Anti-Coagulant Drugs

Question 1

indications for anti-coagulant drugs

Answer 1

venous thrombosis

AF

Question 2

mechanism of action of heparin

Answer 2

potentiates antithrombin

immediate effect

Question 3

how can heparin be administered

Answer 3

IV or SC

Question 4

2 forms of heparin

Answer 4

unfractioned

LMWH

Question 5

differences between LMWH and unfractioned heparin

Answer 5

unfractioned = more suited to antithrombin + thrombin

LMWH = more suited to antithrombin + factor X

Question 6

what is used to monitor heparin

Answer 6

APTT

heparin prolongs APTT

Question 7

when would a patient need to be monitored on heparin

Answer 7

Hx of kidney disease

- heparin is cleared through the kidneys

Question 8

complications of heparin

Answer 8

bleeding

heparin induced thrombocytopenia with thrombosis = HITT

osteoporosis

Question 9

what happens in HITT

Answer 9

can develop antibodies to heparin

• • leads to thrombocytopenia
• • occurs within 5-10 days of starting heparin

Question 10

how do you monitor for HITT

Answer 10

FBC - platelets would drop 5-10 days after starting

Question 11

how do you reverse the effects of heparin induced severe bleeding

Answer 11

protamine sulphate

Question 12

warfarin mechanism of action

Answer 12

inhibits vitamin K

Question 13

where is vitamin K absorbed

Answer 13

upper intestine

fat soluble
requires bile salts for absorption

Question 14

what is vitamin K needed for

Answer 14

carboxylation of clotting factors 2, 7, 9 and 10

protein C and S

Question 15

what is first affected when warfarin is given

Answer 15

protein C and S

- have a much shorter half like than other clotting factors

Question 16

what does vitamin K do

Answer 16

adds COOH group to clotting factors - makes it possible for them to bind to platelet plug

Question 17

effects of warfarin

Answer 17

blocks ability of vit K to carboxylate the vitamin K clotting factors – reduces their coagulant activity

Question 18

where is warfarin metabolised

Answer 18

liver

Question 19

what can interfere with warfarin metabolism

Answer 19

alcohol- metabolised by the same enzyme

Question 20

what is INR

Answer 20

standardisation of PT across labs

Question 21

INR window aimed for on warfarin

Answer 21

INR 2-3

above this = risk of bleeding
below this = drug not doing anything useful

Question 22

complication of warfarin

Answer 22

haemorrhage

-beware drug drug interactions

Question 23

bleeding complications seen on warfarin

Answer 23

mild
- skim bruising, epistaxis, haematuria

severe
- Gi, intracerebral bleed – drop in Hb

Question 24

how can warfarin be reversed

Answer 24

1-2mg oral vitamin K- reverses effects in 6 hours

IV clotting factors- reverses effects immediately (fresh frozen plasma)

Question 25

example of a thrombin inhibitor

Answer 25

dabigatran

Question 26

example of a Xa inhibitor

Answer 26

rivaroxaban

apixaban

Question 27

what is rivaroxaban first line in

Answer 27

AF, DVT, PE

Question 28

mode of action of rivaroxaban

Answer 28

inhibits factor Xa

Question 29

why are new anticoagulants being preferred

Answer 29

taken orally
no monitoring
less drug drug interactions

Question 30

how is LMWH monitored

Answer 30

Anti-Xa assay