Thrombus mechanisms and drugs Flashcards
what are the main stages of thrombus development?
vascular wall damage
primary haemostasis
activation of blood clotting
what do platelets do when they are activated?
extend pseudopodia and synthesis and release thromboxane A2 (TXA2)
what does TXA2 bind to and what does it cause to be released?
it binds to TP receptors which then release serotonin and ADP
what do TXA2 receptors on smooth muscle do?
cause vasoconstriction
what does ADP do when released?
it binds to platelet GPCR purine receptors that act locally to activate further platelets to form a soft plug at site of injury
what initiates coagulation of blood and solid clot formation?
acidic phospholipids which are exposed on the platelet surface
what type of drug is warfarin?
anticoagulation drug
how does warfarin work?
competitively inhibits production of active hydroquinone (against Vit K)
and so renders Factor II, VII, IX and X inactive
what can warfarin be used with to get a rapid coagulation effect?
heparin
how is warfarin administered/
orally
how is over-dosage of warfarin treated?
giving lots of Vit K or a concentrate of plasma clotting factors
give one factor that can lessen warfarins actions?
pregnancy
what is clotting factor II?
prothrombin
what is a significant risk in all anti-coagulants?
haemorrhage
what factors increase the risk of haemorrhage caused by anti-coagulants?
liver disease- decrease in clotting factors
high metabolic rate- increased clearance of clotting factors
drug interactions
