Anticoagulation and Antithrombotic

⚠️ 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.

🧷 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)

⚠️ 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

🧠 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.