A urea-cycle medicine for high ammonia
Carglumic acid
A specialist medicine that lowers high blood ammonia in NAGS deficiency and some organic acidaemias.
What is Carglumic acid?
Carglumic acid is a specialist medicine used to lower dangerously high levels of ammonia in the blood, which can happen in a rare inherited problem of the urea cycle called NAGS deficiency and in some other conditions called organic acidaemias. Ammonia is a waste product that the body normally clears; when it builds up it is a medical emergency that can cause confusion, drowsiness, vomiting and, if untreated, serious harm. Carglumic acid helps restart the body's ammonia-clearing pathway. It is usually used together with a low-protein diet and is managed by a metabolic team with close blood monitoring.
Education and reference only. This is a plain-language guide to Carglumic acid — 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
Carglumic acid is a treatment for high blood ammonia (hyperammonaemia). In a rare inherited urea-cycle disorder called NAGS deficiency, the body cannot make a substance needed to switch on the first step of clearing ammonia, so ammonia builds up; carglumic acid replaces this missing trigger. It is also used to control high ammonia in some organic acidaemias. High ammonia is dangerous and is treated as an emergency. It is taken by mouth and managed by a specialist metabolic centre.
How it works
The urea cycle is the body's way of turning toxic ammonia into harmless urea that is passed in urine. Its very first step needs an activator that, in NAGS deficiency, the body cannot make. Carglumic acid acts as a substitute for this activator, switching on the urea cycle so ammonia can be cleared again. In some organic acidaemias, the natural activator is blocked, and carglumic acid can help restart the cycle there too, bringing high ammonia levels down.
Company & origin
Originated / developed by: Recordati Rare Diseases.
A specialist medicine used in the UK by metabolic centres to lower dangerously high blood ammonia in certain rare conditions.
Practical use
How to take Carglumic acid
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it regularly as your metabolic team directs, and never stop it suddenly without their advice.
- It is usually mixed in a little water and taken just before food, following your team's instructions.
- Keep to any low-protein diet your dietitian has planned, as diet and medicine work together.
- Follow your emergency (sick-day) plan if you become unwell, as ammonia can rise during illness.
- Seek urgent medical help for confusion, drowsiness, repeated vomiting or unusual behaviour, which can signal high ammonia.
Weighing it up
Advantages & disadvantages of Carglumic acid
Advantages
- Helps restart the body's ammonia-clearing pathway, bringing dangerous ammonia levels down.
- Can be used both for sudden rises and as long-term treatment in NAGS deficiency.
- Taken by mouth and used alongside diet to manage a serious inherited condition.
Disadvantages
- It is for specific conditions only, so it does not help every cause of high ammonia.
- Often needs to be combined with a low-protein diet and an emergency plan.
- Requires lifelong specialist care and close blood monitoring.
Practical use
Good to know
The vital point is that high ammonia is a medical emergency: confusion, unusual drowsiness, vomiting, refusing food, irritability or unsteadiness can be warning signs and need urgent medical help, often in hospital. Carglumic acid is used both to treat sudden rises in ammonia and, in NAGS deficiency, as a long-term treatment, usually alongside a low-protein diet planned by a metabolic dietitian. It is taken regularly and must not be stopped without advice, as ammonia can rise quickly. Families are often given an emergency plan for illness, when the body produces more ammonia, and the metabolic team monitors ammonia and overall health closely.
Who should not take it / use with caution
- It should only be used under a metabolic centre for the specific conditions it is licensed for.
- It is not a treatment for high ammonia from causes outside its licensed conditions without specialist guidance.
- Use in pregnancy or breastfeeding is decided by the specialist team after weighing benefits and risks.
Monitoring
- Regular blood tests to check ammonia levels and the response to treatment.
- Close monitoring during illness, when ammonia can rise quickly.
- Reviewing diet, growth and symptoms with the metabolic team and dietitian.
Side effects
- Sweating, fever or feeling sick in some people.
- Tonsillitis or throat infections have been reported.
- Diarrhoea, vomiting or stomach upset.
Key interactions
- Protein intake affects ammonia, so diet is central to how well it works.
- Tell your team about all other medicines, as treatment is overseen by a specialist centre.
- Illness and reduced food intake can raise ammonia, so follow your sick-day plan.
Available as: Dispersible tablets taken by mouth, usually mixed in water.
Answers
Carglumic acid: frequently asked questions
Why is high ammonia so serious?
Ammonia is a toxic waste product; when it builds up it can cause confusion, drowsiness, vomiting and, if untreated, serious harm, so it is treated as a medical emergency.
What signs of high ammonia should I watch for?
Confusion, unusual drowsiness, repeated vomiting, refusing food, irritability or unsteadiness can be warning signs and need urgent medical help.
Do I need a special diet as well?
It is usually used alongside a low-protein diet planned by your metabolic dietitian, as diet and medicine work together to control ammonia.
Can I stop taking it if I feel well?
No, not without your team's advice; in NAGS deficiency it is a long-term treatment, and stopping it can let ammonia rise quickly.
What should I do when I am ill?
Illness can raise ammonia, so follow the emergency (sick-day) plan your metabolic team has given you and seek help early if you are concerned.
Authoritative sources
- BNF
- NICE CKS
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