A common, affordable antibiotic used to treat acne can help stave off the progression of multiple sclerosis in people who’ve experienced early symptoms of the disease, according to a new Canadian study.

A clinical trial led by researchers at the Hotchkiss Brain Institute, part of the University of Calgary’s Cumming School of Medicine, found that the drug minocycline can slow the progress of MS in people who’ve had one episode of what’s known as clinically isolated syndrome (CIS).

In CIS, patients develop numbness, blurred vision or muscle weakness -- symptoms considered harbingers of multiple sclerosis. Some patients never progress to multiple sclerosis, but in those who have a second attack, doctors usually diagnose MS.

The minocycline trial involved 142 people in 12 Canadian sites who experienced one episode of this isolated syndrome.

The incidence of a second attack was reduced by 44 per cent in the first six months in patients who took 100-milligram doses of minocycline twice a day, compared to a placebo pill, said Wee Yong, study co-author and a University of Calgary professor who co-directs the Hotchkiss Brain Institute’s Multiple Sclerosis Program.

The drug appeared to have no effect at the 24-month mark of the trial.The results were published Wednesday in the New England Journal of Medicine

Researchers admit they don’t know exactly how minocycline works, but the antibiotic crosses the blood-brain barrier and appears to reduce inflammation that damages the myelin, a protective coating around the nerves.

Regardless, Yong said the results after six months on minocycline were “very powerful” and support wider use of the drug.

“It can be used immediately in first attack to reduce chances of a second attack. One can get a prescription in a pharmacy and start right away,” he said.

Compared to the cost of current MS therapies, which can range between $20,000 and $40,000 per year, minocycline treatments would cost only about $600 per year, or less than $2 per day.

And because minocycline has already been in use for decades, no new approvals are needed from Health Canada to use it as an off-label prescription for MS, the researchers say.

Jill, a 34-year-old clinical trial participant who did not want her last name published, experienced her first attack when she was 27. She woke up one day with a tingling in her arm, which then progressed to numbness in 50 per cent of her body.

After an MRI confirmed lesions on her brain -- an indication of MS -- Jill was offered the chance to join the minocycline trial. After the two-year trial ended, she kept taking the drug for another four years and never experienced a second attack.

“I feel pretty lucky,” she told CTV News. “I’m very happy I got involved.”

Although Jill stopped taking the drug to give her body a break from the antibiotic, she said most of her symptoms are now gone.

In an editorial written for the New England Journal of Medicine, Dr. Robert Friedlander, head of cerebrovascular neurosurgery at the University of Pittsburgh who has studied minocycline, said the results are intriguing. They suggest the drug is reducing inflammation in the brain and preventing the death of cells as well, he said.

“Minocycline nicely blocks both these events and from a theoretical process is why it should work,” Dr. Friedlander said. But he questioned widespread long term use of an antibiotic.

“At this stage it seems premature to have minocycline widely used in MS,” he said. “So while there is excitement around this new (trial), what’s needed is a larger, longer study.”

Dr. Luanne Metz, the study’s lead author and an Alberta Health Services neurologist, said her clinic has started offering the medication to those with CIS.

Mild side-effects can include dizziness and gastrointestinal issues. A rare but serious side-effect can cause increasing pressure in the brain due to fluid buildup, at which point the medication would be stopped, she said

Dr. Metz also said the use of minocycline could have a global impact, especially in countries where other MS treatments are not easily accessible or financially out of reach for most patients.

Canada has one of the highest rates of MS in the world, with an estimated one in 340 people living with the disease. It is most often diagnosed between the ages of 15 to 40, according to the Multiple Sclerosis Society of Canada.

With a report from CTV’s medical specialist Avis Favaro and Elizabeth St. Philip