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Dear healthcare professional letter on risks from thrombotic microangiopathy and nephrotic syndrome associated with the use of intereferon beta


Medis Adria d.o.o., Bayer d.o.o., Novartis Croatia d.o.o. and Merck d.o.o. have in collaboration with the Agency for Medicinal Products and Medical Devices (HALMED) and European Medicines Agency (EMA) send a letter to healthcare professionals on the risks from thrombotic microangiopathy and nephrotic syndrome associated with the use of interferon beta in treatment of multiple sclerosis.


Cases of thrombotic microangiopathy (TMA), including those with a fatal outcome, have been reported during treatment of multiple sclerosis with interferon beta-containing medicinal products. The majority of TMA cases appear as thrombocytopenic purpura or haemolytic uraemic syndrome. Cases of nephrotic syndrome with various inherent nephropathies have also been reported.

TMA and nephrotic syndrome may be developed a few weeks or a few years after the beginning of treatment with interferon beta. Healthcare professionals should be cautious due to a possible occurrence of these symptoms, and in case of theiroccurrence, the treatment should be started immediately

Recommendations for TMA

  • Clinical features of TMA include thrombocytopenia, new onset hypertension, fever, CNS symptoms (i.e. confusion and paresis) and impaired renal function. If clinical features of TMA are observed further testing of blood platelet levels, serum LDH and renal function is recommended. Testing for erythrocyte fragments in blood films is also recommended.
  • If TMA is diagnosed prompt treatment with plasma exchange is required and immediate discontinuation of interferon beta is recommended.

Recommendations for nephrotic syndrome

  • It is recommended to monitor periodically the renal function and be cautious due to possible occurrence of early symptoms or nephrotic syndrome symptoms such as oedema, proteinuria and renal impairment, especially in patients at high risk of renal diseases. If nephrotic syndrome is diagnosed prompt treatment is required and immediate discontinuation of interferon beta is to be considered.

The following interferon beta-containing medicinal products for treatment of multiple sclerosis are authorised in the Republic of Croatia:

  • Avonex (interferon beta-1a) - Biogen Idec Ltd
  • Rebif (interferon beta -1a) - Merck Serono Europe Ltd
  • Betaferon (interferon beta-1b) - Bayer Pharma AG
  • Extavia (interferon beta-1b) - Novartis Europharm Ltd
  • Plegridy (peginterferon beta 1a) - Biogen Idec Ltd

HALMED has not received any suspected adverse reaction report to interferon beta-containing medicinal product that would be associated to thrombotic microangiopathy or nephrotic syndrome. HALMED will continue to closely monitor the safe use of these medicines and will inform the public promptly about any new findings.

Here you may view the Dear Healthcare Professional Letter.

We remind healthcare professionals 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 via form or on-line application, with recommendation regarding any adverse reaction they discover to consult their doctor or pharmacist about the continuation of their therapy.