Substance(s) Sodium phenyl butyrate
Admission country United Kingdom
Manufacturer Swedish Orphan Biovitrum International AB
Narcotic No
ATC Code A16AX03
Pharmacological group Other alimentary tract and metabolism products

Authorisation holder

Swedish Orphan Biovitrum International AB

Drugs with same active substance

Drug Substance(s) Authorisation holder
AMMONAPS 940 mg/g granules Sodium phenyl butyrate Swedish Orphan Biovitrum International AB

Patient’s Leaflet

What is it and how is it used?

AMMONAPS is prescribed to patients with urea cycle disorders. Patients with these rare disorders have a deficiency of certain liver enzymes and are therefore unable to eliminate nitrogen waste. Nitrogen is a building block of proteins, because of this, there is a build up of nitrogen in the body after eating protein. Nitrogen waste, in the form of ammonia, is especially toxic for the brain and leads, in severe cases, to reduced levels of consciousness and to coma.

AMMONAPS helps the body to eliminate nitrogen waste, reducing the amount of ammonia in your body.


What do you have to consider before using it?

Do not take AMMONAPS if you:
  • are pregnant.
  • are breast-feeding.
  • are allergic (hypersensitive) to sodium phenylbutyrate or any of the other ingredients of AMMONAPS.
Take special care with AMMONAPS
  • if you have difficulty swallowing. AMMONAPS tablets can get stuck in the oesophagus and cause ulcers. If you have difficulty swallowing it is recommended to use AMMONAPS granules instead.
  • if you suffer from heart failure, a decrease in your kidney function or other diseases, where the retention of the sodium salt contained in this medicine, may make your condition worse.
  • if you have decreased kidney or liver function, since AMMONAPS is eliminated from the body through the kidney and liver.
  • when given to small children, since they may not be able to swallow the tablets and may choke. It is recommended to use AMMONAPS granules instead.

AMMONAPS must be combined with a diet reduced in proteins designed especially for you by the doctor and the dietician. You must follow this diet carefully.

AMMONAPS does not completely prevent the occurrence of an acute excess of ammonia in the blood and is not appropriate for treating such a condition, which is a medical emergency.

If you require laboratory tests, it is important to remind your doctor that you are taking AMMONAPS, since sodium phenylbutyrate may influence certain laboratory test results.

Taking other medicines
Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription.

It is especially important to tell your doctor if you are taking medicines containing:

  • valproic acid (an antiepileptic drug),
  • haloperidol (used in certain psychotic disorders),
  • corticosteroids (cortisone-like medicines that are used to provide relief for inflamed areas of the body),
  • probenecid (for treatment of hyperuricemia associated with gout).

These medicines may change the effect of AMMONAPS and you will need more frequent blood controls. If you are uncertain if your medicines contain these substances, you should check with your doctor or pharmacist.

Pregnancy and breast-feeding
Do not use AMMONAPS if you are pregnant, because this medicine can harm your unborn baby. If you are a woman who could get pregnant, you must use reliable contraception, during treatment with AMMONAPS.
Do not use AMMONAPS if you are breast-feeding, because this medicine can pass into the breast-milk and harm your baby.

Driving and using machines

No studies on the effects on the ability to drive and use machines have been performed.

Important information about some of the ingredients of AMMONAPS

Each AMMONAPS tablet contains 62 mg of sodium. To be taken into consideration by patients on a sodium controlled diet.


How is it used?

Always take AMMONAPS exactly as your doctor has told you. You should check with your doctor or pharmacist if you are not sure.


The daily dose of AMMONAPS will be calculated from your protein tolerance, diet and body weight or body surface. You will need regular blood tests to determine the correct daily dose. Your doctor will tell you how many tablets you should take.

Method of administration

You should take AMMONAPS by mouth in equally divided doses with each meal (for example three times per day).You should take AMMONAPS with a large volume of water.

AMMONAPS must be taken with a special diet reduced in protein.

AMMONAPS tablets should not be given to children who are not able to swallow tablets. It is recommended that AMMONAPS granules are used instead.

You will need to have treatment and to follow a diet throughout your life, unless you have a successful liver transplantation.

If you take more AMMONAPS than you should
Patients who have taken very high doses of AMMONAPS experienced:

  • sleepiness, tiredness, light-headedness and less frequently confusion,
  • headache,
  • changes in taste (taste disturbances),
  • decrease in hearing,
  • disorientation,
  • impaired memory,
  • worsening of existing neurological conditions.

If you experience any of these symptoms, you should immediately contact your doctor or the nearest hospital emergency department for supportive treatment.

If you forget to take AMMONAPS
You should take a dose as soon as possible with your next meal. Make sure that there are at least 3 hours between two doses. Do not take a double dose to make up for a forgotten dose.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.


What are possible side effects?

Like all medicines, AMMONAPS can cause side effects, although not everybody gets them.

The frequency of possible side effects is listed below.

Very common Common Uncommon Rare Very rare Not known Affects more than 1 user in 10 Affects 1 to 10 users in 100 Affects 1 to 10 users in 1,000 Affects 1 to 10 users in 10,000 Affects less than 1 user in 10,000 Frequency cannot be estimated from the available data

Very common side effects: irregular menstrual periods and cessation of menstrual periods. If you are sexually active and your period stops altogether, do not assume that this is caused by AMMONAPS. If this occurs, please discuss it with your doctor, because the absence of your period may be caused by pregnancy (see Pregnancy and breast-feeding section above).

Common side effects: changes in number of blood cells (red cells, white cells and platelets), reduced appetite, depression, irritability, headache, fainting, fluid retention (swelling), changes in taste (taste disturbances),pain in the abdomen, vomiting, nausea, constipation, skin odour, rash, abnormal kidney function, weight gain, altered laboratory test values.

Uncommon side effects: deficiency in red blood cells due to bone marrow depression, bruising, altered heart rhythm, rectal bleeding, stomach irritation, stomach ulcer, inflammation of the pancreas.

If any of the side effects get serious, or if you notice any side effects not listed in this leaflet, please tell your doctor or pharmacist.

If persistent vomiting occurs, you should contact your doctor immediately.


How should it be stored?

Keep out of the reach and sight of children.

Do not use AMMONAPS after the expiry date which is stated on the carton and the bottle label after ?EXP?. The expiry date refers to the last day of that month.

Do not store above 30°C.

Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.


Further information

What AMMONAPS contains

The active substance is:

  • sodium phenylbutyrate. Each tablet of AMMONAPS contains 500 mg of sodium phenylbutyrate.The other ingredients are:
  • microcrystalline cellulose, magnesium stearate and colloidal anhydrous silica.

What AMMONAPS looks like and contents of the pack

AMMONAPS tablets are off-white, oval and embossed with ?UCY 500?.

The tablets are packaged in plastic bottles with child-resistant caps. Each bottle contains 250 or 500 tablets.

Marketing Authorisation Holder

Swedish Orphan Biovitrum International AB
SE-112 76 Stockholm

Bioglan AB
PO Box 50310
SE-202 13 Malmö

This leaflet was last approved in


Substance(s) Sodium phenyl butyrate
Admission country United Kingdom
Manufacturer Swedish Orphan Biovitrum International AB
Narcotic No
ATC Code A16AX03
Pharmacological group Other alimentary tract and metabolism products



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