heparin and warfarin

Question 1

what does heparin do?

Answer 1

potentiates anti-thrombin = increases inactivation of thrombin

Question 2

what investigations are useful for LMWH?

Answer 2

anti-Xa assay (5a)

Question 3

what investigations are useful for unfractionated heparin?

Answer 3

APTT

Question 4

what are the complications of heparin?

Answer 4

bleeding
heparin induced thrombocytopenia
osteoporosis

Question 5

what does warfarin do?

Answer 5

inhibits vitamin K = targets clotting factors 10, 9, 7, 2

Question 6

why should we be careful when initiating warfarin?

Answer 6

initially protein C and S drop = increased risk of VTE occurring

Question 7

what should we do when initially starting warfarin to prevent VTE risk increasing?

Answer 7

bridge with LMWH
after 4-7 days should be fine

Question 8

what is the therapeutic window of warfarin?

Answer 8

narrow

Question 9

how do we monitor warfarin?

Answer 9

INR = patients PTT/mean normal PTT

Question 10

what is the target INR for patients on warfarin?

Answer 10

2-3

Question 11

what does the higher the number of INR mean?

Answer 11

less likely of thrombosis occurring, more likely to bleed

Question 12

what are complications of warfarin?

Answer 12

bleeding
interactions with drugs metabolised in the liver