6.2 Antiplatelets

Question 1

pathophysiology of venous thrombosis

Answer 1

stasis of blood, +/- damage to veins

Question 2

pathophysiology of arterial thrombosis

Answer 2

forms at site of atherosclerosis following plaque rupture

Question 3

compare the cell content of venous and arterial thrombi

Answer 3

venous- high RBC, high fibrin, low platelet

arterial- low fibrin, higher platelet

Question 4

describe the process of platelet activation and aggregation

Answer 4

-endothelial damage so platelets come and adhere
-release chemical mediators (thromboxane A2, ADP, serotonin, PAF)
-more platelets recruited by signalling cascade, into platelet plug
-chemical mediators cause increased calcium
-activates GP11b/111a receptors and fibrinogen

Question 5

which type of drugs are used for
1. arterial thrombi
2. venous thrombi

Answer 5

1. antiplatelts and fibrinolytics
2. anticoagulants

Question 6

MOA aspirin

Answer 6

inhibits COX-1 so less thromboxane A2 produced so less platelet aggregation

IRREVERSIBLE

Question 7

why doesn’t aspirin completely inhibit platelet aggregation?

Answer 7

-other chemical mediators apart from thromboxane A2 cause aggregation
-can inhibit COX-1 on every platelet

Question 8

2 doses of aspirin

Answer 8

75mg- non analgesia, children
300mg- loading dose, ACS

Question 9

adverse effects of aspirin

Answer 9

GI irruption, dyspepsia, bleeding, haemorrhage

Question 10

reye’s syndrome

Answer 10

hepatic failure and cognitive disruption typically post viral, can be fatal

so avoid aspirin

Question 11

when to avoid aspirin

Answer 11

reyes syndrome
third trimester (premature closure of ductus arterioles)
hypersensitivity

Question 12

drugs to be careful with when on aspirin

Answer 12

other antiplatelets or anticoagulants (synergistic effect)

Question 13

why does anti-lately effect last the lifespan of platelets (7-10 days)?

Answer 13

no nuclei so cant produce more COX, irreversibly inhibited

Question 14

indications for aspirin

Answer 14

AF post stroke
stroke/TIA secondary
ACS secondary
post PCI/stent
NSTEMI/STEMI 300mg

Question 15

what to presicbe when on aspirin long term

Answer 15

PPI for gastric protection

Question 16

name 3 ADP receptor antagonists

Answer 16

clopidogrel
prasugrel
ticagrelor

Question 17

adverse effects of ADP receptor antagonists

Answer 17

bleeding dyspepsia
thrombocytopenia

Question 18

contraindications for ADP receptor antagonists

Answer 18

high bleed risk with renal/hepatic impairment

Question 19

important DDIs for ADP receptor antagonists

Answer 19

CYP inhibitors
other gnutplatelts/anticoagulants
NSAIDs

Question 20

indications for ADP receptor antagonists

Answer 20

ischameic stroke/ TIA
aspirin contraindicated

Question 21

phosphodiesterase inhibitors
-adverse effects
-contraindicstions
-indications

Answer 21

-V+D, dizziness
-antiplatelets, anticoagulants, adenosine
-ishcaemic stroke/ TIA secondary

Question 22

why are GP11b/111a inhibitors effective?

Answer 22

target final common pathway of platelet aggregation

Question 23

tranexamic acid indications

Answer 23

iachasmeic stroke
heavy periods
epistaxis
big bleeds

Question 24

why can streptokinase only be used once?

Answer 24

antibodies develop

Question 25

reperfusion injury from PCI

Answer 25

calcium and ROS flood into tissue

Question 26

typical drug regime for secondary ACS prevention when haemodynamically stable

Answer 26

ACEi (or ARB)
B blcoker
75mg aspirin + ADP receptor antagonist
statin

Question 27

GLP-1
-how can we target it?
-is promoting its action good?

Answer 27

-DPP4 inhibitors, and GLP-1 agonists
-yes, insulin secretion and senses increased glucose levels