Anticoagulants: Heparin, Warfarin, and DOACs

Anticoagulants are high-alert medications used to prevent and treat thromboembolic disorders. This guide compares the three major classes — heparin, warfarin, and DOACs — focusing on the monitoring, antidotes, and safety priorities nursing students must master for exams and clinical practice.

Anticoagulant Classes

• Heparin — Parenteral anticoagulant; immediate action.
• Warfarin — Vitamin K antagonist; delayed onset.
• Apixaban / Rivaroxaban — DOACs (Factor Xa inhibitors); no routine lab monitoring.

Heparin

• Administered IV or subcutaneous.
• Produces an immediate anticoagulant effect.
• Used for acute anticoagulation.

Monitoring & Antidote

• Lab: aPTT
• Therapeutic range: 1.5–2.5 × normal
• Antidote: Protamine sulfate

Warfarin

• Oral anticoagulant.
• Delayed onset of action.
• Many food and drug interactions (especially vitamin K–containing foods).

Monitoring & Antidote

• Lab: INR
• Therapeutic range: 2.0–3.0
• Antidote: Vitamin K

DOACs – Factor Xa Inhibitors

• Oral anticoagulants.
• Predictable dosing.
• No routine lab monitoring required.

Antidote

• Andexanet alfa — Factor Xa reversal agent.

Anticoagulant Comparison

Common Side Effects

• Heparin: Bleeding, HIT (heparin-induced thrombocytopenia).
• Warfarin: Bleeding.
• DOACs: Bleeding.

Nursing Safety Rules

• Assess for bleeding — gums, urine, stool.
• Avoid IM injections.
• Use a soft toothbrush and electric razor.
• Double-check doses (high-alert medications).
• Match the correct lab to the correct drug.

Common Exam Traps

• Mixing up INR and aPTT.
• Giving warfarin during pregnancy (contraindicated).
• Ignoring signs of bleeding.
• Assuming DOACs do not cause bleeding.
• Forgetting antidotes.

Key takeaways

• Heparin → aPTT → Protamine sulfate
• Warfarin → INR → Vitamin K
• DOACs → no routine labs → Andexanet alfa
• All anticoagulants increase bleeding risk — monitor closely.
• Heparin is the safest anticoagulant in pregnancy.