Anticoagulation Meds Flashcards
Anticoagulation
Suppression of clot formation from getting bigger
Stage one: coagulation
Platelet plug formation:
platelet aggregation starts when platelets come in contact with collagen at the site of damaged blood vessels
Stage two: coagulation
Production of fibrin to reinforce the platelet plug
Clotting cascade begins when clot factors turn into their active forms
How do we prevent excess clotting?
Body has antithrombin III
*protein that binds with clotting factors and inhibits their activities “turning off” clotting cascade
Arterial thrombosis
Local issue
Platelets will adhere to a damaged arterial wall
The platelets released ADP and TXA2 attracting additional platelets forming the plug
Venous thrombosis
Systemic issue
Develops at sites where blood flow is stagnant
*this intiates coagulation cascade leading to production of fibrin
The fibrin traps RBCs and platelets forming a thrombus
Thrombi have tails and may break off causing an emboli (systemic issue)
Two main med routes for anticoagulation
IV/SQ:
-heparin (IV,SQ, po not common)
-enoxaparin (Lovenox)
PO:
-warfarin (Coumadin)
-dabigatran (Pradaxa)
Heparin (how it works)
Binds with antithrombin II increasing ability to interact with inactive thrombin
Helps antithrombin III inactivate clot factors
Heparin only suppresses formation of further fibrin and clost
Injection is quick acting but PO could take days to work
Why does Heparin free floating amount vary hour to hour
Bind with many different elements
So continuous monitoring is imperative
The half-life is short : 1.5hrs
So you have to stop it and check 1.5 hrs later
Reasons for heparin use
PE
anticoagulant for pregnancy
DVT
Open heart surgery
Renal dialysis
Post-op for DVT prevention
DIC
AMI
Stroke
Heparin SE/AR
SE:
Hemorrhage
Osteoporosis (long term use)(years)
AR:
Heparin-induced thrombocytopenia (decreased platelets)
Hypersensitivity reactions (made from animal tissue)
Heparin warnings/cautions
Extreme caution for pt showing likelihood of bleeding profusely:
*hemophilia=trouble clotting
*increased capillary permeability
*dissecting aneurysm
*peptic ulcer disease
*severe HTN
*spontaneously threatened abortion
*severe disease of kidney/liver
Heparin antidote
Protamine sulfate
Labs to monitor for heparin
Monitor the aPTT
Normal = 40secs
Therapeutic: 1.5-2 times normal or 60-80secs
Evaluate q4-6 hours
LMWHs
Low-molecular-weight heparins
Can be utilized at home and doesnt require as much monitoring after lab values level out
Ex: enoxaparin (Lovenox)
Warfarin (anticoagulation)
warfarin (Coumadin)
ORAL
Supppresses coagulation by acting as an antagonist to VIT K therfore inhibiting clot factors and prothrombin
Bc of this the antidote to Caoumadin OD or high blood levels is VIT K
warfarin use
Delay action
Will not work on clotting factors already existing in body
Must wait until these clotting factors dissipate
(6hrs —2.5days)
May take t days to reach therapeutic effects and may be seen 2-5 days upon discontinuing the med
DOC for long-term suppression of clotting
*usually start on heparin and then get slowly switched to warfarin for at home use
Warfarin lab test
Monitor PT
INR should be the ultimate lab determination of warfarin therapy
Normal INR <1.1
Therapeutic levels 2-3 but can be 3-4.5 in others
Takes 5-6 days for the INR to adjust to dose
Warfarin drug reactions
Which drug heparin or warfarin more likely to bleed
When to check blood for iv and sq
It has alot of them
More likely to bleed on coumadin than heparin
Draw labs 5 hrs after iv injection and 24 hrs after SQ injection or youll get a false reading
Warfarin SE/AR
SE:
Hemorrhage
Red-orange color urine
AR:
Fetal hemorrhage and teratogenesis (if crosses placenta)
Alopecia
Other PO anticoagulants
Dont require labs but too expensive for insurances to pay
Direct thrombin inhibitors
Do not require PT/INR testing
DVT and PE prevention
A-fib clot formation prevention
Antiplatelets
Prevent clot from happening
Suppress platelet aggregation
Platelet cores are the bulk of the arterial thrombus
3 groups of anti-platelets
Aspirin
ADP receptor antagonists
GP llb/llla receptor antagonists
Asprinin
Suppresses platelet aggregation by inhibiting COX 1&2
Mainly used for prophylaxis for AMI
Low dosage (81mg) sufficient but up to 325mg can be utilized
Enteric-coated to prevent gastric problems
