins (i.e. collagen and von Willebrand factor) result in platelet adherence and activation,
secretion and synthesis of vasoconstrictors and platelet-recruiting and activating molecules[thromboxane A2 issynthesized from acid within
platelets; platelets secrete ADP (a platelet aggregator) and serotonin (stimulates aggregation and vasoconstriction)] = platelet plug
2. Coagulation system cascade is activated resulting in thrombin generation and a fibrin clot, which stabilizes the platelet plug
*1 & 2 occursimultaneously.
Indirect Thrombin
Inhibitors
MOA Dosage Monitoring Clinical Applications Toxicities & Reversal
Unfractionated heparin
(UFH, HMW)
1. Binds to
antithrombin and
inhibits clotting factor
proteases thrombin,
IXa, and Xa
Continuous IV
infusion bolus: 80-100
units/kg followed by
15-22 units/kg per
hour
Low dose prophylaxis:
5000 units subq Q8-
12h
Activated partial
thromboplastin time
(aPTT or PTT), CBC w/
platelet count
Bleeding, hair loss, HIT
(heparin induced
thrombocytopenia)
Long-term: osteoporosis,
spontaneous fractures,
mineralocorticoid
deficiency
Protamine Sulfate: for
every 100 units heparin
remaining in patient, 1mg
protamine sulfate given
IV
Low-Molecular-Weight
Heparin
Enoxaparin/Lovenox
Dalteparin
Tinzaparin
1. Binds to
antithrombin and
inhibits clotting factor
proteases thrombin
and Xa
Prophylactic: 30-40mg
Q or BID
Full dose: 1mg/kg
subq Q12h
Unnecessary
1mg protamine sulfate
may partially neutralize 1
mg enoxaparin
Fondaparinux 1. binds antithrombin,
inhibiting factor Xa
Once daily,subq Unnecessary No reversal agent
Warfarin MOA Dosage Monitoring Clinical Applications Toxicities & Reversal
Warfarin/Coumadin 1. blockade of 5-10mg, usually 5- Prothrombin time Teratogenic effects
Final Exam Study Guide 2
gamma-carboxylation
resulting in
incomplete
coagulation of factor
molecules that are
inactive
7mg/d
Education: increased
vitamin K intake
(leafy greens) reduce
anticoagulant effect
of warfarin
(PT) and INR
INR gaal:2-3
INR goal w/ artificial
heart valves: 2.5-3.5
PO/IV Vitamin K1, FFP,
prothrombin complex
concentrates(KCentra)
Oral Direct Factor Xa
Inhibitors
(aka DOAC)
MOA Dosage Monitoring Clinical Applications Toxicities & Reversal
Rivaroxaban/Xarelto
Apixaban/Eliqui [Show Less]