How do you dose Cannabis for medical purposes?
Determining the appropriate dose of cannabis for a given clinical situation is no easy task. There are many factors to consider, including the nature and severity of the condition(s) being treated, the patient’s physiological response, their goals and values, the method of administration (e.g. Inhalation v. ingestion for example), the phytochemical composition of the cannabis and many others.
The phytochemical composition, and thus potency, is a particularly important consideration. Cannabis is composed of more than 700 compounds which have varying physiological effects in the body.1 More than 100 of these are classified as cannabinoids.2 Cannabinoids are the compounds most frequently studied in the cannabis plant.
Delta-9-tetrahydrocannabinol (THC) is the most well-known. It is thought to be the most psychoactive cannabinoid, and the one primarily responsible for the “high”. Clinically speaking, it may not necessarily be the most important however. That remains to be seen. Other cannabinoids like cannabidiol (CBD), and other compounds like terpenes, have their own effects. Most importantly, these compounds work synergistically to deliver an overall experience for each user.
Dose selection should be based on an understanding of the absolute and relative proportions of these compounds, which can, and should, be documented with modern laboratory testing methods.
Given that cannabis is classified as a Schedule I Controlled Substance by the FDA, any and all clinical research done in the United States to date has used cannabis plants grown on a 12-acre farm at the University of Mississippi. This farm is managed by the National Institute on Drug Abuse (NIDA).3
A recent story broadcast on PBS described the experience of Sue Sisley, a primary care physician and clinical researcher from Scottsdale, Arizona. Dr. Sisley designed a clinical trial using cannabis to treat veterans suffering from chronic post-traumatic stress disorder. When she finally received the cannabis from NIDA, she said: “It didn’t resemble cannabis. It didn’t smell like cannabis,” In addition, subsequent laboratory testing revealed that one sample, labeled as 13% THC contained just 8%.
Not only does this story highlight an important challenge for clinical researchers, but it also highlights the struggle that doctors face when trying to use clinical research for determining an appropriate dose of cannabis for their patients.
Mark Wallace, MD, Professor of Clinical Anesthesiology and Chair of the Division of Pain Medicine at UCSD conducted an interesting study in 2007. He randomized 15 healthy volunteers into 4 groups and gave each of them a different dose of cannabis (Measured by THC concentration: 0% (i.e. Placebo), 2%, 4%, and 8% by weight). After the cannabis was smoked, he measured their response to a painful stimulus - an injection of Capsaicin under the skin on their forearms. He was looking for a dose-response relationship. In other words, he wanted to know if a higher dose would lead to greater mitigation of pain.
The results were interesting. Forty-five minutes after smoking there was no decrease in pain among those who smoked the low dose, and an INCREASE in pain among those who smoked the high dose. It was only the medium dose group that experienced pain relief. Dr. Wallace wrote, “We identified a potential narrow “therapeutic window” for analgesic efficacy.”
While this is only one study, it underscores an important point – Stronger may not necessarily be better.
It’s also important to point out that participants each smoked one “cannabis cigarette” weighing approximately half a gram, with THC concentrations ranging from 0-8%. The vast majority of cannabis sold at dispensaries in California, and beyond, contains well above 8% THC by weight. If fact, most of them are more than twice that amount.
The Bottom Line
Dosing cannabis for medical purposes should be the result of a detailed conversation between doctor and patient. This conversation should include a variety of considerations, including the goals of the patient, their experience with cannabis, and the safe and legal procurement of laboratory-tested cannabis of the right potency.
In health,
Despite the favorable safety profile, dosing and administration of cannabinoids is complicated. The process should be highly individualized, and is best supervised by a trained health care professional. For more information, please consider booking a consultation (telephone or in-person) with Dr. Jamie Corroon, ND, MPH.
References:
1. Roy Upton RH DAyu et al. Cannabis Inflorescence Monograph.; 2014. http://www.herbal-ahp.org/order_popups/CannabisQC_popup.html.
2. NIDA (2017). Marijuana as Medicine. https://www.drugabuse.gov/publications/drugfa. Accessed January 1, 2017.
3. NIDA’s Role in Providing Marijuana for Research | National Institute on Drug Abuse (NIDA). https://www.drugabuse.gov/drugs-abuse/marijuana/nidas-role-in-providing-marijuana-research. Accessed March 31, 2017.
