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Burosumab Dosage

Medically reviewed by Drugs.com. Last updated on May 15, 2018.

Applies to the following strengths: 10 mg/mL; 20 mg/mL; 30 mg/mL

Usual Adult Dose for Familial Hypophosphatemia

Initial dose: 1 mg/kg subcutaneously every 4 weeks
-Dose should be rounded to the nearest 10 mg
Maximum dose: 90 mg

Measure serum phosphorus level 2 weeks post-dose for the first 3 months, then as clinically indicated

Maintenance dose: For serum phosphorus levels within the normal range, continue with same dose.

For serum phosphorus levels ABOVE the normal range: Withhold next dose and reassess serum phosphorus level in 4 weeks
-When serum phosphorus level drops below the normal range, reinitiate therapy at approximately one-half the initial starting dose as follows:
--Previous dose: 40 mg; Re-initiation dose: 20 mg
--Previous dose: 50 mg; Re-initiation dose: 20 mg
--Previous dose: 60 mg; Re-initiation dose: 30 mg
--Previous dose: 70 mg; Re-initiation dose: 30 mg
--Previous dose: 80 or 90 mg; Re-initiation dose: 40 mg
-Reassess serum phosphorus 2 weeks after any dose change; do not adjust dose more frequently than every 4 weeks

Comments:
-Discontinue oral phosphate and active vitamin D analogs 1 week prior to treatment initiation. Prior to starting therapy, fasting serum phosphorus concentration should be below the reference range.

Use: Treatment of X-linked hypophosphatemia.

Usual Pediatric Dose for Familial Hypophosphatemia

1 year or older:
Initial dose: 0.8 mg/kg subcutaneously every 2 weeks
-Dose should be rounded to the nearest 10 mg
Minimum dose: 10 mg
Maximum dose: 90 mg

Measure fasting serum phosphorus every 4 weeks for the first 3 months, then as clinically indicated

Maintenance dose: Continue with dose that keeps serum phosphorus level above the lower limit of the reference range for age and below 5 mg/dL; increases and decreases may be made as follows:

For Serum Phosphorus Levels BELOW the Reference Range for Age: INCREASE dose stepwise to approximately 2 mg/kg administered every 2 weeks as follows:
-Weight 10 to 14 kg: First dose increase to 15 mg; Second dose increase to 20 mg
-Weight 15 to 18 kg: First dose increase to 20 mg; Second dose increase to 30 mg
-Weight 19 to 31 kg: First dose increase to 30 mg; Second dose increase to 40 mg
-Weight 32 to 43 kg: First dose increase to 40 mg; Second dose increase to 60 mg
-Weight 44 to 56 kg: First dose increase to 60 mg; Second dose increase to 80 mg
-Weight 57 to 68 kg: First dose increase to 70 mg; Second dose increase to 90 mg
-Weight 69 kg or greater: First dose increase to 90 mg; Second dose increase to 90 mg

For Serum Phosphorus Levels ABOVE the Reference Range for Age: Withhold next dose and reassess serum phosphorus level in 4 weeks
-When serum phosphorus level drops below the reference range for age, reinitiate therapy at a DECREASED dose as follows:
--Previous dose: 10 mg; Re-initiation dose: 5 mg
--Previous dose: 15 mg, 20 mg or 30 mg; Re-initiation dose: 10 mg
--Previous dose: 40 mg or 50 mg; Re-initiation dose: 20 mg
--Previous dose: 60 mg or 70 mg; Re-initiation dose: 30 mg
--Previous dose: 80 or 90 mg; Re-initiation dose: 40 mg
-Reassess serum phosphorus level 4 weeks after dose adjustment; if level is below the reference range for age after re-initiation, increase dose as described above for serum phosphorus levels below the reference range.

Comments:
-Discontinue oral phosphate and active vitamin D analogs 1 week prior to treatment initiation. Prior to starting therapy, fasting serum phosphorus concentration should be below the reference range for age.
-Serum phosphorus levels should be measured 4 weeks after dose adjustments; therapy should not be adjusted more frequently than every 4 weeks.

Use: Treatment of X-linked hypophosphatemia.

Renal Dose Adjustments

Severe renal impairment or ESRD: Contraindicated

Liver Dose Adjustments

No adjustment recommended

Dose Adjustments

Dose interruption and/or dose reduction may be required based on fasting serum phosphorus levels: see Dosing section

Precautions

CONTRAINDICATIONS:
-Concomitant use with oral phosphate and vitamin D analogs
-Treatment initiation when serum phosphorus is within or above the normal range for age
-Severe renal impairment or ESRD

Safety and efficacy have not been established in patients younger than 1 years.

Consult WARNINGS section for additional precautions.

Dialysis

Contraindicated in severe renal impairment and ESRD

Other Comments

Administration advice:
-To be administered subcutaneously by a healthcare provider
-Rotate injection sites (upper arms, upper thighs, buttocks, or any quadrant of abdomen); do not inject into moles, scars, or areas where the skin is tender bruised, red, hard, or not intact
-Maximum volume per injection site: 1.5 mL; if greater volume is needed, split dose and administer into 2 different sites

Missed dose: If a dose is missed, resume as soon as possible at the prescribed dose

Storage requirements:
-Store refrigerated (36F to 46F [2C to 8C]) in original carton until time of use
-Do not freeze or shake vials
-Single-dose vials; discard unused product

General:
-This is the first therapy approved for the treatment of X-linked hypophosphatemia (XLH).
-Oral phosphate and active vitamin D analogs should be discontinued 1 week prior to therapy initiation.

Monitoring:
Fasting serum phosphorus levels:
-Pediatrics: Baseline, every 4 weeks for the first 3 months, 4 weeks after dose adjustments, and as clinically indicated
-Adults: Baseline, monthly for the first 3 months (measured 2 weeks post-dose), 2 weeks after dose adjustments, and as clinically indicated

Patient advice:
-Patients should be instructed to contact their healthcare provider if they develop hypersensitivity or injection site reactions; or new or worsening symptoms of restless leg syndrome.
-Patients should speak to their healthcare provider if they are, or are considering pregnancy; Report pregnancy to the Ultragenyx Adverse Event reporting line at 1-888-756-8657.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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