Antiplatelets and anticoagulants

Question 1

Aspirin MOA

Answer 1

irreversibly inactivates COX-1
alters balance between thromboxane A2 (TXA2) and prostacyclin (PGI1) in the platelet/vascular endothelium axis

Question 2

Adverse effects of aspirin

Answer 2

GI bleeding (because cytoprotective action of PGs is decreased
bronchospasm in some individuals
toxic doses cause respiratory alkalosis followed by acidosis

Question 3

Alteplase MOA

Answer 3

enzymically activate plasminogen to give plasmin which digests fibrin and fibrinogen, lysing the clot
(tPA = tissue plasminogen activator)

Question 4

Alteplase adverse effects

Answer 4

bleeding
reperfusion dysrhythmias
nausea and vomiting
hypersensitivity reactions

Question 5

Tranexamic acid (TXA) MOA

Answer 5

inhibits plasminogen activation and thus prevents fibrinolysis

Question 6

TXA adverse effects

Answer 6

GIT disturbances
rare = hypersensitivity skin reactions, disturbed colour vision

Question 7

Heparin MOA

Answer 7

accelerates action of antithrombin 3 increasing its inactivation mainly of factors 2a (thrombin) and Xa

Question 8

Heparin adverse effects

Answer 8

bleeding
thrombocytopaenia
hypersensitivity reactions
osteoporosis

Question 9

Heparin reversal agent

Answer 9

protamine sulphate

Question 10

How is heparin dosage monitored

Answer 10

APTT

Question 11

LMWH MOA

Answer 11

accelerate action of antithrombin 3 increasing its inactivation of factor Xa

Question 12

LMWH adverse effects

Answer 12

bleeding
[less likely than heparin to cause thrombocytopaenia, hypersensitivity reactions, osteoporosis]

Question 13

Warfarin MOA

Answer 13

inhibits reduction of vitamin K and thus prevents the gamma carboxylation of the glutamate residues in factors 10, 9, 7 and 2

Question 14

Warfarin adverse effects

Answer 14

bleeding

Question 15

How is warfarin monitored?

Answer 15

prothrombin time (INR)

Question 16

Dabigatran MOA

Answer 16

direct inhibitor of clot-bound and free thrombin (factor 2a)

Question 17

Apixaban/rivaroxaban etc MOA

Answer 17

direct inhibitors of factor Xa

Question 18

Dabigatran reversal agent

Answer 18

Idarucizumab

Question 19

Factor Xa inhibitors reversal agent

Answer 19

Andexanet alfa

Question 20

VTE prophylaxis drugs

Answer 20

LMWH or Fondaparinux

Question 21

VTE treatment drugs

Answer 21

LMWH or DOAC

Question 22

AF stroke prevention drugs

Answer 22

DOAC or warfarin

Question 23

When is warfarin given in AF?

Answer 23

mechanical heart valve
renal failure
where close INR monitoring considered helpful
is reversal agent is likely to be needed (prothrombin complex concentrate cheaper than DOAC reversal)