25/10/2007 00:00:00
Press Release: Smoked Cannabis Proven Effective In Treating Neuropathic
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Smoked Cannabis Proven Effective In Treating Neuropathic Pain
Smoked cannabis eased pain induced in healthy volunteers, according to a
study by researchers at the University of California, San Diego (UCSD)
Center for Medical Cannabis Research (CMCR.) However, the researchers
found that less may be more.
In the placebo controlled study of 15 subjects, a low dose of cannabis
showed no effect, a medium dose provided moderate pain relief, and a
high dose increased the pain response. The results suggest a
"therapeutic window" for cannabis analgesia, according to lead
researcher Mark Wallace, M.D., professor of anesthesiology at UCSD
School of Medicine and Program Director for the UCSD Center for Pain
Medicine.
The study used capsaicin, an alkaloid derived from hot chili peppers
that is an irritant to the skin, to mimic the type of neuropathic pain
experienced by patients with HIV/AIDS, diabetes or shingles -- brief,
intense pain following by a longer-lasting secondary pain. The subjects
were healthy volunteers who inhaled either medical cannabis or a placebo
after pain was induced. The marijuana cigarettes were formulated under
NIH supervision to contain either zero, two, four or eight percent
delta-9-tetrahydrocannabinol (THC.)
"Subjects reported a decrease in pain at the medium dose, and there was
also a significant correlation between plasma levels of THC, the active
ingredient in cannabis, and decreased pain," said Igor Grant, M.D.,
F.R.C.P.(C), professor and Executive Vice-Chair of the Department of
Psychiatry, the director of the CMCR. "Interestingly, the analgesic
effect wasn't immediate; it took about 45 minutes for the cannabis to
have an impact on the pain," he said.
The results, showing a medium-dose (4% THC by weight) of cannabis to be
an effective analgesic, converged with results from the CMCR's first
published study, a paper by UCSF researcher Donald Abrams, M.D.
published in the journal Neurology in February 2007. In that randomized
placebo-controlled trial, patients smoking the same dose of cannabis
experienced a 34% reduction in HIV-associated sensory neuropathy
pain--twice the rate experienced by patients receiving a placebo.
"This study helps to build a case that cannabis does have therapeutic
value at a medium-dose level," said Grant. "It also suggests that higher
doses aren't necessarily better in certain situations -- something also
observed with other medications, such as antidepressants."
The researchers stated that more and larger studies need to be conducted
to measure the efficacy of cannabis, noting that medical marijuana could
play an important role in treating patients who don't respond well to
the usual pain relievers or can't tolerate drugs such as ibuprofen or
opioids used for severe pain.
"The results of this study might help guide others doing clinical
research into pain management," said Wallace.
The paper, to be published in the November issue of the journal
Anesthesiology, is the second published study out of the CMCR.
Headquartered at UCSD, the CMCR is collaboration between UCSD and UC San
Francisco that was funded by a state-funded initiative in 1999 to
rigorously study the safety and efficacy of medicinal cannabis in
treating diseases.
Additional contributors to the study include Gery Schulteis, Ph.D., UCSD
Department of Anesthesiology; J. Hampton Atkinson, M.D., professor, and
Deborah Lazzaretto, M.S., UCSD HIV Neurobehavioral Research Center; Ian
Abramson, Ph.D., UCSD Department of Mathematics and HIV Neurobehavioral
Research Center; Tanya Wolfson, M.A., UCSD Department of Family and
Preventive Medicine; and Heather Bentley and Ben Gouaux, UCSD Center for
Medicinal Cannabis Research.
Adapted from materials provided by University of California - San Diego.
http://www.sciencedaily.com/releases/2007/10/071024141745.htm
Source:
http://www.ukcia.org/news/shownewsarticle.php?articleid=12942
Author:
Science Daily via UKCIA
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