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| Monoclonal antibody | |
|---|---|
| Type | Whole antibody |
| Source | Human |
| Target | FGF 23 |
| Names | |
| Pronunciation | bur OH sue mab |
| Trade names | Crysvita |
| Other names | KRN-23, KRN23, burosumab-twza |
| Clinical data | |
| Main uses | X-linked hypophosphatemia, tumor-induced osteomalacia[1] |
| Side effects | Fever, pain at the site of injection, cough, headache, restless leg syndrome, cavities, tooth abscess[1] |
| Pregnancy category |
|
| Routes of use | Subcutaneous |
| External links | |
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a618034 |
| Legal | |
| License data | |
| Legal status | |
| Pharmacokinetics | |
| Elimination half-life | 16.4 days[7] |
| Chemical and physical data | |
| Formula | C6388H9904N1700O2006S46 |
| Molar mass | 144090.15 g·mol−1 |
Burosumab, sold under the brand name Crysvita, is a medication used to treat X-linked hypophosphatemia and tumor-induced osteomalacia.[1] It may be used in those over 5 months old.[1] It is given by injection under the skin.[8]
Common side effects include fever, pain at the site of injection, cough, headache, restless leg syndrome, cavities, and tooth abscess.[1] Other side effects may include allergic reactions, high phosphate, and nephrocalcinosis.[1] Safety in pregnancy is unclear.[1] It is a monoclonal antibody that binds to and blocks the protein FGF23, allowing the kidneys to reabsorb phosphate.[9]
Burosumab was approved for medical use in the United States and Europe in 2018.[1][9] In the United States 30 mg costs about 12,200 USD as of 2022.[10]
In the United States, burosumab is indicated for the treatment of adults and children ages one year and older with x-linked hypophosphatemia (XLH), a rare, inherited form of rickets,[11] and for the treatment of people age two and older with tumor-induced osteomalacia (TIO), a rare disease that is characterized by the development of tumors that cause weakened and softened bones.[12] The tumors associated with TIO release a peptide hormone-like substance known as fibroblast growth factor 23 (FGF23) that lowers phosphate levels.[12]
In the European Union, burosumab is indicated for the treatment of X-linked hypophosphataemia with radiographic evidence of bone disease in children one year of age and older and adolescents with growing skeletons.[9]
XLH is genetic disorder affecting phosphate metabolism within the body, which results in hypophosphatemia. The disease is characterized by overproduction of the FGF23 hormone in bone cells. The FGF23 hormone is responsible for blocking phosphate re-absorption by the kidney and the suppression of the vitamin D dependent phosphate absorption by the intestine. Due to the excess activity of FGF23, phosphate levels in the blood are abnormally low, which affects the constitution of bone.[13] Thus, burosumab is designed to bind to the FGF23 receptor and inhibit the excess activity of the FGF23 hormone within the body.[medical citation needed]
While burosumab is effective for the treatment of X-linked hypophosphatemia, the National Institute for Health and Care Excellence in England and Wales initially raised concerns regarding the incremental cost-effectiveness of the new treatment[14] but the drug is available through a simple discount scheme.[15]
The dose in adults is 1 mg/kg of body weight, up to a maximum dose of 90 mg every four weeks.[9] The dose in children is 0.8 mg/kg of body weight, up to a maximum dose of 90 mg every two weeks.[9]
This drug was developed by Ultragenyx and is in a collaborative license agreement with Kyowa Hakko Kirin.[16]
The FDA approval fell under both the breakthrough therapy and orphan drug designations.[11][17] The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication.[18]
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