Drugs Flashcards
what is atherosclerosis?
Damage to endothelium
Recruitment of ‘foamy’ macrophages rich in cholesterol
Forms plaques rich in cholesterol
what leads from a plaque rupture to an occlusion?
recruitment of platelets
There is then secretion of various chemicals from the platelets (eg …….. ), which leads to aggregation of platelets at the site of injury.
ADP, thromboxane A2
adhesion
Platelets bind to subendothelial collagen via Glycoprotein 1b and Von Willebrand Factor.
aggregation
Platelets attach to each other via GPIIbIIIa and fibrinogen. At the same time………
activation
Platelets alter their shape to expose more phospholipid on the surface-provides a greater surface area for coagulation activation and fibrin production to stabilise the clot.
Process is augmented by release of granules that further stimulate platelet activation eg Thrombin,Thromboxane A2 and ADP in order to recruit more platelets to the process.
This occurs via receptors to ADP etc on the platelet surface.
how does aspirin work?
Inhibits cyclo-oxygenase which is necessary to produce Thromboxane A2 (a platelet agonist released from granules on activation).
side effects of aspirin
- Bleeding
- Blocks production of prostaglandins:
GI ulceration
Bronchospas
how does clopidogrel work?
ADP receptor antagonist
how does dipyridamole work?
Phosphodiesterase inhibitor -reduces production of cAMP which is a ‘second messenger’ in platelet activation
abciximab
inhibits aggregation
Stop anti-platelet agents … days prior to elective operations
7
If serious bleeding - can reverse antiplatelets with …..
platelet transfusion
heparin
Potentiates antithrombin Immediate effect Parenteral (iv or sc) 2 forms - unfractionated low molecular weight (LMWH)
how do you monitor unfractionated heparin
APTT
