This medication is used to treat certain types of cancer (such as lung cancer, thyroid cancer, medullary thyroid cancer, certain other solid tumors). Selpercatinib belongs to a class of drugs known as kinase inhibitors. It works by slowing or stopping the growth of cancer cells.

Read the Patient Information Leaflet if available from your pharmacist before you start taking selpercatinib and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with or without food as directed by your doctor, usually twice daily or three times daily. Swallow the medication whole. Do not crush or chew.

The dosage is based on your weight, medical condition, response to treatment, and other medications you may be taking. Children's dosage may also be based on body size. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Medications which reduce or block stomach acid (such as proton pump inhibitors-PPIs, H2 blockers, antacids) may reduce the absorption of selpercatinib, making it work less well. If you take a PPI (such as omeprazole, lansoprazole), take selpercatinib with food. If you take an antacid, take selpercatinib at least 2 hours before or 2 hours after taking the antacid. If you take a H2 blocker (such as famotidine, ranitidine), take selpercatinib at least 2 hours before or at least 10 hours after taking the H2 blocker.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.

Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of serious side effects will increase.

If you vomit your dose of selpercatinib, do not take another dose. Take your next dose at your regular scheduled time. Do not take two doses at the same time.

Dry mouth, diarrhea, constipation, headache, cough, swelling ankles/feet, nausea, vomiting, or tiredness may occur. Nausea and vomiting can be severe. In some cases, your doctor may prescribe medication to prevent or relieve nausea and vomiting. Eating several small meals, not eating before treatment, or limiting activity may help lessen some of these effects. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high. Your doctor may control your blood pressure with medication.

Tell your doctor right away if you have any serious side effects, including:

• easy bruising/bleeding
• poor wound healing
• signs of underactive thyroid (such as weight gain, unusual tiredness, cold intolerance)
• signs of liver disease (such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine)
• signs of lung problems (such as new or worsening shortness of breath, cough)
• hip/knee pain (in children)

Get medical help right away if you have any very serious side effects, including:

• signs of stomach/intestinal bleeding (such as bloody/black/tarry stools, stomach/abdominal pain, bloody vomit, vomit that looks like coffee grounds)
• fast/irregular heartbeat
• severe dizziness
• fainting

Selpercatinib sometimes causes side effects due to the rapid destruction of cancer cells (tumor lysis syndrome). To lower your risk, your doctor may add a medication and tell you to drink plenty of fluids. Tell your doctor right away if you have symptoms such as:

• low back/side pain (flank pain)
• signs of kidney problems (such as painful urination, pink/bloody urine, change in the amount of urine)
• muscle spasms/weakness

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking selpercatinib, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• liver problems
• high blood pressure

Selpercatinib may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using selpercatinib, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions:

• certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG)
• family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death)

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using selpercatinib safely.

Before having any surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Your doctor or dentist may tell you to stop taking selpercatinib at least 1 week before surgery. This medication may cause wounds to heal more slowly. Follow all instructions about when to stop or restart this medication.

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using selpercatinib. Selpercatinib may harm an unborn baby. Your doctor should order a pregnancy test before you start this medication. Men and women using this medication should ask about reliable forms of birth control during treatment and for some time after the last dose. If you or your partner becomes pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug and for some time after the last dose. Consult your doctor before breastfeeding.

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include tovorafenib, among others.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others.

Lab and/or medical tests (such as liver/thyroid function, heart exam, blood mineral levels, complete blood counts) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments.

If you miss a dose, take it as soon as you remember. If it less than 6 hours before the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.