Anticoagulant Drugs

Question 1

what do anticoagulant drugs target in the haemostatic pathway and why?

Answer 1

formation of the fibrin clot

venous thrombi are rich in fibrin

Question 2

how does a thrombus in the heart cause stroke?

Answer 2

clot dislodges from heart to become an embolus -> common carotid -> internal carotid -> brain

Question 3

MoA of heparin?

Answer 3

increases effect of antithrombin

Question 4

how is heparin given?

Answer 4

IV

SC

Question 5

how is unfractionated heparin monitored?

Answer 5

APTT

Question 6

how is LMWH monitored?

Answer 6

none

anti-Xa assay if needed

Question 7

complications of heparin

Answer 7

bleeding
thrombocytopenia
osteoporosis if long term

Question 8

how can the action of heparin be reduced in acute situations?

Answer 8

stop - short HL

protamine sulfate to reduce antirthrombin effect

Question 9

MoA of coumarin anticoagulants? give an example

Answer 9

vit K antagonists

warfarin

Question 10

vit k is fat soluble/water soluble

Answer 10

fat

Question 11

how does vit K make CFs more negative?

Answer 11

adds a COOH- group

Question 12

why does warfarin need to be monitored?

Answer 12

narrow therapeutic window

Question 13

how should warfarin be taken?

Answer 13

same time every day eg 6pm

Question 14

how to calculate INR?

Answer 14

patients PT in seconds/mean normal PT in seconds

Question 15

how is warfarin action reversed acutely?

Answer 15

omit warfarin dose
administer oral vit k
administer FFP

Question 16

how long does it take for vit k to work?

Answer 16

6hrs

Question 17

how long does it take for clotting factors to work?

Answer 17

immediate effect

Question 18

MoA of dabigatran?

Answer 18

thrombin inhibitor

Question 19

MoA of apixaban/rivaroxaban?

Answer 19

Xa inhibitors