Summary: bind deactivated cholera proteins to cocaine in the blood. The resulting particle is too large to pass the blood-brain barrier and will be "eaten" by the immune system. Thus, cocaine doesn't do anything for people with these proteins in their bloodstream.

This is currently in phase II trial, with good results. The only issue is that some addicts react by taking huge amounts of coke in an attempt to overwhelm the proteins... so finding a big company to produce it and take it into phase III trials is proving difficult.