By RANDOLPH E. SCHMID Associated Press Writer
WASHINGTON (AP) - People who roll up their sleeve for a nicotine patch to quit smoking could one day be rolling it up for a shot.
A vaccine to combat the effects of nicotine, the addictive component of tobacco, is being tested by a team of researchers sponsored by the National Institute on Drug Abuse. If all goes well, human trials could start by 2002.
But even if the vaccine proves safe, ``It's not going to be a magic bullet,'' said Dr. Paul Pentel of the Hennepin County Medical Center in Minneapolis. It would be part of a package designed to help people stop smoking, he said.
While the idea of vaccination is similar, combating a drug like nicotine isn't identical to battling an infectious disease, Pentel said in a telephone interview.
``In a disease, you get a series of immunizations, and you are protected for life,'' he said. ``We do not expect that kind of effect for nicotine. ... It's not clear how long the protection will last.''
The vaccine, now being tested on laboratory rats, is designed to keep nicotine from reaching the brain.
The amount of nicotine in the brains of vaccinated rats was reduced by 64 percent compared with unvaccinated rats when both were given the nicotine equivalent that a human would get from smoking two cigarettes, the team of researchers led by Pentel reported Friday in the journal Pharmacology, Biochemistry and Behavior.
``A nicotine vaccine may be useful for preventing and treating tobacco addiction, because vaccinated persons would not get a kick from the nicotine,'' said Dr. Alan Leshner, director of the National Institute on Drug Abuse. ``Since they would find tobacco less rewarding, they would be less likely to continue using it.''
Leshner said his agency also is supporting efforts to develop vaccines against cocaine and other drugs.
Dr. Gary Giovino of Roswell Park Cancer Institute in Buffalo, N.Y., said the idea of a nicotine vaccine has potential if it proves safe.
Giovino, who was not part of Pentel's team, said developers should be cautious, however, because while the vaccine reduces the effect of nicotine it doesn't eliminate it. Thus, he said, people might simply compensate by smoking more.
``This is still exploratory animal work. We want to do more studies of the efficacy, safety before considering whether it's appropriate for a clinical trial'' in humans, Pentel said. ``We're hopeful. We're encouraged.''
In tests so far, vaccinated rats given nicotine injections did not experience the blood pressure increase that accompanies smoking, nor did they undergo nervous movements that nicotine stimulates in people, Pentel's team found.
Nicotine molecules are so small a smoker's body doesn't naturally develop antibodies to it, Pentel explained, so the researchers combined nicotine with a bacteria the body immediately recognizes as foreign. The immune system develops antibodies to attack the nicotine-bacteria combination, and some of them specifically target the nicotine component, he said.
Thus, when the vaccinated person smokes, the antibodies recognize and bind to the nicotine to create a molecule too large to cross into the brain. That molecule stays in the bloodstream and eventually breaks down into harmless chemicals, researchers said.
The initial target will be to help people quit smoking by eliminating the pleasant effect from smoking to prevent relapses, Pentel said. This doesn't reduce the craving for nicotine, but it eliminates the kick people get from it, he said. The hope is that smoking would cease to be worth the trouble.
Because the vaccine won't make people want to stop smoking, Pentel said, it has to be used along with other social and medical support.
筆者へのメールは kaijinhi@yahoo.co.jp にお願いします。
このニコチンワクチンは臨床試験の研究段階です。
このページは商用目的ではありません。