Drugs and Coagulation Flashcards
What is haemophilic arthropathy?
Joint dmg/type of arthritis caused by bleeding into joints in haemophilia.
Role of vitamin k in blood coagulation?
Synthesis of Gla residues and converting coagulation factors into their mature forms.
Consequences of vit k deficiency?
Bruising, haemorrhagic disease of the newborn.
When is warfarin prescribed?
To those with increased tendency for VTE or as secondary prophylaxis to prevent further episodes.
Safe for lung term use. (Not in pregnancy!)
How does warfarin do it’s thing?
Prevents Gla domain function. So clotting factors and eventually Thrombin and Fibrin aren’t formed.
How does Heparin do it’s thing?
Heparin binds to AT and increases its inhibitory effect against Thrombin.
When is heparin prescribed?
To treat or prevent VTE.
Used for pregnant women at increased risk of thrombosis.
UFH and LMWH
How do DOAC’S do their thing?
Directly inhibit Thrombin or factor Xa.
How do fibrin monomers polymerise?
By Factor XIII which is activated by Thrombin => Factor XIIIa.
Factor XIIIa is a transglutaminase that cross-links fibrin monomers.
How does fibrinolysis occur in the body?
Plasminogen in the blood/clot is converted into plasmin by tPA released by intact endothelial cells.
Plasimin cleaves fibrin into Fibrin Degradation Products (e.g D-dimer).
What tests should accompany an elevated D-dimer test to help make the diagnosis of VTE?
MRI, angiography, CT.
How is fibrinolysis controlled?
tPA requires fibrin as a co-factor.
How is fibrinolysis switched off?
The enzymes that activate fibrinolysis are inactivated.
e.g PAI-1 inhibits plasminogen.
Antiplasmin inhibits plasmin.
What to use for the rapid degradation of occlusive thrombi. e.g in ischaemic stroke.
recombinant tPA.
e.g alteplase
reteplase
tenecteplase.
Only safe <4hrs from ischaemic stroke.
What is tranexamic acid and what does it do?
Synthetic lysine analogue.
Slows plasminogen conversion to plasmin. Therefore acts as an anti-fibrinolytic agent.
Used to reduce bleeding in clinical settings, e.g childbirth, trauma, surgery, etc.
