Burosumab
FGF23-blocking antibodies
FGF23-blocking antibodies
An antibody injection against FGF23. It stops phosphate loss in the urine and heals rickets in X-linked hypophosphataemia.
Also called: Burosumab-twza
Quick facts
- Group
- FGF23-blocking antibodies
- Target
- Fibroblast growth factor 23 (FGF23)
- Used for
- X-linked hypophosphataemia
- Key effects
- Injection-site reactions · Headache · Pain in the arms
- Monitor
- Fasting serum phosphate before
- ATC
- M05BX05
No doses: the clinician sets them by the current guideline.
Mechanism of action
Burosumab is a recombinant human monoclonal antibody that binds and neutralises FGF23. Excess FGF23 in X-linked hypophosphataemia and tumour-induced osteomalacia makes the kidney lose phosphate and suppresses calcitriol. With FGF23 blocked, proximal tubular phosphate reabsorption and calcitriol production recover, serum phosphate rises and bone mineralisation improves.
- Burosumab binds circulating FGF23
- The kidney reabsorbs more phosphate
- Calcitriol production recovers
- Serum phosphate rises and rickets or osteomalacia heals
Indications
- X-linked hypophosphataemia in people aged 6 months and older Rickets and osteomalacia →
- Tumour-induced osteomalacia that cannot be removed surgically, in people aged 2 years and older Hypophosphataemia →
Adverse effects
Common
- Injection-site reactions (redness, rash, swelling, bruising)
- Headache, dizziness and fever
- Pain in the arms, legs or back, and muscle pain
- Vomiting and constipation
Contraindications
- Use with oral phosphate or active vitamin D analogues
- Serum phosphate within or above the normal range
- Severe kidney impairment or end-stage kidney disease
Key interactions
- Oral phosphate supplements
- Stopped a week before starting: risk of too much phosphate
- Active vitamin D (calcitriol, paricalcitol)
- Stopped a week before starting: risk of high phosphate and calcium
What is monitored
- Fasting serum phosphate before and during treatment; doses may be held
- Kidney function and signs of nephrocalcinosis
- Symptoms of restless legs
- Growth and rickets healing in children
Administration and safety
- Subcutaneous injection into the upper arm, upper thigh, buttock or abdomen, with a different site each time
- Given by a doctor or nurse
- Phosphate and active vitamin D supplements are stopped beforehand
Pregnancy and breastfeeding
Information in pregnancy is limited; the prescriber is told about pregnancy, plans for pregnancy or breastfeeding.
Nursing care
- Confirm that phosphate and active vitamin D supplements were stopped
- Check phosphate results before each dose
- Inspect injection sites and ask about rash or itching
- Ask about leg discomfort and an urge to move the legs
Pharmacokinetics
- Absorption
- Given by subcutaneous injection by a health professional, at intervals set by age and condition
Test yourself
Think of the answer, then tap the question to see it.
What does burosumab bind?
Fibroblast growth factor 23 (FGF23), the hormone that causes renal phosphate wasting in X-linked hypophosphataemia.
Which supplements must be stopped before burosumab?
Oral phosphate and active vitamin D such as calcitriol or paricalcitol.
Which blood test guides burosumab treatment?
Serum phosphate, checked before and during treatment; doses are held if it is too high.
Connections
← Back to the class: FGF23-blocking antibodies
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Burosumab-twza Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.