Friday, February 24, 2012

Addiction Vaccines

A recently patented heroin vaccine has shown efficacy in reducing heroin consumption in mice. Vaccines to treat addiction are not a new idea and there are many in development. The concept is quite simple. The vaccine induces the production of antibodies in the patient that are specific to the addictive substance. These antibodies then bind to and neutralize the activity of the substance. In the case of a heroin vaccine, an immunized addict would no longer get high after heroin injection.
As a non-expert, this approach to addiction treatment this seems promising to me. The addict goes through all of the behaviors associated with the addiction and receives no stimulus to the reward pathway. Over time it would make sense that this would result in no reinforcement of the behavior making it easier to stop.
The vaccine approach reminds me of disulfiram (aka Antabuse), for the treatment of alcoholism. This drug causes the addict to have an intense hangover shortly after alcohol consumption. Instead of no reward, as with the vaccine approach, the addict receives a negative experience associated with the addictive substance. Perhaps disulfiram represents a superior approach because of the associated negative consequences of taking the addictive substance. The major problem with disulfiram is patient compliance, however with compliance and as part of a comprehensive treatment disulfiram improves outcomes. Hopefully addiction vaccines will also have positive outcomes in humans.
Unfortunately, so far there are no addiction vaccines that have proven effective in humans. The only example of a phase III clinical study that I am aware of is NicVax. NicVax is a nicotine vaccine that has shown no improvement over placebo in aiding smoking cessation, despite showing earlier promise in animal models. It is a poor indicator for the vaccine approach since addictive drugs share the same reward pathway in the brain of the addict. Perhaps I am oversimplifying the parallels between different addiction vaccines as clearly the approach is not being abandoned. Hopefully there is another difference between stimulants, like nicotine, and depressants, like heroin, that will make this approach a success for heroin addicts.


2 comments:

Anonymous Coward said...

weedvax?

rob said...

The NYtimes article I linked specifically mentions attempts to create a marijuana vaccine. The article stated that the researchers had found that THC does not get enough exposure to the immune system. Try cold turkey, AC.