Anti-Platelet Drugs Flashcards

1
Q

what are anti-platelets used for

A

arterial atherosclerotic events

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2
Q

what causes arterial thrombosis

A

high pressure system

atherosclerosis (formation of cholesterol plaque which rupture and exposes collagen. platelets attracted to collagen forming a plug around the plaque blocking the lumen of the vessel)

platelet rich thrombus

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3
Q

treatment of arterial thrombosis

A

aspirin and other anti-platelets

modify risk factors

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4
Q

what is atherosclerosis

A

damage to endothelium

recruitment of ‘foamy’ macrophages rich in cholesterol

forms cholesterol plaque

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5
Q

what does a stable atherosclerotic plaque cause

A

stable angina

intermittent claudication

(stable is hyalinised and calcified)

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6
Q

what do unstable atherosclerotic plaques cause

A

unable angina
MI
Stroke

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7
Q

what is unstable angina

A

plaque ruptures

platelets are recruited and cause an acute thrombus to form

this occludes the vessel

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8
Q

what is the role of platelets in atherosclerosis

A

plaques only form in high pressure environments

plaque ruptures due to the high pressure

platelets then adhere to the plaque as it exposes damaged epithelium

platelets become activated and release granules that activate coagulation and recruit other platelets to form platelet plug

platelets aggregate via membrane glycoproteins

this forms an acute thrombosis - vessel occlusion

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9
Q

risk factors for arterial thrombosis

A

hypertension

  • damage to endothelium
  • platelet activation

smoking

  • endothelial damage (toxins directly damage and also increase BP causing damage)
  • platelet activation

high cholesterol
-accumulated in plaques

diabetes mellitus

  • endothelium damage (from high glucose)
  • platelet activation
  • more cholesterol
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10
Q

prevention of arterial thrombosis

A
stop smoking 
treat hypertension 
treat diabetes 
lower cholesterol 
anti-platelet drugs
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11
Q

how are platelets formed

A

in the bone marrow by ‘budding’ off from the megakaryocytes

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12
Q

structure of platelets

A

small enucleate discs with a mean lifespan of 7-10 days

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13
Q

what chemicals are secreted by platelets to increase aggregation

A

thromboxane A2

ADP

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14
Q

what allows platelets to attach to each other

A

glycoproteins

fibrinogen

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15
Q

how does aspirin work as an anti-platelet

A

inhibits cyclo-oxygenase which is necessary to produce thromboxane A2 (a platelet agonist released from granules on activation

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16
Q

side effects of aspirin

A

bleeding

blocks production of prostaglandins leading to:

  • GI ulceration
  • Bronchospasm
17
Q

what does cyclo-oxygenase do

A

converts arachidonic acid to prostaglandins

thromboxane synthase then converts prostaglandins to thromboxane

18
Q

what is clopidogrel

A

ADP receptor antagonist

19
Q

what is dipyridamole

A

phosphodiesterase inhibitor

-reduced the production of cAMP which is a ‘second messenger’ in platelet activation

20
Q

what are GP IIb/IIIa inhibitors

A

antiplatlet drug

v potent

only given at high risk time then switched off again

21
Q

side effects of anti-platelet drugs

A

bleeding
(drugs effect platelet’s entire lifespan 7-10 days)

stop anti-platelet agents 7 days proper to elective operations

if serious bleeding reverse with platelet transfusion