Anticoagulation Flashcards
UFH
binds to antithrombin and block factor Xa and IIa
LMWH
binds to antithrombin and blocks factor Xa and IIa with more Xa blocking than IIa
Direct thrombin inhibitors: IV (argatroban and bivalirudin) PO (dabigatran)
directly blocks thrombin
Direct factor Xa inhibitors (rivaroxaban, apixiban, edoxaban)
directly blocks factor xa
Indirect factor Xa inhibitor: fondaparinux
binds to antithrombin to block factor xa
warfarin
inhibits factors II, VII, IX, and X
DOACs vs Warfarin
-DOACs have less drug interactions, less bleeding, and shorter DOA than warfarin
- DOACs are adjusted based on kidney/liver function and not INR
-DOACs are preferred for stroke prevention in AF - unless there is mitral stenosis or MVR
-DOACs are preferred for VTE tx unless patient has antiphospholipid syndrome
Vitamin K
vitamin K is required for the activation of clotting factors II, VII, IX, and X
antithrombin (AT)
inactivates thrombin (factor IIa) and other proteases (like factor Xa)
hematuria
blood in urine
hematemesis
blood in vomit caused by bleeding from the GI tract
UFH: ppx VTE
5000 IU SQ Q8-12H
UFH: tx of VTE
80 IU/kg IV bolus; 18 IU/kg/hr infusion
UFH: tx of ACS/STEMI
60 IU/kg IV bolus; infuse 12 IU/kg/hr
UFH dosing
use TBW
UFH: aPTT/anti-Xa monitoring
check 6 hours after initiation and every 6 hours until therapeutic, then every 24 hours and with every dose change
UFH: aPTT/anti Xa therapeutic range
-aPTT: 1.5-2.5 x control
-anti Xa: 0.3-0.7 IU/mL
HIT
PLT decrease > 50%
heparin antidote
protamine
heparin lock flushes
used to keep IV lines open
LMWH: ppx VTE
30 mg SC Q12H or 40 mg SC daily
-CrCl < 30 mL/min: 30 mg SC daily
LMWH: tx of VTE and UA/NSTEMI
1 mg/kg SC Q12H or 1.5 mg/kg SC daily (only for inpatient VTE tx)
-CrCl < 30 mL/min: 1 mg/kg SC daily
-use TBW
LMWH: tx of STEMI in patients < 75 YOA
-30 mg IV bolus + 1 mg/kg SC dose followed by 1 mg/kg SC Q12H
-CrCl <30 mL/min: 30 mg IV bolus plus a 1 mg/kg SC dose then followed by 1 mg/kg SC daily
LMWH: tx of STEMI in patients < 75 YOA
0.75 mg/kg SC Q12H with no bolus - max of 5 mg for the first two SC doses only
-CrCl < 30 mL/min: 1 mg/kg SC daily with no bolus
LMWH safety
-neuraxial anesthesia (epidural, spinal) are at risk of hematoma and subsequent paralysis
-do not use in HIT
-Anti-Xa level recommended in pregnancy
-monitoring may be done in obesity, LBW, and renal insufficiency
-do not expel air bubble from syringe
when to obtain peak in enoxaprin monitoring
peak anti-Xa levels 4 hours post SC dose
LMWH antidote
protamine
management of HIT
- stop all forms of heparin and LMWH - if on warfarin d/c warfarin and administer vitamin K
- use rapid acting non-heparin anticoagulants (argatroban)
- do not start warfarin therapy until the platelets have recovered to > 150K
- if urgent cardiac surgery or PCI is required - use bivalirudin
Apixaban: nonvavular AF
5 mg PO BID
-unless > 80 YOA, BW < 60 kg, or SCr > 1.5 mg/dL, then give 2.5 mg BID
Apixaban: tx of DVT/PE
initial: 10 mg PO BID x7 days then 5 mg PO BID
- can give 2.5 mg PO BID after least 3 months of initial tx dosing
Apixaban: ppx DVT
2.5 mg PO BID x12 days after knee or x35 days after hip; give first dose 12-24 hrs after surgery
rivaroxaban (xarelto)
doses > 15 mg must be taken with food
rivaroxaban: nonvalvular AF
CrCl > 50: 20 mg QD with evening meal
15-50: 15 mg QD with evening meal
Rivaroxaban: tx of DVT/PE
-initial: 15 mg PO BID x21 days, then 20 mg PO QD with food
-avoid use in CrCl < 30
edoxaban
do not use in those with non-valvular AF and CrCl > 95 mL/min
-reduced efficacy
antidote for apixiban and rivaroxaban
andexanet alfa
fondaparinux
contraindicated in those with CrCl <30 mL/min
converting from warfarin to another oral anticoagulant, stop warfarin and convert to:
-Rivaroxaban when INR < 3
-Edoxaban when INR < 2.5
-Apixaban when INR < 2
-Dabigatran when INR < 2
From DOACs to warfarin
stop DOAC and start parenteral anticoagulant and warfarin at the next scheduled dose
from dabigatran to warfarin
start warfarin 1-3 days before stopping dabigatran
dabigatran and parenteral anticoagulant
always bridge with parenteral anticoagulants for 5-10 days if used for treatment (not needed for ppx)
antidote for argatroban and bivalirudin
no antidote
warfarin and pregnancy
contraindicated unless they have mechanical valve
CYP2C9*2 or *3 alleles and/or polymorphisms of VKORC1 in warfarin
increase risk of bleeding
goal INRs
-most 2-3
-2.5-3.5 for mechanical heart valve
S-warfarin
3-5 times more potent than R-warfarin
carbamazepine, phenobarbital, phenytoin, rifampin, st. johns
decrease INR
amiodarone, azole antifungals, flagyl, and bactrim
increase INR
warfarin and amiodarone
when starting amiodarone decrease the dose of warfarin by 30-50%
warfarin and tamoxifen
avoid use
Please Let Greg Brown Bring Peaches To Your Wedding
Pink - 1 mg
Lavender - 2 mg
Green - 2.5 mg
Brown/Tan - 3 mg
Blue - 4 mg
Peach - 5 mg
Teal - 6 mg
Yellow - 7.5 mg
White - 10 mg
foods high in vitamin k
spinach, broccoli, brussel sprouts, cabbage, beef liver, kale
increases bleeding risk with warfarin
garlic, ginkgo, ginseng, glucosamine, vitamin E, high dose fish oils, willow bark, and wintergreen
decrease effectiveness of warfarin
st. johns wart
protamine for UFH reversal
1 mg will reverse 100 units of heparin
-reverse amount given in the last 2-2.5 hours; max dose 50 mg
protamine for LMWH reversal
1 mg per 1 mg of enoxaprin
dabigatran reversal
idarucizumab (praxbind)
K centra
factors II, VII, IX, X, Protein C, Protein S
-administer with vitamin K
INR above therapeutic range but < 4.5 w/out bleeding
reduce or skip warfarin dose, monitor INR
supratherapeutic INR of 4.5-10 without bleeding
-routine vitamin K is not recommend
-hold 1-2 doses of warfarin
-resume warfarin at lower dose when INR is therapeutic
INR > 10 without bleeding
-hold warfarin
-oral vitamin K 2.5-5 mg
-resume dose when INR is therapeutic
major bleeding
-hold warfarin
-give vitamin K 5-10 mg by slow IV injection and four-factor prothrombin complex concentrate (PCC)
peri-operative anticoagulant management
stop warfarin approx 5 day before major surgery
-those mechanical valve, AF or VTE at high risk for thromboembolism, bridge with LMWH or UFH
-d/c therapeutic LMWH 24 hrs before surgery
VTE: those without cancer
dabigatran and other DOACs are preferred over warfarin for the first 3 months
VTE: those with cancer
DOACs are preferred
AF > 48 hr
anticoagulate for at least 3 weeks prior to and 4 weeks after cardioconversion
AF < 48 hr
start full therapeutic anticoagulation, preform cardioversion, and continue full anticoagulation for at least 4 weeks
CHA2DS2-VASc
estimate risk of stroke in AF
HAS-BLED
bleeding risk
