Class Name(s):

• 90:28.20.92 Interferon Gamma Inhibitor Agents, Miscellaneous

Pronunciation:

• (em" a pal' ue mab)

Brand Name(s):

• Gamifant^®

WHY is this medicine prescribed?

Emapalumab-lzsg injection is used to treat primary hemophagocytic lymphohistiocytosis (HLH; a condition in which the immune system overreacts and damages blood cells, the liver, spleen, and other organs) and HLH/macrophage activation syndrome (MAS; a serious or life-threatening condition in which the body attacks its own tissues) in certain patients with Still's disease (a condition that causes inflammation, fever, rash, headache, fatigue, and joint and muscle pain), including systemic juvenile idiopathic arthritis (SJIA). Emapalumab-lzsg injection is in a class of medications called monoclonal antibodies. It works by blocking the action of a certain protein in the immune system that causes inflammation.

HOW should this medicine be used?

Emapalumab-lzsg comes as a liquid to be injected intravenously (into a vein) over 1 hour by a doctor or nurse in a hospital or medical facility. Your doctor will tell you how often you will receive emapalumab-lzsg injection. The schedule depends on the condition you have and on how your body responds to the medication.

Emapalumab-lzsg injection may cause a severe reaction during or shortly after the infusion of the medication. A doctor or nurse will monitor you carefully while you are receiving the medication. If you experience any of the following symptoms, tell your doctor immediately: skin redness; itching; fever; rash; excessive sweating; chills; nausea; vomiting; lightheadedness; dizziness; headache; bone pain; burning, numbness, or tingling feeling; cold arms, hands, legs, or feet; chest pain; or shortness of breath.

You will be given the Medication Guide when you begin treatment with emapalumab-lzsg injection and each time you receive the medication. Read the information carefully and ask your doctor or pharmacist if you have any questions. You can also visit http://www.fda.gov/Drugs/DrugSafety/ucm085729.htm to obtain the Medication Guide.

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 receiving emapalumab-lzsg injection,

• tell your doctor or pharmacist if you are allergic to this drug, any part of this drug, or any other drugs, foods or substances. Tell your doctor or pharmacist about the allergy and what symptoms you had.
• tell your doctor if you have or have ever had any medical condition.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products 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.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while receiving emapalumab-lzsg injection, call your doctor.
• you should know that emapalumab-lzsg injection may decrease your ability to fight infections and increase the risk that you will get a serious or life-threatening infection. Tell your doctor if you often get any type of infection or if you have or think you may have any type of infection now. This includes minor infections (such as open cuts or sores), infections that come and go (such as herpes or cold sores), and chronic infections that do not go away. Also tell your doctor if you have or if you ever have had herpes zoster (shingles) or a fungal infection such as histoplasmosis. If you experience any of the following symptoms during or shortly after your treatment, call your doctor immediately: fever, sweats, or chills; muscle aches; cough; bloody mucus; shortness of breath; sore throat or difficulty swallowing; warm, red, or painful skin or sores on your body; diarrhea; stomach pain; frequent, urgent, or painful urination; or other signs of infection.
• you should know that you may be infected with tuberculosis (TB; a serious lung infection) but do not have any symptoms of the disease. In this case, emapalumab-lzsg injection may increase the risk that your infection will become more serious and you will develop symptoms. Tell your doctor if you have or have ever had TB, if you have lived in a country where TB is common, or if you have been around someone who has TB. Your doctor will check you for TB before starting treatment. Your doctor may treat you for TB if you have a history of TB or have active TB. If you have any of the following symptoms of TB or if you develop any of these symptoms during your treatment, call your doctor immediately: cough, coughing up blood or mucus, weakness or tiredness, weight loss, loss of appetite, chills, fever, or night sweats.
• do not have any vaccinations without talking to your doctor during your treatment and for at least 4 weeks after your final dose.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What SIDE EFFECTS can this medicine cause?

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

• constipation
• nose bleeds
• irritability
• swelling in the hands, feet, ankles, or lower legs

Some side effects can be serious. If you experience any of these symptoms or those listed in the HOW section and SPECIAL PRECAUTIONS section, call your doctor immediately or get emergency medical treatment:

• fast, slow, or irregular heartbeat
• fast breathing
• bloody or black, tarry stools; or vomiting blood or brown material that resembles coffee grounds

Emapalumab-lzsg injection 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 OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will check your blood pressure regularly and will order certain lab tests before and during your treatment to check your body's response to the medication.

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: October 15, 2025.