CRYSVITA® (burosumab-twza) dosing, administration, and storage

CRYSVITA has a simple dosing schedule

CRYSVITA is given every 2 weeks in children

Every 2 weeks for children (6 months to <18 years of age)1,*

CRYSVITA is given every 4 weeks in adults

Every 4 weeks for adults (≥18 years of age)1

*Effectiveness in patients aged 6 months to 1 year and adolescents is supported by evidence from the studies in pediatric patients aged 1 to <13 years with additional modeling and simulation of adult and pediatric pharmacokinetic (PK) and pharmacodynamic (PD) data to inform dosing.

All patients should discontinue oral phosphate and/or active vitamin D analogs (e.g., calcitriol, paricalcitol, doxercalciferol, calcifediol) 1 week prior to initiation of treatment.

Fasting serum phosphorus concentration should be below the reference range for age prior to initiation of treatment.

Dosing for children

    Recommended starting dose1:

  • For patients who weigh less than 10 kg, starting dose regimen is 1 mg/kg of body weight, rounded to the nearest 1 mg

  • For patients who weigh 10 kg or greater, starting dose regimen is 0.8 mg/kg of body weight, rounded to the nearest 10 mg. The minimum starting dose is 10 mg up to a maximum dose of 90 mg

After initiating CRYSVITA, monitor fasting serum phosphorus levels every 4 weeks for the first 3 months of treatment and thereafter, as appropriate. If serum phosphorus is above the lower limit of the reference range for age and below 5 mg/dL, continue treatment with the same dose. To maintain serum phosphorus within the reference range for age, adjust the dose, as indicated in the full Prescribing Information.1

Dosing of CRYSVITA in pediatric patients

Dose adjustments in children

Reassess fasting serum phosphorus level 4 weeks after dose adjustment.1

Do not adjust CRYSVITA more frequently than every 4 weeks.1

Dose increase: For patients who weigh less than 10 kg, if serum phosphorus is below the reference range for age, the dose may be increased to 1.5 mg/kg, rounded to the nearest 1 mg. If additional dose increases are needed, the dose may be increased to the maximum dose of 2 mg/kg, rounded to the nearest 1 mg.

For patients who weigh 10 kg or more, if serum phosphorus is below the reference range for age, the dose may be increased stepwise up to approximately 2 mg/kg (maximum dose of 90 mg), according to the dosing schedule shown in Table 1.1

Table 1. Pediatric Dose Schedule
for Stepwise Dose Increase
for Patients Weighing 10 kg or More
Body Weight (kg) Starting
Dose (mg)
First Dose
Increase to (mg)
Second Dose
Increase to (mg)
10-14 10 15 20
15-18 10 20 30
19-31 20 30 40
32-43 30 40 60
44-56 40 60 80
57-68 50 70 90
69-80 60 90 90
81-93 70 90 90
94-105 80 90 90
106 and greater 90 90 90

Dose decrease: If serum phosphorus is above 5 mg/dL, withhold the next dose and reassess the serum phosphorus level in 4 weeks. The patient must have serum phosphorus below the reference range for age to reinitiate CRYSVITA. Once serum phosphorus is below the reference range for age, treatment may be restarted.

For patients who weigh less than 10 kg, restart CRYSVITA at 0.5 mg/kg of body weight, rounded to the nearest 1 mg. For patients who weigh 10 kg or more, restart CRYSVITA according to the dose schedule shown in Table 2. Reassess serum phosphorus level 4 weeks after dose adjustment. If the level remains below the reference range for age after the reinitiation dose, the dose can be adjusted according to Table 1.1

Table 2. Pediatric Dose Schedule
for Reinitiation of Therapy for Patients Weighing 10 kg or More
Previous Dose (mg) Reinitiation Dose (mg)
10 5
15 10
20 10
30 10
40 20
50 20
60 30
70 30
80 40
90 40

Dosing for adults

The recommended dose regimen in adults is 1 mg/kg body weight, rounded to the nearest 10 mg up to a maximum dose of 90 mg.1

After initiating CRYSVITA, assess fasting serum phosphorus levels on a monthly basis, measured 2 weeks postdose for the first 3 months of treatment and thereafter, as appropriate. If serum phosphorus is within the normal range, continue with the same dose. To maintain serum phosphorus within the normal range, adjust the dose, as indicated in the full Prescribing Information.1

Dosing of CRYSVITA in adult patients

Dose adjustments in adults

Dose decrease: Reassess fasting serum phosphorus level 2 weeks after dose adjustment.1

Do not adjust CRYSVITA more frequently than every 4 weeks.1

If serum phosphorus is above the normal range, withhold the next dose and reassess the serum phosphorus level after 4 weeks. The patient must have serum phosphorus below the normal range to be able to reinitiate CRYSVITA. Once serum phosphorus is below the normal range, treatment may be restarted at approximately half the initial starting dose up to a maximum dose of 40 mg every 4 weeks, according to the dose schedule shown in Table 3. Reassess serum phosphorus 2 weeks after any change in dose.1

Table 3. Adult Dose Schedule
for Reinitiation of Therapy
Previous Dose (mg) Reinitiation Dose (mg)
40 20
50 20
60 30
70 30
80 and greater 40

Missed dose

If a patient misses a dose, resume CRYSVITA as soon as possible at the prescribed dose. To avoid missed doses, treatments may be administered 3 days either side of the scheduled treatment date.1

25-Hydroxy vitamin D supplementation

Monitor 25-hydroxy vitamin D levels. Supplement with cholecalciferol or ergocalciferol to maintain 25-hydroxy vitamin D levels in the normal range for adults. Do not administer active vitamin D analogs during CRYSVITA treatment.1

Download the CRYSVITA Start Guide for additional information on initiating, dosing, and administering CRYSVITA

How CRYSVITA is supplied

CRYSVITA is a supplied as a sterile solution for subcutaneous injection

CRYSVITA injection for subcutaneous administration is supplied as a sterile, preservative-free, clear to slightly opalescent and colorless to pale brown-yellow solution. The product is available as 1 single-dose vial per carton in the following strengths: 10 mg/mL, 20 mg/mL, and 30 mg/mL.1

Administration

CRYSVITA is administered as a subcutaneous injection by a healthcare provider

CRYSVITA is administered by subcutaneous injection and should be administered by a healthcare provider.

Discontinue oral phosphate and/or active vitamin D analogs (e.g., calcitriol, paricalcitol, doxercalciferol, calcifediol) 1 week prior to initiation of treatment. Fasting serum phosphorus concentration should be below the reference range for age prior to initiation of treatment.

General considerations for administration

Injection sites should be rotated with each injection

Injection sites should be rotated with each injection administered at a different anatomic location (upper arms, upper thighs, buttocks, or any quadrant of abdomen) than the previous injection. Do not inject into moles, scars, or areas where the skin is tender, bruised, red, hard, or not intact.

If a given dose on a dosing day requires multiple vials of CRYSVITA, contents from 2 vials can be combined for injection. The maximum volume of CRYSVITA per injection site is 1.5 mL. If multiple injections are required on a given dosing day, administer at different injection sites. Monitor for signs of reactions.

Visually inspect CRYSVITA for particulate matter and discoloration prior to administration. Do not use if the solution is discolored or cloudy or if the solution contains any particles or foreign particulate matter.

CRYSVITA storage

CRYSVITA is stored in its original carton under refrigerated conditions

Store in original carton to protect from light and under refrigerated conditions at 36°F to 46°F (2°C to 8°C) until time of use.1

CRYSVITA should not be frozen or be shaken

Do not freeze or shake. Do not use CRYSVITA beyond the expiration date stamped on the carton. CRYSVITA vials are single-dose only. Discard any unused product.1

Reference
  1. CRYSVITA (burosumab-twza) US Prescribing Information; September 2019.