Anticoagulation & Blood Disorders: Anticoagulation Flashcards
Two pathways of coagulation cascade
Contact activation pathway (intrinsic) = minor pathway
Tissue factor pathway (extrinsic) = activated by tissue damage/trauma
Warfarin inhibits factors
2,7,9,10
DOAC work on factor
Xa
Direct thrombin inhibitors (DTI) work on…
Thrombin IIa
UFH and LMWH work on factors….
Xa and Thrombin IIa
DOACs vs Warfarin
Use warfarin if moderate-severe mitral stenosis or mechanical heart valve in stroke prevention for AF
Use warfarin if pt has antiphospholipid syndrome or mechanical heart valve in VTE treatment
UFH antidote
protamine
UFH ppx VTE dose
5,000 units SubQ Q8-12h
UFH txm VTE dose
80 units/kg IV bols, 18unit/kg/hr infusion
use TBW
UFH txm ACS/STEMI dose
60/unit/kg IV bous, 12 unit/kg/hr inusion
use TBW
UFH monitoring
aPPT
Platelets, Hgb, Hct baseline and daily ( dec platelets by 50% possible HIT)
LMWH boxed warnings
receiving epidural/spinal anesthesia or spinal puncture due to risk of hematomas and subsequent paralysis
LWMH CI
history of HIT
active major bleed
LMWH ppx VTE dosing
30mg Q24hr or 40mg Q24hr
30mg Q 24hr if CrCl < 30
LMWH txm VTE, UA and NSTEMI
1mg/kg Q12hr
1.5mg/kg QD (in patient VTE only)
1mg/kg Q24hr if CrCl < 30
LMWH txm STEMI in pts < 75yrs of age
30mg IV bolus + 1mg/kg dose + 1mg/kg Q12 (max 100mg 1st 2 doses)
CrCl < 30 = 30mg IV bolus + 1mg/kg dose + 1mg/kg Q24hr
LMWH txm STEMI in pts > 75yrs old
0.75mg/kg Q12hr
CrCk < 30 = 1mg/kg Q24hrs
LMWH antidote
protamine
LMWH monitoring
can monitor anti-Xa levels
4Ts score
probability of HIT calculated using this score
Thrombocytopenia = unexplained drop of > 50% in platelet count
Timing = HIT onset usually 5-10 days after start heparin
Thrombosis = new suspected/confirmed thrombosis, skin lesions
if HIT is likely, ELISA is done and thats confirmed with a serotonin release assay or heparin-induced platelet aggregation assay
HIT management
If suspected or confirmed, stop all heparin/LMWH, if on warfarin then stop and admin Vitamin K.
rapid-acting non-heparin anticoagulant used (argatroban)
Dont restart warfarin until platelets > 150K
if urgent surgery or PCI required, bivalirudin preferred agent
Apixaban nonvalvular AF (stroke ppx) dosing
5mg BID
2.5mg BID IF 2 of the following: > 80, < 60kg or SCr < 1.5
Apixaban txm of DVT/PE dosing
10mg BID for 7 days, then 5mg BID
Extended phase (after > 3 months txm) - 2.5mg BID
Apixaban ppx DVT (after hip/knee replacement)
2.5mg BID (12 days for knee or 35 days for hip)
Edoxaban has reduced efficacy in pts with CrCl that is
> 95
Apixaban and Rivaroxaban antidote is
andexanet alfa (Andexxa)
Rivaroxaban should be taken with…
food for doses > 15mg
10mg doses can be taken without regard to food
Rivaroxaban nonvalvular AF (stroke ppx)
CrCl > 50 = 20mg QD w/ evening meal
CrCl 15-50 = 15mg QD w/ evening meal
CrCl < 15 = dont use
Rivaroxaban txm fo DVT/PE
15mg BID X 21 days, then 20mg QD w/ food
Extended phase (> 3 months) 10mg QD
CrCl < 30 = dont use
Rivaroxaban ppx DVT (after knee/hip replacement) and VTE (acute ill medical pts)
10mg QD X 12 days (knee), 35 days (hip), 31-39 days (acute ill medical patients)
CrCl < 30 = dont use
Rivaroxaban reduction in risk of major CVD events in CAD/PAD
2.5mg BID in combo w/ low dose aspirin
CrCl < 15 = avoid use
Edoxaban non valvular AF (stroke ppx)
CrCl > 95 = dont use
CrCl 51-95 = 60mg QD
CrCl 15-50 = 30mg QD
CrCl < 15 = dont use
Edoxaban txm of DVT/PE
60mg QD, 5-10 days after parenteral anticoag
IF CrCl 15-50, BW < 60kg, on certain P-gp inhib = 30mg QD
Dont use CrCl < 15
Time cut offs for DOAC and surgery
Apixaban = stop 48hrs before if mod-high bleeding risk, 24hrs if low
Rivaroxaban/Edoxaban = stop 24hr before
Converting from warfarin to other anticoagulant
Rivaroxaban when INR < 3
Edoxaban when INR < 2.5
Apixaban when INR < 2
Dabigatran when INR < 2
Fondaparinux ppx of VTE
> 50kg 2.5 mg QD
< 50 kg = CI
Fondaparinux txm of VTE
< 50kg = 5mg QD
50 - 100kg = 7.5mg QD
> 100kg = 10mg QD
Fondaparinux CrCl cut offs
CrCl 30-50 = use caution
CrCl < 30 = CI
Dabigatran CI
treatment of pts with mechanical prosthetic heart valves
Dabigatran Side effects
Dyspepsia
Gastritis like symptoms
Gi bleeding
Dabigatran antidote
idarucizumab (Praxbind)
Dabigatran nonvalvular AF (stroke ppx)
150mg BID
CrCl 15-30 = 75mg BID
CrCl < 15 = dont use
Dabigatran txm of DVT/PE and reduction of recurrent DVT/PE risk
150mg BID, start 5-10 days after parenteral anticoag
CrCl < 30 = dont use
Dabigatran ppx of DVT/PE following hip replacement
110mg Day 1, 220mg QD
CrCl < 30 = avoid use
Dabigatran notes
have to dispense in OG container, and throw out after 4 months of opening
Swallow capsule whole, dont give in NG tube
Argatroban notes
Safe for history of HIT or active HIT
No antidote
Warfarin CI
Pregnancy, unless mechanical heart valve and high risk for TE
Warfarin Warnings
tissue necrosis/gangrene
HIT
VKORC1 gene or CYP2C9*2/3 allele may inc bleeding
Warfarin INR goal for most indications
2-3
Warfarin INR goal of 2.5-3.5 for….
high risk indications such as mechanical mitral valve, 2 mechanical heart valves, or mechanical aortic valve with 1 additional risk factor
Warfarin Antidote
Vitamin K
Kcentra can be used with vitamin K for rapid reversal
Foods high in Vitamin K will do what to INR
decrease, so would have to increase warfarin dose (Dark leafy greens)
important to keep consistent vitamin K balance in diet when on warfarin
Using Vitamin K for over anticoagulation
INR > 4.5 w/o bleeding = reduce or skip dose, monitor INR
INR 4.5 - 10 w/o bleeding = hold 1-2 dose, monitor INR
INR > 10 w/o bleeding = hold warfarin, give Vitamin K
Major bleeding = hold warfarin, give Vitamin K & Kcentra
Any VTE caused by surgery or reversible risk factor should be treated for….
3 months
If VTE is unprovoked, should be treated for….
longer than 3 months of low-mod risk of bleeding
keep at 3 months if high
If 2 episodes of unprovoked VTE then consider….
long term treatment
Medications CI in patients with hx of or current VTE
estrogen containing medications
selective estrogen receptor modulators
pts w/o cancer, dabigatran or DAOC preferred over….
warfarin for 1st 3 months of txm for DVT in leg or PE
pts w/o cancer, what is preferred over warfarin/LMWH?
DOACs
CHA2DS2-VASc Score
C = CHF
H = HTN
A2 = Age > 75 = 2 pts
D = Diabetes
S2 = Prior stroke/TIA = 2 pts
V = Vascular Disease (prior MI, PAD, aortic plaque)
A = age 65-74 = 1 pt
Sc = Sex, Female = 1 pt
HAS-BLED score
H = HTN > 160
A = abnormal liver or renal function = 1-2
S = prior stroke
B = Bleeding tendency or predisposition
L = labile INR if on warfarin
E = elderly > 65
D = Drugs (aspirin/NSAIDs) excess alc use = 1-2
Anticoagulation in pregnancy
LMWH preferred
