Orfarin Special Precautions



Orion Pharma


Full Prescribing Info
Special Precautions
If a rapid antithrombotic effect is needed, heparin therapy must be initiated. After this, heparin therapy is continued along with the initiated warfarin therapy for at least 5 to 7 days until the INR has been at the target level (see Dosage & Administration) for at least two days.
Resistance to warfarin is a very rare phenomenon. Only a few case reports have been published on that. These patients need 5­ to 20­ fold warfarin doses to achieve therapeutic response. If the response of the patient to warfarin treatment is significantly poorer than normal, other causes impairing the effect of the treatment must first be ruled out, e.g. missing drug intake, interaction with food or other medicinal products and potential laboratory errors.
To avoid coumarin necrosis (see Adverse Reactions), patients with a hereditary deficiency of protein C or S should first start heparin for 5 to 7 days along with warfarin therapy. Warfarin therapy is initiated at a dose of 5 mg.
Special caution must be exercised when treating elderly patients. The patient compliance and the abilities to follow strict rules on drug intake must be ascertained. Hepatic metabolism of warfarin as well as the synthesis of coagulation factors are slowed down in the elderly. This may easily result in an excessive therapeutic response. Warfarin therapy must be initiated cautiously (see Dosage & Administration). Concomitant medications must be taken into account to avoid harmful interactions (see Interactions).
Hyperthyroidism, fever and uncompensated heart failure may enhance the warfarin effect. In hypothyroidism the warfarin effect may be reduced. In moderate hepatic insufficiency the effect of warfarin is enhanced. In renal insufficiency and nephrotic syndrome the free fraction of warfarin in plasma may be elevated (depending on the other primary diseases, it may either enhance or reduce the warfarin effect). The clinical status of the patient and the INR values must be carefully monitored under these circumstances.
The tablets contain lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-­galactose malabsorption should not take this medicine.
Calciphylaxis is a rare syndrome of vascular calcification with cutaneous necrosis, associated with high mortality. The condition is mainly observed in patients with end­stage renal disease on dialysis or in patients with known risk factors such as protein C or S deficiency, hyperphosphatemia, hypercalcaemia or hypoalbuminaemia. Rare cases of calciphylaxis have been reported in patients taking warfarin, also in the absense of renal disease. In case calciphylaxis is diagnosed, appropriate treatment should be started and consideration should be given to stopping treatment with warfarin.
Effects on ability to drive and use machines: No effect.
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Already a member? Sign in
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Already a member? Sign in