14 DAY TRIAL // There is a strong advocacy towards using cannabis for relieving pain in many conditions. A new study has come up with a surprising result: even if "moderate" doses of cannabis can ease pain, high doses actually boost it.
"Our study suggests that there is a therapeutic window for analgesia, with low doses being ineffective, medium doses resulting in pain relief, and high doses increasing pain," said lead author Dr. Mark S. Wallace of University of California, San Diego.
His team checked the effects of smoking cannabis on pain sensation in 15 healthy subjects. On different days, the volunteers smoked low, medium, or high doses of cannabis (calculated based on 9-delta-tetrahydrocannabinol [THC], the main active ingredient in cannabis), or a placebo (non active stuff).
Pain was provoked by injecting capsaicin, the "hot" chemical encountered in chili peppers, into the skin, a classical method employed in pain studies. 5 minutes following smoking, none of the three doses induced any effect on pain reactions to capsaicin, but 45 minutes later, the moderate dose dropped significantly the pain sensation, by about 6 points on a 100-point scale, as compared to the placebo case.
On the contrary, 45 minutes later, the high dose rose by about eight points the pain sensation compared with placebo. The low dose of cannabis did not affect pain perception.
All three doses had not effect in controlling the spread of secondary hyperalgesia (pain beyond the zone injected with capsaicin).
THC blood levels were directly connected to decreased pain sensation in case of moderate doses of the drug, but not with the increased pain sensitivity correlated to high-dose weed.
Subjects' sensation of feeling "high" was directly connected to the dose of drug, but not to the pain-relieving effects. "The research can provide an evidence basis for deciding the appropriate use of cannabis and related compounds as medicines. This is the first study using different doses of cannabis and a tightly controlled pain stimulus that suggests that cannabis has a therapeutic window of pain relief," said Wallace.