Warfarin Therapy Aaqid Akram MBChB (2013) Clinical Education Fellow

Objectives Indications for warfarin therapy Counselling Patients How to commence warfarin therapy How to adjust warfarin doses Common warfarin interactions Warfarin therapy reversal Novell Oral Anticoagulation Drugs (NOADs)

Mechanism of Action + Indications Blocks reduction of vitamin K oxidase to vitamin K IndicationTarget Range (INR)Duration DVT Treatment months PE Treatment2-36 months Atrial Fibrillation2-3Until resolved / lifelong Valvular Heart Disease2-3Until resolved / lifelong Tissue Heart Valves2-3Until resolved / lifelong TIA / Stroke2-3Until resolved / lifelong Recurrent DVT / PE2-3 / 3-4lifelong Intravascular stent2-3Until resolved / lifelong Mechanical prosthetic valves – dependent on brand and cardiologist

Counselling Patients Drug (Yellow Book) (name / colours / side effects) Reason Goal (End point / therapeutic range / length) Missed dose Suboptimal therapy symptoms Over – bleeding from sites Under – thromboembolism Interactions Illness / Surgery Check understanding Where to find more information StrengthColour 0.5 mgWhite 1 mgBrown 3 mgBlue 5 mgPink

Interactions Alcohol Allopurinol Amiodarone Aspirin Steroids Cranberry/grapefruit Juice Garlic Omeprazole Papaya Thyroxine Ciprofloxacin Clarithromycin / Erythromycin Fluconazole / Metronidazole Penicillins Phenytoin Azathioprine Bariturates Carbamazepine CoEnzyme Q10 Oral Contraceptive St John's Wort Vitamin K

Commencing Warfarin Urgent Therapeutic LMWH until within INR range for three consecutive days Rapid Induction – 10mg first 3 days High Risk – 5mg first 3 days >60 years old Liver disease Interacting medication Poor nutritional status Recent surgery Congestive heart failure High risk of bleeding Slow Loading – 2mg for first week

INR Testing 3 days – 12 weeks 1.Has the patient experienced any signs of bleeding or bruising? 2.Is the patient planning any dental or other surgery? 3.Has the patient followed their advised dosage instructions? 4.Has there been a change in the patient’s other medications or dietary habits since their last test? No more than 20% of weekly dose increase (ideally 10%) Computerised Decision Support Software (CDSS)

High INR Bleeding Major – ABCDE / Urgent Haematology: Stop Warfarin 10mg vit K IV Octaplex Minor: Stop Warfarin 2mg vit K Oral / 1mg vit K IV No Bleeding <5 – Reduce warfarin dose >5 – Stop Warfarin >8 – Same as minor bleeding

New oral anticoagulation drugs (NOADs) Rivaroxaban / Apixaban / Dabigatran No regular INR testing required Single dose preparation OD/BD Rapid onset and offset of action Fewer drug/diet interactions Stroke risk / Therapeutic VTE / VTE prophylaxis

MOARenal ExcretionLiver MetabolismReversal DabigatranThrombin Inhibitor80%No Charcoal, Haemodialysis, PCC, Desmopressin, Antifibrolytics RivaroxabanFactor Xa Inhibitor35%Yes PCC, Desmopressin, Antifibrinolytics ApixabanFactor Xa Inhibitor25%Yes PCC, Desmopressin, Antifibrinolytics

OSCE Time Counselling stations

67 year old female New onset AF (now 3 months old) – echo has shown mitral stenosis No previous thromboembolic episodes No renal/liver disease Lots of travelling due to husband’s work Mother died of stroke Provide the Patient with relevant further management options

65 year old male PE 2 weeks ago No previous PE / DVT No liver disease Chronic kidney disease Started on warfarin therapy Unhappy at the number of blood tests required Has Googled about rivaroxaban and wants to be started on it Assess the Patient’s queries and provide further information as required

Any Questions? Thank you

Objectives were: Indications for warfarin therapy Counselling Patients How to commence warfarin therapy How to adjust warfarin doses Common warfarin interactions Warfarin therapy reversal Novell Oral Anticoagulation Drugs (NOADs)