week 5 Flashcards
mechanism of action of unfractionated heparin
Binds to antithrombin III (ATIII) → increases its activity
Inhibits: Thrombin (Factor IIa) Factor Xa
mechanism of action of LMWH
Binds to antithrombin III (ATIII) → increases its activity
Selectively inhibits Factor Xa
Too small to inhibit thrombin effectively
Adverse effects of Heparin
Bleeding (main risk)
Heparin-Induced Thrombocytopenia (HIT) – Type II (immune-mediated)
Osteoporosis (long-term use)
Hyperkalaemia (due to hypoaldosteronism)
Skin necrosis (rare)
what is heparin induced thrombocytopenia
antibody mediated thrombocytopenia that is associated with paradoxical thrombosis.
Platelet count should be performed frequently.
Any new thrombus can be the result of heparin.
Reversal agent of heparin
Protamine sulfate
mechanism of action of protamine
binds to heparin to form a stable inactive complex
completely reveres UFH
partially reverses LMWH
Warfarin interactions, examples causing increased INR?
Enzyme inhibitors; amiodarone, macroludes, metronidazole, antifungals
NSAIDs
3rd generation cephalosporins
warfarin interactions, examples decreasing INR
Enzyme inducers; rifampicine, carbamazipine, phenytoin
Cholestyramine
Vitamin K rich foods
Diuretics
mechanism of action of warfarin
Inhibits vitamin K epoxide reductase, reduces synthesis of vitamin K dependent clotting factors
Factors 2,7,9,10, protein C and S
why is effect of warfarin delayed
Due to existing clotting factors that must degrade first.
especially Factor 2
Reversal agents of warfarin
Vitamin K (phytonadione)
FFP
Prothrombinex/Vitamin K combo
what is streptokinase
a fibrinolytic drug, derived from streptococci bacteria
works indirectly activating plasminogen to plasmin
degrades fibrin and clots
mechanism of action of streptokinase
catalyses the formation of plasmin from plasminogen
