Researchers in the United States report they have made important progress on a new anti-cocaine vaccine.
In laboratory tests with non-human primates, the scientists used a radiological tracking technique to confirm the result of earlier tests with mice -- that the vaccine prevented cocaine molecules from reaching the brain and triggering a dopamine-induced high. The successful primate test means human clinical trials could begin within a year.
According to Dr. Ronald Crystal, the lead researcher and chairman of the Department of Genetic Medicine at Weill Cornell Medical Center in New York, the vaccine "eats up the cocaine in the blood like a little Pac-man (video-game character) before it can reach the brain."
Cocaine -- a stimulant derived from the leaves of the coca plant -- produces feelings of ecstasy because it blocks the normal recycling of a brain chemical called dopamine. Dopamine is the body's pleasure neurotransmitter, providing important sensory rewards and governing mood. But when cocaine in the bloodstream causes dopamine to accumulate at nerve endings, the result is a massive flood of the neurotransmitter and an intense rush of pleasure -- the cocaine high.
The vaccine that Dr. Crystal and his colleagues have developed combines pieces of the common cold virus with a molecule that mimics the chemical structure of cocaine. When injected into an animal, the cold virus and its cocaine-like passenger are seen by the body's immune system as an invader, triggering a defensive response. Once the body's immune cells are "educated" to see cocaine as a disease organism, they produce powerful antibodies to destroy cocaine any time the drug enters the body.
Researchers are not sure how often the vaccine would need to be administered in humans to maintain its anti-cocaine effectiveness. One shot lasted 13 weeks in mice studies, and seven weeks in the non-human primate studies. The scientists predict that once the vaccine is determined to be safe, humans addicted to cocaine would probably need a series of vaccinations, or booster shots, to break their habit.
A paper describing successful animal tests of an anti-cocaine vaccine is published online in the journal Neuropsychopharmacology.