Vaccines

Cocaine vaccines aim to reduce the amount of cocaine reaching the brain by stimulating enzymes or antibodies that target cocaine molecules in the bloodstream. They differ from other pharmacological approaches that have targeted neurotransmitter sites within the brain. There are several types of cocaine vaccine that have been tested in animal models and more recently in human volunteers. These include:

1. compounds that stimulate antibodies that bind to psychoactive cocaine metabolites and make them too large to cross the blood brain barrier;
   
   
2. compounds that stimulate antibodies that increase the rate of cocaine metabolism, reducing the amount that crosses the blood brain barrier; and
   
   
3. 'passive' inoculation of cocaine antibodies to block cocaine crossing the blood brain barrier.

The effectiveness and duration of these effects vary and may not be permanent. Therapeutic potential includes overdose, relapse prevention and detoxification. The most advanced trial involves the therapeutic vaccine, TA-CD, currently in dose optimisation trials after initial dose and safety trials found it was well tolerated in a group of 34 abstinent cocaine users (see also Hall & Carter, 2002 for a discussion of ethical issues; Kosten, Rosen, Bond, Settles et al., 2002).