An X-ray of arthritic hands (Image: Getty)
The treatment also appears to slow the excruciating condition's progress by halting the destruction of cartilage - the body's shock absorber. If APPA passes all tests it could be on the market within a decade.
It will have the chance to change the lives of millions of sufferers and slash the health service's annual £1billion bill for joint replacements.
The researchers' early findings have been seen as so "exciting" the Government is funding part of the project to continue human trials of the drug.
Yesterday, consultant rheumatologist Professor Robert Moots, who is leading a trial of the drug at Liverpool University's Institute of Ageing and Chronic Disease, said: "Millions of osteoarthritis patients are suffering every day with severe pain because the current prescription drugs available are often not effective or cannot be used long-term.
"APPA has the potential to be an effective treatment for osteoarthritis that could not only tackle the pain it causes but do so with excellent tolerability and also, we hope, stop the disease causing further joint damage.
How APPA works (Image: Daily Express)
"If the current human trials are successful, it could not only revolutionise arthritis care but also help reduce the NHS's £1billiona-year bill for hip and knee replacement surgery."
Osteoarthritis can affect any joint in the body and causes pain, stiffness, swelling and tenderness. In a healthy joint, a coating of tough but smooth and slippery tissue called cartilage covers the surface of the bones and helps them move against each other without friction. When a person develops the condition, the cartilage breaks down and joints do not move smoothly.
Bony growths, or spurs, can develop and the area may become inflamed. A third of women and a quarter of men between the ages of 45 and 64 have sought treatment for osteoarthritis, according to charity Versus Arthritis.
This rises to almost half of people aged 75 and over. Mark Wilkinson, a spokesman for Versus Arthritis and professor of orthopaedic surgery at the University of Sheffield, said: "Over eight million people in the UK are living with osteoarthritis, many of them in excruciating pain every day.
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Hand exercises for arthritis
"The majority of people with the condition manage their symptoms with painkillers, and joint replacements, as currently there are no drugs licensed for the treatment of osteoarthritis. We look forward to seeing the results of the next phase of testing."
APPA combines two synthetic versions of plant compounds called apocynin and paeonol.
Apocynin comes from a herb that grows in the Himalayas in Nepal and has anti-inflammatory capabilities. It is traditionally used to treat liver and heart problems, jaundice and asthma.
Paeonol is from the peony flower and used in traditional Chinese medicines due to its anti-inflammatory, immune regulatory and anti-tumour effects. David Miles, head of AKL Research & Development, the pharmaceutical company behind the pioneering drug, said: "For the first time it looks like we may have a drug that could halt the progression of the disease. It gives us great hope that many patients could avoid the need for joint replacement surgery." Innovate UK, part of the Government's UK Research and Innovation organisation, has awarded researchers a grant of £675,000 to continue testing in a phase two human trial. This
