Anticoag Flashcards
Where are DVTs most commonly found?
Deep veins in the legs (underlined) - also thighs and pelvis
A number of factors can lead to activation of the coagulation process such as…
blood vessel injury, blood stasis, and pro-thrombotic conditions
True or false: all of the clotting factors have an active and inactive form
True
Once activated, the clotting factor will serve to activate the next clotting factor in the sequence until _____ is formed
fibrin
How do UFH, LMWH, and fondaparinux work?
Bind antirhrombin (AT)
Causes an increase in AT activity 1000-fold
AT inactivates thrombin and other proteases involved in blood clotting, including factor Xa
Difference between UFH and LMWH
LMWHs inhibit factor Xa more specifically than UFH
How is fondaparinux different from UFH/LMWHs
Synthetic pentasaccharide that requires AT binding to selectively inhibit factor Xa
Considered an indirect factor Xa inhibitor vs eliquis/xarelto/savaysa/bevyxxa which are direct factor Xa inhibitors
LMWH and UFH inhibit factor Xa on their own
What factors does warfarin inhibit
II, VII, IX, and X
Which factors are vitamin K dependent
II, VII, IX, and X
Where do direct thrombin inhibitors work?
Block thrombin directly, decreasing the amount of fibrin available for clot formation
Role of IV direct thrombin inhibitors, name one
Used when HIT develops in a hospital setting
IV DTI’s do not cross react with heparin-induced thrombocytopenia antibodies
Argatroban = drug of choice in heparin induced thrombocytopenia
Patients receiving anticoagulants should receive individualized care through a defined process that includes…
standardized ordering, dispensing, administration, monitoring, and patient/caregiver education
UFH moa
Binds to antithrombin (AT) which inactivates thrombin (factor IIa) and factor Xa and prevents conversion of fibrinogen to fibrin
UFH dose VTE prophylaxis, VTE treatment, ACS/STEMI
Side effects
Monitoring
VTE prophylaxis: 5000 units SC q8-12h
VTE tx: 80 units/kg IV bolus followed by 18 units/kg/hr infusion
Treatment of ACS/STEMI: 60 units/kg IV bolus (max 4000 units), 12 units/kg/hr infusion (max 1000 units/hr)
Use ACTUAL body weight for dosing
Side effects = bleeding, thrombocytopenia, HIT, hyperkalemia, osteoporosis (long-term use)
Monitor aPTT, therapeutic range 1.5-2.5 x pt’s baseline; take 6 hours after initiation then every 24 hours
Monitor platelets, Hgb, Hct baseline and daily
UFH antidote
Protamine
1 mg protamine reverses ~100 units of heparin
Max dose 50 mg
Heparin injection vs heparin flushes
Heparin flushes are used to keep IV lines open
Heparin flush dose = 10 or 100 units/mL
Heparin injection doses are 10,000 units/mL
Look and sound alike = fatal errors
Enoxaparin VTE ppx dosing, VTE tx dosing, UA/NSTEMI dosing, STEMI tx dosing Boxed warning Contraindications Side effects Monitoring
PPx VTE: 30 mg SC q12h or 40 mg SC daily
Tx VTE: 1 mg/kg SC q12h or 1.5 mg/kg SC daily for inpatient tx
UA/NSTEMI: 1 mg/kg SC q12h
STEMI:
–Age < 75: 30 mg IV bolus + 1 mg/kg loading dose followed by 1 mg/kg SC q12h maintenance (max 100 mg for first 2 SC doses)
–Age >75: 0.75 mg/kg SC q12h, no bolus - max 75 mg for first 2 doses
—->CrCL < 30: 1 mg/kg SC daily (not q12h)
Boxed warnings: risk of hematomas, subsequent paralysis (pts undergoing neuraxial anesthesia or spinal puncture)
Contraindications: Hx of HIT, active major bleed
Side effects: Bleeding, anemia, inc LFTs, thrombocytopenia, hyperkalemia
Monitoring: platelets, Hgb, Hct, SCr
Anti-Xa levels in pregnancy (obtain 4 hrs post dose)
What is heparin induced thrombocytopenia?
Unexplained drop in platelet count (> 50% drop in baseline), laboratory confirmation of antibodies or platelet activation by heparin
Can lead to a prothrombic state, can lead to thrombosis
How to treat HIT?
D/C heparin and LMWH
If on warfarin d/c warfarin and give vitamin K. Do not restart warfarin until platelets have recovered to at least 150,000
Give argatroban for anticoagulation
Fondaparinux often used off label in clinical practice for HIT
