The following happened when only codeine was prescribed. No, the sky has not collapsed

Fears of converting the analgesic codeine to a prescription drug would make more people abusing stronger pain killers unfounded, according to research published today.

Our research in the Addiction journal revealed that the change from 2018 resulted in a 50% reduction in code overdoses and sales. There was also no increase in overdose with stronger opioids or high-concentration codeine, as some had feared.

Remember, how did we get here?

Australia has a love affair with codeine. It was our most widely used opioid in the past, and data from 2013 showed that we had more codeine than the US, even though we had about 7% of the population.

As of February 2018, however, you could only buy codeine in Australia with a prescription. Previously you could buy low-grade codeine (up to 15 mg per tablet) in pharmacies in combination with paracetamol, ibuprofen and over-the-counter aspirin (OTC). Codeine of higher strength has always required a recipe.

The change of 2018 was not an overnight decision. Codeine has been on government radar for over a decade. The Therapeutic Goods Administration (TGA) set up a codeine working group in 2008 to respond to the increasing abuse. Codeine is an opioid analgesic, which means people can become addicted to it and there is a risk of overdose damage.

There was also a previous attempt to reduce the damage when in 2010 all codeine painkillers were put in the pharmacy behind the counter. Previously, the products of lower strength could be removed from the pharmacy shelf without consulting a pharmacist.

Unfortunately, our previous study showed that this step of storing codeine behind the counter had little effect. Other studies also showed that codeine deaths continued to increase.

The National Drug Strategy Household Survey of 2016 reported that codeine, which is available at a pharmacy behind the counter, is the most widely abused legal opioid in Australia and that abuse is common among adolescents.

This left the TGA with no choice but to reconcile Australia with most other countries restricting codeine to prescription only. The TGA announced the change in December 2016 after a long consultation and entered into force on 1 February 2018.

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Not everyone was happy

The announcement divided community and health professionals. Pharmacy organizations rejected the change, whereas GPs were in favor.

There were also fears that the change would lead to a massive burden on GPs as patients came to request codeine.

Some feared the move would make people use codeine of higher strength. This was because people who want codeine need to see their doctor to get the stronger products that were always prescription only. There was also concern that the change would push people to even stronger analgesics such as oxycodone and morphine.

What happened after that?

Every month, as we work at the NSW Poisons Information Center, we receive hundreds of calls for overdose of opioids. We therefore wanted to investigate whether the change in code availability affects the number of overdoses. Like others, we feared that the change in availability could also have unintended consequences.

The year after the change, we saw an overall decrease in code poisoning by 51%. This mainly concerned low-starch preparations (the category is no longer available without a prescription), with poisonings falling by 79%.

Poisoning with high-concentration codeine or other opioids did not increase. Similarly, sales data showed that total codeine consumption decreased by nearly 50%, with consumption of low-strength codeine being the most affected and decreasing by 87%. Again, there was no increase in the use of high-strength codeine.

Your genetics are also important

Abuse and addiction concerns were not the only reason for the change in code availability. A person's response to codeine is determined by their genes, particularly a gene encoding the enzyme CYP2D6. This enzyme activates codeine by converting it into morphine in the body.

Depending on their DNA, some people do not get codeine effects, others have a "normal" effect, while others find it toxic at a dose that is usually considered safe.

The latter is the most dangerous scenario and has led to several deaths. This included a newborn who died after his mother received a normal dose of codeine for pain after giving birth. It later turned out that the mother has the gene that leads to excessive code inactivation, and a lethal dose of morphine was transferred to her baby in breast milk.

Even if the abuse problems disappeared overnight, codeine advocates argued that a drug with such a variable effect should only be available after a doctor's visit.

How about unintended consequences of the code change?

Future research will need to investigate possible unintended consequences of the change in code availability.

For example, people could have switched to simple analgesics such as acetaminophen and ibuprofen. These products do not have the same potential for abuse, are generally safer and more effective than low strength codeine products. If overdosed, they can still be toxic.

Our research did not investigate whether codeine change caused more people to use or be harmed by acetaminophen or ibuprofen.

The limitation of availability works

Abuse and overdosage of prescription drugs are problems that depend very much on the availability of medication. And as the availability of other medicines has been reduced in Australia and internationally, we have seen the benefits of reducing abuse and poisoning.

This is the case with the opioid analgesics tramadol, hydrocodone and dextropropoxyphene. and the benzodiazepine-alprazolam.

Our study provides a good example of how effective simple strategies can be in combating opioid abuse. Codeine is only a small part of the puzzle, and we look forward to further investment and a systematic strategy to tackle the causes of the rise in fatal prescription drug poisoning over the past decade.

We would like to set up a national center for poisoning research that brings together and supports existing and new researchers. This would focus on the prevention and control of poisoning in order to find a national answer to this clinical and public health problem.