Sodium phenylbutyrate for urea cycle disorders
This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults. Read this leaflet carefully. Keep it somewhere safe so that you can read it again.
Name of medicine
Brand name: Ammonaps, Pheburane
Why is it important for my child to take Sodium phenylbutyrate?
When protein from food is digested, it is broken down into small molecules called amino acids, which are needed by all the cells in the body. If there is too much amino acid in the blood, it is turned to ammonia in the liver, and then into uric acid, which the body gets rid of in urine (wee).
Urea cycle disorders are inherited disorders where ammonia is not turned into uric acid properly and so it builds up in the blood. Your child needs to take sodium phenylbutyrate regularly to help reduce the levels of ammonia in their body.
What is Sodium phenylbutyrate available as?
- Tablets: 500 mg
- Granules: 483 mg or 940 mg in 1 g
- Liquid medicine can be ordered specially from your pharmacist: 1.25 g in 5 mL
When should I give Sodium phenylbutyrate
Sodium phenylbutyrate is usually given three or four times a day.
- Three times a day: This should be in the morning, early afternoon and at bedtime. Ideally, these times are at least 6 hours apart, for example 8am, 2pm and 8pm.
- Four times a day: This is usually first thing in the morning, at about midday, late in the afternoon and at bedtime. Ideally, these times should be at least 4 hours apart, for example 8am, midday, 4pm and 8pm.
Give the medicine at about the same time(s) each day so that this becomes part of your child’s daily routine, which will help you to remember.
How much should I give?
Your doctor will work out the amount of Sodium phenylbutyrate (the dose) that is right for your child. The dose will be shown on the medicine label.
It is important that you follow your doctor’s instructions about how much to give.
How should I give Sodium phenylbutyrate?
- Tablets should be swallowed with a glass of water, squash or juice. Your child should not chew the tablet.
- Sprinkle or stir the granules into a small amount of soft food (e.g. yogurt or feed). Your child should then swallow the food straight away, without chewing. Make sure that they take it all.
- Shake the medicine well. Measure out the right amount using an oral syringe or a medicine spoon. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount.
When should the medicine start working?
The medicine will start working straight away, although you will not see any difference in your child.
What if my child is sick (vomits)?
- If your child is sick less than 30 minutes after having a dose of Sodium phenylbutyrate, give them the same dose again.
- If your child is sick more than 30 minutes after having a dose of Sodium phenylbutyrate, do not give them another dose. Wait until the next normal dose.
If your child is sick again, seek advice from your family doctor, nurse, pharmacist, or hospital. They will decide what to do based on your child’s condition and the specific medicine involved.
What if I forget to give it?
If you miss a dose, wait until the next normal dose. Do not give the missed dose.
What if I give too much?
You are unlikely to cause harm if you give an extra dose of Sodium phenylbutyrate by mistake. If you are concerned that you may have given too much, contact your doctor or local NHS services (details at end of leaflet). Have the medicine or packaging with you if you telephone for advice.
Are there any possible side effects?
We use medicines to make our children better, but sometimes they have other effects that we don’t want (side-effects).
- Girls may find their periods become irregular or stop. If this happens, contact your doctor.
Other side-effects you need to know about
Your child may get some of the following side effects when they first start taking Sodium phenylbutyrate. These usually wear off after a few days as your child gets used to the medicine. If they are still a problem after a week, or you are worried, contact your doctor but continue to give Sodium phenylbutyrate.
Your child may feel less hungry (lose their appetite). Encourage them to eat small meals often.
Your child may experience a metallic or bitter taste in their mouth. Eating citrus fruits (e.g. oranges) or sipping water may help.
Your child may have an unpleasant body odour and bad breath. Using breath fresheners and deodorant will help.
There may sometimes be other side effects that are not listed above. If you notice anything unusual and are concerned, contact your doctor. You can report any suspected side effects to a UK safety scheme at www.mhra.gov.uk/yellowcard
Can other medicines be given at the same time as Sodium phenylbutyrate?
- You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
- Check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal and complementary medicines.
General advice about medicines
- Try to give medicines at about the same times each day, to help you remember.
- Only give this medicine to your child. Never give it to anyone else, even if their condition appears to be the same, as this could do harm.
- If you think someone else may have taken the medicine by accident, contact your doctor for advice.
- Make sure that you always have enough medicine. It may take up to 3 weeks for your pharmacist to order Sodium phenylbutyrate powder or medicine, so make sure you order a new prescription at least 3 weeks before you will run out.
- Make sure that the medicines you have at home have not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.
- If you are not sure a medicine is working, contact your doctor but continue to give the medicine as usual in the meantime. Do not give extra doses, as you may do harm.
Where should I keep this medicine?
- Keep the medicine in a cupboard, away from heat and direct sunlight.
- It does not need to be kept in the fridge.
- Make sure that children cannot see or reach the medicine.
- Keep the medicine in the container it came in.
Who to contact for more information?
Your child’s doctor, pharmacist or nurse will be able to give you more information about Sodium phenylbutyrate and about other medicines used to treat urea cycle disorders.
Version . © NPPG, RCPCH and WellChild, all rights reserved. Review by March 2016.
The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website, www.medicinesforchildren.org.uk.
We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.