An emergency enzyme that rapidly lowers toxic methotrexate levels
Glucarpidase
An emergency enzyme given into a vein to rapidly lower dangerously high methotrexate levels when the kidneys cannot clear it.
What is Glucarpidase?
Glucarpidase is a specialist emergency medicine used in hospital to rapidly lower dangerously high levels of methotrexate, a chemotherapy and immune-system medicine, in people whose kidneys are not clearing it properly. It is an enzyme given into a vein that breaks methotrexate down into harmless pieces, acting as a rescue treatment or antidote. The timing matters: it is used alongside, but kept apart in time from, folinic acid, which is also given to protect the body. Allergic-type and infusion reactions can occur. It is given by a specialist team that monitors closely.
Education and reference only. This is a plain-language guide to Glucarpidase — 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
Glucarpidase is an enzyme used as an emergency rescue treatment when methotrexate, a powerful chemotherapy and immune-system medicine, builds up to dangerously high levels because the kidneys are not removing it fast enough. High methotrexate can damage the kidneys, blood, gut lining and other tissues, so quickly lowering it is important. Glucarpidase is given as an injection into a vein in hospital. It is used as part of a wider plan that also includes folinic acid and good hydration, all overseen by a specialist team.
How it works
Glucarpidase is an enzyme that rapidly breaks methotrexate down into smaller, inactive pieces that the body can handle even when the kidneys are struggling. This lowers the harmful methotrexate level in the blood within a short time, helping to protect the kidneys and other tissues from further damage. Because it works on methotrexate that is in the bloodstream, it is given promptly once dangerously high levels are recognised. It does not replace the other supportive measures, such as folinic acid and fluids, which continue alongside it.
Company & origin
Originated / developed by: Specialist manufacturer.
A specialist hospital medicine used in the UK as an emergency treatment to rapidly lower dangerously high methotrexate levels in people whose kidneys are not clearing it.
Practical use
How to take Glucarpidase
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given by a specialist team as an injection into a vein in hospital, as an emergency rescue treatment.
- Folinic acid is kept apart in time from glucarpidase, because the enzyme also breaks folinic acid down.
- Hydration and other supportive measures are continued alongside it as the team directs.
- Methotrexate levels are checked afterwards, as levels can rise again from methotrexate stored inside cells.
- Any flushing, tingling, rash or feeling unwell during the injection should be reported straight away.
Weighing it up
Advantages & disadvantages of Glucarpidase
Advantages
- Rapidly lowers dangerously high methotrexate levels when the kidneys cannot clear it.
- Acts as a rescue treatment that helps protect the kidneys and other tissues.
- Given as a single injection into a vein in an emergency.
Disadvantages
- Must be timed carefully around folinic acid, which the enzyme also breaks down.
- Can cause allergic-type or infusion reactions.
- Methotrexate levels can rebound from cells, so close monitoring is still needed afterwards.
Practical use
Good to know
The most important practical point with glucarpidase is timing in relation to folinic acid: folinic acid is also broken down by the enzyme, so the two are deliberately kept apart in time, and the team plans exactly when each is given. Glucarpidase works quickly to bring methotrexate levels down, but methotrexate trapped inside cells can leak back out, so levels are checked carefully afterwards and folinic acid is continued as needed. Because it is given into a vein, allergic-type or infusion reactions can occur, such as flushing, tingling or a change in blood pressure, so it is given where these can be managed. After it has been given, certain methotrexate blood tests can read inaccurately for a while, which the laboratory takes into account. It is a one-off rescue treatment rather than an ongoing medicine.
Who should not take it / use with caution
- People who have had a serious allergic reaction to glucarpidase should not be given it.
- It is used under specialist hospital supervision only, where reactions can be managed.
- It is used with care in pregnancy, where the specialist team weighs the urgent need against the risks.
Monitoring
- Checking methotrexate blood levels before and after, as levels can rebound from cells.
- Monitoring kidney function, blood counts and overall recovery.
- Watching for allergic-type or infusion reactions during and after the injection.
Side effects
- Flushing, tingling, headache or nausea around the time of the injection.
- Changes in blood pressure or allergic-type reactions during or shortly after the infusion.
- Rarely, more serious allergic reactions, which is why it is given where these can be treated.
Key interactions
- It breaks down folinic acid as well as methotrexate, so the timing of folinic acid is carefully planned around it.
- It can make certain methotrexate blood tests read inaccurately for a time, which the laboratory accounts for.
- Other supportive treatments, such as fluids, are continued and coordinated by the team.
Available as: A powder made up into a solution for injection into a vein.
Answers
Glucarpidase: frequently asked questions
What is glucarpidase used for?
It is an emergency hospital treatment used to rapidly lower dangerously high methotrexate levels in people whose kidneys are not clearing the methotrexate properly.
How does it work so quickly?
It is an enzyme that breaks methotrexate down into smaller, inactive pieces, lowering the harmful level in the blood within a short time even when the kidneys are struggling.
Why does the timing with folinic acid matter?
The enzyme also breaks down folinic acid, so the two are deliberately kept apart in time, with the team planning exactly when each is given.
Why are methotrexate levels still checked afterwards?
Methotrexate stored inside cells can leak back into the blood, so levels are monitored after treatment and folinic acid is continued as needed.
Is it a one-off treatment?
Yes, it is given as an emergency rescue treatment rather than an ongoing medicine, alongside fluids and other supportive care.
Authoritative sources
- BNF
- NICE CKS
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