Burosumab (CRYSVITA®)
What are bones made of?
Bones are made up of many minerals including calcium and phosphorus.
Low phosphorus levels in the body can lead to poor bone health and symptoms may include bone pain, bowed legs, and softer, weaker bones.
What is X-linked hypophosphatemia?
X-linked hypophosphatemia (XLH) is a genetic disease caused by mutations in the PHEX gene. Mutations in this gene lead to excess production of a protein, Fibroblast Growth Factor 23 (FGF23), which regulates phosphorus levels in your body. Excess FGF23 blocks phosphorus reabsorption by the kidney and suppresses vitamin D-mediated intestinal absorption of phosphorus, leading to low phosphorus levels in the body. Symptoms of XLH tend to appear when a child begins to bear weight on his/her legs.
What is Burosumab and how does it work?
Burosumab is a new medication that is now FDA approved for treating patients with XLH. Burosumab works by attaching to and stopping FGF23 from working. With treatment, your body may be better able to control phosphorus levels.
How is it given?
Burosumab is given as an injection (shot) under the skin similar to a vaccine. It is typically given every two weeks for patients < 17 years and every four weeks for patients > 18 years of age.
Is there anything I should know before getting Burosumab?
Supplements such as phosphorus, calcitriol and other forms of vitamin D are typically stopped at least one week prior to starting burosumab treatment. Your doctor will tell you when to stop and whether to restart taking these supplements. Before starting burosumab, your doctor will measure the amount of phosphorus in your body.
Is there anything I should know after getting Burosumab?
The most common side effects from burosumab in children are headache, pain or redness near where the injection was given, vomiting, fever and body aches. Most side effects are usually mild, happen within one day of getting the injection, and usually go away within one to three days without needing treatment. To see if the medication is working well, your doctor will measure the amount of phosphorus in your body once every four weeks for the first 12 weeks of treatment.
Where should I keep my Burosumab?
Each vial should be kept in its original box and refrigerated until you need to use it. Do not freeze or shake the vial and do not use the medication after the expiration date on the box. Each vial is meant to be used once. Throw away any medication left in the vial after giving the injection.