Mark Borigini M.D.

Overcoming Pain

Marijuana for Chronic Pain

We know so little about the safety and efficacy of pot.

Posted May 04, 2016

The historians tell us that, as early as 5,000 years ago, Chinese texts documented the medicinal benefits of Cannabis sativa (C stiva) extracts unrelated to its psychoactive properties, including alleviation of pain and cramps.  Cannabis was also familiar in the Old World (i.e., ancient Greece, Rome, the Middle East, and North Africa), and its use gradually spread to the New World.

Now, my acquaintances tell me—and they are only that, and not friends—that "marijuana," or cannabis, typically refers to the dried leaves, flowers, stems, and seeds of the plant, known in botanical circles as, of course, C sativa ; some of the chemical components of this hemp plant (cannabinoids) are psychoactive, including delta-9-tetrahydrocannabinol (THC).  Cannabinoids also play a role in lessening pain.

A 2015 systematic review and meta-analysis from 79 clinical trials comprising 6492 participants, published in the Journal of the American Medical Association (JAMA), found moderate-quality evidence to support cannabinoids for therapeutic use in chronic pain, while noting low-quality evidence for improvements in nausea/vomiting in those undergoing chemotherapy, appetite stimulation in patients with HIV infection/AIDS, sleep disorders, and tic severity in Tourette syndrome.  In addition, there was an increased risk of short-term adverse events associated with cannabinoids (e.g., psychiatric, nervous system, musculoskeletal, and hematologic disorders).

Unfortunately, many of these clinical trials involved many different conditions and many different cannabinoids in many different forms, making it difficult to make sound scientific conclusions—which makes it even more difficult to allow for the making of sound scientific treatment recommendations.  Worse, the overwhelming majority of the studies were plagued by investigator bias; it appears that many marijuana researchers really like marijuana.

And while there is more serious marijuana research ongoing in the United States, perhaps as a response to the growing acceptance of legalized marijuana in this country, coupled with the need to find alternatives to opioids for, say, chronic pain, there remain many questions that might have to wait for answers in the real world, not in the laboratory: Three dosage strengths of marijuana for medical research in the United States are currently available:

Low potency: 1.29% THC
Moderate potency: 3.53% THC
High potency: 7% THC

But this in and of itself calls into question the utility of much of the research being performed, as marijuana dispensaries rarely carry cannabis with THC content below 10%; in fact, to stay competitive perhaps, they often carry strains whose THC content is as high as 30%.  Thus, the sanctioned research in the United States actually tells us little regarding both the safety and clinical efficacy of the medical marijuana that is actually being used for presumed medicinal purposes.

Nonetheless, there is increasing evidence regarding the efficacy of medical marijuana in managing chronic pain.  The effects of THC on brain activity related to pain induced by hot red pepper exposure discovered that functional MRI images demonstrated that THC significantly reduced the functional connectivity in the brain between the right amygdala and the primary sensorimotor cortex during ongoing pain. However, further investigation is needed, particularly regarding the long-term efficacy, safety, and best routes of administration.