Poison Center, MacKay Memorial Hospital: Warfarin vs. Superwarfarin

2026年9月20日星期日

Items	Warfarin	Superwarfarin
Substance	Warfarin	Brodifacoum [1]、bromadiolone[1]、difenacoum[2]、difethialone [2]
agent	Anti-coagulant	Rodenticide
Action site	VKORC1（Vitamin K epoxide reductase complex subunit 1 [3]	VKORC1
Mechanism [3]	(reduced vitamin K) to function as a cofactor for enzymes. Warfarin blocks this reduction process, leading to the depletion of active vitamin K in the body.	(reduced vitamin K) to function as a cofactor for enzymes. Warfarin blocks this reduction process, leading to the depletion of active vitamin K in the body.
Affected factors [4]	II、VII、IX、X；Protein C/S	II、VII、IX、X；Protein C/S
Effectiveness after	INR prolonged for 2- 6 hours to 1.5 days [5]	Typically delayed; it may not become noticeable until 24–48 hours later.
Half-life	15–58 hours (35 hours) [5, 6]	Days to weeks; brodifacoum: 16–36 days above ( > 20 days), maybe longer [6].
Fat-soluble	Moderate [7]	Highly [8].
Tissue Accumulation	Relatively limited	Obviously, especially in the liver,
INR normalization	Discontinuation of medication, plus vitamin K if necessary, usually results in faster recovery.	Even if INR temporarily returns to normal, it may rise again.
Vitamin K1	Usually, a low dose is sufficient.	High doses and long-term use are often required.
Time to observe	Days to a week	Weeks to months
Outcome	Proper treatment usually yields good results.	Timely treatment is usually reversible, but delayed diagnosis can lead to severe bleeding or even death.

Clinical Presentation	INR Level	Vitamin K1 Indication & Route	Additional Interventions
Major / Life-Threatening Bleeding	Any elevated INR	IV Vitamin K1: 5-10 mg (slow IV infusion)	4-Factor PCC, 25-50 units/kg +/- FFP [9]
No Bleeding	> 10	Oral Vitamin K1: 2.5-5 mg [10]	Hold warfarin; monitor INR
No Bleeding	4.5-10	Not routinely recommended (Hold 1–2 doses of warfarin) [11]	Monitor INR; give low-dose oral K1 (1-2.5 mg) only if high bleeding risk
No Bleeding	< 4.5	Do NOT give Vitamin K1 [12]	Lower dose or omit next warfarin dose
Urgent / Emergency Surgery	Any elevated INR	IV Vitamin K1: 2.5-5 mg [13]	Consider 4-PCC depending on urgency [13]