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Wednesday 17 July 2019
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Myozyme infusion

Enzyme Replacement Therapy Treatment

This page provides information on Enzyme replacement therapy (ERT) including:


What is Enzyme replacement therapy (ERT)?

ERT is a medical treatment which aims to replace an enzyme in the body which is missing, deficient or not working as well as it should as the result of a gene mutation. It can only be prescribed for patients who meet certain criteria by a specialist metabolic consultant. ERT is not a cure but is intended to slow down the disease process.

ERT is currently available for:

  • Fabry disease, 
  • Gaucher disease, 
  • Pompe disease, 
  • MPS I, 
  • MPS II and 
  • MPS VI. 


ERT is usually funded by NHS England, which is a centralised commissioning body involved in the funding of highly specialised services and drugs, of which LSDs are classed. For patients who live outside of England, funding needs to be applied for on an individual basis through the patient’s local assembly.

How is ERT given?

Enzyme replacement therapy (ERT) is administered via intravenous drip (into the vein) through a cannula which is a small plastic tube which will be inserted prior to each treatment and removed once the treatment has been completed.

Once the vein has been accessed, the drug will be made up and given over a period of time, dependent on the drug and the patient (usually between 40 minutes and 5 hours). The first infusions will always be given in a hospital setting in order to monitor for infusion related reactions, and following this infusions are given at home by one of our homecare teams. The number of hospital infusions needed depends on the drug treatment and how the patient tolerates their treatment. When patients have hospital treatment they will be asked to remain on the ward for 1 hour following each infusion to be observed for delayed reactions.

Vital signs (blood pressure, temperature, oxygen saturations and respiratory rate) will be checked before each infusion to provide a baseline measurement should there be any complications, and the same checks will be done post infusion to ensure the patient is fit to be discharged. Usually in the homecare setting baseline observations are taken before each infusion and these will be checked again should there be any issues during or immediately after the infusion.

Patients are allowed to eat and drink as normal during their infusions and there is nothing that needs to be done prior to infusion. We do however ask that patients inform the department at the first opportunity if they are unwell before their infusion as an assessment will need to be made as to whether or not the infusion can go ahead. Patients are asked not to take paracetamol or ibuprofen before they arrive on the ward for any infusion as this will affect your baseline observations.

Some patients will require premedication prior to their treatment. This depends on the treatment received and whether any infusion related reactions are experienced.

Infusion related reactions

Like all medications one of the main risks associated with enzyme replacement therapy (ERT) is allergic reaction. As this medication is administered directly into the vein, reactions can range from mild to severe and although rare, anaphylactic response is also possible. An anaphylactic response although extremely rare with ERT is a more severe reaction and can be potentially fatal if left untreated. If this type of reaction is experienced then treatment may have to be withdrawn.

In order to monitor for reactions, ERT is started in a hospital setting so that any adverse symptoms can be monitored and reported. Some enzyme products will require a pre-medication (usually 1g paracetamol and 10mg loratadine) for the first infusions in order to help prevent allergic reactions, and these will usually be stopped prior to being discharged to homecare. If allergic reactions are an issue for the patient then pre-medications can be altered and can be given pre-infusion as a long term preventative measure. Sometimes simply changing the rate of the infusion can help reduce the severity of allergic reactions in order to make the treatment more tolerable for the patient.

Allergic reactions can present in many different ways and symptoms can include; itching, flushing, fever, chills, nausea, vomiting, urinary urgency, diarrhoea, tingling in lips and throat, breathing difficulties, rash and swelling particularly to the face and throat. All of these symptoms are manageable both in the hospital setting as well as the home setting with the administration of intravenous antihistamines and steroids as well as oxygen therapy.

Allergic reaction must not be mistaken for side effects. All drugs have potential side effects and details of the side effects of each individual ERT product can be found in the drug information sections below.

Home care and self infusion 

Once patients are stable on their enzyme therapy they no longer need to have their infusions in a hospital setting and infusions are given at home. We employ 4 private homecare companies who provide this service and their nurses will administer treatments in the home setting.

The first contact patients will have with their homecare nurse will be at their home assessment. This is a risk assessment which is essential for health and safety reasons and during this visit the nurse will check that the home is a suitable environment for treatment to be given. During this visit patient may be asked to keep any pets away from the treatment area and patients who smoke may be asked to smoke outside whilst the nurse is in their home.

All patients who have infusions at home will require a medical fridge which will be supplied by the homecare company for storage of their medicines, and this will be maintained by the homecare team. Every fridge will have a thermometer inside and we ask patients to check and record the temperature inside their fridge on a daily basis in order to ensure that their medicines are stored at the optimum temperature. If patients are planning to be away from home for a long period of time we would ask for any medicines to be used before this time in order to minimise drug wastage should the fridge malfunction during the period of absence.

Along with the fridge the patient will be asked to keep some other items such as drip stand, bags of saline and needles in their homes and stock of these items will be delivered on a regular basis. These items should be kept in a secure place in the home away from children and vulnerable adults.

Once the risk assessment has been completed and hospital staff have confirmed that homecare can commence, medicines will be delivered to the home usually on a monthly basis. Dates and times for deliveries will be arranged with the patient by their homecare nurse and there will need to be somebody in the home during the delivery to receive the drugs – this does not have to be the patient, as long as the receiver is registered with the homecare company as a named drug recipient. The driver will put the drugs into the fridge and check stock levels at the time of delivery; however some patients are uncomfortable with this and can refuse to allow the driver into their home.  If the driver is refused entry, a form needs to be signed by the patient confirming that they are happy to take responsibility for the unpacking of their medicines.

Once everything is in place, the homecare nurse will book appointments with the patient to attend their home to give them their infusions. Every effort is made by the nurse to find a time that is convenient for the patient to cause as little disruption to their life as possible. If there are any issues or concerns about any aspect of homecare, patients are asked to speak to their homecare nurse or management team. Any unresolved or ongoing issues with homecare should be discussed with one of the nurses from the hospital team.

During home infusions, the nurse will complete all aspects of the infusion unless the patient expresses a wish to become partially or fully independent. There are different levels of independence and we encourage our patients to become as independent with their treatment as they feel comfortable.

Some patients like the nurse to continue to carry out the whole infusion from start to finish long-term, however others are happier for the nurse to come in and set up their infusions and then the patient or a relative or friend will flush their line and remove their cannula post infusion.

A number of our patients have over time become fully independent with their infusions and sometimes they complete their infusions from start to finish with no assistance. Before this can happen we will have to be satisfied that the patient is low risk of allergic reaction and that compliance will not be an issue. Our homecare teams all have 24 hour help lines which can be contacted by independent patients if there are any difficulties.

Patients who self-infuse will usually have contact on a 6-12 month basis with their homecare nurse to assess their technique and give them an opportunity to discuss any questions or difficulties they may have.

Treatment of LSDs

Managament of LSDs currently consists largely of enzyme replacement therapy (ERT), with substrate replacement therapy (SRT) available for the management of Niemann pick C and for some patients with Gaucher disease. Further details about each disease and its specific management are listed below.

Fabry Disease

There are two enzymes used in the management of Fabry disease and both of these treatments replace alpha-galactosidase enzyme which is either low or absent in Fabry patients. It acts in the same way as naturally occurring alpha-galactosidase and breaks down the GL-3 within cells to help the body remove it. In Fabry disease patients GL-3 builds up in cells and organs to cause damage.


Once patients are established on therapy, Fabrazyme can be given over 90 minutes. The most common side effects seen include headache, paraesthesia (the experience of an unusual sensation that may feel like a burning, tingling or numb sensation), nausea, vomiting, fever and chills.


Replagal is given over 40 minutes in the majority of cases. The most common side effects are headache, flushing, nausea, rigors (shaking), fever and fatigue.


Oral substrate replacement therapy takes alternate days, this treatment is dependent on the amenability of the Fabry mutation.

Gaucher Disease

Gaucher disease can be treated with one of two enzymes, cerezyme or velaglucerase, or some patients are suitable for substrate reduction therapy with zavesca (miglustat) tablets.

The enzyme treatments work by replacing the glucocerebrosidase enzyme with is absent or faulty in patients with gaucher disease. It breaks down glucocerebroside to prevent it building up in vital organs and causing the symptoms of gaucher disease.

The substrate replacement therapy works by preventing the production of glycosphingolipids, meaning the enzyme that is present can break down the waste products and prevent accumulation.


Depending on the dose, Cerezyme is given over 1.5 to 2 hours. The most common side effects experienced are usually related to allergic reactions to the cerezyme and include breathlessness, cough, itching and rashes.


VPRIV is given over 60 minutes, and common side effects include headache, dizziness, bone, back and joint pain, tiredness and fever.


Zavesca (miglustat) is a tablet that has shown benefit in some patients with type 1 Gaucher disease. This isn’t suitable for all patients, and is reviewed on an individual basis. The dose is usually increased over the course of three months to one tablet three times a day, and the main side effect is diarrhoea. The diarrhoea can be reduced by adjusting the diet, for which help can be provided by our dietician.  


MPS I can be treated with Aldurazyme, which substitutes the missing enzyme alpha-L-iduronidase, which allow sufficient enzyme activity to break down GAGs and prevent their build-up.


Aldurazyme is usually given over 2.5 hours, once a patient is stable on the drug, and common side effects include headache, flushing, nausea, abdominal pain, rash, joint and back pain, pain in extremities, temperature and infusion site reactions.


MPS II can be treated with Elaprase which replaces the deficient enzyme iduronate-2-sulfatase, which is necessary to catalyse a step in the breakdown of glycosaminoglycans. Treatment with Elaprase reduces the accumulation of dermatan and heparan sulfate in the cells, therefore reducing the damage in the cells.


Elaprase is given as an infusion over 60 minutes, once the patient is stable on the drug, and its common side effects include headache, hypertension, flushing, wheezing, breathlessness, abdominal pain, nausea, abdominal dyscomfort, diarrhoea, urticaria, rash, itch and chest pain.


MPS IV can be treated with Vimizim (Elosulfase alpha) which replaces the deficient GALNS enzyme which is believed to increase catabolism and reduce the accumulation of Keratan Sulphate responsible for the clinical manifestations of Morquio A

Vimizim (Elosulfase alpha)

Common side effects of elosulfase alfa may include: nausea, vomiting, stomach pain, headache, fever, chills, tired feeling - The infusion usually takes around four hour to administer.


MPS VI can be treated with Naglazyme, which replaces N-acetylgalactosamine-4-sulfatase and therefore reduces the GAG buildup that leads to MPS VI.


The most common side effects seen with Naglazyme use are rash, pain, itch, raised temperature, chills, headache, nausea, vomiting, abdominal pain, and shortness of breath. The infusion usually takes around four hour to administer.


Pompe can be treated with Myozyme, which replaces acid alpha glucosidase, the enzyme low or absent in pompe patients, which ultimately leads to the accumulation of glycogen and development of muscle weakness.


Patients receiving myozyme will usually have between 6 and 8 infusions in hospital, before transferring to homecare. This is because experience has shown us there is a slightly higher chance of an infusion reaction with myozyme compared with the other enzymes. Once stable on treatment, myozyme is usually given over 3 hours.  The most common side effects are dizziness, paraesthesia (the experience of an unusual sensation that may feel like a burning, tingling or numb sensation), headache, flushing, throat tightness, diarrhoea, vomiting and nausea.

Niemann Pick C

Niemann Pick C can be treated with Zavesca, which is a substrate reduction therapy, and is available as a tablet. It works by preventing the production of glycosphingolipids, meaning the enzyme that is present can break down the waste products and prevent accumulation, which causes the symptoms associated with Niemann pick C.


Zavesca (miglustat) is a tablet that is used to slow the progression of Niemann Pick C (it has also shown benefit in some patients with type 1 Gaucher disease). The dose is usually increased over the course of five months to two tablet three times a day, and the main side effect is diarrhoea. The diarrhoea can be reduced by adjusting the diet, for which help can be provided by our dietitian.