The review of 89 placebo-controlled randomized clinical trials of naltrexone is based on 11,194 participants published in BMC Medicine.
Lead author Dr. Monica Bolton, who conducted the research as part of her Master's degree at Manchester said: "Though naltrexone is licensed for the treatment of alcohol addiction, it remains under-utilized.
Naltrexone Under-Utilized by Doctors
"And that has devastating consequences for individuals, health and social services in the UK and around the world.
"As far as we know there is only one contraindication: painkilling opiates, such as codeine. These should not be taken with naltrexone, as it works by blocking opiates in the brain.
"Up to 58% of alcohol-dependent people in England want to reduce their drinking, and this drug could help them succeed.
"It is cost effective and could reduce deaths."
The Costs of Alcohol Problems
According to the Office of National Statistics there were 7,697 alcohol-specific deaths in the UK in 2017, or 12.2 deaths per 100,000 population.
The Department of Health estimates the NHS costs of alcohol-related problems as £3.5 billion every year.
Dr. Alex Hodkinson from The University of Manchester said: "Previous research shows that naltrexone is prescribed to less than 0.5% of those eligible.
"And only 11.7% of those diagnosed with more severe forms of alcohol dependence received relevant drug therapy in the 12 months following diagnosis.
Reluctance to Prescribe Naltrexone
"Like all drugs for alcohol addiction, the chaotic nature of being an addict means this drug is simply not prescribed as much as it should be.
"It's also a cultural issue: there is a reluctance to prescribe one drug to combat addiction in another substance.
"Our review also shows that fears over side-effects are unfounded."
Treats Other Conditions
Naltrexone is being investigated for a range of other conditions such as other addictions, gambling, and other impulse control disorders.
Anecdotal evidence also suggests that at a very low dose, it may also be able to treat a range of immune-modulated conditions including Crohn's disease, HIV, multiple sclerosis, fibromyalgia and Chronic Fatigue Syndrome (ME/CFS).
In the UK, around 1,400 NHS prescriptions for LDN are issued per year while over 12,000 people have received a private prescription in the last 10 years.
However, Dr. Bolton argues that more research is needed to understand if the drug is effective for these conditions.
Safe, Cheap, and Generic
She said: "As it is safe, cheap and long out of patent, naltrexone would seem an excellent candidate for repurposing for a whole range of conditions.
"That is why it is imperative to find ways to fund clinical trials to test if it might one day be possible to license it.
"The problem is, it is extremely difficult to repurpose existing drugs - and naltrexone is just one example of many wasted opportunities to treat people and save the NHS money."