2002-05-13 17:01:56 -0400
By Suzanne Rostler
NEW YORK (Reuters Health) - In findings that contradict earlier research, a team of scientists reports that marijuana does not improve the often painful symptoms of multiple sclerosis (MS).
Their small study found that a synthetic form of tetrahydrocannabinol (THC), the active ingredient in marijuana, and a plant extract were no better at relieving severe spasticity or muscle contraction compared with an inactive placebo. Patients' muscle tone improved while taking marijuana but their self-reported ratings on a scale measuring their overall disability declined.
And while marijuana was found to be safe, some patients experienced mild side effects such as headache and dizziness, particularly after taking the plant extract, according to the report in the May 14th issue of Neurology.
MS is a neurodegenerative disorder in which the slow destruction of myelin--the thin, protective coating that insulates nerve fibers in the brain and spine--can lead to numbness, muscle weakness and stiffness, impaired vision and coordination problems.
A previous study in mice indicated that marijuana might help to relieve these painful spasms. However, the amount of the drug used in mice would not be tolerated in humans, the researchers explain. While their study included just 16 patients, it is the largest randomized, controlled clinical trial to investigate the use of marijuana to treat MS.
"Compared to placebo, neither THC nor plant-extract treatment reduced spasticity," Dr. Joep Killestein from the VU Medical Center in Amsterdam, the Netherlands, told Reuters Health. "Even though the sample size is too small to be conclusive, our study was the largest and longest completed study addressing cannabinoid therapy in MS so far."
The authors suggest that the dose used in the study may have been too low to show any beneficial effects, or giving the drug in capsule form may have slowed its absorption.
"THC is absorbed reasonably well from the gut, but the process is slow," Killestein and colleagues explain.
In the study, patients took an inactive pill (placebo), a marijuana plant-extract or synthetic THC for 4 weeks. The researchers measured muscle tone and overall disability, and patients responded to questions assessing their quality of life.
SOURCE: Neurology 2002;58:1404-1407.
Copyright © 2002 Reuters Limited