Anticoagulant drugs Flashcards
indications for anticoagulant drugs
- venous thrombosis
- atrial fibrillation
naturally occurring anticoagulants
anti-thrombin
protein C and protein S
how is heparin given
IV or subcutaneous
how quickly does heparin work
immediate effect
heparin potentiates _______
antithrombin
what are the 2 forms of heparin
unfractionated
low molecular weight (LMWH)
heparin monitoring for unfractionated
activated partial thromboplastin time (APTT)
does LMWH require monitoring
usually no
heparin complications
Bleeding
Heparin induced thrombocytopenia (with thrombosis) HITT - monitor FBC in patients on heparin
Osteoporosis with long term use
if on heparin and platelets drop, what are we thinking about
Heparin induced thrombocytopenia
what’s the longest we would ever use heparin for
9 months (pregnancy)
which has a shorter half life - LMWH or unfractionated heparin
unfractionated - out the system in about half an hour
heparin summary
immediate effect
given IM or subcut
why must heparin be given too in the first week of warfarin
warfarin takes more time to take effect?
warfarin mechanism of action
competitively inhibits the vitamin K epoxide reductase complex 1 (VKORC1), an essential enzyme for activating the vitamin K available in the body
acts by inhibiting the gamma-carboxylation of glutamic acid residues in the clotting proteins II (prothrombin), VII, IX, and X.
what coagulation factors does warfarin target
II, VII, IX, and X.
what is the most sensitive monitoring test for warfarin
prothrombin time
what is INR
International Normalised Ratio
a mathematical correction of prothrombin time
what factors may influence bleeding risk on warfarin
- Intensity of anticoagulation
- Concomitant clinical disorders
- Concomitant use of other medications
- BEWARE DRUG INTERACTIONS
- Quality of management
mild bleeding complications of anticoagulation
skin bruising
epistaxis
haematuria
severe complications of anticoagulation
gastro-intestinal
intracerebral
significant drop in Hb
how can effect of warfarin be reversed
give vitamin K
administer clotting factors
management of bleeding
- how fast does vit K work?
- how fast does clotting factors work?
vitamin K - 6 hours
Clotting factors - immediate
what INR is high risk of future bleeding
INR >8
