Vaccine Against Heroin High Tested in Animals

(NIH)

Scientists at the Scripps Research Institute in San Diego, California have developed a vaccine against a heroin-induced high and tested its potential in lab rats. Their findings appear online in the Journal of Medicinal Chemistry (paid subscription required).

The team led by chemistry researcher Kim Janda devised a vaccine that generates antibodies to stop heroin and other psychoactive compounds metabolized from heroin from reaching the brain to produce euphoric effects. Janda calls the approach “immunopharmacotherapy” where immune molecules have been shown to blunt the effects of abused drugs, both legal (nicotine) and illegal (e.g., cocaine, methamphetamine). Human clinical trials are under way for the cocaine and nicotine vaccines.

Up to now, heroin has not responded to immunopharmacotherapy, because heroin metabolizes into multiple substances each producing psychoactive effects. To meet this problem, the Scripps team targeted heroin and the other substances produced by its metabolites: 6-acetylmorphine (6AM), and morphine.

The researchers created what they call a dynamic vaccine cocktail to meet these multiple targets that slowly degrades in the body, exposing the immune system to the metabolites 6AM and morphine. They then injected the vaccine into lab rats. For comparison, the researchers injected other rats with a vaccine targeting only morphine.

The results showed that the rats rapidly generated robust antibodies in response to the dynamic heroin vaccine.  The study found that addicted rats were less likely to feed themselves heroin by pressing on a lever after several booster shots of the vaccine. Only three of the seven rats that received the heroin vaccine self-administered heroin. In contrast, all of the comparison rats, including those given the morphine vaccine, self-administered the drug.

The Scripps team also found that the heroin vaccine produced only an antibody response to heroin and 6AM, and not to other opioid-related drugs tested, such as oxycodone as well as drugs used for opioid dependence, such as methadone, naltrexone, and naloxone. Janda says these findings indicate the dynamic heroin vaccine could be used in combination with other rehabilitation therapies.

Read more: Drug in Development Targeting Nicotine Metabolism

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