Tavalisse (Fostamatinib Disodium Hexahydrate) for Immune Thrombocytopenia

Tavalisse (fostamatinib disodium hexahydrate) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat adults with chronic immune thrombocytopenia (ITP).

How Tavalisse Works and How It’s Taken

Tavalisse is a type of medicine called a kinase inhibitor. It works through its active form, called R406. R406 blocks spleen tyrosine kinase (SYK), which helps send immune signals.

This can help reduce the immune system’s destruction of platelets, which may raise platelet counts.

Doctors prescribe Tavalisse for adults with chronic ITP when a previous treatment for ITP did not work well enough.

Tavalisse comes as a tablet taken by mouth. It may be taken with or without food.

Typical Dosing for Immune Thrombocytopenia

Starting dose — Take 100 milligrams by mouth twice daily.
After one month — Your doctor may increase the dose to 150 milligrams twice daily if your platelet count has not increased to at least 50 × 10⁹/L.
Ongoing treatment — Doctors use the lowest dose needed to reach and maintain a platelet count of at least 50 × 10⁹/L, as needed to lower the risk of bleeding. They may lower the dose, pause treatment, or stop treatment if side effects occur.
Discontinuation — Tavalisse should be stopped after 12 weeks if the platelet count does not increase enough to help avoid clinically important bleeding.

This information is based on prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

Tavalisse Side Effects

In clinical studies of Tavalisse in adults with chronic ITP who did not respond well enough to a previous treatment, common side effects occurred in about 6 percent to 31 percent of people. These include:

Diarrhea
Hypertension (increased blood pressure)
Nausea
Respiratory infection (such as a cold)
Dizziness
Increased liver enzymes (ALT or AST, which can be a sign of liver problems)
Rash
Abdominal pain (stomach pain)
Fatigue (feeling unusually tired)
Chest pain
Neutropenia (low neutrophils, a type of white blood cell)

Serious Side Effects and Warnings

Hypertension — Increased blood pressure during treatment can be severe.
Hepatotoxicity — Liver problems, including liver injury, can occur and may cause severe changes in liver blood tests.
Severe diarrhea — Diarrhea can become severe and may lead to dehydration.
Neutropenia and febrile neutropenia — Low neutrophil counts, sometimes with fever, can raise the risk of infection.
Embryo-fetal toxicity — Tavalisse can harm your baby if you are pregnant.

Get medical help right away if you think you are having a serious reaction.

How To Save on Tavalisse

Rigel Pharmaceuticals, the manufacturer of Tavalisse, offers the TAVALISSE Copay Assistance Program. The program also offers support through RIGEL ONECARE, including help understanding insurance coverage, determining eligibility for copay and financial assistance programs, enrolling in available support programs, and answering questions during treatment.

To learn more, visit the TAVALISSE Copay Assistance Program or Rigel OneCare, or call 833-744-3562 or 650-449-8646.

What To Know Before Taking Tavalisse

Before starting Tavalisse, your doctor will check baseline blood tests, including a complete blood count that measures platelets. Your doctor will also check liver blood tests and your blood pressure.

Your doctor will check whether you are pregnant before you start Tavalisse if you can become pregnant.

Tell your doctor if you have any allergies to fostamatinib disodium hexahydrate or any ingredients in Tavalisse.

Tell your doctor about all medicines you take, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements.

Before you take Tavalisse, tell your doctor about all of your medical conditions, including if you have:

High blood pressure
Liver problems

If you miss a dose of Tavalisse, take your next dose at its regularly scheduled time.

If you are pregnant, planning to become pregnant, or breastfeeding, talk with your doctor about the risks and benefits before starting Tavalisse.

Tavalisse can harm your baby if you are pregnant. If you can become pregnant, use effective birth control during treatment and for at least one month after your last dose.

Do not breastfeed during treatment with Tavalisse and for at least one month after your last dose.

Community FAQs

These answers are fact-checked by our editorial staff.

How effective is Tavalisse for ITP?

Tavalisse was studied in two clinical studies that lasted 24 weeks. The studies included adults with persistent or chronic ITP who had not responded well enough to earlier treatment.

In one study, 18 percent of people taking Tavalisse had a stable platelet response. This was compared with 0 percent of people taking placebo (an inactive treatment).

In the other study, 16 percent of people taking Tavalisse had a stable platelet response. This was compared with 4 percent of people taking placebo.

A stable platelet response meant having a platelet count of at least 50 × 10⁹/L on at least four of the six visits between weeks 14 and 24.

In these studies, rescue medicine was needed by 30 percent of people taking Tavalisse and 45 percent of people taking placebo.

How long does Tavalisse take to work for ITP?

The prescribing information does not give an exact time for when each person may improve.

The recommended starting dose is 100 milligrams by mouth twice daily. After one month, your doctor may increase the dose to 150 milligrams twice daily if your platelet count has not increased to at least 50 × 10⁹/L.

Tavalisse should be stopped after 12 weeks of treatment if the platelet count does not increase enough to help avoid clinically important bleeding.

What tests or monitoring are needed with Tavalisse for ITP?

Your doctor will check your blood counts, including platelet counts, every month until your platelet count is stable at 50 × 10⁹/L or higher. After that, your doctor will continue checking your blood counts regularly, including neutrophils, a type of white blood cell.

Your doctor will also check liver blood tests every month. Your blood pressure should be checked every two weeks until your dose is stable, then every month.