Antiplatelets Flashcards
What are antiplatelets used for?
arterial thrombosis
primary haemostasis
What is atherosclerosis?
damage to the endothelium and resultant recruitment of foamy macrophages rich in cholesterol
What is stable atherosclerosis?
hyalinised and calcified
stable angina or intermittent claudication
What is unstable atherosclerosis?
likely to rupture and cause acute thrombosis
unstable angina, MI, stroke
What are the risk factors for arterial thrombosis?
smoking
high cholesterol
diabetes
hypertension
What chemicals are secreted once platelets are adhesied to the site of injury?
thromboxane A2
ADP
How do platelets bind to subendothelial collagen?
glycoprotein Ib and VWF
How do platelets attach to each other?
GPIIb/IIa and fibrinogen
How do platelets increase coagulation activiation?
change shape to expose more phospholipid on the surface
What is the mechanism of action of aspirin?
inhibits COX which is necessary to produce thromboxane A2
What are the side effects of aspirin?
bleeding
blocks production of prostaglandins causing GI ulceration and bronchospasm
What is the role of clopidogrel/prasugrel?
ADP receptor agonists (only the ones on platelets)
What is the role of dipyridamole?
phosphodiesterase inhibitor - reduced production of cAMP whch is a secondary messenger in platelet aggregation
What is the role of Abciximab?
GPIib/IIa inhibitor - inhibits the aggregation of platelets
How long do antiplatelet drugs affect platelet function?
7-10 days (their lifespan)
so stop 7 - 10 days before surgery
