Researchers say a drug used to block the effects of heroin could be the answer to treating long COVID.
A team on the Gold Coast is collaborating with a doctor in Western Australia to run a clinical trial examining the impacts of low-dose naltrexone (LDN) on people suffering from the illness.
"Naltrexone in high doses is kind of the antidote to morphine; it blocks the opioid receptors," Perth-based pain specialist and anaesthetist James Jarman said.
"In high doses it's used to block the effects of, for example, a heroin user getting a high from heroin, and in alcoholism to stop some of the buzz that alcoholics get from alcohol.
"The doses we're using are about one 20th of that dose."
Dr Jarman contacted Griffith University's National Centre for Neuroimmunology and Emerging Diseases (NCNED) after hearing centre director Sonya Marshall-Gradisnik tell the ABC about her research into long COVID.
Low-dose naltrexone research
Earlier this year, the NCNED team published research showing laboratory-based evidence of an overlap between long COVID and chronic fatigue syndrome (ME/CFS).
"There's an overlap in symptoms, yes, but we had identified a dysfunction in cells that are consistent between both illnesses," NCNED researcher Natalie Eaton-Fitch said.
The researchers have also been looking at the effects of LDN on people experiencing chronic fatigue.
Dr Eaton-Fitch said they have so far found that the drug targets and restores the faulty ion channels in the body that cause the fatigue symptoms.
"This is a continuation on a project that we've done in the lab, that overlap," Dr Eaton-Fitch said.
"It provides laboratory evidence on the benefits of LDN before we move to a clinical trial.
"So, we can use that experience and use that laboratory knowledge to then apply it in a clinical trial."
Clinical experience
Dr Jarman has been prescribing LDN to treat his patients with chronic fatigue syndrome and fibromyalgia for 10 years.
"It's almost identical to the fibromyalgia patients I've been treating for almost 10 years with naltrexone," he said.
Dr Jarman is working with Griffith University and the University of Notre Dame to carry out the trial.
"Not being clinicians, they had little experience using it in real life, whereas I've been using it for 10 years."
The trial is looking for participants who have experienced certain long COVID symptoms.
"We're also looking for people with the symptom cluster of fatigue, rather than breathlessness or other symptom clusters," Dr Jarman said.
"They can't be on any opioid-type painkillers, any morphine-type painkillers."
The trial will run for several months early next year.
The researchers hope to publish their findings in late 2023 or early 2024.
