A DRUG derived from cannabis might one day be used on Hong Kong AIDS patients suffering from low appetite and severe wasting, according to an AIDS expert. Dr Patrick Li Chung-ki of Queen Elizabeth Hospital said the drug was yet to be registered in Hong Kong, but he was prepared to offer it to patients when the need arises. Dr Li said an overseas study had shown the drug had a positive effect on patients suffering weight loss and poor appetite. 'The help was not just psychological, but an actual gain in body weight,' said Dr Li. Severe weight loss, diarrhoea and poor appetite are typically suffered by AIDS patients, resulting in a poor quality of life. In the US, a campaign is growing nationwide to legalise cannabis for medical use. At the forefront of the campaign is the Cannabis Buyers' Club on Market Street, San Francisco. An anonymous-looking four-storey office building from the outside, within it is a modern version of a Prohibition-era speakeasy. The air is heavy with marijuana smoke and the rhythms of Annie Lennox. This lunchtime the trade is hectic at both of its 'bars' which, as well as cannabis by the 2.5-gram bag, also sell pot-laced pastries, water pipes and other cannabis-taking paraphernalia. 'What we are doing is totally, absolutely illegal,' confesses the club's director and founder, Dennis Peron, an impish grin breaking out from under his white hair. But this is by no means a frivolous venture - the club is reserved for customers with serious, mostly chronic diseases, in particular AIDS and cancer. And no one gets membership without a written diagnosis from their doctor. Nor is this an ordinary day at the club, one of about 26 operating across America. When 1pm comes, Mr Peron leads 100 of his members on a march down Market Street to publicise the latest phase of his campaign: a drive to collect 600,000 signatures to put a popular petition to California's voters next November, asking them to let doctors prescribe marijuana to the gravely ill. The police have shown up in strength but, this being San Francisco and an oasis of liberal politics in America, they actually help the marchers. Passing cars honk with approval, their drivers flashing the thumbs-up sign. It was after the death of his former lover from AIDS that Mr Peron founded the club in 1991, the first of its kind. He has seen its membership explode to more than 7,000. The club is also a place for social contact and mutual support. Curtis, for example, who is 34 and has had HIV for nine years, comes to the club about twice a week to linger for a couple of hours and meet friends. More importantly, he is certain it has helped his body cope with the virus. He says that it helps him sleep, restores his appetite and suppresses the nausea that is brought on by the anti-AIDS drug, AZT. A fresh joint in his hands, he explains: 'If I didn't take pot, it would just be an endless cycle of getting up in the morning and not being able to eat anything and then not taking the AZT because it makes me feel so bad.' Several others at the bar offer similar testimonies. 'If it wasn't for the club, I would be dead by now,' says Peter Dekon, who has a brain tumour. 'I'm certain of it.' On the legal front, however, Mr Peron's experience has been more frustrating. The federal government continues resolutely to resist revising its designation of cannabis as a category one drug, too dangerous even for doctors to prescribe on however limited a basis. Cocaine and morphine, by contrast, are category two drugs. The California assembly finally this year did pass a law offering a limited legalisation of the drug for medical use, only to see it instantly vetoed by Governor Pete Wilson. In Hong Kong, senior judges have called for cannabis to be legalised, but met with stiff community opposition. But Dr Li of Queen Elizabeth Hospital believes the answer to patients' problems is not legalisation of cannabis. 'I think it is more reliable with controlled prescription and patients using drugs under close supervision,' he said. 'With this cannabis-derived drug, we could control the amount and frequency. 'For those with HIV-wasting, we will find ways to improve their appetite using different drugs. If there is no other option, we are ready to offer this cannabis-derived drug as an alternative.' Dr Li warned that with illegal purchases the source would be uncertain. IN the US, the notion of allowing marijuana use for therapeutic purposes only is increasingly being debated. Officials insist there is no scientific evidence proving the benefits of marijuana as a treatment. But the Journal of the American Medical Association published an article advocating limited legalisation which was co-authored by Lester Grinspoon, a professor of psychiatry at Harvard. 'The ostensible indifference of physicians should no longer be used as a justification for keeping this medicine in the shadows,' the article argued. Back at the club, Mr Peron remains convinced that he will one day be vindicated. With the California petition, he may be making an important start. If he can get the signatures he needs to qualify for a place on the ballot, his latest initiative could become law. 'This is just now beginning to achieve a critical mass,' he says. 'Soon the whole of the country will know about what we're doing and then the whole of the world.'