warfarin, Coumadin
GENERIC NAME: warfarin
BRAND NAME: Coumadin
DRUG CLASS AND MECHANISM: Coumadin is an oral
anticoagulant that
inhibits the synthesis of clotting factors, thus preventing
blood clot
formation. Blood clots can occur in the veins of the lower
extremities,
usually after periods of immobility. These clots can break off
and become
lodged in the blood vessels of the lung (pulmonary embolism),
causing
shortness of breath, chest pain, and even life-threatening
shock. Blood
clots can also occur in the atria of the heart during
atrial
fibrillation, and around artificial heart
valves. One of
these clots can also break off and obstruct a blood vessel in
the brain,
causing an embolic stroke with paralysis. Coumadin is important
in
preventing the formation of blood clots. It is also important
to prevent
extension of clots already formed, and to minimize the risk of
blood clot
embolization to other vital organs such as the lungs and brain.
PRESCRIPTION: yes
GENERIC AVAILABLE: yes
PREPARATIONS: tablets (1mg, 2mg, 2.5mg, 5mg, 7.5mg,
10mg)
STORAGE: Store at room temperature in tight, light
resistant
container.
PRESCRIBED FOR: Coumadin is used in treating patients
with blood
clots in the lower extremities to prevent extension of the
clot, and to
reduce the risk of pulmonary embolism. Patients with pulmonary
embolism
are treated with Coumadin to prevent further blood clot emboli. Coumadin is also used in patients with atrial fibrillation and
artificial heart
valves to reduce the risk of strokes. It is also helpful in
preventing
blood clot formation in certain orthopedic surgeries such as
knee or hip
replacements. Coumadin is also used in preventing blood clot
closure of
coronary artery stents.
DOSING: Coumadin may be taken with or without food.
Since Coumadin is metabolized by the liver and excreted by the
kidneys, dosages
need to be lowered in patients with liver and kidney
dysfunction. Frequent
blood tests are performed to measure blood clotting time
(protime) during Coumadin treatment. Protime results help doctors adjust
medication dose to
avoid excessive blood thinning and risk of bleeding.
DRUG INTERACTIONS: Many drugs, both prescription and
nonprescription (OTC), can affect the anticoagulant action of Coumadin.
Some medications can enhance the action of Coumadin and cause
excessive
blood thinning and life-threatening bleeding. A few examples of
such
medications include Aspirin,
acetaminophen (Tylenol and
others), alcohol, ibuprofen (Motrin),
cimetidine (Tagamet),
oxandrolone (Oxandrin), certain vitamins, and antibiotics.
Patients on Coumadin should regularly consult their doctor before
instituting any
medications on their own. It is also advisable for patients on Coumadin to
carry identifications to alert other health professionals.
PREGNANCY: Coumadin should be avoided by
pregnant women
or women
who may become pregnant. Birth defects and fetal bleeding have
been
reported.
SIDE EFFECTS: The two most serious side effects are
bleeding and necrosis (gangrene) of the skin. Bleeding can occur in any organ or
tissue. Bleeding around the brain can cause severe headache and paralysis.
Bleeding in the joints can cause joint pain and swelling. Bleeding in the
stomach or intestines can cause weakness, fainting spells, black tarry stools,
vomiting of blood, or coffee ground material. Bleeding in the kidneys can cause
back pain and blood in urine. Other side effects include purple, painful toes,
rash, hair loss, bloating, diarrhea, and jaundice
(yellowing of eyes and skin). Signs of overdose include
bleeding gums,
bruising, nosebleeds, heavy menstrual bleeding, and prolonged
bleeding
from cuts.
Reference: FDA Prescribing Information
Last Editorial Review: 8/24/1999
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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