Anticoagulants, antiplatelet and antifibrinolytic drugs Flashcards
(56 cards)
What is the process of haemostasis?
- Constriction of damaged vessels
- Mechanical blockage of the hole by a platelet plug
- Coagulation cascade
- Fibrinolysis
What stimulates platelet aggregation? （4 points)
ADP
Thromboxane A2
Fibrinogen
Thrombin
What is thrombolysis?
Fibrin mesh prevented from increasing and slowly dissolved by the enzyme plasmin
What can be used to prevent or treat atherosclerosis as well as arterial and venous thrombosis?
Antiplatelet therapy
Anticoagulant therapy
Thrombolytic therapy
What are the different types of antiplatelet drugs?
Cyclooxygenase inhibitors
ADP receptor antagonists
Adenosine re-uptake inhibitors
What are some indications for antiplatelet therapy?
Previous myocardial infarction
Acute myocardial infarction
Previous stroke or TIA
Acute stroke
Stable angina
Intermittent claudication
Atrial fibrillation
What are some examples of antiplatelet drugs?
Aspirin
Clopidogrel
Prasugrel
Dipyridamole
What roles do antiplatelet drugs play in acute cardiac events?
Reduce the risk of complications eg aspirin in unstable angina
Improve prognosis eg aspirin in acute MI
What is the mechanism of aspirin?
Irreversibly inhibits the synthesis of thromboxane A2 in the platelet by blocking the enzyme cyclooxygenase
What is thromboxane A2?
A prostaglandin that promotes platelet aggregation
How long does the effect of aspirin last?
7-10 days
How can dental professionals manage the increased risk of postoperative haemorrhage in patients who take aspirin?
Limit initial treatment area
Consider carrying out treatments with higher post-op bleeding complications in a staged manner, where possible, over multiple visits
Local measures (packing with haemostatic agent eg Surgicel, suturing)
Aspirin (___mg/day) is used therapeutically for long-term maintenance or ___________ in patients with established CVD/post-___________ __________ surgery as well as reducing the risk of _______________ disorders.
75, prophylaxis, coronary bypass, thromboembolic
What are some contraindications to aspirin?
Allergy
Age <12y/o (risk of Reye’s Syndrome)
Active peptic ulceration
Recent gastrointestinal bleeding
Recent intracranial haemorrhage
Bleeding disorders
Severe liver disease
Warfarin
How does clopidogrel work?
ADP receptor antagonist
Inhibits ADP-induced platelet aggregation
How is clopidogrel safer than aspirin?
Lower risk of gastrointestinal bleeding
Less haematological toxicity
When is clopidogrel prescribed in combination with aspirin?
For patients suffering from acute coronary syndrome
In the prevention of atherosclerotic events in peripheral artery disease, or following MI or stroke
If complications occur whilst on aspirin, what can be prescribed alternatively?
Clopidogrel
Dipyridamole is a __________ and _________ __________ inhibitor as well as a potent __________. It modifies various aspects of platelet function such as _________, _________ and __________,
Phosphodiesterase, adenosine reuptake, vasodilator,
adhesion, aggregation, survival
Dipyridamole is used as an _______ for oral anticoagulants for the prophylaxis of ________ associated with prosthetic heart valves. It is also used as an alternative or an ________ to aspirin following a __________ or transient ischaemic attack (TIA).
Adjunct, thromboembolism, adjunct, stroke
Heparin works as an anticoagulant by enhancing the activity of ______________ III, which neutralises _________ ___________ IXa, Xa, XIa, XIIa. This inhibits ________ by inactivating __________, therefore impairing _______ function.
Antithrombin, clotting factors, thrombin, prothrombin, platelet
Why can heparin only be given parenterally?
Heparin is a large, highly ionised molecule that is poorly absorbed from the gut
Is heparin given in low or high doses subcutaneously?
Low
What dosage is heparin given intravenously?
High doses
