Class Name(s):

• 10:00 Antineoplastic Agents

Pronunciation:

• (a" va pri' ti nib)

Brand Name(s):

• Ayvakit^®

WHY is this medicine prescribed?

Avapritinib is used to treat a certain type of gastrointestinal stromal tumor (GIST; a type of tumor that grows in the wall of the stomach, intestine [bowel], or esophagus [tube that connects the throat with the stomach]) in adults that has spread to other parts of the body or that cannot be removed by surgery. It is also used to treat certain types of mastocytosis (a blood disorder in which there are too many mast cells [a certain kind of white blood cell]). Avapritinib is in a class of medications called kinase inhibitors. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps to stop or slow the spread of cancer cells.

HOW should this medicine be used?

Avapritinib comes as a tablet to take by mouth. It is usually taken once daily on an empty stomach, at least 1 hour before and 2 hours after a meal. Take avapritinib at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take avapritinib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you vomit after taking avapritinib, do not take another dose. Continue your regular dosing schedule.

Your doctor may decrease your avapritinib dose or temporarily or permanently stop your treatment depending on how well the medication works for you and if you experience any side effects. Be sure to tell your doctor how you are feeling during your treatment with avapritinib. Do not stop taking avapritinib without talking to your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Are there OTHER USES for this medication?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking avapritinib,

• tell your doctor and pharmacist if you are allergic to avapritinib, any other medications, or any of the ingredients in avapritinib tablets. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• The following nonprescription or herbal products may interact with avapritinib: St. John's wort. Be sure to let your healthcare provider know that you are taking this medication before you start taking avapritinib. Do not start this medication while taking avapritinib without talking to your healthcare provider.
• tell your doctor if you have or have ever had bleeding in your brain, low platelet (a type of blood cell) counts, or liver or kidney disease. Also, tell your doctor if you have or have ever had a stroke, especially if it has happened within the past year.
• tell your doctor if you are pregnant, plan to become pregnant, or if you plan on fathering a child. If you can become pregnant, you will need to take a pregnancy test before you start treatment and use birth control to prevent pregnancy during your treatment and for 6 weeks after your final dose. If your partner can become pregnant, you and your partner should use birth control during your treatment and for 6 weeks after your final dose. Talk to your doctor about birth control methods that you can use during your treatment. If you or your partner become pregnant while taking avapritinib, call your doctor immediately. Avapritinib may harm the fetus.
• tell your doctor if you are breast-feeding. You should not breast-feed while you are taking avapritinib and for at least 2 weeks after your final dose.
• you should know that this medication may decrease fertility in men and women. Talk to your doctor about the risks of taking avapritinib.
• you should know that avapritinib may make you dizzy, drowsy, or confused. Do not drive a car or operate machinery until you know how this medication affects you.
• plan to avoid unnecessary or prolonged exposure to sunlight and to wear protective clothing, sunglasses, and sunscreen during your treatment with avapritinib and for 1 week after your final dose. Avapritinib may make your skin sensitive to sunlight.

What SPECIAL DIETARY instructions should I follow?

Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medication.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if the next dose is due in less than 8 hours, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

Avapritinib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• stomach pain
• vomiting
• nausea
• diarrhea
• constipation
• heartburn
• headache
• tiredness or weakness
• difficulty falling asleep or staying asleep
• hair loss
• hair color changes
• weight loss
• teary eyes
• taste changes
• rash
• joint pain
• decreased appetite
• flushing

Some side effects can be serious. If you experience any of these symptoms, stop taking avapritinib and call your doctor immediately or get emergency medical treatment:

• swelling of face, eyes, mouth, or throat
• swelling of hands, ankles, or feet
• vomiting blood or material that looks like coffee grounds or red or tarry black stools
• nosebleeds or other unusual bleeding or bruising
• severe headache, vomiting, confusion, vision problems, drowsiness, extreme tiredness, or weakness on one side of your body
• forgetfulness, confusion, drowsiness or difficulty staying awake, dizziness, trouble thinking, difficulty speaking, hallucinations, or changes in mood or behavior
• shortness of breath
• fever or other signs of infection

Avapritinib may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light excess heat and moisture (not in the bathroom).

Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach. http://www.upandaway.org

Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website http://goo.gl/c4Rm4p for more information.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor may order a lab test before you begin your treatment to see whether your cancer can be treated with avapritinib. Your doctor may order certain lab tests to check your body's response to avapritinib.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™ Copyright, 2025. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: December 15, 2024.