week 3 Flashcards
What is primary haemostasis?
Formation of the platelet plug after bleeding
What is secondary haemostasis?
Formation of the fibrin clot
What are the indications for anticoagulant drugs?
Venous thrombosis
Atrial fbrillation
What part of the clotting do anticoagulant drugs target
the fibrin clot
How does Heparin work?
Potentiates Antithrombin
How is heparin administered ?
Iv or SC
What blood test would you look at to monitor heparin?
APTT
Activated partial thromboplastin time
What are the common complications from heparin use?
Bleeding
heparin induced thrombocytopenia
osteoporosis
How can you reverse the effects of heparin?
Protamine Sulphate
What does heparin do to stop clots?
Activates antithrombin III which stops thrombim and a bunch of the coag cascade which are required to make a fibrin clot
What is heparin induced thrombocytopenia?
auto immune reaction to platelet factor 4
results in prothrombic condition 10 days after starting treatment
What side effect can heparin sometimes cause?
Hyperkalaemia
Name some coumarin anticoagulants
Warfarin
Phenindione
Acenocoumarin
How does warfarin work?
Antagonist of vitamin K
Results in synthesis of non function prothrombin and factors 7,9 and 10
How is Vitamin K absorbed?
Fat soluble vitamin found in leafy greens
Requires bile to be absorbed within the upper intestine
What does vitamin K do?
It is used to make prothrombin , and factors 7,9 and 10
What is important to remember when taking warfarin?
Narrow theraputic range so should be monitored carefully
Dose to be taken at the same time everyday
What does INR look at?
Patients prothrombin time vs normal prothrombin time
How do you reverse wafarins effect if for example the patient sustaines massive haemorrage?
Stop warfarin
give oral Vitamin K
give clotting factor concentrate
How long does giving vitamin K as an antidote take to kick in?
6 hours
What is dabigatran?
Direct thrombin inhibitor
How does rivaroxaban work?
Direct factor X inhibitor
Whats the problem with using new anticoagulants?
no current antidote
long term side effects unkown
What do platelets need to bind on to exposed collagen?
Glycoprotein 1b
and
Von Willebrand Factor
