Anticoagulants II Flashcards
what is the coumarin anticoagulant and how does it work
warfarin, an oral anticoagulant (unlike heparin)
inhibits vit K epoxide reductase leading to production of inactive clotting factors II, VII, IX, X since they lack the gamma carboxyl glutamic side chain
warfarin’s effect on thrombus
has no effect on pre established thrombus but will further prevent increase in the size of the thrombus
how to overcome warfarin
give vitamin K and see reversed changes in 24 hours
why must warfarin be monitored and how is it monitored
has a narrow therapeutic window
measured using PT which measure extrinsic and common pathway of coagulation
uses of warfarin
- warfarin used to prevent progression or recurrence of DVT or PE after initial heparin use
- prevent venous thromboembolism
- given with initial heparin, fondaparinux, or LMWH which is discontinued once INR is in therapeutic range for two straight days
adverse effects of warfarin
- hemorrhage
- cutaneous necrosis due to reduced activity of protein C
- crosses placenta and cause hemorrhagic disorder in fetus and abnormal bone formation
SO DO NOT GIVE TO PREGGOS
drugs that inhibit warfarin metabolism and what they cause
Cimetidine, Chloramphenicol, Disulfarim, Fluconazole, Metronidazole, Phenylbutazone, Sulfinpyrazone, TMP-SMX (trimethoprim-sulfamethoxazole)
CC-DF-MP-ST
potentiate anticoagulation –> bleeding
drugs that stimulate warfarin metabolism and what they cause
barbiturates, carbamazepine, phenytoin, rifampin
RiP CB
reduce anticoagulation
what are the thrombolytic drugs
STUART
Streptokinase, Thrombolytics, Urokinase, Alteplase, Reteplase, Tenecteplase
mechanism of thrombolytics
convert inactive zymogen plasminogen to active protease plasmin which then digests fibrin –> lysing of already formed blood clots
who are thrombolytics contraindicated in
healing wounds
pregnancy
history of cerebrovascular accident
metastatic cancer
what is streptokinase produced by and what does it catalyze the degradation of
produced by beta hemolytic strep
degrades fibrinogen, factor V and VII
what is streptokinase used for
acute MI
acute PE
arterial thrombosis
occluded access shunts
what is Urokinase found and what is it used for
- since it is synthesized by kidney, it is found in urine
- used for lysis of PE
how does Alteplase, Reteplase, and Tenecteplase work
they are tissue plasminogen activator (t-Pa) (serine protease) that rapidly activate plasminogen already bound to fibrin in a thrombus
poor activators of free plasminogen
what does higher concentration of tissue plasminogen (t-Pa) lead to
activation of circulating plasminogen –> hemorrhage
uses of alteplase, reteplase, and tenecteplase
alteplase: acute MI and acute ischemic stroke
reteplase and tenecteplase: acute MI
how do you prevent and treat venous thrombosis
with LMWH, UFH, or fondaparinux
-could also use warfarin but must monitor
drugs used to treat arterial thrombosis
aspirin and clopidogrel
what are the drugs used to treat bleeding
VAPP
Vit K, Aminocaproic acid, Protamine sulfate, plasma fractions
all plasminogen activation inhibitors
how does aminocaproic acid and tranexamic acid work
synthetic inhibitors of fibrinolysis which competitively inhibit plasminogen activation
what is aminocaproic acid and tranexamic acid used for
adjunct therapy in hemophilia
therapy for bleeding from fibrinolytic therapy
adverse effect of aminocaproic acid and tranexamic acid
intravascular thrombosis
mechanism of protamine sulfate
chemical antagonist of heparin hence inactive against fondaparinux
adverse effects of protamine sulfate
hypersensitivity dyspnea flushing bradycardia hypotension
when is vit k an excellent choice to stop bleeding
if vit K deficiency
on warfarin therapy
