Medicinal Products

Direct healthcare professional communication emphasizing that Ammonaps (sodium phenylbutyrate) tablets and granules should only be used when there is no alternative treatment


Swedish Orphan Biovitrum International AB (Sobi), in agreement with the Agency for Medicinal Products and Medical Devices (HALMED) and the European Medicines Agency (EMA), has informed healthcare professionals that Ammonaps (sodium phenylbutyrate) tablets and granules should only be used when there is no alternative treatment.


  • The manufacturing site of Ammonaps (sodium phenylbutyrate) was found to have several shortcomings in relation to good manufacturing practice (GMP). There is no indication of risk to patients and corrective measures are being taken to address the shortcomings.
  • While the measures are being implemented, Ammonaps tablets and granules should, as a precaution, now only be used in patients when other sodium or glycerol phenylbutyrate-containing medicines cannot be used instead.
  • If the alternative phenylbutyrate medicine is not suitable for patients with nasogastric tube or gastrostomy, Ammonaps granules can continue to be used in these patients.

Further information

Ammonaps (sodium phenylbutyrate) is indicated for use as adjunctive therapy in the chronic management of urea cycle disorders, involving deficiency of carbamylphosphate synthetase, ornithine transcarbamylase or argininosuccinate synthetase. Ammonaps is available in Croatia only in the form of granules.

The communication provides healthcare professionals with information on precautions due to shortcomings in relation to good manufacturing practice. Until now there has been no evidence of specific adverse effects as a consequence of the specified shortcomings.

HALMED considers Ammonaps granules to be of key importance for patients as an alternative medicinal product is not available. Therefore, Ammonaps granules will remain available in the Republic of Croatia, as this medicinal product is used to treat a rare disease and is considered essential for public health.

Here you may view the direct healthcare professional communication.

Healthcare professionals are reminded that they should report any adverse reaction, as well as quality defect to HALMED. Patients who have developed any adverse reaction to medicinal product may report it directly to HALMED. HALMED recommends patients to contact their doctor or pharmacist regarding any adverse reaction they notice.