Burosumab-twza

• Crysvita

Body weight: Clearance and volume of distribution of burosumab-twza increases with body weight.

Note: Prior to initiating burosumab-twza, oral phosphate and active vitamin D analogs should be discontinued for at least 1 week. Confirm baseline fasting serum phosphorus level is below the reference range for patient age before initiating burosumab-twza.

Hypophosphatemia, X-linked (XLH): SubQ: Initial: 1 mg/kg every 4 weeks; calculated dose should be rounded to the nearest 10 mg; maximum dose: 90 mg

Dosage adjustment based on serum phosphorus: Evaluate fasting serum phosphorous 2 weeks after treatment initiation and continue every 4 weeks for the first 12 weeks of therapy. Adjust dose accordingly based on fasting serum phosphorus level; see Reference Range for phosphorus age-based normal limits. Do not adjust dose more frequently than every 4 weeks.

If low serum phosphorus: There are no dosage adjustments provided in the manufacturer's labeling.

If normal serum phosphorus: Continue same dose.

If high serum phosphorous:

If fasting serum phosphorus above the normal age-based range, withhold next dose and reassess in 4 weeks; once serum phosphorus falls below the age-based normal range, may re-initiate burosumab-twza at approximately one-half the initial starting dose up to a maximum dose of 40 mg every 4 weeks:

Table has been converted to the following text:

Previous dose: 40 mg/dose every 2 weeks; Re-initiation dose: 20 mg/dose every 2 weeks

Previous dose: 50 mg/dose every 2 weeks; Re-initiation dose: 20 mg/dose every 2 weeks

Previous dose: 60 mg/dose every 2 weeks; Re-initiation dose: 30 mg/dose every 2 weeks

Previous dose: 70 mg/dose every 2 weeks; Re-initiation dose: 30 mg/dose every 2 weeks

Previous dose: ≥80 mg/dose every 2 weeks; Re-initiation dose: 40 mg/dose every 2 weeks

Refer to adult dosing.

Store at 36°F to 46°F (2°C to 8°C) in the original carton; do not freeze. Protect from light. Do not shake.

>10%:

Central nervous system: Headache (children: 8% to 73%; adults: 13%), dizziness (10% to 15%), restless leg syndrome (adults: 12%)

Dermatologic: Skin rash (children: 8% to 27%)

Endocrine & metabolic: Vitamin D deficiency (children: 15% to 37%; adults: 12%)

Gastrointestinal: Vomiting (children: 46% to 48%), toothache (children: 15% to 23%), tooth infection (adults: 13%)

Infection: Tooth abscess (children: 15% to 23%)

Local: Injection site reaction (children: 23% to 67%; including urticaria, erythema, rash, swelling, bruising, pain, pruritus, and hematoma)

Neuromuscular & skeletal: Limb pain (children: 23% to 46%), myalgia (children: 8% to 17%), back pain (adults: 15%)

Miscellaneous: Fever (children: 44% to 62%)

1% to 10%:

Dermatologic: Rash at injection site (children: 6%), urticaria (children: 5%)

Endocrine & metabolic: Hyperphosphatemia (adults: 6% to 7%)

Gastrointestinal: Constipation (adults: 9%)

Hypersensitivity: Hypersensitivity reaction (6%)

Frequency not defined: Immunologic: Antibody development

Burosumab-twza is a recombinant DNA-derived human immunoglobulin G1 (IgG1) antibody specific for human fibroblast growth factor 23 (FGF23).1

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Medical Disclaimer

This is not a complete list of Burosumab-twzadrug interactions. Ask your doctor or pharmacist for more information.