Anticoagulation Flashcards
what is the MOA of heparin?
binds to antithrombin III (ATIII) and inactivates thrombin factor IIa and Factor Xa and prevents the conversion of fibrinogen to fibrin
What is the prophylatic and treatment dose of VTE? Heparin
Prevention: 5,000 units SC Q 8-12H
Tx: 80units/kg IV bolus (5,000 units); 18units/kg/hr (1,000 units/hr) infusion
What is the heparin dose for ACS/STEMI?
60units/kg IV bolus (max 4000) or 12 units/kg/hr( max 1000units/hr) infusion
For dose, do you use ideal or actual body weight? what is the onset and half-life of heparin?
Use actual body weight for dosing
onset IV- immediate SC- 30 mins- 2hr
half-live= 1.5hrs
how do you assess HIT?
Look for a drop in platelet count of > 50% from baseline. HIT has cross-sensitivity with LMWHs
What is the antidote for heparin?
Protamine 1mg. 1mg can reverse 100units of heparin. Max dose 50mg
How is heparin monitored?
heparin is monitored via the aPTT. taken 6 hrs after iniation and q6h until therapeutic range of 1.5-2.5 x control, then daily
What is used to KVO (Keep vein open)
Heparin (Lock-flushes) (Hep-lock Hep-flush) they are not used for anticoagulation. Heparin injection 10,000 units/ml and Hep-Lock 10units/ml
what are the side effects of heparin?
Bleeding, HIT, hyperkalemia and osteoporosis (long term use)
What is the MOA of LMWHs?
same as heparin but the inhibiton of Xa is greater
LMWHs
Enoxaparin (Lovenox) Preg Cat. B
Dalteparin (Fragmin)
Tinzaparin (Innohep)
what is the prophylaxis dose of enoxaparin?
30mg SC bid or 40mg SC daily
CrCl <30ml/min 30mg SC daily
what is the treatment dose of enoxaparin?
1mg/kg SC bid or 1.5mg/kg SC daily
if Crcl <30ml/min use 1mg/kg SC daily
What is treatment dose of enoxaparin for STEMI?
age < 75
age > 75
if last SC dose was given MORE THAN 8 hours before balloon inflation dose::
75 0.75mg/kg SC bid (no bolus, max 75mg for 1st two doses) in pts managed w/ PCI if last dose was given 8hrs b4 balloon, give 0.3mg/kg IV bolus
What LMWH is contraindicated in sulfite allergy?
Tinzaparin
Difference between UFH & LMWHs
monitoring
anticoagulation response
Where should enoxaparin be injected?
on the right or left side of the abdomen, at least 2 inches from the belly button
Proper SC administration of enoxaparin?
choose an area on the abdomen
pull cap straight off, do not twist (can bend the needle)
do not expel the air bubble in the syringe prior to injection
inject at 90 degree angle.
do not rub site of injection may lead to bruising.
what is the MOA of fondaparinux?
Arixtra is a synthetic pentasaccarhide that selectively inhibits factor Xa via antithrombin III. Preg Cat. B, monitor platelet and Scr. C.I. crcl <50kg
CLUE; THE X= 10
What is the prophylaxis and treatment dose of fondaparinux?dosing how?
weightbased
Prevention 2.5mg SC daily
Tx >50kg 5mg Sc daily
50-100kg 7.5mg SC daily
>100kg 10mg SC daily Do not expel air bubbles from syringe prior to injecting
most ppl would be 7.5 cause b/w 50-100 kg
Direct Thrombin Inhibitors (IV)
3 ttypes and whom for? monitor?
Directly inhbit thrombin (Factor IIa)- used in pts w/ hx of HIT
Argatroban (Novastan)-HIT w/thrombosis, undergoing PCI
Bivalirudin (Angiomax)-ACS undergoing PTCA
Lepirudin (Refludan)-HIT w/ thrombosis
monitor- aPTT and/or ACT
Direct thrombin inhibitor (oral) dose
bottle rule
Dabigatran (Pradaxa) 150mg bid 75mg bid if Crcl <15-30ml/min. once bottles are opened the product must be used w/in 4 mos. Keep bottle tightly closed. Store in original package to protect from moisture. Blister packs are good until date on the pack 6-12mos
Dabigatran (Pradaxa)indiacation and INR rule for warfarin to dabigatran
reduce the risk of stroke and systemic embolism in pts w/ non-valvular atrial fibrillation. INR must be <2.0 when switching from warfarin to dabigatran
MOA of Rivaroxaban and dosing for non-valvular A.Fib
oral factor Xa inhibitor.Dosing A.Fib >50ml/min: 20mg PO d with the evening meal. Crcl 15-50ml/min 15mg PO d with the evening meal CrCl < 15 avoid use
Rivaroxaban for DVT prophylaxis
10mg po daily without regards to meals. Do not use in Crcl <30 take for 35 days for hip replacement and 12 days for knee replacement. Preg Cat. C
Drug Interactions of Rivoroxaban
Avoid use w/ 3A4 inducers or pglycoprotein. A dose increase of rivaroxaban to 20mg if these drugs are coadministered. The 20mg dose should be taken with food
What is the MOA of wafarin?
inhibits the C1 subunit of the vitamin K epoxide reductase (VKORC1) to vitamin k epoxide causing depletion of clotting factors and protein C and S.
What is the initial starting dose of warfarin?
Start b/w 10mg for the first 1-2 days. starting dose <5 is recommended for elderly, debiliated, malnourished, those pts take meds that increase sensitivity to warfarin, liver impairment, heart failure
Warfarin
isomer
prego
SE
Coumadin, Jantoven. S is 2-4x more potent than R. Preg Cat. X, skin necrosis and purple toe syndrome
What drugs can increase bleeding, but no effect on INR?
NSAIDS, gingko, SSRIs SNRIs
Peripoperative pts on warfarin
Stop warfarin 5 days B4 major surgery. Bridge w/ LMWH given SC or UFH (IV) D/c LMWH 24 hrs b4 surgery. 4 hrs if using UFH. if INR is still elevated 1-2 days B4 rx give low dose vitamin K (1-2mg). Resume rx 12-24hrs after surgery
High risk factors for warfarin use
Prior Stroke, TIA, and systemic embolism
Moderate risk factors
Age >75, HTN, HF <35%, Diabetes
CHADS2 Score
C-CHF H-HTN A- Age >75 D-Diabetes S- prior stroke/TIA
what are the two pathways
contact activation pathway (intrinsic pathway) or the tissue factor pathway ( extrinsic pathway)
direct thrombin inhibitors moa
block thrombin and decrease the amt of fibrin available for clot formation.
heparin has what kind of response predictable or unpredictable
unpredictable anticoag response. has variable and extensive binding to plasma protein and cells.
heparin given sc or IM
SC If you give IM risk of hematoma
LMWH BBW
pts given neuraxial anesthesia (epidural, spinal) are at risk of hematomas and subsequent paralsysis.
fondaparinux bbw
SAME as lmwh
pts given neuraxial anesthesia (epidural, spinal) are at risk of hematomas and subsequent paralsysis.
fondaparinux CI
CrCL < 30
bacterial endocarditis
active bleeding
<50 kg for ppx
thrombocytopenia with +test for antibody
epistaxis meaning
nose bleed
ecchymosis
bleeding into skin (blood bruise)
dabigatran side effects
gastritis like symptons bleeding( more GI) no monitoring of efficacy.
monitoring for dabigatran
none for efficacy for safety monitor renal function if > 75 or if CrCl < 50.
3 indication for rivaroxaban
nonvalvular afib
VTE tx and secondary ppx
VTE ppx after knee/hip replacement
rivaroxaban CI in pts with and monitoring?
moderate to severe hepatic impairment. and CrCl < 15 in A.fib, CrCl<30 in other indications
NO MONITORING required
warfarin durg interaction 4 main
nsaids, aspirin, ssri, snri
M- metronidazole/macrolides
A-amiodarone/azoles
S- SMX/TMP
T - Tamoxifen, tigecycline, tetracycline
FQ
cefalosporines
amoxicillin
perioperative management of warfarin pts when to stop?
5 days before major surgery. if pt is modertate to high risk of thromboembolism bridge with LMWH given SC. d/c LMWH 24 hrs before surgery (4 hrs if heparin)
if INR elevated before surgery
give low dose 1-2.5 mg vitamin koral
when to resume warfarin after surgery
12-24 hrs after
stop antiplatelet agents how many days before surgery
5-10days
if you have afib of X hrs or unknown start therapy
48 hrs
anticoag duration for afib
3 weeks prior and 4 weeks after NSR restored w/ cardioversion or normal pharcological therapy.
afib w/ no risk factors
no therapy
1 MODERATE risk factor
oral Anticoagulant preverred but if CI consider aspirin+clopidogrel
anticoagulant: dabigatran prefered over warfarin
any high risk factors > 2 or moderate risk factors
oral anticoagulants
high risk factors
stroke, tia or embolism rest moderate
CHAD
CHADS2 (2 high)
warfarin- chest 2012
starting dose of 10 mg for first 2 doses then adjust INR
check inr how often per chest 2012
q 12 weeks if pt has been stable
chest guidelines and aspirin
recommends AGAINST the use of aspirin for vte prophylaxis alone.
warfarin INR. if w/in X then dont change dose and carry on
patients taking warfarin with previously stable therapeutic INRs who present with a single out-of-range INR _0.5 below or above therapeutic, the guidelines recommend continuing the current dose and testing the INR within 1-2 weeks.
mechanical mitral vavle
2.5-3.5
dabigatran should not be used with interact
rifampin and pglycopritein INDUCERS
rifampin effect on warfarin
increase the dsoe.
chest guideliens post stroke 1a
aspirin and clopidogrel.
unprovoked VTE treatmen duraiton w/ warfarin
3 months
INR increase by greater than X hold dose
(greater than 0.4 per day). Recommend holding the warfarin and/or decreasing the dose.
after how many hrs restart LMWH after surgery
48-72 hrs 2-3 days
smoking
decrease INR
alcohol
increase INR
diarrhea
INcrease INR, b/c perhaps lose vitamin K
when does inr fluctuate
if you take low amts of vitamin k, hence just switch to dabi
doan generic
mag sulfate. not good w/ warfarin
bactrim
2c9 inhibitor decrease warfarin dose.
PST-
self monitoring INR not accurte for
HCT < 30,
antiphosolipids and concurrent use of LMWH or heparin
for cancer pts LMWH or warfarin
LMWH
mechanical aortic valve
2 to 3
LMWH
IS MORE COST effective than heparin. less osteoporsis, and less HIT
