A Scientific American article about Sativex, a cannabis extract spray that the FDA may approve for treatment of cancer pain after clinical trials are completed in 2014 or so, assures us (citing "experts") that the product has "little potential for abuse":
Because the drug is delivered through ingestion, rather than smoking, it would take much longer to have an effect — at least an hour, compared with the minutes it takes to get high after smoking marijuana, said Margaret Haney, a professor of clinical neurobiology at Columbia University. This means drug users seeking a high would be less likely to abuse it. "Smoking is a really effective way to get a chemical into the brain," Haney said. The mouth spray "is a far safer administration," she said.
Actually, Sativex, which contains delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), is sprayed under the tongue or on the inside of the cheek and is meant to be absorbed through the mucous membranes of the mouth. Hence it has a faster onset of action than Marinol, a capsule containing synthetic THC that was approved by the FDA in 1985. "Following administration of Sativex (four sprays)," says Drugs.com, "both THC and CBD are absorbed fairly rapidly and appear in the plasma within 15 minutes after single oromucosal administration." By comparison, the effects of Marinol, which is absorbed by the gastrointestinal system, are felt after 30 minutes to an hour—similar to the lag for swallowed cannabis. Faster action is one of Sativex's advantages over Marinol, both because patients feel relief sooner and because they can more easily titrate their doses, taking an additional spray after 15 minutes or so if the initial dose proves inadequate. They can also avoid taking too much, which is hard when you swallow a standardized dose whose full effects may not be felt for hours. (A related issue with Marinol: It is processed by the liver, producing a THC variant that may compound any unpleasant psychoactive effects.) Sativex's manufacturer, GW Pharmaceuticals, brags that "the spray is quickly absorbed through the oral mucosa, is easy to use for patients and enables them to optimally adjust their dosage."
While it's still true that smoking (or vaporizing) cannabis delivers THC and other active ingredients faster than spraying an extract in your mouth, people have been known to "abuse" pot cookies and brownies, which make impatient cannabis consumers wait substantially longer for a buzz than Sativex does. A more plausible reason why Sativex probably won't attract many recreational users: Why go to the trouble of obtaining an expensive prescription drug when you can get more bang for your buck from the original plant? But that question also applies to patients, especially since vaporization, like an oral spray, avoids the hazards of smoking. Another possible advantage of marijuana is that its components may have a synergistic effect that can't be replicated by one or two ingredients. Not surprisingly, GW Pharmaceuticals, as channeled by Scientific American, sees that feature as a bug:
While marijuana is a hodgepodge of about 64 different substances, Sativex is composed mainly of two ingredients: THC and another cannabinoid called CBD. The latter component is thought to ameliorate some of the side effects of THC, including the high that marijuana users feel.
Notice that the "high," an elevation of mood that seriously ill people might actually welcome, is treated as an unwanted side effect. And how does GW Pharmaceuticals know that THC and CBD entirely account for marijuana's beneficial effects? Unimed, Marinol's manufacturer, thought THC was all that patients needed.
In terms of marketing the drug to bureaucrats, however, GW Pharmaceuticals seems to know what it's doing. So far it has won approval of Sativex in the U.K., Spain, Germany, Denmark, New Zealand, and Canada for treatment of neuropathic pain and spasticity caused by multiple sclerosis. Although the distinctions drawn by the company may be be puzzling, they show how a disreputable drug can be transformed into a respectable one: emphasize isolated chemicals instead of raw plant matter, claim the product acts quickly enough to be better than the competition but not so quickly that it would appeal to recreational users, and never admit that patients might enjoy taking it.
Previous coverage of Sativex here.
[Thanks to Richard Cowan for the tip.]