Research tracks impact of reverse-switching codeine

Research tracks impact of reverse-switching codeine

31 March 2020 - Deborah Wilkes

Paracetamol medicines were the main beneficiary when codeine medicines were reverse-switched from non-prescription to prescription-only status in Australia on 1 February 2018, according to research just published in the Medical Journal of Australia.

Researchers from the University of New South Wales (UNSW) said sales to pharmacies of paracetamol, paracetamol combinations, and ibuprofen medicines had increased but sales of prescription analgesics had not risen.

Meanwhile, sales of non-prescription cold and flu products containing the opioid derivative dextromethorphan had increased slightly, said the researchers, but sales of cough products containing dextromethorphan, dihydrocodeine or pholcodine had not.

Lead author Andrea Schaffer said the team had previously shown that reverse-switching codeine had led to a substantial reduction in codeine poisoning calls to the NSW Poison Information Centre, and an 87% drop in sales of low-strength codeine products.

Commenting on the latest findings, Schaffer said paracetamol, ibuprofen and paracetamol combinations “carry less risk of dependence” but “using them excessively or inappropriately is also associated with harms”.

“Misuse and overuse of paracetamol has been associated with serious adverse events such as liver failure, and, in the case of ibuprofen, with gastrointestinal complications or kidney impairment,” remarked Schaffer.

According to Schaffer, there was a need to “monitor future numbers of adverse events – like paracetamol overdose-related hospital admissions and liver injuries – particularly given these had already been increasing in Australia prior to the rescheduling”.

Key findings

The researchers observed a “sizeable increase” in overall non-prescription non-codeine painkiller sales following the reverse-switch of codeine. They said there had been a 41% increase in tablets sold, and a 13% increase in packs sold.

The increase in sales of paracetamol, ibuprofen and paracetamol/ibuprofen combination products, they added, had “far offset” the reduction in non-prescription codeine sales post-rescheduling.

Paracetamol medicines were the main beneficiary. Tablet sales had increased by more than 75%, said the researchers, lifting the market share from 44.9% of all packs of non-prescription analgesics to 60.1% of all packs.

Combination medicines containing paracetamol and ibuprofen had also benefited, noted the researchers, with sales “more than quadrupling” after rescheduling.

“The dramatic increase was likely related to increased marketing of these products,” said the researchers, “and the fact that they have similar pain-relieving effects to codeine combined with paracetamol or ibuprofen.”

Prescriptions for codeine medicines

Commenting on prescriptions for codeine, the researchers said the increase in prescription codeine was much smaller than the volume of sales there had been in the OTC market before the rescheduling.

The researchers said pharmacies had sold 23.5 million packs of non-prescription codeine medicines in the year before the rescheduling announcement.

“Contrary to our expectations, we observed only a slight increase in prescribed codeine post rescheduling,” commented Schaffer, adding the team had previously shown that this was due to “increases in sales of low-strength preparations, rather than high-strength”.

“This suggests that only a small number of people seem to be switching to prescription products,” added Schaffer, noting that this meant that “OTC codeine use was likely – at least in part – driven by convenience and easy access”.

Concerns about the reverse-switch

The researchers said one of the initial concerns about the reverse-switch had been an anticipated increase in sales of products containing opioid derivatives – such as non-prescription cold and flu products or cough suppressants containing dextromethorphan or dihydrocodeine.

“Experts were initially worried that consumers who previously bought codeine-containing painkillers may be switching to opioid derivatives – but it doesn’t look like that’s what’s happening, which is good news,” said Schaffer.

Schaffer added that this confirmed studies by other researchers that had found a “non-increase in non-codeine opioid sales”.

“In recent years there has been increased awareness about the harms of opioid over-prescribing, which may partly explain why there were no increased sales in that area,” commented Schaffer.

The research looked at the change in sales to pharmacies of non-prescription and prescription analgesics, cold and flu products, and cough suppressants. It covered the period from March 2015 until March 2019, excluding the 12 months between the announcement and the implementation of the reverse-switch.

The IQVIA data captured around 96% of all non-prescription and prescription pharmaceuticals sales to pharmacies in Australia. Sales to hospital pharmacies were excluded.

Australia's Therapeutic Goods Administration (TGA) announced in December 2016 that non-prescription medicines containing codeine should only be available on prescription. The move was prompted by "overuse and abuse" of such products (click here to read the News story).

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