Not All Marijuana-Based Treatments Are Created Equal
WASHINGTON, DC—Limited data about efficacy and inconsistency among available preparations are two of the many challenges associated with prescribing medical marijuana for neurologic disorders, according to a presentation at the 67th Annual Meeting of the American Academy of Neurology (AAN). Decriminalization of marijuana for medical use varies from state to state in a rapidly changing legal landscape. But most importantly, from a medical standpoint, many physicians mistakenly compare the different products as if they were comparing “apples to apples,” said Anup Patel, MD.
“Marijuana is made up of more than 60 distinct pharmacologically active compounds. The most psychoactive one, and the one that gets a lot of press, is THC,” Dr. Patel noted. “However, what many people do not understand about marijuana … is that the various compounds should not be lumped together as one entity.”
In addition to THC (Δ-9-tetrahydrocannabinol), cannabidiol (CBD) is a compound that is widely extracted from medical marijuana preparations. Unlike THC, which may promote recreational use because of its euphoric effects, CBD is not psychoactive. Dr. Patel noted that research is ongoing, and the compound’s mechanism of action has not yet been determined.
Preparations and Formulations Vary
While the FDA has not approved the marijuana plant for medical use, it has approved one drug in capsule form that contains a synthetic version of THC and one that contains a synthetic substance that acts similarly to THC but is not present in marijuana. In 2013, a medication made from purified CBD was granted orphan drug designation to treat childhood-onset epilepsy. Dr. Patel, a pediatric epileptologist at Nationwide Children’s Hospital at the Ohio State University Medical Center in Columbus, disclosed that he is a consultant for the manufacturer of that medication and that he prescribes the medication to patients in his practice through the FDA approved trials and compassionate use program.
“We are not legally allowed to prescribe medical marijuana in Ohio. But I have been able to prescribe this particular medication legally because it is allowed by the federal government,” said Dr. Patel. “We do it through an expanded access program. The medication is currently being investigated in ongoing double-blind randomized controlled trials.”
Other medications under investigation include a product for epilepsy that contains a high ratio of CBD to THC. Another, nabiximols, is designed to treat spasticity resulting from multiple sclerosis and advanced cancer pain and has roughly equal amounts of CBD and THC, Dr. Patel pointed out.
In states where medical marijuana is decriminalized for medical purposes, products are available by prescription to be smoked, vaporized, eaten as cookies or candy, or taken as a liquid extract. These natural products are not monitored by the FDA, so patients may not be receiving exactly what their doctors are prescribing, Dr. Patel warned. “They may claim to have a high content of CBD, THC, or another component, but the content could fluctuate from dose to dose [or from] batch to batch. This changeability may also affect any potential toxicity.”
Recent case reports have linked recreational use of synthetic marijuana products high in THC with strokes. To date, no reports have shown this association in products with high CBD and low THC content, he added.
Potential Dangers
Dangers associated with the increased availability of marijuana in states where it has been decriminalized have been a subject of research, Dr. Patel noted. One retrospective cohort study examined the number of children who presented to a Colorado emergency department from January 2005 through December 2011 for unintentional ingestion of any product. The researchers found that none of the 790 cases evaluated before decriminalization in October 2009 were related to marijuana exposure. After 2009, 14 of the 588 unintended ingestion cases were related to marijuana exposure, and eight cases involved medical marijuana.
Similarly, a 2014 retrospective review of unintentional pediatric marijuana exposure looked at call volume to US poison centers from 2005 through 2011. The call rate increased by more than 30% per year in states where medical marijuana had been decriminalized before 2005. In states where decriminalization laws were enacted between 2005 and 2011, there was a trend toward an 11.5% increase in call volume per year. The call rate to poison centers in states where marijuana was illegal did not change from 2005 to 2011. Interpreting the data is difficult, however, because the numbers were low overall, Dr. Patel added.
Furthermore, recreational marijuana use may skew the results of sleep studies. In a retrospective study published earlier this year, 383 patients younger than 21 underwent urine drug screens on the morning before multiple sleep latency tests (MSLTs). The researchers found that a higher proportion of patients with a positive screen for THC showed findings consistent with narcolepsy or had multiple sleep-onset REM periods, compared with patients with negative screens.
