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Azide impurity in 'sartan' blood pressure medicines

TGA investigation - low levels of contamination with azidomethyl-biphenyl-tetrazole (AZBT)

20 August 2021

The Therapeutic Goods Administration (TGA) is investigating contamination of some 'sartan' medicines with unacceptable levels of an azide impurity, known as azidomethyl-biphenyl-tetrazole[1] (AZBT). Sponsors of some sartan medicines have advised the TGA that very low levels of this impurity have been detected in batches of losartan and irbesartan products. The TGA is working with sponsors to investigate and ensure the issue is appropriately addressed.

'Sartans', which are also called angiotensin II receptor blockers, are medicines used to treat high blood pressure (also known as hypertension).

In Australia, batches of losartan and irbesartan found to contain unacceptable levels of this azide impurity have been recalled from pharmacies. Details of the recalls are available in the TGA's System for Australian Recall Actions database. Some types of sartan products may be unavailable while this issue is investigated. Any medicine shortages reported to the TGA will be published in the TGA's Medicine Shortage Reports Database.

In 2018, several sartan medicines were recalled due to nitrosamine impurities. The investigation of the current azide impurity is unrelated, although both impurities have similar safety concerns.

What is the azide impurity?

The impurity, known as azidomethyl-biphenyl-tetrazole (AZBT), is a compound that can form during the manufacture of the active ingredient in some sartan medicines. It is known to damage DNA, and as a result long-term exposure over years may increase an individual's risk of developing cancer.

The risk posed by this azide impurity at the levels detected in sartan medicines to date is very low. However, such contamination is considered unacceptable for a medicine. The actual health risks from the impurity depend on the dose of the medicine and will vary from person to person.

What should consumers do?

Patients taking sartan medicines should not stop their treatment without first consulting a doctor or pharmacist. As the risks are very low, and associated with long-term exposure, there is no immediate health risk.

Consumers who find that their usual brand of sartan medicine is unavailable should discuss alternatives with their doctor or pharmacist.

If you have any other questions or concerns about this issue, you should speak to your health professional.

What should health professionals do?

Please be aware of this issue and advise patients accordingly. There is no reason to stop prescribing sartans. However, there may be limited availability of some irbesartan and losartan brands due to current shortages.

You may wish to remind patients of the importance of keeping their blood pressure under control and reassure them that that the risk posed by the impurity at the trace levels observed to date is very low.

What is the TGA doing?

The TGA has reviewed results reported by affected Australian sponsors of sartan medicines being supplied in Australia.

Sponsors of affected medicines are introducing changes to their manufacturing processes and have put in place controls to limit the levels of the azide impurity to ensure that only batches that comply with internationally acceptable intake limits are released.

Updated information will be published on this issue, when it becomes available.

Reporting problems

Consumers and health professionals are encouraged to report problems with medicines or vaccines. Your report will contribute to the TGA's monitoring of these products.

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medicine or vaccine.


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