Makindo Medical Notes

Always watch for a drop in platelets which could be due to Heparin-induced thrombocytopenia (HIT) and thrombosis.

About: ALWAYS CHECK BNF or equivalent

• Most of us who deal with vascular disease of one sort or another spend our time trying to nudge a patient's clotting in their favour through the use of antithrombotic and anticoagulants drugs.
• You need to have a basic grasp of these agents. Misused, they can have serious and lethal side effects. Always take expert help if unsure. Safety first.
• Long-term anticoagulation carries the risk of major haemorrhage (4% per annum) and death (about 0.5% per annum).

Antithrombotic

• Aspirin: Usually given as 300 mg loading dose followed by 75 mg daily afterwards. Some may use unorthodox doses such as 150 mg od. The main side effect is gastric irritation, and those with dyspepsia will often also be prescribed a PPI. In stroke, a dose of 300 mg for 2 weeks may be used initially, as this was a trial protocol. Some physicians adhere to this, while others ignore it. Follow local conventions.
• Clopidogrel: Usually given as a single 300-600 mg loading dose, especially in ACS. The maintenance dose is Clopidogrel 75 mg od.
• Dipyridamole: Given as a capsule of Dipyridamole MR 200 mg daily and was in the past given with Aspirin in secondary stroke prevention. However, since Clopidogrel is now off license and cheaper, Clopidogrel has replaced both these drugs and is given as a single antithrombotic agent.
• Aspirin and Dipyridamole: Used as a combination for secondary stroke and TIA prevention, but NICE now favours Clopidogrel instead based on cost and compliance.
• Aspirin and Clopidogrel: May be used post-ACS for a defined time period. Significant bleeding risk, so risks and benefits must be constantly assessed. Not used in stroke disease except in exceptional cases under specialist review.
• Dabigatran: A direct thrombin inhibitor and alternative to Warfarin. No need for regular blood tests. May be used for AF and VTE prevention post knee/hip replacement.
• Apixaban, Rivaroxaban, Edoxaban: Newer Factor Xa inhibitors used in AF and VTE.

Unfractionated Heparin

• Used where there is a need to closely regulate and stop anticoagulation. It requires close monitoring. Unfortunately, unless in a CCU or HDU, staffing levels may not be sufficient to provide the degree of supervision needed.
• It may be reversed with protamine given IV. Dosing - Check local policy first as there are many treatment algorithms.

Fractionated: Low Molecular Weight Heparins (LMWH) in the UK

• Enoxaparin (Clexane)
  • Dose for Venous Thromboembolism (VTE) Prophylaxis:
    • General medical or surgical patients: 40 mg subcutaneously once daily.
    • In patients with severe renal impairment (CrCl <30 mL/min): 20 mg subcutaneously once daily.
  • Dose for VTE Treatment (Deep Vein Thrombosis or Pulmonary Embolism):
    • 1.5 mg/kg subcutaneously once daily or 1 mg/kg subcutaneously twice daily.
    • For patients with CrCl <30 mL/min: 1 mg/kg subcutaneously once daily.
  • Dose for Acute Coronary Syndrome (ACS):
    • 1 mg/kg subcutaneously every 12 hours.
• Dalteparin (Fragmin)
  • Dose for VTE Prophylaxis:
    • General medical or surgical patients: 5000 IU subcutaneously once daily.
    • Moderate-risk surgery: 2500 IU subcutaneously before surgery, then 2500 IU daily.
  • Dose for VTE Treatment (DVT/PE):
    • 200 IU/kg subcutaneously once daily (maximum 18,000 IU).
    • In cancer-associated thrombosis: 200 IU/kg once daily for 30 days, followed by 150 IU/kg once daily.
  • Dose for Unstable Angina or Non-ST Elevation Myocardial Infarction (NSTEMI):
    • 120 IU/kg subcutaneously every 12 hours (maximum 10,000 IU per dose).
• Tinzaparin (Innohep)
  • Dose for VTE Prophylaxis:
    • 4500 IU subcutaneously once daily.
    • Lower dose for elderly patients (>70 years): 3500 IU subcutaneously once daily.
  • Dose for VTE Treatment (DVT/PE):
    • 175 IU/kg subcutaneously once daily.
  • Dose for Acute Coronary Syndrome (ACS):
    • 175 IU/kg subcutaneously once daily.

Indications for LMWH in the UK

• Venous Thromboembolism (VTE) Prophylaxis: Used to prevent deep vein thrombosis (DVT) and pulmonary embolism (PE) in hospitalized patients, including those undergoing surgery or with acute medical conditions.
• Venous Thromboembolism (VTE) Treatment: Used to treat DVT and PE, particularly in cases of cancer-associated thrombosis.
• Acute Coronary Syndromes (ACS): Used to treat conditions such as unstable angina and non-ST elevation myocardial infarction (NSTEMI).

DOACs (Direct Oral Anticoagulants) in the UK

• Apixaban (Eliquis)
  • Dose for Non-Valvular Atrial Fibrillation (AF): 5 mg twice daily.
  • Dose for VTE (DVT/PE) Treatment: 10 mg twice daily for 7 days, followed by 5 mg twice daily.
  • Dose for VTE (DVT/PE) Prevention after Initial Treatment: 2.5 mg twice daily after at least 6 months of treatment for VTE.
  • Renal Adjustment: Reduce to 2.5 mg twice daily if two of the following criteria are met: Age ≥80 years, Weight ≤60 kg, or Serum Creatinine ≥133 μmol/L.
• Rivaroxaban (Xarelto)
  • Dose for Non-Valvular Atrial Fibrillation (AF): 20 mg once daily with food.
  • Dose for VTE (DVT/PE) Treatment: 15 mg twice daily for 21 days, followed by 20 mg once daily with food.
  • Dose for VTE (DVT/PE) Prevention after Initial Treatment: 10 mg once daily (after at least 6 months of treatment).
  • Renal Adjustment: Reduce to 15 mg once daily for AF if creatinine clearance (CrCl) is 15-49 mL/min. Avoid use if CrCl <15 mL/min.
• Dabigatran (Pradaxa)
  • Dose for Non-Valvular Atrial Fibrillation (AF): 150 mg twice daily.
  • Dose for VTE (DVT/PE) Treatment: 150 mg twice daily after 5-10 days of parenteral anticoagulation.
  • Dose for VTE (DVT/PE) Prevention after Initial Treatment: 150 mg twice daily.
  • Renal Adjustment: 110 mg twice daily if CrCl is 30-50 mL/min, and avoid if CrCl <30 mL/min. Also consider dose reduction in elderly patients (≥80 years).
• Edoxaban (Lixiana)
  • Dose for Non-Valvular Atrial Fibrillation (AF): 60 mg once daily.
  • Dose for VTE (DVT/PE) Treatment: 60 mg once daily after 5-10 days of parenteral anticoagulation.
  • Dose for VTE (DVT/PE) Prevention after Initial Treatment: 60 mg once daily.
  • Renal Adjustment: 30 mg once daily if CrCl is 15-50 mL/min, body weight ≤60 kg, or when used with certain P-glycoprotein inhibitors. Avoid if CrCl <15 mL/min.

Indications for DOACs in the UK

• Non-Valvular Atrial Fibrillation (AF): Used for stroke prevention in patients with non-valvular AF.
• Venous Thromboembolism (VTE) Treatment: Used for the treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE).
• VTE Prevention after Surgery: Used to prevent DVT/PE in patients undergoing major orthopedic surgeries such as hip or knee replacements.
• VTE Secondary Prevention: Used for long-term prevention of recurrent DVT and PE after initial treatment.