⚠️ Safety Alert: Always monitor for a platelet fall (>50% or to <150) between days 5–14 of heparin exposure → may signal Heparin-Induced Thrombocytopenia (HIT), which is pro-thrombotic, not bleeding-related. ➡️ Stop all heparin immediately and seek urgent haematology advice.

📘 About - ALWAYS CHECK BNF / Local Policy

💉 Antithrombotics and anticoagulants are high-risk drugs: life-saving when used correctly, catastrophic when misused.
⚠️ Long-term anticoagulation carries a major bleeding risk ≈ 3–4% per year, with mortality ≈ 0.5% per year.
👨‍⚕️ Always involve senior or haematology advice in complex cases (peri-operative care, renal failure, pregnancy, malignancy).
📋 Document indication, duration, review date, and bleeding risk clearly.

🩸 Antithrombotic (Antiplatelet) Drugs

Aspirin 🟢
• Loading: 300 mg stat → Maintenance: 75 mg OD
• Uses: ACS, post-MI, secondary stroke prevention
• Adverse effects: GI irritation, bleeding → consider PPI
Clopidogrel 🟢
• Loading: 300–600 mg (ACS) → 75 mg OD
• NICE-preferred for secondary stroke prevention
• CYP2C19 interaction → reduced effect with omeprazole
Dipyridamole MR 🟡
• 200 mg BD (modified release)
• Historical role with aspirin - now largely replaced by clopidogrel
Dual Antiplatelet Therapy (DAPT) 🔥
• Aspirin + clopidogrel (or ticagrelor) post-ACS / stenting
• Time-limited (e.g. 6–12 months)
• Not for long-term stroke prevention

💉 Unfractionated Heparin (UFH)

Used when rapid reversal or short half-life is required (e.g. peri-operative, severe renal failure).
Administered as IV infusion with weight-based bolus.
🧪 Requires close monitoring using aPTT ratio.
🛑 Fully reversible with Protamine sulfate IV.

⚖️ UFH Adjustment Protocol (Example)
aPTT Ratio	Action	Recheck
<1.3	Bolus 5000 IU, ↑ infusion by 5000 IU / 24 h	6 h
1.3–1.4	↑ infusion by 5000 IU / 24 h	6 h
1.5–2.4	No change	12–24 h
2.5–3.0	Stop 30 min, ↓ by 5000 IU / 24 h	6 h
3.1–4.0	Stop 60 min, ↓ by 5000 IU / 24 h	6 h
>4.0	Stop infusion, urgent senior review	3–6 h

🧷 LMWH - Low Molecular Weight Heparin (UK)

Enoxaparin (Clexane)
• Prophylaxis: 40 mg SC OD (20 mg if CrCl <30)
• Treatment: 1 mg/kg BD or 1.5 mg/kg OD
Dalteparin (Fragmin)
• Prophylaxis: 5000 IU SC OD
• Treatment: 200 IU/kg OD (max 18,000 IU)
• Cancer-associated thrombosis: 200 IU/kg OD ×30 days → 150 IU/kg OD
Tinzaparin (Innohep)
• Prophylaxis: 4500 IU SC OD
• Treatment: 175 IU/kg OD

📌 Indications for LMWH

VTE prophylaxis in medical, surgical, and immobile patients.
Treatment of DVT and PE.
Preferred anticoagulant in pregnancy and active cancer.
Acute coronary syndromes (e.g. NSTEMI).

💊 DOACs - Direct Oral Anticoagulants (UK)

Apixaban (Eliquis)
• AF: 5 mg BD
• VTE: 10 mg BD ×7 days → 5 mg BD
• Reduce to 2.5 mg BD if ≥2 of: age ≥80, weight ≤60 kg, creat ≥133 μmol/L
Rivaroxaban (Xarelto)
• AF: 20 mg OD with food
• VTE: 15 mg BD ×21 days → 20 mg OD
• Reduce to 15 mg OD if CrCl 15–49
Dabigatran (Pradaxa)
• AF: 150 mg BD
• VTE: 150 mg BD after 5–10 days LMWH
• Avoid if CrCl <30
Edoxaban (Lixiana)
• AF: 60 mg OD
• VTE: 60 mg OD after LMWH lead-in
• Reduce to 30 mg OD if CrCl 15–50 or weight ≤60 kg

📌 Indications for DOACs

Stroke prevention in non-valvular AF.
Treatment and secondary prevention of DVT / PE.
Post-operative VTE prevention (hip/knee replacement).

🧠 Makindo clinical pearl: Always ask WHY the patient is anticoagulated, HOW LONG for, and WHEN it should be reviewed. Anticoagulants don’t cause bleeding - they unmask it.

🚨 Anticoagulant Reversal Agents (UK)

Drug	Reversal Agent	Dose / Notes
Warfarin	Vitamin K + PCC	• Vitamin K 5–10 mg IV (slow) • PCC (Beriplex/Octaplex) per INR & weight • Use FFP if PCC unavailable
UFH	Protamine sulfate	• 1 mg protamine per 100 IU heparin (max 50 mg) • Give IV slowly (hypotension/anaphylaxis risk)
LMWH	Protamine (partial)	• Partial reversal only • 1 mg per 1 mg enoxaparin if within 8 h
Dabigatran	Idarucizumab	• 5 g IV (2 × 2.5 g) • Immediate and complete reversal
Apixaban / Rivaroxaban	Andexanet alfa*	• Specialist use only • PCC often used if unavailable

⚠️ Makindo safety tip: Reversal decisions depend on bleeding severity, drug timing, and thrombotic risk. Always involve haematology in major bleeding.

🩸 Major Bleeding on Anticoagulants - Practical Algorithm

🛑 Stop anticoagulant immediately.
🧠 ABCDE approach - early airway protection if needed.
🧪 Urgent bloods: FBC, clotting, fibrinogen, U&E, lactate, group & crossmatch.
🩸 Activate major haemorrhage protocol if unstable.
💊 Give specific reversal agent (see table above).
🧑‍⚕️ Early haematology + specialty input.
🔄 Reassess need/timing for re-anticoagulation once bleeding controlled.

⚖️ Anticoagulants - Quick Comparison

Feature	UFH	LMWH	DOACs	Warfarin
Onset	Immediate	Hours	Rapid	Slow (days)
Monitoring	aPTT	None*	None	INR
Renal failure	✔ Safe	⚠ Dose adjust	⚠ Often avoid	✔ Safe
Reversal	✔ Protamine	⚠ Partial	✔ (agent-specific)	✔ Vit K / PCC
Pregnancy	✔	✔ First-line	✖ Avoid	✖ Teratogenic

🧠 Makindo final pearl: If a patient on anticoagulation deteriorates, always ask: Is this bleeding? Is this HIT? Or is this the disease progressing? Pattern recognition + physiology beats rote dosing every time.

The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms.

Anticoagulation and Antithrombotic