asfotase alfa at a glance
Medicine class
Bone-targeted enzyme replacement therapy
Licensed use
Bone manifestations of paediatric-onset hypophosphatasia in patients of any age
Administration
Injection under the skin; self-injection requires appropriate training
What is asfotase alfa used for?
UK-licensed use:
Treating bone manifestations of paediatric-onset hypophosphatasia in children and adults.
How does asfotase alfa work?
Hypophosphatasia causes deficient tissue-nonspecific alkaline phosphatase, allowing substances that inhibit mineral formation to accumulate. Asfotase alfa replaces this enzyme and binds to bone, supporting skeletal mineralisation.
How to take asfotase alfa
Inject under the skin, not into a vein or muscle. A specialist should teach the patient or caregiver how to prepare and inject it safely.
Rotate suitable injection areas; avoid painful areas, lumps or firm knots.
Use each vial once and discard any remaining solution.
Do not use discoloured solution or solution containing lumps or large particles.
Let the refrigerated vial reach room temperature naturally; do not microwave it or place it in hot water.
Keep refrigerated, protected from light, and do not freeze.
asfotase alfa side effects
Common or expected effects
- Injection-site redness, pain, itching, swelling, discolouration, nodules or changes in fatty tissue
- Headache
- Fever or irritability
- Pain in the arms or legs
- Bruising
- Nausea, muscle pain, hot flushes or mouth numbness
- Low blood calcium or kidney stones
Get urgent medical advice
- Difficulty breathing, choking, swelling around the eyes or severe dizziness may indicate a serious allergic reaction requiring emergency help.
- A severe injection-site reaction, spreading redness or suspected cellulitis needs prompt medical assessment.
- Report new visual problems because eye calcification can occur in hypophosphatasia.
- Changes in an infant's head shape need prompt specialist review because craniosynostosis can occur in young children with hypophosphatasia.
asfotase alfa in pregnancy
Human pregnancy data are insufficient. UK product information does not recommend asfotase alfa during pregnancy or for people who could become pregnant without contraception. Discuss pregnancy, plans to conceive or contraception with the specialist prescriber; do not stop treatment without advice.
asfotase alfa while breastfeeding
It is unknown whether asfotase alfa passes into human milk, and risk to a breastfed infant cannot be excluded. The specialist team should weigh the benefits of breastfeeding against the importance of treatment before deciding whether to interrupt breastfeeding or therapy.
asfotase alfa interactions
Formal interaction studies have not been performed. The main concern is interference with laboratory testing rather than a known medicine–medicine interaction.
Laboratory assays using alkaline phosphatase detection systems
Asfotase alfa can cause misleadingly high serum alkaline phosphatase readings and falsely high or low results in some other assays. Tell the laboratory so it can select a suitable method.
Medicines metabolised by cytochrome P450 enzymes
A metabolic interaction is considered unlikely, although dedicated interaction studies have not been conducted.
Common questions about asfotase alfa
Answers are fully visible for fast scanning and source review.
What is asfotase alfa used for?
It treats bone manifestations of hypophosphatasia that began in childhood, including in adults with childhood-onset disease.
How is it injected?
Into fatty tissue beneath the skin, not into a vein or muscle. Self-injection requires appropriate training.
Can it affect blood-test results?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.