The recent wave of state legislatures considering and often approving medical marijuana raises significant concerns. By allowing marijuana therapy for patients with diseases such as difficult-to-control epilepsy, are state legislatures endorsing the medical benefits and safety of a broad range of marijuana species and strains before they have been carefully tested and vetted? Marijuana contains around 80 cannabinoids (THC is the major psychoactive cannabinoid, largely responsible for the high) and more than 400 other compounds. The chemical composition of two genetically identical plants can vary based on growing conditions, soil content, parasites and many other factors.

While the language of the legislation may be cautious, there is an implied endorsement of medical benefit for marijuana when a legislature passes a bill and a governor signs it into law, and the tremendous gaps in our knowledge are not effectively conveyed to the public.

Where is the data showing that marijuana is effective for epilepsy? Although parents may report improvements in their children, it is important to remember that the placebo response is powerful, and the placebo response is greater in pediatric than adult studies.

Before more children are exposed to potential risks, before more desperate families uproot themselves and spend their life savings on unproven miracle marijuana cures, we need objective data from randomized placebo-controlled trials.

Based on studies showing that CBD can prevent seizures in animals and safety data from patients treated with a drug containing CBD and THC in Europe for multiple sclerosis spasms, we and other academic epilepsy centers are planning a controlled trial with pure CBD. As an initial step, we have approval from the Food and Drug Administration, the Drug Enforcement Administration and the Bureau of Narcotic Enforcement to treat children with CBD derived from marijuana plants in order to understand its safety and tolerability and potential drug interactions. This information will help us plan the placebo-controlled trials that we hope will begin in 2014 and will be completed within two years. There is no reason such studies cannot be done with other products derived from marijuana, such as the oil with high CBD and low THC sold in Colorado that was used by Charlotte Figi.