A 35-year-old man is admitted to the ICU 6 hours after ingesting rat poison (warfarin-based rodenticide) in a deliberate self-harm attempt. He is alert, hemodynamically stable, and has no active bleeding. INR is 8.2, PT is 45 seconds (normal 12–14 s), and hemoglobin is 14 g/dL. Which of the following is the most appropriate initial management?

Explanation

## Warfarin Overdose: Management Without Active Bleeding ### Pathophysiology of Warfarin Toxicity Warfarin inhibits vitamin K-dependent carboxylation of clotting factors **II, VII, IX, and X**. Overdose causes prolonged PT/INR and risk of bleeding. Vitamin K1 (phylloquinone) is the specific antidote that restores hepatic synthesis of these factors over 12–24 hours. ### Clinical Context This patient has: - **INR 8.2** — significantly elevated - **No active bleeding** — hemodynamically stable, Hb 14 g/dL - **Acute ingestion (6 hours ago)** — warfarin-based rodenticide ### Management Algorithm for Warfarin Overdose (No Active Bleeding) | Situation | Recommended Management | |-----------|----------------------| | INR elevated, **no active bleeding** | **Vitamin K1 alone** (oral or IV) | | INR elevated, **active bleeding** or urgent surgery | Vitamin K1 **+** FFP or PCC | | INR mildly elevated, no bleeding | Withhold warfarin ± low-dose vitamin K1 | **Key Point:** According to standard guidelines (Harrison's Principles of Internal Medicine, KD Tripathi Essentials of Medical Pharmacology), **FFP is reserved for patients with active bleeding or those requiring urgent surgical intervention**. In a hemodynamically stable patient with no active bleeding — even with a markedly elevated INR — **Vitamin K1 alone is the appropriate initial treatment**. ### Why Vitamin K1 Alone (Option B) is Correct - **Specific antidote:** Vitamin K1 10 mg IV (slow infusion) directly reverses warfarin's mechanism by restoring hepatic carboxylation of clotting factors - **Onset:** 12–24 hours for full effect; partial correction begins within 6–8 hours - **Duration:** Sustained reversal over 7–14 days - **Repeated daily for 3 days** accounts for the prolonged half-life of warfarin-based rodenticides (superwarfarins may require weeks of therapy) - **No active bleeding** = no immediate need for factor replacement via FFP ### Why NOT FFP + Vitamin K1 (Option C)? - FFP is **not indicated** in the absence of active bleeding or urgent invasive procedure - FFP carries risks: volume overload, transfusion reactions, infection, citrate toxicity, alloimmunization - Adding FFP to a stable, non-bleeding patient is not supported by evidence-based guidelines (Harrison's, British Committee for Standards in Haematology) - The combination is appropriate **only when immediate hemostasis is required** (active hemorrhage, emergency surgery) ### Why NOT Observation Alone (Option D)? - INR of 8.2 is dangerously elevated and warrants active treatment - Delaying vitamin K1 administration is inappropriate in acute overdose ### Why NOT FFP Alone (Option A)? - FFP corrects INR for only 4–6 hours without addressing the underlying cause - Without vitamin K1, INR rebounds as FFP is metabolized **Clinical Pearl (NEET PG High-Yield):** The critical distinction is **active bleeding vs. no active bleeding**. In warfarin overdose **without active bleeding**, Vitamin K1 alone is the first-line treatment. FFP/PCC is added only when there is active hemorrhage or an urgent procedure is needed. This is a classic NEET PG discriminator. *Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.; Harrison's Principles of Internal Medicine, 21st ed.*