Pronunciation:

fos-ta-MA-ti-nib dye-SOE-dee-um

Classifications:

Pharmacologic—

Fostamatinib

Uses of This Medicine:

Fostamatinib is used to treat low platelet levels (thrombocytopenia) in the blood in patients with chronic immune thrombocytopenia (ITP) who have received treatment that did not work well.

This medicine is available only with your doctor's prescription.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies—

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children—

Appropriate studies on the relationship of age to the effects of fostamatinib have not been performed in the pediatric population. Use is not recommended in children. Safety and efficacy have not been established.

Older adults—

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of fostamatinib in the elderly. However, elderly patients are more likely to have serious unwanted effects, which may require caution in patients receiving fostamatinib.

Breast-feeding—

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Abametapir
• Carbamazepine
• Enzalutamide
• Fedratinib
• Fexinidazole
• Fosphenytoin
• Itraconazole
• Lumacaftor
• Mavacamten
• Mitotane
• Omaveloxolone
• Phenobarbital
• Phenytoin
• Primidone
• Rifampin
• Rosuvastatin
• St John's Wort
• Voriconazole

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems—

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Blood clot in your leg or lungs, recent or
• Hypertension (high blood pressure) or
• Infection, recent or
• Liver disease or
• Surgery (eg, splenectomy)—Use with caution. May cause side effects to become worse.

Proper Use of This Medicine:

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

This medicine should come with a patient information leaflet. Read and follow these instructions carefully. Ask your doctor if you have any questions.

You may take this medicine with or without food.

Dosing—

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):
  • For thrombocytopenia:
    • Adults—The starting dose is usually 100 milligrams (mg) 2 times a day. Your doctor may increase your dose as needed.
    • Children—Use is not recommended.

Missed dose—

If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using This Medicine:

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine and for at least 1 month after the last dose. If you think you have become pregnant while using this medicine, tell your doctor right away.

Your blood pressure might get too high while you are using this medicine. This may cause headaches, dizziness, or blurred vision. You might need to measure your blood pressure at home. If you think your blood pressure is too high, call your doctor right away.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

Black, tarry, stools

blurred vision

chest pain

chills

cough

diarrhea

dizziness

fever

headache

lower back or side pain

nervousness

painful or difficult urination

pale skin

pounding in the ears

slow or fast heartbeat

sore throat

stomach pain

ulcers, sores, or white spots in the mouth

unusual bleeding or bruising

unusual tiredness or weakness

Check with your doctor immediately if any of the following side effects occur:

More common

Nausea

rash

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.