Scientists are reporting development and successful initial laboratory tests on the key ingredient（原料，要素） for a much-needed vaccine to help individuals addicted to heroin abstain from（放弃，戒绝） the illicit drug. Their study appears in ACS' Journal of Medicinal Chemistry. Kim D. Janda and colleagues note that heroin use cost the United States more than $22 billion in 1996 annually due to medical and law enforcement expenses and productivity loss. Although behavioral therapy and certain medicines help heroin-addicted patients, many experience relapse（复发） , lack access to treatment, or develop unwanted side effects from the treatments themselves. To overcome these challenges, the researchers made and tested a new vaccine formulation that might serve as an additional tool in helping addicts maintain abstinence（节欲） . Janda's team previously reported development of vaccines for cocaine, methamphetamine, and nicotine.

Thus with laboratory rats that were given the vaccine they showed less willingness to self-administer heroin and other signs of its effectiveness. The report explains why the potential new vaccine is an improvement over previous experimental vaccines. "In conclusion, a vaccine for heroin addiction could prove to be a useful tool for combating heroin addiction, wherein it exploits a motivated recovering addict's own immune system to blunt（使迟钝） heroin's psychoactive（影响心理状态的） effects in the case of relapse," the researchers say.