Anti-thrombotic therapy Flashcards
(24 cards)
What is the most important feature of the haemostatic system?
Maintain integrity of vascular endothelium
Maintain blood fluidity (balance between haemorrhage and thrombosis)
What is a thrombus?
Solid clot made by platelets, fibrin and trapped blood cells
What is primary thrombosis?
Partial or total obstruction of blood vessel by thrombi
What is an embolism?
Migration of a clot or part of it to another site
What is a thromboembolism?
Obstruction of blood vessel by a clot that has become dislodge from another site in circulation
What can cause endothelial damage?
Trauma Catheterisation Neoplasia Parasites Amyloidosis
What can cause hyperviscosity of blood?
Dehydration
Leukaemia
Hyperglobulinaemia
Hyeprfibrinogenaemia
What can cause hypecoaguability of the blood?
Platelet hyperaggregability
Reduced coagulation factors
Hypofibronolysis
What are the 2 types of anti-thrombotic therapies?
Thrombolytics - for existing thrombi
Preventive - prevent new thrombi formation
Give examples of thrombolytic treatments (break down blood clots)
Surgical extraction
Recombinant tissue plasminogen activates (rt-PA)
Streptokinase
Urokinase
What does rt-PA (recombinant tissue plasminogen activator) do? What are the risks? Give an example
Increase transformation of plasminogen to plasmin
Spontaneous bleeding
Reteplase
What produces streptokinase? What does it do?
Streptococci bacteria
Enhances plasmin formation
What is plasmin?
Enzyme that degrades fibrin clots
When may streptokinase may not be an effective thrombolytic?
If had previous streptococcus infection, as have streptococcus antibodies
How does urokinase work?
Activates plasminogen (which causes plasmin formation, which degrades fibrin clots))
What are the 3 types of preventive anti-thrombotic treatments?
Anti platelet drugs
Heparin
Vitamin K antagonists
How do vitamin K antagonists work as preventive anti-thrombotics?
Vitamin K required for coagulation factors
Less vitamin K - less coagulation
Anti-PLT drugs can be COX inhibitors, ADR-receptor agonists and more. Give an example of a COX inhibitor. Are the effects permanent or temporary? What are side effects?
Aspirin
Permanent - last platelet lifetime (7 days)
GI ulcers (antiprostaglandin) and kidney damage
Give an example of an ADR receptor antagonist used as a preventive antithrombotic
Clopidogrel
What are the 2 types of heparin?
Unfractioned heparin
Low molecular weight heparin
What are the advantages of low molecular weight heparin drugs?
More predictable pharmacokinetics
Longer half life
In an arterial thrombosis, what is predominant? What should therapy target? Give 2 examples of treatment
Platelets
Platelet aggregation - aspirin, clopidogrel
In venous thrombosis, what is predominant? What should therapy target? Give an example of treatment
Fibrin and RBCs dominant
Target secondary haemostasis
Heparin
If a thrombus is of unknown location (arterial or venous), what treatment should be used?
Combined
Therapy against PLT aggregation (arteries) and therapy against secondary haemostasis (venous)
