Drugs

Susan Louw

Haematology Registrar

4 Questions to ask:

Can I stop? (What is the risk of thrombosis?)

Should I stop? (What is the risk of bleeding?)

When should I stop?

Should I bridge?

Can I stop?

What is the indication for anticoagulation?

How long ago did the event occur?

How serious was the event?

Is life long anticoagulation indicated?

Should I stop?

Surgery in vulnerable sites

Laparoscopic surgery

Extent of “trauma”

Upper airway

When should I stop?

Duration of therapeutic effect after discontinuation

Onset of therapeutic effect

Antiplatelet agents

Aspirin– “No doctor, I am on no medication…” – Commonest cause of post op wound

oozing– No serious bleeding

Food

Over the counter medication

Anticoagulants

Warfarin therapy and Bleeding Most serious complication of Warfarin Most common sites of serious bleeding

– GIT– Soft tissue including wounds

Highest risk of bleeding:– At initiation of treatment and 1st year thereafter– Age > 65 years– Hypertension– Alcoholism and liver disease– Hx of stroke / GIT bleeding– History of difficulty in controlling the INR– Concomittant therapy

Incidence of Bleeding in Warfarin therapyFatal bleeding(Bleeding is cause of death)

0.1-1%

Major bleeding

(GIT, retroperitoneal, intracranial or intraoccular bleedingor any bleeding from an orifice + shock / needing transfusion or invasive procedure)

0.5-6.5%

Minor bleeding 6.2 - 21.8%

Management of Overanticoagulated Patient on Warfarin Look for and correct cause

– dosing, compliance, diet, liver disease, other illnesses

Management depends on– INR level– Severity of bleeding

Management of Overanticoagulated patient on Warfarin: No or minor Bleeding

INR < 5 Omit 1 Warfarin dose

INR monitoring frequency (2-3 x per wk)

Resume Rx at 10-20% lower dose

INR 5-9 Omit 1-2 doses

INR monitoring frequency (Daily)

Resume Rx at 10-20% lower dose

High risk: ? Vit K 2-3 mg PO

INR >9 Stop Warfarin temporarily

? Vit K 3-5 mg PO

Dly INR + repeat Vit K if INR not at 24 - 48hrs

Resume Rx at 20% lower dose once INR therapeutic

> Frequent INR monitoring

Management of Overanticoagulated patient on Warfarin: Serious or life-threatening Bleeding

Admit to Hospital (ICU) – urgent referral Stop Warfarin temporarily Local control of bleeding FFP / Other blood products (Recombinant

Factor VIIa & Prothrombin cmplex) Vit K 5 – 10 mg slowly IV Monitor INR 6 hrly and repeat Rx

Dosage adjustment for patients on Warfarin maintenance

INR Dosage Adjustment< 1.5 wkly dose by 20% & extra dose of 20% wkly dose

1.5 - 1.9 Wkly dose by 10%

2 - 3 No change

3.1-3.9 No change – recheck in 1 week. If persists, wkly dose by 10-20%

4 - 5 Omit 1 dose & wkly dose by 10-20%. Recheck in 2 –5 days

>5 See treatment of Overanticoagulated patients above

Vitamin K

Safe / Convenient / Effective Route:

– PO: preferred route– Subcut: unpredictable absorption– IM: haemorrhage– IV: SE (e.g. hypotension, chest pain) use only in emergency and

give slowly Effect:

– PO in 24 hrs– IV in 6 – 8 hrs

May be difficult to re-anticoagulate – must give lowest dose orally Oral formulation (tablets) not available any more

– give parenteral preparations orally

Thrombotic Complications

Complication of under-warfarinisation On arterial or venous side Can occur in any organ

– Brain: cerebrovascular accident (stroke)– Heart: myocardial infarction (heart attack) /

malfunction of artificial heart valves– Limbs: deep vein thrombosis (PE) / gangrene

Can be life-threatening

Thrombotic Complications: cont

Management – Referral and possible admission– Anticoagulation with Heparin

• LMWH / UFH

– Need quick onset of action– Cannot afford a hypercoagulable state

Close monitoring when re-warfarinised

Patient Education

Reason for Warfarin and duration of Rx Need to comply: dose, time of administration

and testing Importance of monitoring Importance of diet Caution with all other drugs and alcohol Avoid pregnancy Warfarin side-effects (when to call a doctor) Influence of intercurrent illness