Anticoagulants: Heparin and Warfarin

By VeriScorePrep Team · 5 min

Anticoagulants prevent clot formation or extension but carry bleeding risk. The two classic agents, heparin and warfarin, are tested often because of their monitoring and reversal differences.

Heparin

Fast-acting, given IV or subcutaneously. Monitored by aPTT. Antidote: protamine sulfate. Low-molecular-weight heparins (enoxaparin) do not require routine aPTT monitoring.

Warfarin

Oral, delayed onset (days). Monitored by PT/INR (therapeutic INR typically 2–3 for most indications, 2.5–3.5 for mechanical valves). Antidote: vitamin K (slow, hours to days) and, for rapid reversal, prothrombin complex concentrate. Watch for bleeding — black tarry stools (melena) warrants immediate provider notification.

Patient teaching

Consistent vitamin K intake (don't suddenly change leafy green consumption), avoid NSAIDs unless approved, use a soft toothbrush and electric razor, report any unusual bruising or bleeding, and attend labs as scheduled.