Last reviewed by Miljan Krcobic on September 4th, 2018.
What is Eliquis (apixaban)?
Eliquis is a Brand name for a drug containing apixaban as an active ingredient. Apixaban belongs to the class of drugs that are known as inhibitors of coagulation factor Xa.
It works by blocking the action of body substance that helps forming the blood clots. It is used to help preventing the blood clots and strokes in patients with atrial fibrillation that is not caused by heart valve disease.
Atrial fibrillation is a health condition with irregular heartbeats that can increase the chance of clots forming in the body and possibly causing strokes.
Eliquis is also indicated in prevention of deep vein thrombosis (a blood clot, usually formed in the leg) and pulmonary embolism (a blood clot formed in the lung) in patients who are having knee or hip replacement surgery. Eliquis is available in tablet dosage form in doses of 2.5 and 5 mg.
Why is Warfarin prescribed?
Warfarin is an anticoagulant (or blood thinner) drug. This medicine works by preventing the formation of blood clots as well as their migration by inhibiting vitamin K-dependent coagulation factors.
In 1950s, studies found that warfarin is relatively safe and effective for prevention of thrombosis and thromboembolism in many disorders. In 1954., it was approved for use as a medicine and has become very popular ever since.
Warfarin is the most widely prescribed oral anticoagulant drug in North America Warfarin indications are: treatment and prophylaxis of venous thrombosis and pulmonary embolism as its extension, treatment and prophylaxis of thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement, reduction of recurrent myocardial infarction and thromboembolic events (such as stroke or systemic embolization) after myocardial infarction and therefore the reduction the risk of death.
Warfarin brand names
Most common Brand names for warfarin products on the market are:
- Waran and Warfant.
Coumadin has no effects on an established thrombus, and can’t reverse ischemic tissue damage. The main targets of anticoagulant therapy are to prevent further extension of the formed blood clot and to prevent the risk of secondary thromboembolic complications that may result in serious and possibly fatal outcomes.
Despite its effectiveness, warfarin therapy has several issues. Many drugs interact with warfarin, as well as some foods (such as leaf vegetable foods because they typically contain large amounts of vitamin K1) and its activity has to be monitored by blood testing for parameter INR – International Normalized Ratio to be ensured that adequate safe dose is taken.
If INR value is high, patients are predisposed to an increased risk of bleeding, while low INR values indicates that the dose of warfarin is uneffective to protect against thromboembolic events.
How does Warfarin and Eliquis (apixaban) work in the body?
Warfarin works by inhibiting the enzyme activity of vitamin K reductase, which results in depletion of vitamin KH2 – the reduced form of vitamin K.
Vitamin K is a cofactor for the carboxylation reactions of glutamate residues of vitamin K-dependent proteins, so this inhibition limits the gamma-carboxylation reactions and activation of the vitamin K-dependent coagulant proteins.
Therefore, the synthesis of vitamin K-dependent coagulation factors II, VII, IX, and X and anticoagulant proteins S and C is inhibited. Decreased levels of 3 of the 4 vitamin K-dependent coagulation factors (II, VII, and X) results in decreased prothrombin levels in blood and a decrease in the amount of thrombin generated and bound to fibrin. This reduces the thrombogenicity of clots.
Apixaban acts by inhibiting the process of coagulation, and therefore prevents progression of blood clots. The results of FXa inhibition are prolonged clotting tests such as The International normalazed ratio (INR), prothrombin time (PT), and activated partial thromboplastin time (aPTT).
Changes observed in these clotting tests at the expected therapeutic dose, however, are small, subject to a high degree of variability, and not useful in monitoring the anticoagulation effect of apixaban.
Difference between Warfarin and Apixaban
Not too long ago,there were not many choices for doctors to choose blood thinner drug for the prevention of stroke. Warfarin (Coumadin) was the only way to go.
However, in the past 3 years, though, three new anticoagulants have been approved by FDA for atrial fibrillation and one of them was apixaban with a Brand name Eliquis.
Health professional says that warfarin is very difficult drug to take, because the optimal dose varies from person to person, and it is strictly based on individual aspect.
Dosage can vary on age, diet and other medications being taken at the same time. The dosing is also hard to choose. If it is given too much, the risk of bleeding rises, sometimes very dangerously.
If it is given too little, the stroke risk remains. Prothrombin time or INR should be monitored closely in patients on Coumadin therapy, and in many cases therapy need dose adjustment.
Patients must get blood tests on monthly basis or even more often and watch their vitamin K intake. Vitamin K can be found in foods such as kale spinach and chard.
Patients should also take care about of Vitamin K amount that is taken, because too much vitamin K in the blood can lessen the effectiveness of warfarin. So patients should have to keep the level of their vitamin-K constant, and at a fairly moderate level.
With new drug such as Eliquis, there is no longer a requirement for constant surveillance, blood tests and dietary issues. Studies have found that besides lowering the risk of stroke, Eliquis (apixaban) is associated with a lesser likelihood of bleeding that could be very troublesome and life threatening such as intracranial hemorrhage or brain bleeding, a very known side effect of warfarin.
However, if Eliquis blood levels rise too much there is no ”antidote” as there is with warfarin use. If blood levels of warfarin rise too much, giving the antidote- vitamin K lowers it down.
For Eliquis there’s is no antidote for overshooting, unless giving the fresh plasma, which has its own risks. High blood levels of Eliquis can become an issue if a patient needs emergency surgery, as bleeding risk would be raised.
Also, warfarin has big list of interactions with other drugs taken at the same time while this is not the case for Eliquis. There are some drugs that should not be mixed with Eliquis, but not nearly as many as with warfarin.
There are also pharmacokinetic differences between these two drugs. Warfarin is rapidly absorbed following oral administration with considerable interindividual variations while Apixaban is absorbed in the stomach and small intestine and the absolute bioavailability is about 50%.
Warfarin is 99% bound primarily to albumin while Apixaban is about 87% plasma protein bound. The warfarin elimination is almost entirely by metabolism.
Very little warfarin is excreted unchanged in urine while 25% of the apoxiban administered dose is eliminated in the feces and urine. Half-life of R-warfarin is 37-89 hours and for S-warfarin is 21-43 hours while for apixaban is about 12 hours.
One big study of more than 18,000 patients comparing Eliquis with warfarin showed that those on Eliquis were 21% less likely to have a stroke.
However, all additions of Eliquis as a new member of blood thinner family that have some benefits over the old warfarin shouldn’t mean that patients should drop their warfarin prescription.
Patients should stay on warfarin if they have kidney failure. The same goes if they have mechanical heart valves, because new medicines such as Eliquis may not be safe for those situations.
Also, if warfarin works well, if patients are stable, don’t have bleeding problems doctor might not suggest a change and there is no a compelling reason to switch therapy.
Warfarin side effects
The table below shows the incidence of side effects after Warfarin administration in recommendable doses. The incidence can be increased if warfarin is overdosed.
|Frequency not defined||Headache, Intraocular hemorrhage, Cholesterol embolus syndrome, Abdominal pain, Alopecia, Rash, Taste disturbance, Pruritus, Tissue necrosis, Hematuria, Anemia, Hepatitis, Respiratory tract bleeding, Flatulence, Hypersensitivity reaction, Hemorrhage, Dizziness, Blood dyscrasias, Increased fracture risk with long-term usage, “Purple toe” syndrome, Lethargy, Fever|
Eliquis side effects
The table below shows the incidence of side effects after Eliquis administration in recommendable doses. The incidence can be increased if Wliquis is overdosed.
|Frequency not defined||Blood in the eyes, bloody or black, tarry stools, blood in the urine, bruising or purple areas on the skin, confusion, constipation, coughing up blood, redness of the eye, severe stomach pain, shortness of breath,tightness in the chest, difficulty swallowing, dizziness, fainting, fast heartbeat, headache, hives, itching, skin rash, joint pain or swelling, nausea and vomiting, decreased alertness, nosebleeds, puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue, unusual tiredness or weakness, vomiting of blood or material that looks like coffee grounds|
Special precautions and warnings during Warfarin and Eliquis administration:
- Patients should tell their doctor and pharmacist if they are allergic to Warfarin or Eliquis or any other medications, or any of the ingredients in these products.
- Patients should tell their doctor and pharmacist what prescription and nonprescription medicines, nutritional supplements, vitamins and herbal preparations they are taking or plan to take. There are many drugs that have interaction with Warafarin and Eliquis and those interactions can cause serious side effects.
- Patients should tell their doctor and pharmacist if they have or have ever had diseases such as: diabetes; atherosclerosis, some liver or kidney disease; bleeding problems; porphyria, cardiovascular disease such as chest pain (angina), arrhythmias, high blood pressure or heart attack; an underactive adrenal or pituitary gland, or any condition that makes swallow difficult.
- Patients using Warfarin should tell their doctor and pharmacist what herbal or botanical products they are taking, especially if they are using coenzyme Q10 prparation, Echinacea, Ginkgo biloba, garlic, goldenseal, ginseng, and St. John’s wort. There are also many other herbal or botanical products which might affect body’s response to Warfarin.
- Patients should tell their doctor if they have or have ever had diabetes. Also they should tell their doctor if they have an infection, a gastrointestinal illness such as diarrhea, or sprue or an indwelling catheter.
- Patients should also tell their doctor if they are pregnant or plan to become pregnant or if they are breast-feeding. If they become pregnant while using these drugs they should call their doctor immediately. Pregnant women should not take warfarin unless they have a mechanical heart valve. Warfarin may harm the fetus.
- If patients should have surgery, including dental surgery, they should tell their doctor or dentist that they are using these drugs. Doctor may tell to stop taking warfarin before the surgery or procedure or change your dosage of warfarin before the surgery or procedure.
- Cigarette smoking may decrease the effectiveness of warfarin.
- Patients using Eliquis should tell their doctor what herbal products they are taking, especially if they are taking St. John’s wort.
- Patients should also know that Eliquis may interact with some drugs that may be used for the treatment of stroke or other medical emergency.
- Patients should tell their doctor if they have an artificial heart valve or if they have heavy bleeding anywhere in their body that cannot be stopped. Doctor will probably tell patients not to take Eliquis.
- Patients using Eliquis should also tell their doctor if they are 80 years of age or older, if they weigh 132 pounds or less, and if you have or have ever had any type of bleeding problem, or liver kidney disease.
- Womens on Eliquis therapy should tell their doctor if they are pregnant, plan to become pregnant, or are breast-feeding. If they become pregnant while taking Eliquis, they should call their doctor.
- If patients are having surgery, including dental surgery, they should tell their doctor or dentist that you are taking Eliquis. Doctor may tell patient to stop taking Eliquis before the surgery or procedure. If they need to stop taking Eliquis because they are having surgery, doctor may prescribe other drug to prevent blood clots during this period of time. Doctor will tell patient when he/she should start taking Eliquis again after surgery. Patients should follow these directions carefully.
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