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At The Scribbs Research Institute in La Jolla, California, a team of researchers have created a vaccine that can block heroin’s effects and could provide a potential therapy for heroin addiction.
This research was carried out on animal models that responded successfully to the vaccine, demonstrating how this could have effective results also in humans.
Kim D. Janda, Jr. Chaired Professor of Chemistry and Immunology at The Scripps Research Institute, member of The Skaggs Institute for Chemical Biology, and main researcher of the study said: “In my 25 years of making drug-of-abuse vaccines, I haven’t seen such a strong immune response as I have with what we term a dynamic anti-heroin vaccine.” “It is just extremely effective. The hope is that such a protective vaccine will be an effective therapeutic option for those trying to break their addiction to heroin”.
The Scribbs Research Institute’s study was recently published on the Journal of Medicinal Chemistry of the American Chemical Society, and reported by EurekAlert!. It shows how heroin’s euphoric effects can be blocked by specific antibodies produced by the vaccine, which provoke an immune response of the organism.
When metabolized, heroin degrades into multiple psychoactive compounds each with psychotropic effects on the brain, making the previous attempts of other researchers to create an efficacious vaccine difficult and often times misleading.
“Heroin, however, presents a particularly challenging immunotherapeutic target, as it is metabolized to multiple psychoactive molecules. To reconcile this dilemma, we examined the idea of a singular vaccine with the potential to display multiple drug-like antigens, two haptens were synthesized, one heroin-like and another morphine-like in chemical structure,” wrote the authors.
Therefore, the innovation of the vaccine developed by Janda’s team consists exactly of targeting not only heroin itself but also the other compounds, such as morphine and 6-acetylmorphine (6AM), blocking all the euphoric effects that can be produced.
“Heroin is lipophilic and is rapidly degraded to 6AM, both readily cross the blood-brain barrier and gain access to the opioid receptors in the brain, explained G. Neil Stowe, a research associate in Janda’s laboratory and first author of the study.”Critically, the vaccine produces antibodies to a constantly changing drug target,” added Stowe. “Such an approach has never before been engaged with drug-of-abuse vaccines.”
“A key feature in this approach is that immunopresentation with the heroin-like hapten is thought to be immunochemically dynamic such that multiple haptens are simultaneously presented to the immune system,” explained the authors in their study.
The results seem to be very successful. The responses to the heroin vaccine of the rats subjected to the study are very encouraging. They generated strong antibodies and also showed good response regarding heroin addiction. Out of seven addicted rats that received the vaccine only three kept on self-administering heroin by pressing on a lever after several boosters. In contrast, all the control rats self-administered the drug.
“To have an animal vaccinated and not show a response to heroin is pretty amazing,” said George F. Koob, chair of the Scripps Research Committee on the Neurobiology of Addictive Disorders and co-author of the study. “We saw a very robust and specific response from this heroin vaccine. […] I think a humanized version could be of real help to those who need and want it.”
The study also demonstrates the specificity of the vaccine which produces antibody response only to heroin and 6AM, and not to other opioid drugs tested such as methadone, naloxone and naltrexone.
“The importance of this is that it indicates these vaccines could be used in combination with other heroin rehabilitation therapies,” said Janda.
The study was funded by the National Institute of Drug Abuse of the National Institutes of Health and the Skaggs Institute for Chemical Biology at Scripps Research.