burosumab: clinical use

Prescribing considerations

• Initiation should be supervised by a physician experienced in metabolic bone disease.
• Confirm fasting serum phosphate is below the age-adjusted reference range before initiation.
• Discontinue oral phosphate and active vitamin D analogues before starting burosumab.
• Record the product name and batch number for biological-medicine traceability.
• Evidence is limited in older adults, and renal impairment has not been adequately studied.

Contraindications and cautions

• Hypersensitivity to burosumab or an excipient
• Concurrent oral phosphate or active vitamin D analogue treatment
• Fasting serum phosphate above the age-adjusted normal range
• Severe renal impairment or end-stage renal disease

Monitoring

• Fasting serum phosphate, including after treatment adjustments
• Calcium, alkaline phosphatase, parathyroid hormone and creatinine
• Urinary calcium and phosphate
• Renal ultrasonography for nephrocalcinosis or other ectopic mineralisation
• Injection-site and hypersensitivity reactions
• Vitamin D status

Clinical pharmacology

Burosumab is a recombinant human IgG1 antibody that neutralises FGF23, increasing renal tubular phosphate reabsorption and 1,25-dihydroxyvitamin D. Subcutaneous absorption is nearly complete; elimination is expected through normal immunoglobulin degradation pathways, and clearance is body-weight dependent.

Formulation and product differences

• UK presentations include single-use vials and single-use pre-filled syringes.
• Pre-filled syringes may support trained patient or carer administration; vials require aseptic withdrawal using a sterile syringe and needle.
• Both presentations require refrigeration and protection from light and freezing.
• Do not shake vials. Pre-filled syringe strengths have colour-coded plunger rods.

Injection

Route: Parenteral

Strengths: 10 mg, 20 mg, 30 mg