TA-CD is an active vaccine developed by the Xenova Group which is used to negate the effects of cocaine, making it suitable for use in treatment of addiction. It is created by combining norcocaine with inactivated cholera toxin.
It works in much the same way as a regular vaccine. A large protein molecule attaches to cocaine, which stimulates response from antibodies which destroy the molecule. This also prevents the cocaine from crossing the blood–brain barrier, negating the euphoric high and rewarding effect of cocaine caused from stimulation of dopamine release in the mesolimbic reward pathway. The vaccine does not affect the users "desire" for cocaine, only the physical effects of the drug.