Pharmacology

1. Domina Petric, MD
Warfarin in
primary care

2. Indications
Warfarin tbl. 3 mg or 5 mg
treatment and prevention of deep venous thrombosis and pulmonary embolism
secondary prevention of myocardial infarction and prevention of thromboembolic
complications (cerebrovascular insult, systemic embolism) after myocardial infarction
prevention of thromboembolic complications in patients with atrial fibrillation, heart valve
diseases or artificial heart valves

3. Dose (adults)
Treatment goal are INR values 2,5-3,5 (patients with arteficial heart valves) or INR values 2,0-3,0 (for other indications).
Patients with normal body weigh and initial INR value 1,2: 10 mg of warfarin (two tablets of 5 mg or three and one third of 3 mg
tablets) during first three days.
INR is measured the fourth day and then the dose should be titrated.
If the INR value is too low, the dose should be increased.
If the INR value is good, the dose should be the same.
If the INR value is too high, the dose should be lowered (or one day without a single tablet).

4. If there is risk of bleeding
Patients without signs of bleeding:
INR Treatment
4-5 One day without a single tablet, next day a lower dose,
control after 7 days.
5-9 Stop one day (one day without a single tablet) and K vitami
n 2-3 mg per os, control tomorrow.
>9 Stop one day the treatment and K vitamin 5 mg per os,
control tomorrow.

5. If there is bleeding
Patients with signs of bleeding:
INR Treatment
Smaller bleeding What is the cause of
bleeding? Lower the dose and
vitamin K per os if necessary.
Larger bleeding Hospitalisation!
Life threatening bleeding Emergent hospitalisation!

6. Elective surgical procedures
Seven days before elective surgery check your patient´s INR value!
INR When to stop treatment?
>4 Stop the treatment five days before surgery.
3-4 Stop the treatment three days before surgery.
2-3 Stop the treatment two days before surgery.

7. Contraindications
Listed below:
 first trimester and last four weeks of pregnancy
 von Willebrand disease, hemophilia, thrombocytopenia, damaged thrombocyte function
 severe liver failure or cirrhosis
 poorly controled arterial hypertension
 recent intracranial bleeding
 surgical procedure on the brain or on the eye
 gastrointestinal bleeding
 infective endocarditis, pericardial effusion
 dementia, psychosis, alcoholism
 hypersensitivity
 Hypericum perforatum

8. Warfarin should never be combined with NSAR!!!
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