Anticoagulation in ICU Direct Thrombin Inhibitors

Question 1

Direct Thrombin Inhibitors-IV
General characterstics

Answer 1

Intravenous Direct Thrombin Inhibitors
* Act independently of antithrombin III.
* Inhibit fibrin-bound thrombin → more complete anticoagulation.
* More predictable than heparins (do not bind to other plasma proteins)

Common IV DTIs:
* Bivalirudin
* Argatroban

Question 2

Bivalirudin

Answer 2

Bivalirudin
* Analog of hirudin (from leech saliva).
* Directly binds thrombin → onset within 5 minutes.
* Used in critically ill patients with HIT.
* Reversible binding (cleaved by thrombin).
* Short half-life (~25 minutes).
* Metabolism: renal + proteolytic.
* Monitoring: ACT (no set standards for target).
* Can be Cleared by hemodialysis.
* Caution in AKI → limited ICU use.

Question 3

Argatroban

Answer 3

Argatroban
* Also reversibly inhibits thrombin.
* Used mainly in HIT.
* Hepatic metabolism → suitable for renal failure.
* Administered by continuous infusion (rapid onset, short half-life).
* Monitoring: ACT or aPTT.
* Alters PT/INR → complicates warfarin transition.
* No reversal agent.