Drug treatment charities yesterday welcomed the first scientific evidence that a new "vaccine" against cocaine addiction could provide an extra line of defence in fighting drug abuse, helping users to quit by preventing them from getting high.

In early medical trials, the vaccine helped to reduce the likelihood of a relapse in recovering addicts - and made taking the drug less pleasurable for those who succumbed.

Experts believe cocaine use has become far more prevalent in Britain in the last 10 years. A recent survey by the music magazine MixMag suggested it could soon overtake ecstasy as the dance drug of choice in clubs, and Aidan Gray, director of the Conference on Crack and Cocaine (Coca), says existing drug users have been turning to cocaine - instead of heroin, for example - in recent years.

"Britain is becoming much more a stimulant orientated society than opiate orientated, and cocaine's at the head of that," he said. "It's market-led; dealers make a better profit on crack cocaine, and a crack user comes back more quickly than a heroin user."

Despite the common belief that it is a non-addictive, "lifestyle" drug, counsellors say cocaine exerts a strong psychological pull on its regular users, and can also have serious physical withdrawal symptoms.

According to the charity Drugscope, those who try to give up "will very quickly start to feel tired, panicky, exhausted and unable to sleep, often causing extreme emotional and physical distress. This can manifest itself in symptoms such as diarrhoea, vomiting, the shakes, insomnia, anorexia and sweating, which for some can prove unbearable."

Mr Gray said the social effects of regular use could also be very serious. "When a cocaine habit gets really bad, it's as bad as a heroin addict. There are so many health consequences - and it's also what it does to your life: do you keep your job?; does your partner leave you? - it may be affecting your moods and your personality."

Dependency

According to the most recent British Crime Survey figures, for 2001-2, 58,000 people had used the smokable and highly addictive "crack" form of cocaine within the previous 12 months, and 622,000 people had used pure cocaine. In the US, it is estimated that 900,000 people a year present themselves at clinics for treatment for cocaine dependency.

The government published a national plan for "tackling crack" two years ago, but with success rates for drug rehabilitation programmes low, it is hoped that a "vaccine" approach, which attenuates the effect the drug has on the brain, could one day supplement more conventional therapy.

Yesterday's trial results showed that in a small-scale study at Yale Medical School in the US, the cocaine vaccine prevented three-quarters of a group of nine recovering addicts from relapsing into cocaine use. In a second group of 13 regular users, it helped 58% to quit and remain cocaine-free for the 12 weeks of the study.

Perhaps more importantly, among those participants in the trial who relapsed into taking cocaine within six months, most - 88% in one study and 63% in the other - said the euphoric effect had decreased. The vaccine works by stimulating the body to produce antibodies against cocaine, which prevent it passing through the blood-brain barrier and giving users the drug's euphoric kick.

Xenova, the small Slough-based firm which is developing the vaccine, is one of a number of pharmaceutical firms hoping to cash in on helping patients to resist their cravings.

Sanofi-Synthélabo, the French drugs giant which is about to clinch an audacious takeover of its French rival Aventis, has a drug called Rimonabant in development, which it claims can help patients both to quit smoking and to lose weight. Scientists developed the drug by tracing the way cannabis-use creates the hunger pangs popularly known as the "munchies". And a British firm, Phytopharm, which specialises in plant-based medicines, is in the final stages of developing an appetite suppressant based on an African cactus.

With the links between lifestyle and illness - and obesity in particular - high on the public policy agenda, firms which give patients a helping hand in conquering their habits expect to generate healthy sales. Xenova is already developing a nicotine vaccine using a similar approach.

Mr Gray, of Coca, said if the anti-cocaine injection proves successful in larger-scale trials, which will take several years to complete, it could be useful.

"If it works in the way they say it going to work, it could be adopted by drug-treatment centres - but you have to look at all the other things that help someone get off a drug," he said.

It takes many years for a pharmaceutical product to reach the market - Xenova has already begun a much larger study of its cocaine vaccine on 130 patients, which should report in 2006, and it will then have to carry out a third wave of even larger trials, before trying to convince regulators to give their approval to putting the drug on the market. Even then, a spokesman for the charity Drugscope agreed, cautioning against looking for a quick-fix "cure" for any addiction. "It seems this has worked for a number of people, but it's important to make sure you've found out what's going on in that person's life," she said.