Clinical anticoagulants Flashcards
Why are platelets important for clotting?
They provide the phospholipid surface
Contain clotting factors
binds collagen, vWF and fibrinogen
What is the structure of serine proteases?
They have a GIa domain which is hydrophobic to bind to the phospholipid surface
what are some serine proteases?
Clotting factors II,VII,FIX,X
in brief how is the fibrin strand produced?
Prothrombin is converted to thrombin by FX.
thrombin can then convert fibrinogen to fibrin.
what are some indications for anticoagulation?
- AF
- Valvular heart disease
- cardiomyopathy
- VTE
- MI
what factors does the CHAD 2 score take into account?
CHF hypertension Stroke/TIA Age>75 Diabetes valvular disease female
what factors does HASBLED take into account?
- hypertension
- abdominal, renal or liver dysfunction
- Stroke
- Bleeding
- INR
- eldery
- drugs/ alcohol
using the CHAD system who gets anticoagulants?
all men with a score of 1
anyone with a score of 2
why can factor 8 increase after surgery?
its an acute phase reactant
what are absolute contraindications of anticoagulants?
Acute bleedings
what are relative contraindications of anticoagulation?
Active peptic ulceration alcohol or drug use poor compliance severe liver disease renal impairment uncontrolled hypertension dementia pregnancy
what is unfractionated heparin?
a linear sulphated polysaccharide consisting of negatively charged glycosaminoglycans with a 1;1 raio of anti X and anti II
what is low molecular weight heparin?
Has differing Anti X and anti II ratio’s
produced by depolymerisation of unfractionated heparin
how is heparin produced?f
from bovine lung/ porcine intestine
what is the MOA of heparin?
it binds to anti thrombin causing a conformational change, this increases the inhibiton of FX and thrombin
how is unfractionated heparin cleared?
reticuloendothelial
what is the half life of unfractionated heparin?
1.5 hours
how is unfractionated heparin given?
IV or sc
what is the reversal for unfractionated heparin?
protamine
how is LMWH cleared?
renal
what is the half life of LMWH?
12 hours
what is the amount of time before LMWH is peak?
3-4hours
how is LMWH administered?
Sc
what is the reversal for LMWH?
minimal reversal can be achieved with protamin
what people need anti Xa monitoring?
Pregnant people
renal impairment
Obesity
what tests will unfractionated heparin effect?
APTT
What tests will LMWH effect?
Anti Xa
what tests will vitamin K antagonists affect?
PT/INR
what tests will dabigatren affect?
TT
what are the side effects of heparin?
- bleeding
- thrombocytopenia
- osteoporosis
what do you do for heparin induced thrombocytopenia with thrombosis?
stop heparin and given danaparoid or hirudin
how does warfarin work?
Its a vitamin K antagonist
What process does vitamin K interfer with?
gamma carboxylation of GIa domain
what does gamma carboxylation of the GIa domain normally allow?
interaction with the phospholipid of platelet membranes which localises coagulation
how is warfarin initiated in patients with thrombosis?
with heparin
what is warfarin dose sensitive to?
diet
drugs
ethnicity
age
what test is warfarin monitored with?
INR/PT
For warfarin VTE prophylaxis what INR is ideal?
2-2.5
For people on warfarin due to mechanical heart valves what INR value is ideal?
3-4
for people on warfarin due to antiphospholipid syndrome what INR is a good range?
2.5-3.5
what are the side effects of warfarin?
Bleeding, skin necrosis, birth skeletal abnormalities, increased foetal loss
what does warfarin cause skin necrosis?
Due to a protein C deficiency
what does warfarin cause birth skeletal abnormalities
Lack of gamma carboxylation of bone protein takens place
how do DOAC’s work?
targeted inhibition of Xa or thrombin
what tests can be done to monitor dabigatran?
aPTTR
what does a normal TT mean in dabigatran?
It excludes the possibility that there is any circulation
what is the reversal agent for dabigatran?
idarucizumab
