Thrombin Inhibitors

Question 0

Fractionated Heparin

Answer 0

Lovenox
Low molecular weight 5500 daltons
Half life 3-7 hrs

Question 1

Unfractionated Heparin

Answer 1

Very acidic due to carboxyl and sulfate groups 
Lives in mast cells
HMWH 5-30K daltons
ATIII X 1000, acts on thrombin AND Xa
Half life 1-2 hrs

Question 2

Fondaparinux

Answer 2

Arixtra
Synthetic LMWH
Half life is 20 hours
No risk of HIT II

Question 3

Warfarin

Answer 3

Coumadin
Blocks Vit K epoxide reductase
Recycling of Vit K in liver ceases
Not an antagonist! Incomplete factors still made
Peak effect 2-4days, highly protein bound
hard to manage , 5-7mg/day

Question 4

Lepirudin

Answer 4

Refludan
Synthetic hirudin, direct IRREVERSIBLE thrombin inhibitor
One molecule binds one molecule thrombin
Half life 1 hr, more than 3 days with renal insuff
HALF of patients develop antibody, preventing excretion
Monitor PTT and renal function
N

Question 5

Bivalirudin

Answer 5

Angiomax
Synthetic, hirudin-like, expensive
Easier on kidneys than lepirudin
half life 25 min, up to 3 hrs depending on renal function
High sieving coefficient with hemoconcentrators
Used in HIT or PCTA, best is ecarin clotting time, act used

Question 6

Vitamin K

Answer 6

Phytonadione , Mephyton

Question 7

Argatroban

Answer 7

Direct thrombin inhibitor
45 min half life
Monitored PTT
Hepatic clearance