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12 Articles in this Series
Central Post-Stroke Pain – How Central Is It?
False-Positive Urine Drug Monitoring Results and Aspirin
Medical Marijuana & Pain
More Potential Uses for Low-Dose IV Naloxone
On the Horizon: A Brief Look at Potential Analgesics of the Future
Preview of PAINWeek 2018 - Know Before You Go
Stem Cells & Beyond
Underlying Causes of Small Fiber Neuropathies
Understanding Sexual Pain – A Physical Therapist’s Perspective
Video: Drs. Gudin & Fudin on PAINWeek 2018 and PPM's Future
Where Does the Patient-Centered Pain Practitioner Stand Today?
Why Interventional Tactics Should be Used for Chronic Pain Patients Now, Not Later

Medical Marijuana & Pain

Can medical cannabis help your pain patients? The latest research—and some disturbing trends. A PAINWeek 2018 highlight with Michael Schatman, PhD.

At the start of his PAINWeek presentation on "Reefer Madness Revisited: Taking the Insanity Out of Medical Cannabinoids," speaker Michael Schatman, PhD, CPE, DASPE, opened with the usual disclosure information but added a blunt caveat: "If you are expecting a pro-medical marijuana talk, you should get up and leave now." Over the next 50 minutes, he covered the pros, cons, and ever-shifting legalities of medical marijuana, along with information about some disturbing trends, including the increasing use of marijuana during pregnancy.1

First, Know the Law & Politics

"Medical marijuana laws vary from state to state, and regulations are all over the map," said Dr. Schatman, an adjunct assistant clinical professor at Tufts University School of Medicine and a veteran researcher. "There is no medical marijuana law, there are laws, and they all vary. If you are considering using medical marijuana in your state, know the law."

Currently, medical marijuana is legal in 31 states plus Washington, DC. Another 17 states have legalized medical cannabidiol (CBD), the so-called non-psychoactive component of marijuana (more accurately termed non-euphoriant.)

"In the eyes of the pro-marijuana zealots, all marijuana is medical, but in the eyes of the FDA, no marijuana is medical," stressed Dr. Schatman, referring to the agency’s classification of marijuana as a Schedule I drug. Currently, the Rohrabacher-Blumenauer amendment, passed in 2014, is in force, Dr. Schatman said, which prohibits the Department of Justice from using federal funds to interfere with state medical marijuana programs.

Understand the Facts & Trends

"Marijuana contains over 100 constituents called cannabinoids," Dr. Schatman said, with tetrahydrocannabinol (THC) and CBD among the most discussed and researched. Among the concerning trends:

  • Changing ratio of THC to CBD. In a study of more than 5,000 samples of cannabis seized in California from 1996 through 2008, THC levels increased from 4.56% to 11.75%. At the same time, CBD levels decreased from 0.24% to 0.08%.2 A more recent study found the THC to CBD ratio rose to 80:1 in 2014.3  The increasing proportions of THC to CBD are believed due to the shift from traditional marijuana strains to sinsemilla.
  • Dosing of edibles. They are infused with nearly pure THC. They take 30 to 90 minutes to take effect, reach a peak in 2 to 3 hours, and may last up to 12 hours. Edible-related ER visits have risen and deaths have been reported.4
  • Use of marijuana during pregnancy. This practice increases the risk of stillbirth or miscarriage, and the trend is increasing. A recent study found that 22% of pregnant women use marijuana.
  • Cannabinoid hyperemesis syndrome is on the rise. Marijuana smokers throw up uncontrollably, have abdominal pain, and experience a compulsive need to shower. "Women show up in the ER with it and doctors unfamiliar with it say, 'Oh, it's an eating disorder,'" Dr. Schatman said. However, he cited 2.75 million cases annually in the US, including some related fatalities.6,7

"Smoking is still the most common route of administration [of marijuana]," he said, "and the pulmonary effects are worse than we thought."  Marijuana lung is an unfortunate new term among pulmonologists, he noted. The drug’s use has also been linked with an increased rate of myocardial infarction, cardiovascular mortality, and heart failure.8,9

Read the Research

Advocates and critics alike bemoan the lack of scientific research on medical marijuana for pain, and that's partially due to the requirement that in the US all federally funded researchers must use low-grade marijuana grown at the University of Mississippi for the National Institute on Drug Abuse (NIDA). The highest potency grown there is 7%, Dr. Schatman said.  What is available on the market is a much higher concentration. However, NIDA recently approved a 13.4% THC for research and a study for pain is underway, he noted.


With regard to neuropathic pain, specifically, he said that studies have gone back and forth, with higher doses of 7% or more leading to cognitive defects. More recent research, however, has found that a low dose, at 1.29%, gave a clinically significant outcome without significant cognitive effects. Another review suggested that CBD may be better than THC in this regard, but that was based on animal studies. Overall, "the evidence is weak" for neuropathic pain, he concluded.

First isolated in 1934 and synthesized in 1967, CBD may have a mild antidepressant effect in those with low serotonin levels, Dr. Schatman explained.  Its safety is well-established, he said, and even NIDA Director Nora Volkow, MD, has been quoted citing its safety. (Federally, however, CBD from whole plant marijuana [not hemp] is considered a Schedule I drug; the exception is FDA-approved Epidioloex.)

Most research on CBD and pain has been preclinical, Dr. Schatman warned the audience, although some early studies have suggested anti-inflammatory effects for back pain and arthritis. Other research has demonstrated that high-dose CBD may be hypnotic, easing sleep, while low-dose may help individuals  stay alert, he added.12

Put Agreements in Place

For physicians who decide to recommend medical cannabis to their patients, one good practice, Dr. Schatman advised, is a doctor-patient agreement. "We have opioid agreements. Why not have medical marijuana agreements?" he proposed.  "We know medical marijuana is heavily abused." A medical cannabis agreement, among other points, could warn against driving a car or operating machinery while on it, and that a medical marijuana authorization will not protect a patient's job—news to many, he said.

While Dr. Schatman turned an often-critical eye to medical cannabinoids during the talk, his bottom line was not entirely pessimistic. "Improving the quality and quantity of medical marijuana research is imperative if marijuana is ever going to become real medicine," he said. "I want it to become real medicine because our choices for pain management are pretty stinky or going away."

Dr. Schatman disclosed that he is a consultant and Speaker’s Bureau member for Kaleo.



1Schatman M. Reefer Madness Revisited: Taking the Insanity Out of Medical Cannabinoids. Presented at PAINWeek 2018, September 4-8, Las Vegas.

2Burgdorf JR, et. al. Heterogenicity in the composition of marijuana seized in California. Drug Alc Dependen. 2011:117:59-61.

3ElSohly MA, et al. Changes in Cannabis Potency Over the Last 2 Decades (1995-2014) Analysis of Current Data in the United States. Biol Psychiatry, 2016;1:79:613-619.

4Grotenhermen F. Pharmacokinetcs and pharmadynamics of cannabinoids. Clin  Pharmacokin. 2003; 42: 327-360.

5Oga,EA et al. Cigarette smoking status and substance use in pregnancy. Matern Child Health J.  ePub June 7, 2018. Available at: https://www.ncbi.nlm.nih.gov/pubmed/29882032. Accessed September 12, 2018.

6Kim HS et al. Cyclic vomiting presentations following marijuana liberalization in Colorado. Academy of Emerg Med. 2015; 22: 694-699.

7Nourbakhsh M, et al. Cannabinoid Hyperemesis Syndrome: Reports of Fatal Cases. J Forensic Sci. ePub May 16, 2018. Available at https://www.ncbi.nlm.nih.gov/pubmed/29768651. Accessed September 12, 2018.

8Franz CA, Frishman WH. Marijuana use and cardiovascular disease. Cardiol Rev. 2016;24:158-162.

9Kalla A, et al.  Cannabis use predicts rates of heart failure and cerebrovascular accidents: results from the National Inpatient Sample. J Cardiovasc Med (Hagerstown). 2018; 19:480-484.

10Casey SL, et. al. Plant-based cannabinoids for the treatment of chronic neuropathic pain. Medicines (Basel). 2018 5(3).Pii:E67

11Wilsey B, et al. Low-dose vaporized cannabis significantly improves neuropathic pain. J Pain. 2013;14 (2):136-48.

12Babson KA, et. al. Cannabis, cannabinoids and sleep: a review of the literature. Curr Psychiatry Rep. 2017;19:23.
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