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U of G research show pot helps sick people cope
THANA DHARMARAJAH | GuelphMercury.com | Jul 29, 2006

Marco Renda's fits of vomiting have stopped since he started inhaling marijuana vapours.

The 46-year-old was diagnosed with hepatitis C more than 20 years ago and spent many days hospitalized because of his vomiting attacks.

"Even when there was no vomiting, there was retching," said the Dundalk-area man, who is now allowed by Health Canada to grow and use marijuana to combat his illness.

Renda said at one point he distributed marijuana to several cancer chemotherapy patients in Canada to help them find relief from similar symptoms of nausea. Now, he provides advice so patients can find the strain of the drug that gives them maximum relief.

Linda Parker, a University of Guelph behaviour neuroscientist, recently discovered marijuana may help prevent nausea among chemotherapy patients in a way anti-vomit and anti-nausea drugs can't.

Many cancer patients get nauseated when they go in for treatment because they're anticipating the effects of the chemotherapy, and even the environment of the hospital can trigger nausea, she said.

Parker's research has been published in recent issues of the journal Physiology and Behavior.

She said there's always been anecdotal evidence marijuana reduced nausea in cancer patients, but it was only in the 1990s that researchers figured out how it affected the brain and the body.

In her work, she's used rats and shrews to figure out how two compounds -- THC, a chemical that makes people high, and cannabidiol -- can treat vomiting and nausea.

Parker said rats and other rodents don't vomit but they do open their mouths as though they're about to retch when they feel nauseous, she said.

In the study, she placed shrews and rats in a test chamber several times and injected a drug to cause vomiting.

When she put them back in the chamber later without the drug, she noticed the shrew retched and the rat gaped although they didn't have a toxin in their system, because they were anticipating nausea in the way a chemotherapy patient might anticipate nausea upon entering a hospital.

Parker then gave them THC or cannabidiol and noticed their reactions were suppressed.

She said both compounds have the same effect, but cannabidiol isn't intoxicating in the way THC is, so it could be used to develop treatments that won't make people feel high.

The drug Sativex incorporates both compounds and is already on the market. It's applied by spraying it into their mouth.

tdharmarajah@guelphmercury.com