What Are Inhibitors?

What Are Inhibitors?

Inhibitors, A to B.

Inhibitors might seem mysterious. But understanding them better can help you understand your condition. And get on with life.

What's an inhibitor, anyway?2,3


  • People with hemophilia A or B can develop inhibitors, which prevent their factor VIII or IX treatment from working to form a clot to stop bleeding.

    People with hemophilia A or B can develop inhibitors, which prevent their factor VIII or IX treatment from working to form a clot to stop bleeding.
  • People with hemophilia lack certain clotting factor proteins necessary to control bleeds.

    Their treatment contains factor that replaces missing proteins and helps their blood clot.

    People with hemophilia lack certain clotting factor proteins necessary to control bleeds. Their treatment contains factor that replaces missing proteins and helps their blood clot.
  • But for some people, the factor may suddenly stop working—and antibodies are to blame.

    Antibodies are a part of your body's natural defense system, attacking foreign substances that enter the body. They're valuable for fending off viruses and bacteria.

    Antibodies are a part of your body’s natural defense system, attacking foreign substances that enter the body. They’re valuable for fending off viruses and bacteria.
  • For some people with hemophilia, these antibodies view the factor treatment as foreign and attack it, stopping it from working. The antibodies are called inhibitors.

    For some people with hemophilia, these antibodies view the factor treatment as foreign and attack it, stopping it from working. Those antibodies are called inhibitors.

  • People with hemophilia A or B can develop inhibitors, which prevent their factor VIII or IX treatment from working to form a clot to stop bleeding.

    People with hemophilia A or B can develop inhibitors, which prevent their factor VIII or IX treatment from working to form a clot to stop bleeding.
  • People with hemophilia lack certain clotting factor proteins necessary to control bleeds.

    Their treatment contains factor that replaces missing proteins and helps their blood clot.

    People with hemophilia lack certain clotting factor proteins necessary to control bleeds. Their treatment contains factor that replaces missing proteins and helps their blood clot.
  • But for some people, the factor may suddenly stop working—and antibodies are to blame.

    Antibodies are a part of your body's natural defense system, attacking foreign substances that enter the body. They're valuable for fending off viruses and bacteria.

    Antibodies are a part of your body’s natural defense system, attacking foreign substances that enter the body. They’re valuable for fending off viruses and bacteria.
  • For some people with hemophilia, these antibodies view the factor treatment as foreign and attack it, stopping it from working. The antibodies are called inhibitors.

    For some people with hemophilia, these antibodies view the factor treatment as foreign and attack it, stopping it from working. Those antibodies are called inhibitors.

Inhibitors can happen.

Inhibitors usually appear in young children. But they can develop at any age.4 Some people with hemophilia may be more at risk for getting inhibitors than others.

Severe hemophilia A
up to 3 out of every 10 people5

Hemophilia B
up to 1 out of every 20 people5

Who's most at risk for developing inhibitors?6

  • People with severe hemophilia
  • Children (inhibitors usually develop during childhood)
  • People with a family history of inhibitors
  • African-Americans and Hispanics (higher frequency of inhibitors)7

Some people with hemophilia A or B may develop inhibitors in response to a treatment that contains factor VIII or factor IX. Most inhibitors appear within the first 150 days of exposure to factor VIII.2,8

We don't know why some people get inhibitors and others don't, but scientists are trying to find out.

Complications: 5 things to know

1

Severe hemophilia patients with inhibitors don't bleed more often than other severe hemophilia patients. But their bleeds are more difficult to manage because they don't always respond to standard treatment.9

2

Inhibitor patients may develop serious complications, like uncontrollable bleeding, joint disease, and disabilities.4,10

3

Moderate and mild hemophilia patients may experience a change in bleeding pattern. They're also at risk for serious complications; many experience severe spontaneous bleeding in joints and muscles.11

4

Patients with inhibitors are at increased risk for life-threatening bleeding and are hospitalized more frequently.12

5

Surgeons may be reluctant to perform joint procedures and other operations meant to help improve an inhibitor patient's joint condition and mobility if they're concerned about uncontrollable bleeding.13

FEIBA. Made to help manage inhibitors.

Inhibitors aren't easy to understand. But they may be manageable.

Want to learn more? Check out our About FEIBA page.

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FEIBA [Anti-Inhibitor Coagulant Complex] Indications

What is FEIBA used for?
FEIBA (Anti-Inhibitor Coagulant Complex) is used for people with Hemophilia A or B with Inhibitors to control and prevent bleeding episodes, before surgery, or routinely to prevent or reduce the number of bleeding episodes. It is NOT used to treat bleeding conditions without inhibitors to Factor VIII or Factor IX.

Detailed Important Risk Information

When should I not take FEIBA?
You should not take FEIBA if you have had hypersensitivity or an allergic reaction to FEIBA or any of its components, including factors of the kinin generating system, if you have a condition called Disseminated Intravascular Coagulation, which is small blood clots in various organs throughout the body, or currently have blood clots or are having a heart attack. Make sure to talk to your healthcare provider about your medical history.

What Warnings should I know about FEIBA?
FEIBA can cause blood clots, including clots in the lungs, heart attack, or stroke, particularly after high doses of FEIBA or in people with a high risk of blood clots. Patients that have a risk of developing blood clots should discuss the risks and benefits of FEIBA with their healthcare provider since FEIBA may cause blood clots. FEIBA can cause hypersensitivity or allergic reactions and infusions site reactions, and these reactions can be serious. Because FEIBA is made from human plasma, it may carry the risk of transmitting infectious agents, for example, viruses, including Creutzfeldt-Jakob disease (CJD) agent, and the variant CJD agent. Although steps have been taken to minimize the risk of virus transmission, there is still a potential risk of virus transmission.

What should I tell my healthcare provider?
Make sure to discuss all health conditions and medications with your healthcare provider. If you are pregnant or are planning to become pregnant, or are a nursing mother, make sure to talk with your healthcare provider for advice on using FEIBA.

What are the side effects of FEIBA?
The most frequent side effects of FEIBA are: low red blood cell count, diarrhea, joint pain, hepatitis B surface antibody positivity, nausea, and vomiting. The most serious side effects of FEIBA include: hypersensitivity reactions, including anaphylaxis, stroke, blood clots in the lungs, and blood clots in the veins. Always immediately talk with your healthcare provider if you think you are experiencing a side effect.

What other medications might interact with FEIBA?
The use of other clotting agents with FEIBA is not recommended, for example, tranexamic acid and aminocaproic acid. Be sure to talk with your healthcare provider and pharmacist about all medications and supplements you are taking.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.

The risk information provided here is not comprehensive. To learn more, talk about FEIBA with your healthcare provider or pharmacist. The FDA-approved product labeling can be found at http://www.feiba.com/us/forms/feiba_pi.pdf or by calling 1-800-423-2090 and selecting option 5.