Phase 3 trial to provide clearer picture of CBD’s side effects: researcher

May 14, 2015

By Deron Hamel

The third phase of a study examining the impact of cannabidiol (CBD) on people living with severe, drug-resistant forms of epilepsy will paint a clearer picture as to whether or not the cannabis extract has any side effects, says epilepsy researcher Dr. McIntyre Burnham.

CBD_300Phase 2 of the multi-centre study, which was presented at a recent American Academy of Neurology meeting, involved 213 people aged two to 26 living with more than 10 severe, drug-resistant types of epilepsy, including Dravet syndrome and Lennox-Gastaut syndrome, both of which can result in lifelong seizures and intellectual disability.

CBD is an extract from the cannabis – or marijuana – plant. Unlike THC, the most abundant chemical compound in cannabis, CBD will not get people “high.” CBD is the most abundant, non-psychoactive chemical compound in cannabis.

Study participants were given a liquid form of CBD, administered orally to complement their regular treatment. The study was an open-label trial, meaning there were no placebos administered to participants.

Only 10 participants – five per cent of those involved with the study – stopped taking CBD because of side effects.

“They’ve never found very many serious side effects of this compound,” Burnham tells Voices of Epilepsy. “In the recent trials, generally speaking, the side effects were not too serious and passed. The most common ones were sleepiness and some stomach upset.”

However, Burnham says that because the study was an open-label trial, the participants, plus their families and the researchers, were aware they were taking CBD, which can create a margin of error.

“You don’t really trust reports of side effects until you have it in a double-blind situation,” he says.

Phase 3 of the study will be double-blind trials. In other words, neither the doctors nor the participants will know who is getting CBD and who is taking the placebo.

“In double-blind trials you always assess how many of the patients are in the drug arm and compare it to how many patients in the placebo arm got it (the adverse event). We don’t have the placebo arm in (Phase 2 of the) study, so you can’t really make much statement about side effects,” Burnham says.

“Everyone’s always very careful about interpreting Phase 2 studies.”

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