Sativex and the pain-relieving powers of THC

April 26, 2005

There are few diseases as baffling and scary as multiple sclerosis (MS). You know this if you have it, or know someone who does -- and, since this is Canada, you probably do.

Our place on the globe is an MS hot zone. Around the world there is a noticeable "latitudinal gradient" in the incidence of MS; it is most common in Scandinavia, Iceland, Scotland and here. And even within countries like Italy, Australia and the United States, it becomes more common as you move north. (A recent study confirmed the existence of an equally weird "calendar gradient" among Brits, Canadians, Danes and Swedes; if you were born in November, your MS risk is almost 20% lower than if you were born in May.)

But despite such powerful clues, theories about the disease's cause remain tenuous. Is it environmental? Dietary? Genetic? Viral? There is no conclusive answer. Acting with a keen consciousness of medicine's helplessness, Health Canada announced on April 13 that it is extending conditional approval to a new drug for the treatment of chronic pain in MS patients. But the new drug has a familiar face. The active ingredients in GW Pharmaceuticals' Sativex are THC and cannibidiol -- which also happen to be the main active ingredients in marijuana.

One can only admire the lightning speed with which this U.K.-based firm has moved to capitalize on our national doublethink about cannabis. Canada is the first jurisdiction to approve the product, an oral spray said to taste a little like Guinness. (The price has not yet been set, but Sativex is expected to go on sale in June.) We were targeted first, it seems, because of our high MS incidence and our relative openness to marijuana.

Then again, if marijuana were actually legal here, there might not be such a sizable market for a new form of the stuff. Thousands of Canadian MS sufferers are already smoking pot on the sly, and will attest to the pain-relieving powers of THC.

Health Canada's approval of Sativex is based on one paltry four-week study, and is contingent on further research by GW. The drug was approved only because there are no other MS-specific pain drugs on the market. And it was passed despite a high incidence -- nearly 90% -- of "adverse events" in the GW study. The punchline is that most of these adverse events fell into two categories: mild pain or irritation in the mouth, which is attributable to the delivery method, and "intoxication," which is attributable to, uh, the fact that it's weed.

Sativex is billed by its maker as pot for squares: GW spokesman Mark Rogerson told the Edmonton Journal that "With Sativex you don't need to get high to manage your symptoms." It's being left to MS patients to set their own dosage, on the premise that they will gradually find an amount that relieves pain without getting them high. On the other hand, if they want to get high, there certainly won't be anything stopping them. (Moreover, what kind of sadist would begrudge them the relaxation?)

The genius of Sativex is that it takes moral pressure off the physician. Ever since the Liberals began to contemplate medical licensing of smokeable marijuana, the Canadian Medical Association and individual MDs have occasionally complained about being asked to prescribe a "poorly understood" substance in a non-titrated form. The complaint is partly valid, since black-market marijuana varies widely in strength. And partly, it has an unstated basis: Doctors don't want to become society's sole legitimate conduit for a recreational drug that is widely tolerated and used, but officially illegal.

Still, there are thousands of studies of marijuana in the medical literature, and it has millions of habitual users. Drugs are prescribed every day which are understood 1% as well as THC and other cannabinoids. The truth is that most doctors understand marijuana to be fairly harmless (which is why the CMA's journal of record officially supports decriminalization).

Sativex is literally just marijuana without the smoke, and while it may liberate doctors from the burden of cannabis hypocrisy, it will intensify it for the rest of us. The availability of licensed, patented pseudopot alternatives shouldn't open the door for renewed crackdowns on "compassion clubs" -- which would mean taking traditional marijuana away from patients, and replacing a naturally occurring substance with expensive simulacra that might be therapeutically inferior. Above all, it's not pot smoke that we need to eliminate, but cloudy thinking.



Colby Cosh
© National Post 2005