HEME 2.6 Flashcards
Define anticoagulants
substances that prevent the synthesis of fibrin network which inhibits coagulation and the formation of thrombi
Define thrombolytics/fibrinolytics
substances that promote the destruction of already formed blood clots of thrombi by disrupting the FIBRIN MESH
define antiplatelets
drungs that reduce the adhesion and aggregation of platelets
define antifibrinolytics
drugs that promote the formation of clots and prevent excess bleeding
True or false: anticoagulants can create an immediate defect in clotting mechinism and should be treated with caution
TRUE
why must anticoagulants be monitored very closely
the range between sufficient therapy and hemorrhagic rist is narrow and varies considerably from patient to patient
what must be taken into consideration before starting anticoagulants
unrelated drugs can effect the dose of the anticoagulant needed
individual treatment and frequent laboratory tests are imparitive
what are the Four classes of anticoagulants
- indirect thrombin inhibitors (heparin)
- Coumarin anticoagulants (Warfarin)
- Direct thrombin inhibitors
- Directs factor X inhibitors
what is the makeup of Heparin
A mixture of heparins with a wide range of molecular weights
what are the two most common preparation of heparin
Unfractionated heparin (UHF – heparin sodium
Low-molecular-weight heparin (LMWH) – Fragmin, innohep, lovenox
what is the mechanism Heperin uses to prevent clots
Heparin stimulates antithrombin III, which in turn neutralizes the activity of factor X
what does neutralizing the activity of Factor X accomplish
Prothrombin cannot be converted into Thrombin, which prevents the fibrin formation from fibrinogen
what has heparin been “dubbed” as
indirect Thrombin Inhibitor
besides neutralizing factor X, what else does heparin accomplish
stimulates heparin cofactor ll, which inhibits thrombin
how is unfractionated heparin (UHF) administered
typically by IV (bolus or infusion)
what is UFH usually monitored by
APTT (activated partial thromboplastin time)
how is low molecular weight heparins andministered
sub cutaneous on a body weight basis WITHOUT the need for laboratory testing (in hospital or at home)
what is the only major coumarin anticoagulant in the USA
Warfarin (coumadin)
what can warfarin be used as
rodent poisons
How does Warfarin work
interfering with the hepatic synthesis of Vit. K dependent clotting factors (ll, Vll, lX, X)
Warfarin is a long term treatment or prophylaxis of
venous thrombosis
PE
when is warfarin usually administered
post MI or Post op
for prevention of systemic thromboembolism in patients with prosthetic hearts valves or atrial fibrilation
how is warfarin monitored
INR - for most patients is shoud be between 2-3
what are four common drugs that inhibit warfarin
- cimetidine (tagamet)
- acetominophen (tylenol)
- High dose, acute alcohol
- many antibiotics
what antibiotics inhibit warfarin
azithromyocin (zithromax)
- ciprofloxacin
- clarithromycin
- erythromycin
what may potentiate the effects of warfarin
synthetic thyroid hormones by increase catabolism of many clotting factors
what may diminish the desired effects of warfarin
- chronic alcohol use
- phenytoin
- Oral contraceptives (increase the synthesis of clotting factors)
what types of food may decrease the effectiveness of warfarin
foods high in Vit. K
how are warfarin overdoses typically treated
Vit. K and transfusions
what is the most common side effect of warfarin
bleeeding
why shouldn’t warfarin be taken while pregnant
contraindicated (catagory X) because it can cross the placenta and is teratogenic
