Coumadin

What ethnic group needs special considerations when taking warfarin?

Asian patients and those who carry the CYP2C9*2 allele and/or the CYP2C9*3 allele, or those with VKORC1 AA genotype may require more frequent monitoring and lower doses

What does warfarin treat?

treatment of: Venous thrombosis, Pulmonary embolism, Atrial fibrillation with embolization. Management of MI, prevention of thrombus formation and embolization after prosthetic valve placement.

Generic name for Coumadin?

warfarin sodium

What is PT/INR

standardized measure of the degree to which a patient's blood coagulability has been reduced by the drug

Pediatric considerations

Achieving and maintaining therapeutic PT/INR ranges may be more difficult in pediatric patients. Assess PT/INR levels more frequently

Brand names?

Coumadin, Jantoven

Which herbal products interact with warfarin and cause an increase in bleeding?

Dong quai, garlic, ginkgo

What determines the dosage?

INR (usually 1-10mg/day orally)

Most dangerous side effects?

Necrosis, severe bleeding, bloody stool

How does it work?

In order for your blood to form a clot, you have to have certain proteins in your blood. Normally, your liver makes these proteins and it requires vitamin K to do so. You get vitamin K from many of the foods you eat (especially green vegetables and certain oils). Warfarin reduces your liver's ability to use vitamin K to make these blood clotting proteins, which makes it harder for your blood to clot. Vitamin K and warfarin tend to work against each other. For this reason warfarin is often referred to as a vitamin K antagonist (VKA). If your intake of vitamin K increases, you will need more warfarin to keep your blood from clotting. If your intake of vitamin K is reduced, your dose of warfarin will also have to be reduced in order to keep you from bleeding.

Why is it recommended to take warfarin at night?

On those days when the blood test is checked, the dose can be adjusted that day, if needed, rather than having to wait until the next day's dose.

What must be carefully monitored?

PT/INR (prothrombin time/ international normalized ratio)

What should you monitor for?

PT/INR, dietary considerations (should be consistent), Monitor hepatic function and CBC before and periodically, Monitor stool and urine for occult blood before and periodically

Geriatric considerations

Patients over 60 yr exhibit greater than expected PT/INR response. Monitor for side effects at lower therapeutic ranges

Who should not use warfarin?

Patients who went through recent brain, eye, or spinal cord injury or surgery; Severe liver or kidney disease; Uncontrolled hypertension; pregnant women

What herbal product reduces warfarin's effect?

St. John's wort

What to teach the patient?

Try to take at the same time every day, review foods high in Vitamin K, keep a consistent diet, do not drink, take other meds, OTC, or herbal meds at the same time (especially aspirins or NSAIDs), let physician know if planning on pregnancy, emphasize importance of frequent lab tests, avoid cranberry juice

When what drug is combined with warfarin is it recommended the dosage of warfarin be cut in half?

When amiodarone is added to warfarin therapy, it is recommended the warfarin is cut in half

Pregnancy category?

X

What drugs have significant and common interactions with warfarin? (6)

amiodarone, fluconazole, erythromycin, metronidazole, sulfonamide antibiotics, cimetidine

Therapy class

anticoagulant

Pharmacy class?

coumarin

Common side effects?

easy bruising and bleeding, altered sense of taste, GI issues

Which foods may reduce warfarin's ability to clot?

foods high in Vitamin K (kale, spinach, collard greens)

Coumadin route

oral and IV, but also exclusively used as oral