A manufacturer of highly addictive painkillers has been using data-matching techniques to track people's Google health searches and target them with ads that increase in intensity until they respond.

Key points: Pharmaceutical company Mundipharma uses health searches on Google to target ads

The ads appear in web browsers and indirectly reference a brand of addictive oxycodone

The banner ads get more intense until people click on them

Pharmaceutical giant Mundipharma and marketing agency Affinity produced a marketing campaign for the drug oxycodone, which used Google's ad searches tool to identify patients who were unhappy with their current pain medication.

As part of a pilot project in the Coffs Harbour area of New South Wales, they monitored Google searches to specifically identify patients who were looking up terms like "blocked up due to pain meds".

After people used the search terms, the marketeers "followed them around the internet" and ran banner ads for the company's Blocked Pipes campaign in their internet browser, which told them to "ask your doctor" about symptoms like constipation.

The advertisement indirectly referenced Targin, a blend of oxycodone and a second ingredient that relieves the digestive symptoms associated with long-term opioid use, which is common among people taking it for chronic pain.

While the advertisements did not specifically name Targin, they actively pressured people with chronic pain to ask their doctor about the product.

The banner ads got more exaggerated each time the patient ignored them, moving from phrases like "why suffer?" to "don't ignore the problem" and "it won't go away by itself".

Samples of the online ads used in the Mundipharma campaign show they increased in intensity until users clicked on them. ( Supplied )

In promotional material, Affinity said the third and most alarmist advertisement in the series got the most clicks.

It was part of a broader print, radio and online campaign that ran for 18 months between July 2014 and December 2015.

The pilot project in Coffs Harbour was so successful at getting consumers interested in its product, Affinity said it would be rolled out nationally, but it ultimately only ran in Sydney.

The Coffs Harbour location was chosen because the companies were targeting "high incidence pain medication areas in regional areas".

That is despite laws specifically banning drug companies from marketing their products direct to consumers.

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'Not a bad outcome', ad company Affinity claims

On its website, Affinity spruiked the success of its internet campaign.

"Due to medical regulation, the results of our Coffs Harbour pilot campaign remain confidential, but needless to say, we exceeded expectations," it stated online.

"Not a bad outcome considering we weren't even able to mention the brand name."

Following the ABC's inquiries, Affinity removed the page promoting its work and said it was unable to comment because of confidentiality requirements in its agreement with Mundipharma.

Mundipharma is the sister company of Purdue Pharma, the US company facing hundreds of millions of dollars in legal action over allegations its misleading marketing practices led to the country's opioid crisis.

In a statement, a spokesman for Mundipharma said the campaign was a "disease state awareness initiative" and was not promotional.

"A number of disease state websites and awareness initiatives are active at any given time in Australia," he said.

He said the promotion did not reference any medications and was compliant with the Medicines Australia Code of Conduct and Therapeutic Goods Administration (TGA) regulations.

The company suggested patients who spoke to their doctor after seeing the advertisement may have also been advised to use laxatives or make changes to their dose or brand of pain medication, not necessarily use Targin.

"The agency [Affinity] description of the initiative was inaccurate and unauthorised by Mundipharma," a spokesman said.

"We were not aware that they had referenced the initiative on their website, nor did they have permission to do so.

"Individuals were only shown sequenced advertisements for the website if they had previously visited it."

Mundipharma said the campaign ran in Coffs Harbour and Sydney.

Advertisements for a Mundipharma oxycodone product that appeared in internet browsers and increased in severity until people clicked on it. ( Supplied )

Details about the campaign have been revealed after the ABC reported Mundipharma was using a regulatory loophole in Australia to avoid scrutiny of its marketing to general practitioners.

It was continuing to promote the use of opioids to treat chronic pain even though current science and medical guidelines suggest they should be avoided and can potentially make chronic pain worse.

Opioids, however, are still considered appropriate in palliative care, cancer treatment and after surgery.

Mundi campaign 'appalling': expert

Public health expert Ken Harvey, from Monash University, has lobbied for reforms to advertising rules for pharmaceutical products and other therapeutic goods.

He described the Mundipharma campaign as "appalling".

"The pharmaceutical industry is not allowed to advertise prescription drugs to the public, but clearly there are loopholes in what they call disease awareness campaigns," Associate Professor Harvey said.

"It's a classic example stretching the limits — it may be within the legality of the law but it's certainly not within the spirit of the law.

"There is a lot of evidence that this sort of advertising sends people to a doctor who can sometimes prescribe just because that gets people out of their consulting room, rather than trying to do a long, involved explanation about perhaps getting off or reducing opioid use."

Ken Harvey said the campaign was a classic example of "stretching the limits". ( ABC News )

Associate Professor Harvey said he took part in a Federal Government working party established to consider reforms to pharmaceutical advertising regulations in 2011.

It recommended streamlining codes of conduct from nine industries into one and making adherence to the code and participation in the complaints process a condition of getting a therapeutic good approved in Australia.

Under current laws, companies that breach regulations can face warnings, fines, enforceable undertakings and, in extreme cases, criminal prosecution leading to prison.

Associate Professor Harvey said the recommendation was never adopted by the then-Labor government and has not been considered by the current government.

"Nothing has happened," he said.

"There should be a uniform code with uniform penalties applying to all players.

"To me, it's just appalling and [Health] Minister Greg Hunt should act."

Following the ABC's inquiries, a spokesman for the Health Minister said the TGA would investigate whether the advertisement had breached the terms of its product registration.

If it has breached the terms of registration, it faces having its product deregistered, or possible criminal and civil penalties.

"The Government supports the values and principles of honesty, integrity, transparency, accountability and oversight for the relationship between the medicines and medical device industry in its dealing with healthcare professionals," the Minister's spokesman said.

It understood that in order to get a medicine registered in Australia, pharmaceutical companies must agree to abide by the Medicines Australia Code of Conduct for promotion of products to medical practitioners, even if they do not elect to become a member of that industry body.

A spokeswoman for Google said there were strict policies that governed the type of ads allowed on the platform.

"When we find ads that violate our policies, we remove them," she said.