Factor Replacement Therapy
Factor replacement therapy is a treatment for some bleeding disorders that raises the level of factor that is missing in the body. This therapy allows for better clotting and less bleeding. It is important to work with your health care provider to determine which treatment is best for you.
Often referred to as “factor,” these clotting factor products use a molecule that is either similar to natural factor found in humans (recombinant) or use an actual human molecule (plasma derived.) These treatments increase the amount of factor in the body to levels that lead to better clotting, and therefore less bleeding. There are two types of factor replacement therapies: standard half-life (SHL) and extended half-life (EHL). Click here to see how standard and extended half-life therapies work. Half-life is the amount of time it takes the body to "use up" half of the clotting factor level circulating in the body.
- Standard half-life therapies: Standard half-life therapies are used to treat hemophilia A and B, some types of von Willebrand disease, and some rare factor disorders. Dosing can be anywhere from three times a week to every day, depending on the person.
- Extended half-life (EHL) therapies: EHL factor has been modified in some way so that it takes longer to break down in the body. This means factor levels stay higher for longer, so you have to infuse less often. How long the factor is effective in the body depends on the person. EHLs are mostly used to treat hemophilia A and B.
- Bypassing agents are used to treat bleeds in people with hemophilia with inhibitors. These treatments contain other factors that can help the body form a clot and stop bleeding.
The National Hemophilia Foundation's (NHF) Medical and Scientific Advisory Council (MASAC) encourages using recombinant factor products. Because recombinant products do not contain human blood, they cannot transmit harmful viruses such as hepatitis. Clotting factors that contain human blood are safer today because of better screening of blood donors and better methods to destroy any blood-borne viruses that could be present in the donated blood. Discuss with your health care provider the benefits and challenges of each treatment plan to determine which type of clotting factor product is right for your specific needs.
Learn more about FDA-approved products for the treatment of bleeding disorders.
Factor Replacement Therapy “Infusions”
For factor replacement therapy the medicine is given by an injection into a vein, also known as an intravenous (IV) injection. This process is also called "infusion." Clotting factor products are in the form of dried powder. It is mixed with water to become a liquid that can be given through the infusion. Infusion happens by placing a needle into a vein so that medicine goes through the needle into the vein. This process takes time; it isn't like getting a quick shot.
Patients who are first diagnosed and need immediate treatment will initially be treated at the hemophilia treatment center (HTC), the doctor's office, or the emergency department. Later, patients (or caregivers) will learn to infuse the factor at home (called home therapy).
Various devices (ports, catheters, or PICC lines) may be used to make it easier to administer clotting factor products into the bloodstream. Some of these devices may be surgically inserted under the skin in the chest area. You and your health care provider will decide which device is best for you.
Clotting Factor Amounts
The amount of clotting factor (called factor) needed to treat a particular type of bleeding episode will vary based on some of the conditions below:
- The location of the bleeding site
- If it is a site of repeated bleeding (for example, if it is at a target joint)
- If the bleeding could cause damage to the brain or other vital organs
Sometimes another dose of factor is needed several hours after taking the first dose to stop the bleeding. The amount of factor depends on several other things as well, including:
- Weight - As weight increases, dosages will tend to get larger.
- The number of units in the bottle (called a vial) can vary depending on the product type.
Your treatment team will help you learn how much factor you need and when to treat a potential bleeding episode.
Clotting Factor Half-Life
When factor replacement therapy is given, the level of clotting factor in the blood rises; but this rise lasts only for a certain number of hours based on the factor’s half-life. Half-life is the amount of time it takes the body to "use up" half of the clotting factor level circulating in the body.
Here is a video to learn more about half-life: Making Your Clotting Factor Work for You: Understanding Half-Life in Your Life
If some time has passed since you have infused and you still have pain, stiffness, or other signs of bleeding, you may need another dose of factor treatment. Sometimes another dose of treatment is recommended to be sure that a stable clot has formed, and the bleeding does not start again once the level of clotting factor drops after treatment.
Your HTC can provide exact instructions on when to repeat treatment.
Having factor available is important because you never know when a bleed might occur, and prompt treatment is very important. You should always have factor with you, including when you're home, in the car, on vacation, and even when you go to the emergency room.
The Centers for Disease Control and Prevention's (CDC) rule of thumb is to always have available at least enough clotting factor to give 2 high-dose treatments. This amount is enough to treat a major traumatic event, such as a head bleed.
Talk to your HTC about the factor and supplies you need, their storage and disposal, and how to order supplies.
