THC-containing cannabis oil shows promise for treating Dravet syndrome epilepsy

Toronto researchers have determined what dosage of a specially formulated cannabis oil is safe and can be tolerated by children with Dravet syndrome, a rare genetic form of epilepsy that causes lifelong seizures. Researchers at the Hospital for Sick Children tested the cannabis oil, which contains CBD (cannabidiol) and a small amount of marijuana’s psychoactive ingredient THC (tetrahydrocannabidiol) in 20 children with Dravet syndrome, whose seizures were not well-controlled with standard anti-convulsant medications. Cannabis oil containing only CBD has been shown to have antiseizure effects in children with Dravet’s, but the Sick Kids research team wanted to assess the benefits of a preparation that also included THC, with a primary goal of determining a safe pediatric dose and any side-effects the drug caused. Children with Dravet syndrome experience ongoing seizures - in some cases, more than a hundred a day - leading to developmental delays and significant learning disabilities. Dravet’s is responsible for up to 30 per cent of all cases of epilepsy; it is difficult to treat and has no cure. “We saw an overall median reduction (in seizures) of 70 per cent,” said neurologist Dr. Blathnaid McCoy, lead author of the study published Wednesday in the Annals of Clinical and Translational Neurology. “And one of the things we tracked was seizure-free days ... which went from a mean of 11.8 days to 18.3 days, which is essentially an extra week (and) which is clinically very meaningful.” However, not all of the children responded positively: four saw their seizures increase in frequency while taking oral doses of the oil, a pharmacy-grade preparation produced by Tilray Inc. However, McCoy said that increased seizure activity could also be due to the nature of Dravet’s, which is known to cause “peaks and troughs, even if we don’t do anything.” For Laura Weightman, whose 16-year-old daughter Abigail had her first Dravet seizure at eight months old, the cannabis oil therapy has meant new hope for her child’s future. The Pickering, Ont., mother of four said Abigail had experienced about 100 seizures a month from about age three to five, a number that was subsequently reduced to about 10 to 20 per month.