SAN DIEGO – Is pot a valid alternative to opioids for patients with chronic pain? The verdict on the use of medical marijuana is still hazy, a pain specialist told primary care colleagues. “There’s some evidence for pain, but it’s not extensive,” said Timothy Furnish, MD, of the University of California at San Diego.
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Still, he said, studies suggest that the expanding legal use of medical marijuana isn’t boosting opioid use or worsening traffic accident rates. (JAMA Intern Med. 2018;178[5]:667-72; Am J Public Health. 2016 Nov;106[11]:2032-7) And, he said, two things are clear: “There is no one who has overdosed and died specifically from marijuana ... and compared to opioids, cannabinoids have a relatively good safety profile.”
Dr. Furnish spoke in a presentation at Pain Care for Primary Care, a symposium held by the American Pain Society and Global Academy for Medical Education.
Thirty-three states and the District of Columbia allow – or will soon allow – the medical use of marijuana, although their laws and policies vary widely. The newest states to join the list are Utah, Missouri, and Oklahoma, where voters passed medical marijuana measures this year.
Ten states and the District of Columbia also allow the recreational use of marijuana.
However, most states in the South, including Texas and Georgia, don’t allow medical marijuana. The other states that continue to forbid it are in the Midwest and Rocky Mountain regions.
How does cannabis fare against pain? Dr. Furnish pointed to a 2011 systematic review of 18 randomized trials in noncancer chronic pain that showed that “overall there is evidence that cannabinoids are safe and modestly effective in neuropathic pain with preliminary evidence of efficacy in fibromyalgia and rheumatoid arthritis” (Br J Clin Pharmacol. 2011 Nov;72[5]:735-44).
More recently, a 2018 systematic review and meta-analysis of 104 studies found that “it seems unlikely that cannabinoids are highly effective medicines” for chronic noncancer pain (Pain. 2018 Oct;159[10]:1932-54).
In cancer pain, Dr. Furnish said, evidence supporting marijuana is limited and mainly involves nabiximols (Sativex), a cannabis-based inhaled spray that is approved in several nations outside the United States as a treatment for muscle stiffness and spasm in MS. The drug is still an investigational medication in the United States.
How much marijuana should patients with pain take? In the clinic, Dr. Furnish said, “patients actually do best on a relatively modest dose or low dose. High doses are probably more escape than pain relief.”
Dr. Furnish said that because of safety concerns, he never advises patients to smoke marijuana. “Vaporizing may be safer,” he said, noting that the inhaled route has a relatively rapid onset (2-10 minutes) and lasts for 2-4 hours.
Be aware, he said, that cannabis taken orally may not kick in for 30-90 minutes – “it will depend on what they’ve already ingested, and if they have recently consumed a fatty meal” – and patients may have trouble titrating their doses properly. “It’s a little bit easier to ingest more than they intended,” he said.
If you do want to give patients guidance about medical marijuana, keep in mind that “we can’t write a prescription. We only make recommendations,” he said.
“Use some of the same criteria that you’d use in suggesting a patient for opioid therapy,” he said. For example, exclude patients with active psychosis and schizophrenia.
Another red flag is a significant substance abuse history, since there is “abuse and dependence” in marijuana, he said. “Regular heavy users can experience withdrawal, but it tends to be a lot lighter than opioid withdrawal.”
Also be aware, he said, that there’s no federal oversight of medical marijuana, and “production, purity, potency, and state oversight vary widely.”
Global Academy for Medical Education and this news organization are owned by the same parent company.
Dr. Furnish has no disclosures.