Get a Shot, Kick the Habit
Aug. 8, 2000 (Chicago) -- Would it help smokers quit if smoking did nothing for them? Researchers are now trying to take the fun out of smoking by developing a vaccine against nicotine, and early results in animals show that it may be effective in blocking the addictive substance from reaching the brain.
In a presentation Tuesday at the 11th World Conference on Tobacco OR Health, Paul Pentel, MD, a physician at Hennepin County Medical Center in Minnesota, detailed rat studies that show an experimental vaccine appears to tie up and metabolize nicotine in the bloodstream before it can concentrate in the brain, thus reducing the "pleasure" experienced by smokers.
The vaccine works by prompting the creation of nicotine-specific antibodies by the body's immune system. Fellow vaccine researcher David Malin, PhD, a professor of psychology and neuroscience at the University of Houston-Clear Lake, tells WebMD, "This vaccine involves a large protein that's coated with nicotine molecules ... that is perceived as an invader by the body's immune system."
In the rat research, one group received no vaccine; a test group was given the vaccine regularly over a six-week period, then a dose of nicotine equivalent to two cigarettes. In the test group, the concentration of antibodies to nicotine was much higher, indicating that nicotine was trapped in the blood and not reaching the brain. Compared with the rats not immunized with the nicotine-blocking vaccine, the vaccinated rats also had lower blood pressure and were less hyperactive.
In a separate presentation, Alan Leshner, PhD, director of the National Institute on Drug Abuse, hailed the "very important" research into this "promising" vaccine. But, he added, "It's not a magic bullet. Don't get your hopes up." The institute is funding the research through the biotech firm Nabi, which developed the vaccine. Human trials may start after further evaluation of the vaccine in animals.
According to Pentel, the vaccine appears effective against nicotine withdrawal and smoking relapse, although he acknowledged that he didn't yet know how long the vaccine's effects last. "It will not treat all aspects of nicotine dependence," Pentel added, since it only acts on nicotine when it is in the body, meaning long-term nicotine craving would require other treatments.
Pentel raised the possibility that a vaccine could be used in conjunction with the drug Zyban, which has demonstrated clinical effectiveness in helping smokers stop.
"The vaccine does not cross-react with [Zyban]," Malin tells WebMD. "The hope is that the vaccine would make smoking ineffective -- people wouldn't get anything from smoking -- while [Zyban] might reduce the longer-term craving." But, he adds, "Whether it would work out that way remains to be seen."
The safety of the vaccine is another unknown. Pentel tells WebMD, "It needs some more safety testing, and we're doing that."