Apixaban

Stroke Prevention in Atrial Fibrillation

Apixaban is primarily prescribed to lower the risk of stroke and systemic embolism in people with nonvalvular atrial fibrillation (AFib). This is a type of irregular heartbeat not caused by a heart valve problem. In AFib, blood can pool in the heart and form clots, which may then travel to the brain and cause a stroke.

Treatment of DVT and PE

This medication is used to treat two specific types of blood clots:

• Deep vein thrombosis (DVT): A blood clot that forms in a vein deep in the body, usually in the legs.
• Pulmonary embolism (PE): A blood clot that travels to the lungs and blocks a blood vessel.

Apixaban is also used to reduce the risk of these clots happening again after initial treatment.

Prevention After Surgery

Healthcare providers may prescribe apixaban to prevent DVT and PE in patients who have recently undergone hip or knee replacement surgery. These procedures increase the risk of blood clots forming in the legs during the recovery period.

Mechanism of Action

Apixaban belongs to a class of medications known as factor Xa inhibitors. It works by blocking the activity of factor Xa, which is a natural substance in the blood necessary for blood to clot.

How It Prevents Clots

The blood clotting process involves a series of steps called the coagulation cascade. Factor Xa plays a central role in this process by helping to create thrombin. Thrombin is the enzyme that converts fibrinogen into fibrin, which forms the physical structure of a blood clot.

By inhibiting factor Xa, apixaban achieves the following:

• Reduces thrombin production: Lower levels of factor Xa mean less thrombin is generated in the body.
• Slows clot formation: Without enough thrombin, the blood cannot easily form a solid clot.
• Prevents existing clots from growing: While it does not dissolve existing clots, it can help stop them from getting larger while the body naturally breaks them down over time.

Because it targets a specific part of the clotting process, apixaban helps lower the risk of dangerous blood clots forming in the heart, legs, or lungs. This action is used to help prevent strokes in people with certain heart rhythm disorders and to treat or prevent deep vein thrombosis and pulmonary embolisms.

Common Side Effects

Some people may experience mild side effects while taking apixaban. These often do not require medical attention unless they persist or become bothersome:

• Easy bruising
• Minor nosebleeds
• Bleeding from the gums when brushing teeth
• Nausea
• Anemia (low red blood cell count)

Serious Side Effects

Apixaban can cause serious bleeding that may be life-threatening. Seek immediate medical attention if you experience any of the following:

• Unusual or heavy bleeding that will not stop
• Vomit that is bloody or looks like coffee grounds
• Pink, red, or brown urine
• Black, bloody, or tarry stools
• Coughing up blood or blood clots
• Heavy menstrual bleeding or unusual vaginal bleeding
• Severe headache, dizziness, or fainting
• Sudden weakness, especially on one side of the body
• Joint pain, swelling, or discomfort

Allergic Reactions

Although rare, some people may have a severe allergic reaction to apixaban. Get emergency help if you notice:

• Skin rash or hives
• Swelling of the face, lips, tongue, or throat
• Difficulty breathing or wheezing
• Chest pain or pressure

Boxed Warnings

Stopping apixaban earlier than directed by a healthcare provider increases the risk of serious blood clots, such as a stroke. If the medication must be discontinued for a reason other than major bleeding or completion of a course of therapy, another anticoagulant may be considered to prevent clots from forming.

People receiving spinal anesthesia, epidural injections, or spinal punctures while taking apixaban are at risk of developing a blood clot in the spine (hematoma). This can lead to long-term or permanent paralysis. Risk factors include the use of indwelling epidural catheters, the use of other medications that affect blood clotting (such as NSAIDs or platelet inhibitors), and a history of traumatic or repeated spinal procedures.

Bleeding Risk

Apixaban increases the risk of bleeding, which can be serious or even fatal. Because this medication decreases the body's ability to form clots, bleeding can occur internally or externally. Caution is necessary when using other drugs that increase bleeding risk, including:

• Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs)
• Warfarin or heparin
• Selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs)

Contraindications

Apixaban should not be used by individuals with active pathological bleeding. It is also contraindicated for those who have had a severe hypersensitivity reaction, such as anaphylaxis, to the medication.

Other Precautions

• Prosthetic Heart Valves: The safety and efficacy of apixaban have not been established for patients with prosthetic heart valves, especially mechanical valves. Use is generally not recommended in these patients.
• Antiphospholipid Syndrome (APS): Use is typically not recommended for patients with triple-positive APS due to a potentially increased risk of blood clots compared to other therapies.
• Surgery and Procedures: The medication may need to be stopped temporarily before surgery or dental procedures to reduce the risk of excessive bleeding.
• Renal and Hepatic Impairment: Dose adjustments may be required for patients with decreased kidney function. Use is generally not recommended for those with severe liver impairment.

Pregnancy

There is limited information regarding the safety of apixaban use during pregnancy. Clinical data is currently insufficient to determine if the drug causes birth defects or miscarriage. However, taking an anticoagulant like apixaban may increase the risk of bleeding for both the mother and the fetus, particularly during labor and delivery.

Breastfeeding

It is not known if apixaban is present in human breast milk. Animal studies have shown that the medication passes into the milk of lactating rats. Due to the potential for serious bleeding or other adverse reactions in a nursing infant, breastfeeding is generally not recommended while taking this medication.

Discussion with a Healthcare Provider

Individuals who are pregnant, planning to become pregnant, or breastfeeding should consult their healthcare provider. A doctor can help evaluate the risks of the medication versus the risks of untreated blood clots to determine the most appropriate treatment plan.

Available Forms

Apixaban is available in the following form for oral administration:

• Oral Tablet: These are film-coated tablets designed to be swallowed whole.

For patients who have difficulty swallowing, the tablets may be crushed and mixed with water, apple juice, or applesauce, or administered through a nasogastric tube as directed by a healthcare professional.

FDA Approval and Indications

The U.S. Food and Drug Administration (FDA) first approved apixaban in 2012. It is currently approved for several specific uses related to blood clot prevention and treatment:

• Reducing the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation.
• Treating deep vein thrombosis (DVT) and pulmonary embolism (PE).
• Reducing the risk of DVT and PE recurring after initial treatment.
• Preventing DVT and PE in patients who have recently undergone hip or knee replacement surgery.

Boxed Warnings

The FDA requires a boxed warning—its most serious type of warning—for apixaban due to two significant safety concerns:

• Premature Discontinuation: Stopping apixaban earlier than recommended by a healthcare provider increases the risk of having a stroke or developing other serious blood clots. If the medication must be stopped for reasons other than pathological bleeding or completion of a course of therapy, another anticoagulant should be considered.
• Spinal or Epidural Hematoma: Patients taking apixaban who undergo spinal anesthesia or a spinal puncture are at risk of developing a blood clot (hematoma) near the spine. This can result in long-term or permanent paralysis. Factors that increase this risk include the use of indwelling epidural catheters, the use of other medications that affect bleeding (such as NSAIDs), or a history of traumatic or repeated spinal procedures.

Generic Availability

The FDA approved the first generic versions of apixaban in 2019. While generic versions have received regulatory approval, their actual availability in pharmacies may be affected by patent protections and legal agreements between manufacturers.

Reversal Agent for Apixaban

Apixaban is an anticoagulant that increases the risk of serious or life-threatening bleeding. If an emergency occurs, a specific reversal agent known as andexanet alfa is available to neutralize the effects of the medication.

How the Antidote Works

The reversal agent acts as a decoy that binds to the apixaban in the blood. By doing so, it stops the medication from blocking Factor Xa, which is a protein the body needs to form blood clots. This process helps to restore the blood's ability to clot during a bleeding event.

Clinical Use

This treatment is administered by medical professionals in a hospital setting, typically through an intravenous (IV) injection. It is generally reserved for patients with life-threatening or uncontrolled bleeding. If the specific reversal agent is not available, healthcare providers may consider other options to manage bleeding, such as:

• Prothrombin complex concentrates
• Factor replacement therapies

The effectiveness of these alternative treatments for reversing apixaban is less established than the specific reversal agent.