Product Information

Registration Status: Active

CRYSVITA® SOLUTION FOR INJECTION 20 MG/ML is approved to be sold in Singapore with effective from 2021-05-03. It is marketed by KYOWA KIRIN ASIA PACIFIC PTE LTD, with the registration number of SIN16176P.

This product contains Burosumab 20 mg/ml in the form of INJECTION, SOLUTION. It is approved for SUBCUTANEOUS use.

This product is manufactured by KYOWA KIRIN CO. in JAPAN.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.



Burosumab (KRN23) is an entirely human monoclonal IgG1 antibody that binds excess fibroblast growth factor 23 (FGF23) and has been successfully tested in clinical trials in children with X-linked hypophosphatemic rickets [A32593]. The U.S. Food and Drug Administration approved Crysvita (burosumab) in April 2018. This is the first drug approved to treat adults and children ages 1 year and older with X-linked hypophosphatemia (XLH), which is a rare, inherited form of rickets. X-linked hypophosphatemia causes low circulating levels of phosphorus in the blood. It causes impaired bone growth and development in children and adolescents and issues with bone mineralization throughout a patient’s life [L2346]. XLH is a serious disease which affects about 3,000 children and 12,000 adults in the United States. Most children with XLH suffer from bowed or bent legs, short stature, bone pain and severe dental pain. Some adults with this condition suffer from persistent, unrelenting discomfort and complications, such as joint pain, impaired mobility, tooth abscesses and hearing loss [L2346].


This drug is indicated for the treatment of X-linked hypophosphatemia with radiological evidence of bone disease in children of 1 year of age and older and adolescents with growing skeletons [L2347].

Mechanism of Action

Burosumab is a recombinant human monoclonal antibody (IgG1) that both binds to and inhibits the actions of fibroblast growth factor 23 (FGF23). By inhibiting this growth factor, burosumab increases the tubular reabsorption of phosphate from the kidney and thus increases serum concentration of 1, 25 dihydroxy-Vitamin D [L2347]. This form of vitamin D enhances intestinal absorption of phosphate and calcium, supporting bone mineralization [L2351].


Burosumab absorption after subcutaneous injection sites into to the blood circulation is nearly complete. Following the subcutaneous route of administration, the time to reach maximum serum concentrations (Tmax) of burosumab is estimated at 5-10 days. The peak serum concentration (Cmax) and area under the concentration-time curve (AUC) of serum burosumab is proportional to the dose, over the dose range of 0.1-2.0 mg/kg [L2347].
Burosumab is comprised solely of amino acids and carbohydrates as a native immunoglobulin and is not likeluy to be eliminated by hepatic metabolic mechanisms. The metabolism of burosumab and elimination are expected to follow the immunoglobulin clearance pathways, which results in its degradation to smaller peptides and amino acids [L2347].
Burosumab is composed solely of amino acids and carbohydrates as a native immunoglobulin and is unlikely to be eliminated via hepatic metabolic mechanisms. Its metabolism and elimination are expected to follow the immunoglobulin clearance pathways, resulting in degradation to small peptides and individual amino acids [L2347].


The clearance of burosumab depends on weight and is estimated to be 0.290 L/day and 0.136 L/day in a typical adult (70 kg) and pediatric (30 kg) XLH patient, respectively [L2347].


The toxicity of Crysvita can be classified into several categories [L2347]: **Ectopic mineralisation**: Clinically manifested by nephrocalcinosis, has been seen in patients with XLH treated with oral phosphorous and vitamin D analogues. These drugs should be stopped at least 1 week before starting burosumab treatment [L2347]. Monitoring for signs and symptoms of nephrocalcinosis, e.g. by renal ultrasonography, is recommended at the beginning of treatment and at intervals of every 6 months for the first 12 months of treatment, and yearly thereafter. Regular monitoring of plasma alkaline phosphatases, Calcium, PTH, and creatinine is advised at 6 months intervals(every 3 months for children 1- 2 years) or as indicated [L2347]. Monitoring of urine calcium and phosphate is suggested every 3 months. **Hyperphosphatemia** Fasting serum phosphate level must be followed due to the risk of hyperphosphatemia while taking this drug. To decrease the risk for ectopic mineralization, it is advised that fasting serum phosphate is aimed to be in the lower end of the normal reference range for any given age. Dose interruption and/or dose reduction may be required. Regular measurement of postprandial serum phosphate is advised [L2347]. **Serum parathyroid hormone increases** Increases in serum parathyroid hormone have been measured in some XLH patients while undergoing treatment with burosumab. Regular measurement of serum parathyroid hormone is recommended [L2347]. **Injection site reactions** Administration of burosumab, like other injections, can lead to local injection site reactions. Administration of this drug should cease in any patient experiencing severe injection site reactions and appropriate medical therapy administered [L2347]. **Hypersensitivity** Burosumab should be discontinued if serious hypersensitivity reactions occur and appropriate medical treatment should be provided [L2347]. **Reproductive toxicity/pregnancy** There are no or limited amount of data available from the use of burosumab in pregnant women. Studies in animals have demonstrated reproductive toxicity. Burosumab use is not advised during pregnancy and in women of childbearing potential/age currently not using contraception [L2347].

Active Ingredient/Synonyms

Burosumab (genetical recombination) | burosumab-twza | Burosumab |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank