Although cocaine use has declined steadily since its peak in the early 1980s, public health officials estimate that about 7 million Americans used the drug at least once last year. Many of these folks are addicted to the drug, and its intense, short-lived euphoric effects mean the addiction is terribly difficult to overcome.
Addiction specialists believe existing treatment paradigms for cocaine addiction can be enhanced by a vaccine that prevents the drug from crossing the blood-brain barrier, thus blunting its euphoric effects. Scientists have worked hard to develop such a vaccine, but have had limited success so far.
About a year ago for example, Thomas Kosten and colleagues at Baylor reported partial success in a human trial of a cocaine vaccine. In that trial, 38% of subjects who received all 5 shots in the vaccine series achieved sufficient antibody levels to blunt the effects of the drug. In that subset, 53% of the subjects stopped using cocaine, meaning that overall, the vaccine worked about 20% of the time.
Unfortunately, some subjects began snorting massive amounts of the drug in an effort to overcome the vaccine’s effects. Some people managed to amass 10 times more of the drug in their systems than was present before the trial began. Cocaine levels like that can kill people. In addition, the cocaine antibodies, when they developed at all, remained in the bloodstream of subjects for only 8-10 weeks; it takes longer than that to assure the behavioral aspects of the addiction are overcome.
Last week, Martin Hicks, Ronald Crystal and colleagues at Cornell reported that they had developed an alternative vaccine and that it was quite effective…in mice.
The Cornell team attached a chemical congener of cocaine onto a specially prepared version of an adenovirus, the virus responsible for many common colds. The latter vector was chosen to assure that the body’s immune system would recognize the newly created molecule as foreign and create antibodies against it. The trick of course, was to assure that the antibodies so created would recognize “pure” cocaine after it was ingested, and prevent it from crossing the blood brain barrier. (more…)