For DOs managing the care of patients with chronic neuropathic or cancer pain, cannabis may be a viable treatment option. However, physicians are urged to counsel patients on the appropriate use of cannabis due to the possibility of varied and unpredictable effects, including schizophrenia and other psychiatric issues, according to comprehensive research in The Journal of the American Osteopathic Association.
Cannabis is currently classified in Schedule 1 of the Controlled Substances Act, a category for drugs such as heroin, but is legal for medicinal purposes in 30 states and the District of Columbia and recreational use in 8 states and the District of Columbia. Legalization of cannabis is under review in 12 additional states this year, leading to an increased need for physician awareness on how to counsel patients when prescribing cannabis.
“One of the biggest risks involves the potential aggravation or activation of latent psychiatric issues, such as schizophrenia,” says Jeramy Peters, DO, lead study author and psychiatrist at Oregon Health and Science University in Portland. “This is a special concern for young people in their late teens and early twenties, when their brains are still developing.”
Cannabis contains tetrahydrocannabinol (THC), which is responsible for the “high” people often experience, as well as cannabidiol (CBD), which is theorized to have antipsychotic and anxiolytic properties. Currently, CBD is being studied for its possible antiseizure and anti-inflammatory properties.
The strength of cannabis has been increasing over the past half century. During the 1960s, cannabis was typically about 1% to 5% THC by weight. Many strains available today range from 15% to 25% THC by weight, with some strains reaching 30% or higher.
The key to dosing cannabis safely for patients may be rooted in whether it is inhaled via a vaporizer or if it is ingested orally. When inhaling, the user absorbs up to 33% of the total cannabinoids. If cannabis is smoked or vaped, about 25% of the cannabinoids present in herbal cannabis are absorbed. In both scenarios, intoxication occurs within minutes and lasts 2-4 hours.
By comparison, when ingested orally, THC is absorbed inconsistently. Users typically experience the effects of THC about 2 to 4 hours after ingestion, and its effects last for 6 to 8 hours, with a more intense and longer-lasting effect, increasing the possibility of overdose and negative effects.
‘Low and slow’
“The best advice we can give is start low and go slow,” says Walter Prozialeck, PhD, professor and chair of the Department of Pharmacology, Chicago College of Osteopathic Medicine at Midwestern University. He adds that more research is needed from the medical community to create specific protocols that physicians can use to better counsel patients.
Some longer-term effects associated with cannabis use include impaired memory, impaired concentration, and amotivation.
“It is very difficult to tell someone what effect they can expect without knowing the specifics of the product,” says Prozialeck. “How much THC is in the product, how it’s consumed—and, of course, the individual’s physiology—all play a role in determining their experience.”