Burosumab-twza Injection

Burosumab-twza injection is used to treat X-linked hypophosphatemia (XLH; an inherited disease where the body doesn't maintain phosphorus and that leads to weak bones) in adults and children 6 months of age and older. It is also used to treat tumor-induced osteomalacia (a tumor that causes a loss of phosphorus in the body that leads to weak bones) that cannot be surgically removed in adults and children 2 years of age and older, Burosumab-twza injection is in a class of medications called fibroblast growth factor 23 (FGF23) blocking antibodies. It works by blocking the action of a certain natural substance in the body which causes the symptoms of XLH.

Burosumab-twza injection comes as a solution (liquid) to be injected subcutaneously (under the skin) by a doctor or nurse. For the treatment of X-linked hypophosphatemia, it is usually injected once every 2 weeks for children 6 months to 17 years of age, and once every 4 weeks for adults. For the treatment of tumor-induced osteomalacia, in children 2 to 17 years of age, it is usually injected once every 2 weeks. For the treatment of tumor-induced osteomalacia in adults, it is usually injected every 4 weeks and as the dose is increased it may be injected every 2 weeks. Your doctor or nurse will inject the medication in either your upper arm, upper thigh, buttocks, or stomach area, and use a different injection site each time.

Tell your doctor if you are taking any phosphate supplements or certain vitamin D supplements such as calcitriol (Rocaltrol) or paricalcitol (Zemplar). You will need to stop taking these 1 week before you start treatment.

Your doctor may increase your dose (not more than once every 4 weeks), or may skip a dose, depending on the results of your lab tests.

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

Before using burosumab-twza injection,

• tell your doctor and pharmacist if you are allergic to burosumab-twza, any other medications, or any of the ingredients in burosumab-twza injection. Ask your pharmacist for a list of the ingredients.
• some medications should not be taken with burosuma-twza injection. Other medications may cause dosing changes or extra monitoring when taken with burosuma-twza injection. Make sure you have discussed any medications you are currently taking or plan to take before using burosuma-twza injection with your doctor and pharmacist. Before starting, stopping, or changing any medications while using burosuma-twza injection, please get the advice of your doctor or pharmacist
• tell your doctor if you have kidney disease. Your doctor may tell you not to use burosumab-twza injection.
• tell your doctor if you have or have ever had restless leg syndrome (RLS; a condition that causes discomfort in the legs and a strong urge to move the legs, especially at night and when sitting or lying down).
• tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while receiving burosumab-twza injection, call your doctor.

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

If you miss an appointment to receive a dose, make another appointment as soon as possible.

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

• headache
• vomiting
• fever
• pain in arms, legs, or back
• muscle pain
• constipation
• dizziness

Some side effects can be serious. If you experience any of these symptoms, call your doctor:

• redness, rash, hives, itching, swelling, pain, or bruising near or at the spot that the medication was injected
• rash or hives
• discomfort in the legs; a strong urge to move the legs, especially at night and when sitting or lying down

Burosumab-twza injection may cause other side effects. Call your doctor if you have any unusual problems while receiving 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 (https://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests before and during your treatment to check your body's response to burosumab-twza injection.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

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