coagulation modifiers Flashcards
hemostasis
process that stops bleeding
coagulation
hemostasis that occurs because of clotting of blood
thrombus
blood clot
embolus
thrombus that moves through blood vessels. can cause DVT, heart attack, stroke
result of a coagulation system
fibrin (clot forming substance)
fibrinolysis
mechanism where thrombi are killed to prevent vessel blockage
fibrinolytic system steps
-fibrin binds to plasminogen
-plasminogen into plasmin
- plasmin breaks down fibrin
hemophilia
genetic disorder where coagulation and hemostasis factors are absent
anticoagulants MOA
-prevent the formation of clots
- no direct effect on a blood clot thats already formed
- prevent intravascular thrombosis by decreasing blood coagulability
thrombotic events
- myocardial infarction (coronary artery)
- brain vessel (stroke)
- lungs (pulmonary embolism)
- vein in leg (DVT)
what are two drug classes of anticoagulants
heparin and warfarin
unfractionated heparin
aka heparin sodium
- requires frequent lab monitoring for bleeding times (aPTT)
- big molecule
- no monitoring for catheter flush
LMWH
- low molecular weight heparin
- small molecule, more predictable
- doesn’t need frequent monitoring
- subcut. can cause bruising
heparin indications
- prevent thrombotic events
- used as bridge therapy for going off warfarin (ex- take heparin after surgery before warfarin kicks in bc it takes 5-7 days to work)
warfarin (Coumadin) MOA
inhibit vitamin K synthesis in GI tract
- inhibits vit K clotting factors synthesized in the liver
- prevention of clot formation
example of an antithrombin med and MOA
synthetic dabigatran (Pradaxa).
inhibits thrombin
ex of direct acting Xa inhibitors
rivaroxaban (Xarelto) PO
ex of direct thrombin inhibitor
dabigatran
is dabigatran a pro drug
yuh. must pass through liver in order to work
anticoagulant indications
used to prevent clot formation in certain settings in which clot formation is likely. ex-myocardial infarction, unstable angina, atrial fibrillation, indwelling devices, slowed blood flow
anticoagulant contraindications
- allergy
- acute bleeding
- kidney disease
- warfarin= contraindicated in pregnancy
- LMWH= contraindicated in pt w/ indwelling epidural catheter. Risk of epidural hematoma
anticoagulant adverse effects
- bleeding
- heparin-induced thrombocytopenia
- nausea, vomiting, cramps, thrombocytopenia
warfarin adverse effects
bleeding, lethargy, muscle pain, skin necrosis, purple toes syndrome
HIT type 1
- gradual reduction in platelets
- heparin therapy can be continued
HIT type 2
- acute fall in # of platelets (platelets start to clot in response to heparin)
- discontinue heparin therapy
HIT clinical manifestations and treatment
- thrombosis that is fatal
- treat with argatroban (thrombin inhibitor)
- higher incidence with bovine than with porcine heparins
symptoms of toxic effects of warfarin
hematuria, melena (blood in stool), petechiae, ecchymoses, gum/ mucous membrane bleeding
IV treatment for toxic effects of heparin
not for HIT. protamine sulphate 1mg can reverse 100U of heparin. 1mg for 1mg of LMWH.
how long after discontinuing warfarin does the liver resynthesize clotting factors
36-42 hrs
what drug can hasten the return to normal coagulation
vitamin K (phytonadione)
- high doses can reverse anticoagulation in 6 hrs
how long will warfarin resistance occur after vit K is given
up to 7 days
IV vit K risk of anaphylaxis is diminished by
diluting it and giving it over 30 mins
interactions that increase anticoagulant activity
- enzyme inhibition of metabolism
- displacement of drug from inactive protein binding sites
- decrease in vit K absorption by large intestine
- alteration in the platelet count
heparin sodium
natural anticoagulant obtained from lungs or intestinal mucosa of pigs
heparin sodium is also used for
DVT prophylaxis (prevention treatment for DVT)
- 5000U SUBCUT 2/3 times a day
heparin sodium therapeutic route
IV
measurement of aPTT is necessary
heparin flushes
heparin leo
- small vial of aq IV flush sol
risk of HIT has caused most institutions to use
0.9% normal saline as a flush for heparin-lock IV ports
what values do you need to monitor on warfarin
prothrombin time (PT) and the international normalized ratio (INR)
normal INR without warfarin
0.8-1.2
therapeutic INR with warfarin
2-3.5
warfarin sodium dietary considerations
too much vitamin K can reduce warfarins ability to form clots
ex of direct thrombin inhibitors
dabigitran etexilate mesylate (pradaxa)
dabigitran etexilate mesylate is the first oral direct thrombin inhibitor used for….
stroke and thrombus prevention for pts with atrial fibrillation
which direct thrombin inhibitor has no antidote
dabigitran etexilate mesylate
what are 3 anti platelet drugs
aspirin, clopidogrel bisulfate (plavix), eptifibatide (Integrilin)
aspirin effect
-vasodilation and prevention of platelet aggregation and clot formation
- used in stroke prevention
when do you chew aspirin
myocardial infarction
do not use aspirin for
pregnant ppl and kids
clopidogrel (Plavix) MOA
alters platelet membrane so it can no longer receive signals to form a plug
clopidogrel is used for
reducing number of MI, strokes, vascular death, preventing TIA and post MI thrombotic prevention
eptifibatide is administered when
critical care or catheterization lab settings where continuous cardiac monitoring is available.
- used to treat acute unstable angina, MI, and during PCI
eptifibatide route
IV only
what do thrombolytic drugs do
break down or lyse preformed clots in the coronary arteries
current thrombolytic drugs
alteplase (Activase) and tenecteplase (TNKase)
thrombolytic drugs MOA
-activate fibrinolytic system to break down clot in blood vessels quickly
-activate plasminogen to plasmin which lyses the thrombus
thrombolytic drugs indications
- acute MI
-arterial thrombolysis - DVT
- occlusion of shunts
- pulmonary embolism
- acute ischemic stroke
thrombolytic drugs adverse effects
- bleeding: internal, intracranial, superficial
- nausea, vomiting, hypotension, hypersensitivity, anaphylactoid reactions, cardiac dysrhythmias
antifibrinolytic drugs
- prevents lysis of fibrin
- promotes clot formation
- treatment for excessive bleeding from hyperfibrinolysis
- treatment of hemophilia A or type 1 von Willebrand disease or desmopressin
ex of antifibrinolytic drug
desmopressin acetate (DDAVP)
desmopressin acetate used for
-surgical and post op hemostasis
- type 1 von willebrands disease and hemophilia A
- not as common
antifibrinolytic adverse effects
uncommon
rare reports of thrombotic events
dysrhythmia, orthostatic hypotension, bradycardia, dizziness, fatigue, nausea vomiting
what can be given as an antidote incase of excessive anticoagulation
protamine sulphate
where is LMWH given
subcut in abdomen
antidote for warfarin
vitamin k
herbal products that can increase bleeding
capsicum pepper, garlic, ginger, ginkgo, st johns wort, feverfew, ginsing
pt education with anticoagulants
- wear a medical alert bracelet
- avoid foods high in vit K
- consult physician before taking OTC
what to monitor for pts taking thrombolytic drugs
bleeding from gums, mucous membranes, nose and injection sites
signs of internal bleeding
decreased BP, restlessness, increased pulse.
