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Safety doubts raised over sulfonylureas

A new study has thrown the safety of sulfonylureas into doubt after finding they raised mortality in diabetes patients, writes Daniel Cressey.

Canadian researchers found those exposed to high doses of first-generation sulfonylureas were at a doubled risk of dying, while the newer glyburide increased mortality by 30 per cent. The drugs had similar effects on risk of death from acute ischaemic events. There was no such association with metformin.

The Medicines and Healthcare Products Regulatory Agency pledged to 'carefully review' the new research and decide if product information needed to be amended. Specialists warned the drugs should be removed from their current position in national guidelines as second-line treatment for diabetes.

Study leader Dr Jeffrey Johnson, associate professor in the department of public health sciences at the University of Alberta, said: 'We observed a dose-response relation between sul- fonylurea exposure and risk of death.

'This evidence, taken within the context of observations collected over the last 30 years, suggests clinicians should carefully assess the need for sulfonylurea therapy in subjects at high risk of cardiovascular events ­ particularly now when several other classes of anti-diabetes oral medications are available.'

Current national guidance recommends sulfonylureas as second-line, with NICE guidance not due until 2008.

But in a commentary on the study, Professor David Bell, emeritus professor of medicine at the University of Alabama, insisted sulfonylureas should now be relegated to third-line agents after metformin and thiazolidinediones.

He warned that sulfonylureas appeared to be having the opposite effect from intended ­ by increasing the risk of cardiovascular events.

Dr Colin Kenny, chair of the Primary Care Diabetes Society, said: 'This finishes the argument about what should be first-line ­ that's metformin.'

Dr Kenny, a GP in Co. Down, Northern Ireland, added: 'There has been a suspicion that the older sulfonylureas did cause mortality. It will probably reinforce the need to move to new agents but it still casts a shadow over the class in general.'

He agreed relegating sulfonylureas to third-line might be sensible, but warned it had 'very big cost implications' because of the price of thiazolidinediones.

The retrospective cohort study of 5,795 patients with type 2 diabetes was published this week in the Canadian Medical Association Journal.

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