sing schedule shown in Table 1.
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 re-initiation dose, the dose can be adjusted according to Table 1.
Table 2:Pediatric Dose Schedule for Re-Initiation of Therapy
Previous Dose (mg) Re-Initiation Dose (mg)
10 5
15 10
20 10
30 10
40 20
50 20
60 30
70 30
80 40
90 40
2.2 Adult Patients with X-linked Hypophosphatemia (18 years of age and older)
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 four weeks.
After initiation of treatment with CRYSVITA, assess fasting serum phosphorus on a monthly basis, measured 2 weeks post-dose, for the first 3 months of treatment, and thereafter as appropriate. If serum phosphorus is within the normal range, continue with the same dose.
Dose Decrease
Reassess fasting serum phosphorus level 2 weeks after dose adjustment.
Do not adjust CRYSVITA more frequently than every 4 weeks.
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.
Table 3: Adult Dose Schedule for Re-Initiation of Therapy
Previous Dose (mg) Re-Initiation Dose (mg)
40 20
50 20
60 30
70 30
80 and greater 40
2.3 Missed Dose
If a patient misses a dose, resume CRYSVITA as soon as possible at the prescribed dose.
2.4 General Considerations for Subcutaneous 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 sig |
