Operation pain relief flagged as new hopes pinned on ‘horse tranquilliser’ drug

THE painkiller ketamine is being tested as a potential preventive for chronic postsurgery pain in a $4.8 million Melbourne-led international trial.

Short-term pain is a normal and expected side effect of surgery.

But a third of patients who undergo a major operation will develop severe pain that still lingers a year after the procedure, long after surgical wounds have healed.

The chief investigator, University of Melbourne and Austin Health anaesthetic research professor Philip Peyton, said there was evidence from animal studies and small human trials that ketamine may intercept pain circuits that “go into overdrive and don’t settle down” after surgery.

Colloquially known as a “horse tranquilliser” for its origins and current use as an effective anaesthetic agent for animals, ketamine has become popular as a party drug for its hallucinogenic properties.

It is also being tested as a treatment for severe depression, as well as replacing morphine as the preferred rapid pain relief on the battlefield.

“Ketamine has become the go-to drug for patients with severe or difficult-to-manage pain,” Prof Peyton said.

“There is reason to think that ketamine might have some useful role in cutting that connection between acute pain and chronic pain.

“Treating chronic pain once it’s established is really hard. This is about getting in there early and preventing acute pain from becoming chronic.”

More than 800 Australians die each year from overdoses of prescription painkillers, while President Donald Trump has labelled the opioid epidemic a “national health emergency” in the US.

Almost 5000 patients will be recruited to the trial.