Cannabidiol, one of the nonpsychoactive cannabinoids extracted from cannabis plants, has been demonstrated to show efficacy in forms of epilepsy.

While initially such reports were only anecdotal, research is evolving to support the initial findings. It remains essential to closely monitor children, adolescents and adults using cannabidiol treatments as there are identified side effects, and further there are side effects that have yet to be explored.

Doctors in Seoul, South Korea, recently reported a review of the research related to cannabidiol in the Journal of Epilepsy Research. They discussed the results of 10 separate studies in the United States since 2013 and concluded that while some studies showed efficacy, the study designs were limited with most being open label or survey design. Future studies need to be double-blind and controlled.

They also reported adverse effects such as drowsiness, diarrhea and decreased appetite. In some cases, the reactions were severe such as status epilepticus but were not always conclusively associated with the cannabidiol.

An alarming side effect of cannabidiol that has been reported in humans and animals is the elevation of pressure within the eye. In other words, cannabidiol has been shown to precipitate a temporary form of glaucoma.

One of the few papers that studied the effect of cannabinoids on human eyes and glaucoma reported in 2006 a decrease in the pressure with the cannabinoid tetrahydrocannabinol (THC). THC is the ingredient in marijuana/cannabis that causes the high sought by recreational users.

This same study also identified a time delay, relative to the THC action, of cannabidiol causing an increase in the pressure of the eye. While the lowering eye pressure effect of the THC identified in the 2006 study is frequently cited, the elevating effect on eye pressure caused by cannabidiol is rarely, if ever, reported. This is an important side effect of cannabidiol that, if present, requires close monitoring by an eye care professional.

The findings from an animal model of treatment with cannabidiol were reported at the International Cannabinoid Research Society conference held in Montreal last month. Sally Miller, Ph.D., and Alex Straiker, Ph.D., from The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences at Indiana University, reported their findings in their oral presentation, "Delta9-THC and CBD Differentially Regulate Intraocular Pressure."

They used a mouse model and found that the effect of THC acted on two types of eye cannabinoid receptors and was sex-dependent, while the cannabidiol had two opposing actions — both lowering and raising pressure, dependent on a yet-unclear mechanism.

A topical application of THC lowered the pressure, but the action was slower in females and the lowering of pressure in females was only half that of the males. The cannabidiol, when used topically, raised the pressure. The occurrence of pressure lowering with cannabidiol only occurred with a genetically modified mouse.

The indication of cannabidiol raising the eye pressure in a human is a matter of serious concern. Spiking of eye pressure, even if intermittently, can cause a significant loss of retinal receptors. The consequence can be a loss of vision.

Orrin Devinsky, M.D., from the New York University Langone Comprehensive Epilepsy Center, recently led a group that investigated the use of cannabidiol in Dravet syndrome, a rare genetic epileptic disorder that has seizures resistant to drug treatment and a high mortality rate.

The study followed 120 children and young adults. The study participants received either a dose of cannabidiol based on their body weight or a placebo. Those with Dravet syndrome achieved a lower rate of seizure and fewer adverse events. This certainly speaks for cannabidiol having an influence and contributing to a better quality of life for these patients.

Patients with complex chronic disease need to be closely monitored when receiving treatments. Those being treated with cannabidiol are no exception.

These patients should have assessments of the systems that are known to be impacted by cannabidiol. This includes systems negatively affected, such as spikes in the pressure of the eye. This needs to be monitored and studied.