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Warfarin
- take 48-72 hours to take effect
- Needs continual monitoring of INR
- Counteracted by Vitamin K injections
Mechanism of action
- Antagonise Vit K,
- prevents gamma carboxylation of
- VIII
- IX
- X
- prothrombin (II)
Route of administration
- oral
- Onset of action is 2-3 days
- duration of action is 5 days
Indications
- Treatment of deep vein thrombosis/ pulmonary embolism
- Atrial
fibrillation
- mitral stenosis
- thyrotoxicosis,
- chronic sino-atrial disease
- congestive cardiomyopathy
- ischaemic heart disease (it reduces the morbidity from embolism
especially stroke)
- Moderate to severe mitral stenosis in sinus rhythm
- prosthetic valve replacements
Unwanted effects
- Haemorrhage
- unexplained drop in haemocrit
- hypersensitivity reactions
- hepatic dysfunction
- alopecia
- GI disturbance
- diarrhoea
- nausea
- vomiting
- purple toes
- skin necrosis
- pancreatitis
Contraindications
- Pregnancy
- Peptic ulcer
- Severe hypertension
- Bacterial endocarditis
Reversed by
- Vitamin K (phytomenadione)
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