Medicinal Cannabis in Clinical Practice

LAS VEGAS—Medicinal cannabis is a better choice than opioids when standard first-line pain medications have failed to relieve chronic pain, according to Gregory T. Carter, MD, MS, clinical professor of medicine at the University of Washington in Seattle. Speaking at a session titled “Medical Marijuana: Science, Practice, Policy, & Ethics,” he noted that medicinal cannabis has fewer drug-drug interactions than opioids and does not cause respiratory suppression or constipation. Cannabis, he noted, decreases inflammation, is neuroprotective, and has anti-tumor properties.

Dr. Carter reviewed ways in which patients can administer medicinal cannabis, including inhalation of cannabis vapors. Cannabinoids boil and vaporize when heated to between 285°F and 392°F, he told attendees. Studies show that vaporization is most effective at around 338°F. Using this method, patients should take two or three inhalations, stop, and wait 10 minutes before resuming inhalations, Dr. Carter advised. Patients do not need to be high to get pain relief, he pointed out. Other routes of administration are transdermal application of a liniment or, as Dr. Carter advised, as a tincture for ingestion for faster effects.

Clinicians should counsel patients to use high quality cannabis to improve efficacy. The cannabis should be high in cannabidiol and low in tetrahydrocannabinol (THC). Dr. Carter cautioned that medicinal cannabis is not for all patients.

Some patients cannot tolerate the drug, and some do not experience pain relief from it. Additionally, cannabis may result in psychological addiction in some patients, although it is associated with minimal physical dependence. Tolerance may develop in long-term heavy users, who may require higher doses, he said.

Side effects of medicinal cannabis include disinhibition, relaxation, and drowsiness, feelings of well being and euphoria, perceptual changes, decreased muscle strength, impaired balance and motor skills, impaired judgment, slowed reaction time, disorganized thoughts and confusion, and, possibly, paranoia or agitation. Adverse effects are mainly seen in new users, and they are short lived and reversible, he said. Patients should start low and go slow.