Regulators have approved a cannabis-based drug

Where it all started

SUFFERERS from multiple sclerosis (MS) and other painful illnesses have long smoked marijuana to alleviate the discomforts of their condition. On June 21st the first legal cannabis-based medicine went on sale in Britain. Doctors who had previously advised their patients to buy the drug from shady types on streetcorners will now be able to write them a private prescription costing about £11 a day. Free supplies courtesy of the National Health Service await a formal finding that the medicine is cost-effective.

Around 100,000 people in Britain have MS. Muscle cramps and spasms prevent about a third of them from performing simple tasks such as unscrewing a lid, getting dressed or climbing out of a car. Doctors will be able to prescribe the new drug, called Sativex, only to MS patients with cramps and spasms for whom other treatments have failed. And there is to be no funky smoking of the stuff; patients will spray the fluid under their tongues about eight times a day.

There are attempts to head off a black market, too: the drug lacks the mind-bending effects of the plant from which it is derived, if it is correctly administered as a medicine. It is unusual in that it contains compounds extracted directly from cannabis, rather than artificially-manufactured copies of the chemicals.

To develop and bring the drug to market has taken more than a decade. GW Pharmaceuticals, the firm that did the work, was founded in 1998 and granted a licence by the Home Office to grow marijuana at an undisclosed location. It began running clinical trials on Sativex in Britain a year later.

Elsewhere, the process has been faster. Canada approved Sativex for relieving pain (but not spasms) in MS patients, albeit under strict conditions, in 2005. Two years later people with advanced cancer were also allowed to take it. Clinical trials are under way now in Spain, where GW hopes Sativex will be approved for use later this year. In America the Food and Drug Administration gave its blessing in 2005 to clinical trials involving cancer patients, and these too are due to conclude this year.

While scientists in Britain have been struggling to demonstrate the merit of drugs derived from marijuana, others have agitated for legalisation of the plant itself, and to treat a broader range of ailments than MS. A House of Lords investigation in 1998 broadly hailed the medical potential of cannabis, as well as of compounds obtained from it. California has allowed its use in some circumstances since 1996 and, since then, 13 American states and the District of Columbia have followed suit.

Despite the long-delayed promise of approval for Sativex, a willingness among police and prosecutors to avoid pursuing sick people has blunted calls to legalise old-fashioned, herbal marijuana. The drug’s final approval may kill the campaign altogether.