Enzyme replacement for MPS II (Hunter)
Idursulfase
A weekly drip that replaces the missing enzyme in MPS II (Hunter syndrome), an inherited lysosomal storage disorder.
What is Idursulfase?
Idursulfase is an enzyme replacement therapy for mucopolysaccharidosis type II, also known as Hunter syndrome. In this inherited condition, complex sugars build up because an enzyme is missing, affecting many parts of the body such as the joints, heart, airways and liver. Idursulfase is given as a slow drip into a vein once a week and for life, at a specialist metabolic centre. It does not cure Hunter syndrome but helps control the physical features. The most common issue is an infusion reaction, managed with pre-medication and by slowing the drip.
Education and reference only. This is a plain-language guide to Idursulfase — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Idursulfase is a man-made version of iduronate-2-sulfatase, the enzyme that people with Hunter syndrome (MPS II) lack. Hunter syndrome is a rare inherited 'lysosomal storage' disorder that mainly affects boys, in which complex sugars called glycosaminoglycans that should be broken down build up in cells across the body. This can affect the joints, bones, heart, airways and liver, and in some forms the brain. Idursulfase (brand name Elaprase) is given as a weekly drip into a vein and is started and supervised by a specialist metabolic team.
How it works
Idursulfase supplies the working enzyme that people with Hunter syndrome are missing, so the complex sugars building up in cells can be broken down. Given as a weekly drip into a vein, it helps reduce these deposits in tissues such as the liver and around the joints and airways, which can improve walking distance and breathing and ease some physical symptoms over time. Like other enzyme drips, it does not cross well into the brain, so it does not treat the brain-related features of the more severe form. Because the body keeps producing the sugars, the enzyme must be replaced each week, so treatment is lifelong.
Company & origin
Originated / developed by: Specialist (Takeda).
A laboratory-made copy of a missing enzyme, given by weekly drip in UK specialist metabolic centres to treat the inherited condition mucopolysaccharidosis type II.
Practical use
How to take Idursulfase
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as a slow drip into a vein at a specialist centre once a week, by trained staff.
- Pre-medication, such as an antihistamine or paracetamol, may be given to reduce the chance of an infusion reaction.
- Tell the staff at once if you or your child develops flushing, fever, a rash, sickness or breathing trouble during the drip.
- Keep to the weekly schedule, as missing infusions lets the complex sugars build up again.
- Attend the wider checks of the heart, airways, joints and growth that go alongside the infusions.
Weighing it up
Advantages & disadvantages of Idursulfase
Advantages
- Replaces the missing enzyme and can improve walking distance, breathing and some physical symptoms.
- Can shrink an enlarged liver and ease pressure on the airways and joints over time.
- Helps many people with Hunter syndrome function better in daily life.
Disadvantages
- Does not cure Hunter syndrome and must be given by drip every week for life.
- Does not cross well into the brain, so it does not treat the brain-related features of the severe form.
- Commonly causes infusion reactions needing pre-medication and monitoring.
Practical use
Good to know
Idursulfase controls the physical features of Hunter syndrome but does not cure it, so the weekly drips continue for life and are arranged through a specialist metabolic centre. It does not cross well into the brain, so it does not treat the learning and behaviour features of the more severe form. The most common issue is an infusion reaction, with flushing, fever, chills, headache, a rash or feeling sick during or soon after the drip; pre-medication and a slower rate often help. Some people make antibodies to the enzyme, which the team monitors. Care usually involves a wider team for the heart, airways, joints and bones, and breathing problems mean any anaesthetic needs careful planning.
Who should not take it / use with caution
- People who have had a severe allergic reaction to idursulfase should not receive it again unless specialists advise.
- It is used with extra care in those who develop antibodies that reduce its effect or worsen reactions.
- Other illnesses, pregnancy or breastfeeding should be discussed with the metabolic team before continuing.
Monitoring
- Regular checks of breathing, walking distance, the heart, joints, liver size and growth to track response.
- Watching for infusion reactions during and after each drip and for antibodies over time.
- Ongoing specialist review and careful planning around any anaesthetic because of airway problems.
Side effects
- Infusion reactions such as flushing, fever, chills, headache, rash or nausea are the most common.
- Less commonly, a fast heartbeat, wheeze or breathing changes during or after the drip.
- Rarely, a serious allergic reaction, which is why infusions are given where staff can respond quickly.
Key interactions
- No major routine medicine interactions are well established, but tell the team everything you or your child takes.
- Care for the heart, airways and joints is coordinated by the specialist centre alongside the infusions.
- Any planned anaesthetic or new medicine should be discussed early, given the airway involvement.
Available as: A drip (infusion) into a vein, given weekly at a specialist centre.
Answers
Idursulfase: frequently asked questions
How often is idursulfase given?
It is given as a drip into a vein once a week at a specialist centre, and treatment continues for life.
Will it cure Hunter syndrome?
No. It replaces the missing enzyme and helps the physical features, but it does not cure the condition, so the weekly drips are needed for life.
Does it help the brain symptoms?
It does not cross well into the brain, so it does not treat the learning and behaviour features of the more severe form.
Why might there be a reaction during the drip?
Infusion reactions such as flushing, fever or a rash are common; pre-medication and slowing the rate usually help settle them.
Is anything special needed before an operation?
Hunter syndrome can affect the airways, so any anaesthetic needs careful planning; always tell the team about planned operations.
Authoritative sources
- BNF
- NICE CKS
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