CRYSVITA® (burosumab-twza) has a simple dosing schedule

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CRYSVITA dosing schedule for pediatric patients (1 to <18 years of age)

Every 2 weeks¹

CRYSVITA dosing schedule for adult patients (≥18 years of age)

Every 4 weeks¹

Dosing for pediatric patients

The recommended starting dose regimen is 0.8 mg/kg of body weight, rounded to the nearest 10 mg, administered every 2 weeks. The minimum starting dose is 10 mg up to a maximum dose of 90 mg¹.

After initiation of treatment with CRYSVITA, measure fasting serum phosphorus 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. Follow dose adjustment schedule below to maintain serum phosphorus within the reference range for age.¹

Dosing of CRYSVITA in pediatric patients

Dose adjustments

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

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

Dose increase: If serum phosphorus is below the reference range for age, the dose may be increased stepwise up to approximately 2 mg/kg, administered every 2 weeks (maximum dose of 90 mg), according to the dosing schedule shown in Table 1 below¹:

Table 1. Pediatric Dose Schedule for Stepwise Dose Increase
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 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
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 adult patients

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, administered every 4 weeks.¹

After initiation of treatment with CRYSVITA, assess fasting serum phosphorus 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.¹

Dose adjustments

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.¹

How CRYSVITA is supplied

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 one single-dose vial per carton in the following strengths: 10 mg/mL, 20 mg/mL, and 30 mg/mL.¹

Administration

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

Discontinue oral phosphate and active vitamin D analogs 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 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.

The maximum volume of CRYSVITA per injection site is 1.5 mL. If more than 1.5 mL is required on a given dosing day, the total volume of CRYSVITA should be split and administered at two different injection sites. Monitor for signs of reactions.