Australia's drug regulator has found three-quarters of a popular heartburn medication it recently tested contained heightened levels of a suspected cancer-causing agent.

Key points: Popular heartburn medication Zantac, known generically as ranitidine, has been recalled

Popular heartburn medication Zantac, known generically as ranitidine, has been recalled The drug has been found to contain NDMA, an agent which probably causes cancer

The drug has been found to contain NDMA, an agent which probably causes cancer Seventy five per cent of ranitidine drugs tested by the Australian regulator were found to contain heightened levels of NDMA

"We're just validating those results and we'll be publishing that on our website soon," Professor Paul Kelly, the Therapeutic Goods Administration's chief medical advisor, told 7.30.

The TGA recalled the popular drug Zantac, also known by its generic name ranitidine, on October 4 after regulators in other countries found the pharmaceutical had been contaminated with the probable carcinogen NDMA.

Although the risk to consumers was believed to be low, the TGA took what it described as a "very precautionary approach" by recalling the products and carrying out its own testing.

"In terms of the level of concern, it's three parts per million. Very, very small amounts," Professor Kelly said.

"We've now tested 135 different batches of this medicine, and we're finding about 75 per cent of those are positive above that level of three parts per million.

"If someone were to take a ranitidine tablet for their entire life for 70 years, every day, then the risk of cancer may go up by about one in 100,000, so I think you can see from those figures it's a very small risk."

'It's pretty scary'

Heartburn drug Zantac, also known generically as ranitidine, has been recalled in Australia. ( ABC News: Peter McCutcheon )

The recall of the drug was a shock for Sydney mother Jade Wood, who relied on Zantac to treat her two children with severe reflux.

"I would love to know the batch we've got is not contaminated. I'd love to hear that ASAP, so I wouldn't have to stop it," she told 7.30.

"It's pretty scary and you get quite angry that a fault like this could happen. It's not just a slip-up."

The drug has been on the market since the early 1980s and was at one time the most popular medication in the world.

How it became contaminated remains a mystery.

Dean of pharmacy at the University of Sydney, Professor Andrew McLachlan, believes it may be something inherent in how the drug breaks down.

"It's quite possible that this break down product coming from that drug has probably been in those products for quite some time," he said.

"There's no one manufacturer, so this doesn't appear to be a manufacturing issue, particularly because globally we set a very high standard."

The TGA agrees this is a possibility.

"We've found a range of manufacturers in different countries — five altogether — and that's spread across a number of suppliers," Professor Kelly said.

"So yes, it could be a generic issue with the actual manufacture or it could be something to do with the drug itself."

'Safe alternatives are available'

Many users of Zantac have moved to other drugs. ( iStockphoto/Ohmega1982 )

Brisbane pharmacist Chris Owen says some customers have been worried, but there has been no sign of panic.

"A lot of people who are taking Zantac were a little bit worried, justifiably," Mr Owen said.

"There is a low-risk carcinogen in the product but at this stage we haven't had anyone who couldn't go onto another treatment. They've been able to talk to their doctor or their pharmacist and get an alternative."

Professor McLachlan said "there are some very effective and known-to-be-safe alternatives that are available".

The company responsible for Zantac in Australia is Aspen Australia. In a statement it said: "Aspen Australia treats the quality of its products with utmost diligence and will continue to work closely with the TGA on this matter."

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