Pubdate: Tue, 06 May 2003 Source: Newsday (NY) Copyright: 2003 Newsday Inc. Contact: http://www.newsday.com/ Details: http://www.mapinc.org/media/308 Author: Jamie Talan Bookmark: http://www.mapinc.org/coke.htm (Cocaine) VACCINE TESTS TO PREVENT COCAINE ADDICTS' RELAPSE New York scientists are testing an experimental vaccine that could help fight cocaine addiction. If it's proven effective, it could help prevent former cocaine users from relapsing. Historically, vaccines have been developed to prevent disease by exposing the body to snippets of the infecting agent, which allows the body's immune system to mount a defense against the disease. The antibodies formed during this process act like soldiers guarding against invasion. But recently, a different vaccine approach has emerged. Again, the theory is based on the body's calling upon the immune system for help. This new approach is based on the antibody's ability to block cocaine as it enters the bloodstream on its way to the brain, where it triggers euphoria. About 500,000 Americans are addicted to the powerful stimulant. About 2 million others are occasional users. The cocaine molecule is small and can easily sneak into the body without letting the immune system know it's present. In vaccine development, scientists attached the cocaine molecule to a larger molecule, and thus were able to generate an immune response - antibodies - which proceeded to mop up cocaine in the bloodstream before it got to the brain. Scientists say the vaccine is designed to prevent relapse and would probably not work to stop cocaine use. "It doesn't affect the craving for cocaine," explained Dr. John St. Clair Roberts, medical director of Xenova Group, a biotech company in England. "But it can prevent reinforcement of the craving." For the former addict "it means that if they fall off and take a snort of cocaine, it would neutralize that slip." A small number of human addicts has received injections of the vaccine in a test of its safety. A study now under way at Columbia University College of Physicians and Surgeons will test how well it works. The study is being run by Margaret Haney, associate professor of clinical neuroscience at Columbia. Haney worked closely with the late Marian Fischman, who in the late 1980s created one of the country's first 24-hour cocaine research laboratories at Columbia. Volunteers in the study will be given cocaine under strict laboratory conditions and then receive four injections over eight weeks. At 12 weeks, they will be given cocaine again in an effort to determine if the vaccine is effective. The scientists have permission from the Food and Drug Administration to study 10 patients. "We expect the changes [in the experience of pleasure] to be significantly reduced after vaccination," St. Clair Roberts said. The study will be completed within a year. But some cocaine researchers worry that users will learn how to overcome the antibody response. "We'll certainly need many different ways to help cocaine addicts," said Dr. Nora Volkow, associate lab director for life sciences at Brookhaven National Laboratory in Upton. Next month, Volkow becomes the new director of the National Institute on Drug Abuse, which is funding the study. "The vaccine by itself will not be sufficient." That's because cocaine is a powerful stimulant that turns on the brain's dopamine cells, which signal that something is pleasurable. Cocaine works directly on these cells, Volkow explained. The British scientists developing the vaccine admit that it's not likely that the treatment would block all cocaine in the bloodstream from getting into the brain. "It's an interesting strategy," said Michael Kuhar, the Chandler professor of pharmacology at Emory University in Atlanta. He has been studying cocaine for decades and has discovered about 500 molecules that look like cocaine "but are more selective, more potent or slower to get into the brain," he said. - --- MAP posted-by: Doc-Hawk