Warfarin (Coumadin) Toxicity


Pathophysiology

  1. Interferes w/ hepatic synthesis of vit K-dependent clotting factors (II, VII, IX, X)
  2. Risk factors for toxicity
  3. Kinetics
  4. Morbidity/mortality

History/Symptoms

Physical Exam

Diagnosis

Treatment

  1. ABCs, IV, O2, monitor
  2. Acute intoxication
  3. Chronic intoxications
  4. Serious or life-threatening bleeding, elevated INR
  5. ICH in warfarin-Tx pt
  6. Additional mgmt

Disposition

  1. Admit
  2. Discharge
INR Bleeding Present Rapid Reduction Required Management*
<5 No No Lower dose or omit dose;
-- Resume at lower dose when INR is therapeutic
5-9 No No Omit one or two doses
- Re-check INR in 2 days.
-- Resume at lower dose.
No Yes -
High risk
May give vitamin K 1-2.5 mg PO if at increased risk for bleeding.
No Yes -
Surgery
2 - 4 mg PO vitamin K for reduction of INR in 24 hours;
If INR still high, can repeat with 1-2 mg orally.
≥9 No No Hold dose.
Give vitamin K 5 - 10 mg orally to reduce INR in 24 to 48 hours; may use additional vitamin K as necessary.
-- Resume at lower dose when therapeutic.
Any
Yes


Serious Bleeding 
Yes Hold dose.
Give Vitamin K 10 mg by slow IV infusion, supplemented with FFP, prothrombin complex, or recombinant factor VIIa;
Vitamin K may be repeated every 12 hours.
Any Yes

Life Threatening
Yes Hold dose.
Give prothrombin complex supplemented with Vitamin K 10 mg by slow IV infusion;
Repeat if necessary depending on INR.