Rixubis is an FDA-approved prescription medicine used to prevent and control bleeding episodes in people with hemophilia B. Hemophilia B is an inherited bleeding disorder in which the body does not produce enough functional clotting factor IX, a protein needed for normal blood clotting. As a result, bleeding can last longer than normal. People with more severe hemophilia B may also experience spontaneous bleeding, including bleeding into the joints and muscles. 

For people with hemophilia B, factor IX replacement therapies such as Rixubis can help prevent or control bleeding by replacing the deficient clotting factor IX. In this article, we’ll cover important information about Rixubis, including its uses, side effects, dosing, precautions, and more. 

What Is Rixubis?

Rixubis is a recombinant factor IX replacement medicine used to replace deficient factor IX in people with hemophilia B. It contains recombinant (laboratory-produced) coagulation factor IX. Rixubis comes as a lyophilized powder that is mixed with sterile water before use. You will receive it by intravenous infusion (into a vein).

Rixubis was initially approved by the FDA in 2013 for adults with hemophilia B. Later in 2014, its approval was expanded to include children [1][2]. Rixubis is available in several strengths, including 250 IU, 500 IU, 1,000 IU, 2,000 IU, and 3,000 IU [3].

What Is Rixubis Used For?

Rixubis is FDA-approved for adults and children with hemophilia B. It is FDA-approved for [3]:

On-Demand Treatment and Control of Bleeding: A person with hemophilia B can use Rixubis when a bleeding episode occurs. Replacing factor IX increases the amount of clotting factor available in the bloodstream. This helps your body stop the bleeding.

Routine Prophylaxis: You can use Rixubis regularly as a preventive treatment. Regular use of Rixubis increases factor IX activity and helps reduce the frequency of bleeding episodes. 

Perioperative Management: Rixubis can be used around the time of surgery to maintain adequate factor IX activity and reduce the risk of excessive bleeding.

Please note that Rixubis does not cure hemophilia B. Instead, it temporarily replaces the missing clotting factor and helps prevent or control bleeding.

How Does Rixubis Work?

Factor IX is a protein that plays an important role in blood clotting. It participates in a series of reactions known as the coagulation cascade. These reactions eventually produce thrombin, which helps convert fibrinogen into fibrin. Fibrin forms a strong mesh that stabilizes the blood clot.

People with hemophilia B have insufficient factor IX, so this clotting process does not work properly. As a result, they experience bleeding for an unusually long time.

Rixubis contains recombinant factor IX. When infused into a vein, it temporarily increases factor IX activity in the blood, supporting the coagulation cascade and helping the body form stable blood clots to prevent or control bleeding. 

Rixubis Side Effects

Like any medicine, Rixubis can cause side effects. Some are mild, and others are serious enough to need immediate medical attention. Here are some of the common and serious side effects of Rixubis [3][4]:

Common Side Effects

• Unusual or altered taste in the mouth
• Pain in the arms or legs
• A positive test for furin antibodies

Tell your healthcare provider if you experience side effects that are persistent, bothersome, or concerning. 

Serious Side Effects 

Serious side effects from Rixubis are rare, but they can happen. Serious side effects associated with Rixubis include: 

Serious Allergic Reactions: Rixubis can cause serious allergic reactions, including anaphylaxis. Patients should be monitored for signs and symptoms of hypersensitivity. Get emergency care if you develop hives, swelling, chest tightness, trouble breathing, wheezing, dizziness, or fainting.

Factor IX Inhibitors: Some patients can develop neutralizing antibodies, called inhibitors, against factor IX. These inhibitors can reduce the effectiveness of factor IX replacement therapy. Your doctor may test your blood for inhibitors, especially if bleeding doesn’t stop as expected or your factor IX levels don’t rise enough.

Blood Clots: Factor IX medicines have been linked to abnormal blood clot formation inside blood vessels. Your doctor may watch you more closely if you have liver disease, are having surgery, show signs of abnormal clotting, or have other risk factors.

Please note that this is not a list of all possible side effects. Contact your healthcare provider if you experience concerning side effects. Seek emergency medical care for symptoms of a severe allergic reaction, such as difficulty breathing, wheezing, chest tightness, dizziness, fainting, or swelling of the face or throat. 

Dosing of Rixubis

Rixubis is given as an IV infusion after the powder is mixed with sterile water. Your dose and treatment schedule depend on your age, weight, factor IX activity, the location and severity of bleeding, and how you respond to treatment. Your healthcare provider will individualize the dose based on your clinical response and may measure factor IX activity to make sure the desired level is achieved. 

For patients 12 and older, 1 IU/kg of Rixubis raises factor IX activity by about 0.9 IU/dl. For children younger than 12, the increase is about 0.7 IU/dl [3]. Here is the usual recommended dosage [3]:

For Routine Prophylaxis: The recommended dose for adults and children 12 years of age and older is 40 to 60 international units per kg twice weekly. For children younger than 12, the recommended dose is 60–80 IU/kg twice weekly.

For Bleeding Episodes: The dose and treatment duration depend on the location and severity of bleeding and your individual response.

For minor bleeding, the desired factor IX activity is generally 20–30 IU/dl. Treatment is generally given every 12–24 hours for at least 1 day, until healing is achieved.

For moderate bleeding, the desired factor IX activity is generally 25–50 IU/dl. Treatment is generally given every 12–24 hours for 2–7 days, until bleeding stops and healing is achieved.

For major bleeding, the desired factor IX activity is generally 50–100 IU/dl. Treatment is generally given every 12–24 hours for 7–10 days, until bleeding stops and healing is achieved.

For Surgery: Rixubis can be used before, during, and after surgery to maintain adequate factor IX activity and reduce the risk of excessive bleeding. For minor surgery, the target factor IX activity is generally 30–60 IU/dl, with treatment generally given every 24 hours for at least 1 day, until healing is achieved. For major surgery, the target is generally 80–100 IU/dl, with treatment generally given every 8–24 hours for 7–10 days, until healing is achieved. Dosing should be individualized based on factor IX activity and clinical response. 

Before Starting Rixubis

Before you start Rixubis, tell your doctor your full medical history. Let them know if you [4]:

• Have had an allergic reaction to Rixubis or any of its ingredients
• Are allergic to hamster proteins
• Have or have had factor IX inhibitors
• Have liver disease or problems with blood clotting
• Are pregnant, planning to become pregnant, or breastfeeding
• Take prescription medicines, over-the-counter medicines, vitamins, or herbal supplements

A few other things to keep in mind before you start:

• Rixubis is contraindicated in patients with known hypersensitivity to Rixubis or its components, including hamster protein. 
• Tell your doctor about any signs of an allergic reaction during or after your infusion.
• Your doctor may monitor your factor IX levels and check for inhibitors during treatment.
• Don’t use Rixubis to induce immune tolerance. Its safety and effectiveness for that haven’t been established.

Rixubis Cost

The cost of Rixubis can vary considerably depending on the prescribed dose, body weight, frequency of treatment, insurance coverage, specialty pharmacy or distributor, and other factors. Because Rixubis dosing is based partly on body weight and treatment needs, the amount of medication required can differ substantially from one patient to another.

The amount you pay out of pocket may also differ from the medication’s listed or pharmacy price. Patients and caregivers can contact their insurance provider or specialty pharmacy for an estimate based on their prescribed dose and coverage. If cost is a concern, contact us to explore financial and copay assistance for Rixubis.