Why is oral warfarin started about 5 days before a continuous heparin infusion is discontinued?

Why is oral warfarin started about 5 days before a continuous heparin infusion is discontinued?

• A. Warfarin takes several days to reach therapeutic levels
• B. Heparin has a longer half-life
• C. Warfarin is given only after bleeding risk evaluation
• D. Warfarin is more potent than heparin

Answer: (A)

Warfarin takes several days to reach therapeutic levels because it works by blocking the production of vitamin K–dependent clotting factors, and the existing factors must be depleted before anticoagulation becomes effective. To provide immediate protection against thrombosis during this delay, a rapid-acting anticoagulant like heparin is continued. Once warfarin has achieved a therapeutic effect (usually when the INR is in range), the heparin infusion can be stopped. This timing—starting warfarin now and overlapping with heparin for about 4–5 days—ensures continuous anticoagulation as warfarin reaches steady state.

Warfarin takes several days to reach therapeutic levels because it works by blocking the production of vitamin K–dependent clotting factors, and the existing factors must be depleted before anticoagulation becomes effective. To provide immediate protection against thrombosis during this delay, a rapid-acting anticoagulant like heparin is continued. Once warfarin has achieved a therapeutic effect (usually when the INR is in range), the heparin infusion can be stopped. This timing—starting warfarin now and overlapping with heparin for about 4–5 days—ensures continuous anticoagulation as warfarin reaches steady state.