Maybe you’ve heard about medications called blood thinners or you
or a relative takes them, and you want to learn more about them.
Pulse recently spoke with Mark Lurie, MD, cardiology director at the Melanie
and Richard Lundquist Cardiovascular Institute at Torrance Memorial Medical
Center, to get the latest information on these life-saving, frequently-prescribed drugs.
WHAT ARE THE MORE COMMONLY PRESCRIBED BLOOD THINNERS AND HOW DO THEY WORK?
The most commonly prescribed oral blood thinner is warfarin, known by the
brand name of Coumadin. The blood-clotting process is one that involves
a cascade of events within our bodies. Warfarin is an anticoagulant and
works at one level of the intricate clotting process to thin the blood.
One reason it’s frequently prescribed is its low cost—it’s
very economical for patients. One problem with warfarin however, is the
patient must have their blood monitored at least once per month to evaluate
the level of blood thinning that is actually occurring from the medication.
One example to illustrate the importance of regular blood testing when
on warfarin is to consider a patient with the condition known as A-Fib
(atrial fibrillation). Patients with A-Fib have a six-fold increased risk
of having a stroke. If their blood is not thin enough, they are at higher
risk of having a cardio embolic stroke (a stroke from a blood clot). However
if their blood becomes too thin, it places them at risk for excessive
bleeding, including a hemorrhagic stroke.
One common IV (intravenous) blood thinner used in hospitalized patients
is the drug heparin. It’s one of the oldest blood thinners and is
short- acting. An injectable used in hospitalized patients and postoperatively
to help prevent DVT (deep vein thrombosis) and pulmonary embolism (a blood
clot in the lung) is called enoxaparin, known by the brand name of Lovenox.
This drug does not require monitoring of the blood when a patient is on it.
WHY MIGHT A PHYSICIAN PRESCRIBE ONE BLOOD THINNER OVER ANOTHER OR USE DIFFERENT
BLOOD THINNERS FOR A PATIENT?
Warfarin takes approximately three to five days to work and reach the level
of blood thinning that a physician wants to achieve. So if a patient has
just been prescribed warfarin, they might be given shots of enoxaparin
in the interim while waiting for the warfarin to take effect.
Now there are four new medications to thin the blood, known as novel oral
anticoagulants (NOAC). The new drugs are: Dabigatran (Pradaxa), rivaroxaban
(Xarelto), apixaban (Eliquis) and edoxaban (Lixiana). These medications
can have many advantages as they have a fixed effect, they work immediately
(within one day) and they don’t require monitoring of the blood.
One concern about warfarin is the variations that can occur with a patient’s
blood level known as their protime (PT). One recent study found the safe
range for patients’ level of anticoagulation was achieved only 65%
of the time. With the NOAC medications, there is generally not a significant
variation of the patient’s level of anticoagulation. So for many
patients these medications may be more advantageous. However for patients
who have a mechanical prosthetic heart valve, they need warfarin to prevent
blood clots. They are not eligible for the newer NOAC medications. The
advantages of using warfarin over the newer, novel oral anticoagulants
are it’s cheaper and it has a reversal agent.
WHAT ABOUT ASPIRIN, NSAIDS (IBUPROFEN AND NAPROXEN) AND FISH OIL? IT’S
BEEN SAID THAT THESE DRUGS THIN THE BLOOD. DO THEY?
These medications can affect clotting but they are not anticoagulants.
They work on the platelets in the blood. For example, aspirin is an antithrombotic
and works on platelets. Anticoagulants such as warfarin and the NOAC drugs
affect the clotting factors in the blood ARE THERE ANY ADVERSE REACTIONS
WITH FOODS OR OTHER MEDICATIONS PATIENTS SHOULD BE AWARE OF WHEN TAKING
Many foods and drugs can negatively react with warfarin (Coumadin). First,
warfarin is a vitamin K antagonist so foods such as green, leafy vegetables
negatively interact with it. Multivitamins with vitamin K can also negatively
interact with it. Also drugs such as, but not limited to, aspirin, NSAIDS
and antibiotics can cause adverse reactions with warfarin. Always tell
your physician about herbal and dietary supplements you are taking. They
also can interact negatively. The newer NOAC medications are not affected
by green, leafy vegetables.
WHAT PRECAUTIONS NEED TO BE TAKEN WHEN USING BLOOD THINNERS?
Patients are at an increased risk of bruising and bleeding, so contact
sports should be avoided. For patients who are elderly or frail and at
a higher risk of falling, extra precautions need to be taken to prevent
falls. Certainly any spontaneous bleeding needs to be reported to your
Whether you’re using OTC or prescription drugs to thin your blood,
it’s important to read the medications’ instructions and precautions,
and check with your doctor anytime a new medication is added to your medication