Millions of people already take minocycline to treat acne, but University of Calgary researchers have found the inexpensive antibiotic also helps to control multiple sclerosis (MS).

Their work opens up new treatment options for people who have experienced clinically isolated syndrome (CIS) — a first episode of neurologic symptoms that often develops into MS.

"It's a big discovery because it's a cheap, generic, oral medication, which means that patients with a CIS can now be treated with a pill rather than an injectable therapy," said Dr. Luanne Metz, a neurologist at the U of C and lead investigator of the study.

"That can be started immediately when a physician makes a diagnosis of CIS, rather than waiting for insurance approvals and to learn how to inject," she added.

Dr. Wee Yong, a neuroscientist who contributed to the study, said the acne medication is far less expensive than the current standard of injectable treatments, which can cost as much as $20,000 per year in Canada and $50,000 per year in the United States.

He said a year's worth of minocycline, by contrast, would cost about $600.

"I think this will make medications available to a global population," Yong said.

The team's research is to be published in the June 1 issue of the prestigious New England Journal of Medicine.

How the study worked

The researchers started recruiting participants with CIS for the study in 2008, and gradually enrolled more and more people until they had 142 patients, in total, by 2013.

Participants were randomly assigned either a regimen of minocycline or a placebo, and followed for up to two years afterward.

Those who received the real drug had a 33 per cent chance of developing MS after six months, Metz said, while those who received the placebo has a 61 per cent chance.

Dr. Wee Yong, a neuroscientist at the University of Calgary, says Minocycline will make treatment for MS far more readily available for people around the world. (Justin Pennell/CBC)

"So we had a very large improvement in the risk of getting multiple sclerosis over six months," she said of minocycline's effect.

"We continued to follow people out to 24 months, if they did not get multiple sclerosis in that time, and we showed that there was a proven treatment benefit at 12 months, too."

There were not enough participants for conclusive results of the drug's effect after 24 months, Metz said.

"So we don't know if it's still effective over the long term and it will be up to physicians treating patients with this to know whether the patient is benefiting over the long term," she said.

In an editorial in the same issue of the New England Journal of Medicine where the results were published, Dr. Zongqi Xia and Dr. Robert Friedlander said the study`s findings suggest a clinical benefit of the drug in early stage MS.

"Given the safety profile and low cost of minocycline, these intriguing results, notwithstanding their limitations, make a compelling case for the further study of the effect of minocycline in multiple sclerosis."

However, the editorial said the use of the drug in MS cannot be supported without further study involving larger, long-term trials.

Safe for long-term use

Minocycline has been around for more than 50 years and Yong said six million people in the United Kingdom alone have used the antibiotic over a period of six months or more.

As such, he said it's considered safe for long-term use with minimal side effects and relatively few concerns about antibiotic resistance.

He said MS researchers have been interested in minocycline for years because the drug is known to affect immune cell migration and inhibit inflammatory cells from making their way into the central nervous system.

"In MS, the migration of immune cells into the brain and spinal cord is what produces the injury of the condition," Yong said.

MS is an autoimmune disease that attacks the protective covering of nerves and disrupts nerve function.

Canada has the highest rate of MS in the world, with roughly 1 in 340 adults living with the disease, according to the Multiple Sclerosis Society of Canada.