26 June 2003 12:00 GMT

by Alec Venter

A nicotine vaccine developed by US researchers could help millions of smokers kick the habit. Despite their best efforts, 70% of smokers who try to quit are unsuccessful.

A vaccine against nicotine addiction may seem unlikely, but just such a product has shown promise in animal studies. Team leader Kim Janda, professor of chemistry at The Scripps Research Institute (TSRI) in La Jolla, California, says that the vaccine allows the body to "soak up" nicotine before it reaches receptors in the brain. The body does not normally produce antibodies against nicotine, explained Janda, "What we've done is ... alert the immune system to say 'yes, this is a foreign invader.'"

Neal Benowitz, professor of medicine at the University of California San Francisco (UCSF), has been studying nicotine addiction for over 20 years. He sees a need for a nicotine vaccine, and believes it would help smokers quit the habit and ex-smokers avoid relapse. Ten seconds after inhaling, a smoker experiences an adrenaline rush, followed by a surge of dopamine, which signals the body to calm down. For regular smoker, the brain needs nicotine to function normally and avoid the cravings, anxiety, depression and lack of concentration associated with withdrawal.

"If you block the effects of nicotine, nothing good will happen," said Benowitz. A vaccine would work, he said, "because people don't continue smoking cigarettes without nicotine in them."

Team leader Janda says that the nicotine vaccine, which research associate Michael Meijler synthesized de novo, is different from candidates developed in other labs. Unlike other potential nicotine vaccines, which have shifting forms when in solution, the TSRI vaccine has a rigid conformation. Instead of resulting in low levels of various versions of anti-nicotine antibodies, Janda believes the rigid shape "gives a more potent effect."

Janda's lab has had previous success creating a cocaine vaccine, which has been tested in rodents. "I think this approach can work for almost any of the drugs of abuse that you're considering . . . I guess it's just a logical extension why we went to nicotine," said Janda, who hopes to attract the interest of biotech companies to carry out clinical trials of the nicotine and cocaine vaccines.

UK firm Xenova Research has had encouraging results in preliminary human trials with their own nicotine and cocaine vaccines.

Every year tobacco kills over 430,000 US citizens, according to the U.S. National Institute of Drug Abuse. Even so, current over-the-counter treatment options have only a 10% success rate, which raises to 20-30% when combined with counselling.

"[The nicotine vaccine] will be very useful for people who have tried other treatments and failed," concluded UCSF's Benowitz.