People with chronic pain who aren't getting enough relief from medications may be able to ease their pain by smoking small amounts of marijuana, a new study suggests.
Marijuana also helps pain patients fall asleep more easily and sleep more soundly, according to the report, one of the first real-world studies to look at the medicinal use of smoked marijuana. Most previous research has used extracts of tetrahydrocannabinol (THC), the active ingredient in the cannabis plant.
"This is the first time anyone has done a trial of smoked cannabis on an outpatient basis," says the lead researcher, Mark Ware, M.B.B.S., the director of clinical research at McGill University's Alan Edwards Centre for Research on Pain, in Montreal.
Each patient in the study smoked four different strengths of marijuana over a period of 56 days. The THC potency ranged from 9.4 percent -- the strongest dose the researchers could obtain legally -- to 0 percent, a "placebo" pot that looked and tasted like the real thing but was stripped of THC. (By comparison, the strongest marijuana available on the street has a THC potency of about 15 percent, Ware estimates.)
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The participants -- who weren't told which strength they were getting -- were instructed to smoke a thimbleful (25 milligrams) from a small pipe three times a day for five days. After a nine-day break, they switched to a different potency.
The highest dose of THC yielded the best results. It lessened pain and improved sleep more effectively than the placebo and the two medium-strength doses (which produced no measurable relief), and it also reduced anxiety and depression.
The effects lasted for about 90 minutes to two hours, according to the study.