Drug information of Burosumab


Drug group:

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.

Mechanism of effect

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. This form of vitamin D enhances intestinal absorption of phosphate and calcium, supporting bone mineralization.


This drug has the ability to reduce the loss of phosphate, to improve pathologically low serum phosphate concentrations and other metabolic changes, as well as to reduce the severity of rickets as seen radiographically. In summary, this drug works to support of bone mineralization.


Steady-state trough: 5.8 mcg/mL

Peak plasma time: 8-11 days

Vd: 8 L

Metabolism: Exact metabolic pathway has not been characterized; expected to degrade into small peptides and amino acids via catabolic pathways

Half-life: ~19 days

Clearance is 0.290 L/day


X-Linked Hypophosphatemia


Indicated for X-linked hypophosphatemia (XLH), a rare inherited form of rickets

1 mg/kg SC q4Weeks; round dose to nearest 10 mg

Not to exceed 90 mg/dose


<1 year: Safety and efficacy not established

≥1 year: 0.8 mg/kg SC q2Weeks; round dose to nearest 10 mg

Minimum weight-based starting dose is 10 mg up to a maximum dose of 90 mg


Hypersensitivity reactions (eg, rash, urticaria) reported; discontinue if serious hypersensitivity reactions occur and initiate appropriate medical treatment

Increases in serum phosphorus to >ULN may be associated with increased risk of nephrocalcinosis; for patients already taking burosumab, dose interruption and/or dose reduction may be required based serum phosphorus levels

Local injection site reactions may occur; discontinue if severe injection site reactions occur and administer appropriate medical treatment

Points of recommendation

At least 1 week before your first injection, stop using oral phosphate and vitamin D medications.

Burosumab doses are based on weight in children. Your child's dose needs may change if the child gains or loses weight.

You may need frequent medical tests. Even if you have no symptoms, tests can help your doctor determine if this medicine is effective.

Pregnancy level

Not assigned

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