New York, Dec 24 (IANS): A medical marijuana derivative was found safe and effective in reducing the frequency of seizures in most children and young adults enrolled in a year-long study led by epilepsy specialists in the US.

The findings provide the first estimates of safety, tolerability and efficacy of prescription cannabidiol (CBD), a medical marijuana derivative, in children and adults with severe, highly treatment-resistant epilepsy, the study said.

"We are very encouraged by our trial results showing that CBD was safe and well-tolerated for most patients, and that seizures dropped significantly," said lead researchers Orrin Devinsky, professor at New York University Langone Medical Centre in the US.

The study took place at 11 epilepsy centres across the US. Patients were given the oral CBD treatment Epidiolex over a 12-week treatment period.

Results showed a median 36.5 percent reduction in monthly motor seizures, with the median monthly frequency of motor seizures falling from 30 motor seizures a month at the study's start to 15.8 over the 12 weeks.

Equally important, CBD was shown to have a sufficient safety profile and was well-tolerated by many patients, despite some isolated adverse events.

The study was published in the journal Lancet Neurology.