New York, Feb 17 (IANS): With the use of synthetic opioid "designer drugs" on the rise, scientists have developed a vaccine to curb addiction and even prevent fatal overdoses.

In preclinical tests, the vaccine was found to prevent the synthetic opioid fentanyl - a painkiller 50 to 500 times more potent than morphine - which some drug dealers now use as a mix-in or substitute for heroin - from reaching the brain, according to the study published in the journal Angewandte Chemie.

"We want to stay one step ahead of these clandestine laboratories making illegal opioids for black market demand," said one of the researcher Kim Janda, professor of chemistry at The Scripps Research Institute (TSRI) in San Diego, US.

"The importance of this new vaccine is that it can block the toxic effects of this drug, a first in the field," Janda noted.

The US Centers for Disease Control and Prevention reported a 200-percent increase in overdose deaths involving opioids from 2000 to 2014, citing the availability of fentanyl and fentanyl variants as a major contributor.

While there are treatments such as naloxone for opioid overdose or methadone for addiction, Janda noted that many people still relapse.

"These treatments are working for some people, but there is clearly a gap that needs attention," he said.

The new vaccine takes advantage of the body's own immune system. The vaccine cocktail contains a molecule that mimics fentanyl's core structure. When given the vaccine, the immune system is "trained" to produce antibodies to neutralise it, the study said.

Janda and his colleagues tested the vaccine in mouse models of fentanyl addiction and overdose.

For the study, mice were given three vaccinations, each two weeks apart - like a series of booster shots. By studying antibodies in the blood, the researchers saw that the immune system was successfully neutralising fentanyl for months after the last injection.

In further tests, the researchers observed that vaccinated mice given fentanyl did not demonstrate "high" behaviour (such as ignoring discomfort).

In fact, a 30-fold greater-than-normal dose of fentanyl was necessary for the drug to activate neural circuits in vaccinated mice, the researchers said.

"To the best of our knowledge, our active vaccine is the first to ablate lethal doses of any drug of abuse," study co-first author Atsushi Kimishima from TSRI said.