TGA to review diabetes drug

The Therapeutic Goods Administration is reviewing new research linking bladder cancer with the use of the diabetes drug pioglitazone.

A TGA spokesperson said the organisation had previously advised health professionals and consumers about the potential risk through alerts and articles on its websites, and was aware of the new research.

“The TGA will review the information in the article to determine whether further action is needed in relation to this risk,” the spokesperson told the limbic this week.

The revelation follows the publication of research in the BMJ again linking the drug with an increased risk of bladder cancer.

The findings also suggested that the risk increases with increasing duration of use and dose.

However, the researchers stress that, in absolute terms the risk remains low but recommend doctors and patients should be aware of the association when assessing overall risk and benefits of the therapy.

The association between use of the drug and bladder cancer has been controversial, with studies reporting contradictory findings.

The Canadian-based researchers analysed data for 145,806 UK patients who were newly treated with diabetes drugs between 2000 and 2013. When compared with no thiazolidinedione use, the use of pioglitazone was association with an overall 63% increased risk of bladder cancer.

Interestingly, they found no increased risk associated with the use of rosiglitazone – a drug that belongs to the same class of thiazolidinedione – suggesting that the risk is drug-specific not class-specific.

However, rosiglitazone been linked to an increased risk of cardiovascular disorders. It has been the subject of a TGA advisory statement issued in 2010 and updated in December 2015, warning that this drug should not be used in patients with known ischaemic heart disease.

Pioglitazone has also been the subject of a number of official safety alerts in Australia. The first was in July, 2011, when the TGA published a safety advisory regarding pioglitazone and risk of bladder cancer. A further safety review published in the publication Medicines Safety Update and completed in 2013 found that the drug has a favourable long-term risk-benefit balance.

The latest research has attracted plenty of attention, especially in mainstream media. Leading endocrinologist, Associate Professor Stephen Stranks, director of Southern Adelaide Diabetes and Endocrine Services said he had not had any questions from patients since the research came out.

But he said he did not expect it, given that he only uses the drug occasionally. However he said he was not surprised by the research.

“This has been a concern that has been around for a long time,” he told the limbic.

However he pointed out that the studies to date have been generally observational.

“We don’t absolutely know that this association is real,” Professor Stranks said.

Professor Stranks said that it was important to be mindful of the risk, and even though he only used the drug rarely he was always careful to avoid it in people with existing bladder cancer or increased risk.

Patients were always warned to be on the lookout for signs and symptoms of changes in the bladder, such as blood in the urine.

“Every treatment will have risks, but not treating their diabetes will have risk also,” he said.

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