This past week, I noticed a confluence of patient situations. One day, I had three consecutive new patients who were each taking medical marijuana. In California, medical marijuana is legal, and it seems this is an increasing trend. In the U.S., four states allow legalized recreational marijuana use¹, and 25 states and Washington DC have legalized marijuana for medical use².

When I was in training, medical marijuana was highly rare, though of course recreational marijuana has always been common. Thus it feels somewhat novel for me to have so many patients now taking this medication as a regular occurrence. Perhaps this is due to my practicing in California (one of the states in which medical marijuana is legal), but I imagine this will become ever more common for all of us, whether you agree with cannabis legalization or not. As such, healthcare providers need to remain up-to-date on this substance, just as we do with any drug our patients take. To that end, let’s review some info about marijuana and consider it as an option for our patients with neuropathic pain syndromes.

As mentioned above, many states have legalized cannabis use. However, currently the use of this drug is illegal at the federal level.

Those of you who love chemistry will note the overall similarity of THC with anandamide but with the aromatic ring formation in THC. Its similarity is the reason it acts on the CB₁ receptor, and its difference is the reason it binds less selectively to this receptor and has more “global” body effects.

There are currently two FDA approved cannabinoid medications available in the United States, both of which are synthesized analogues of THC. Dronabinol (brand name Marinol^®, Solvay Pharmaceuticals, Marietta, GA) and nabilone (brand name Cesamet^®, Meda Pharmaceuticals, Somerset, NJ)³ are currently approved for chemotherapy induced nausea and vomiting and appetite stimulation. Other medications similar to these are available outside of United States.⁴ All other uses of these medications are considered off-label. Additionally, the use of marijuana that is currently considered is a Schedule 1 drug by the DEA. Keep in mind that means most of us are unable to prescribe this medication.

How well does this medication potentially work for patients with peripheral neuropathy? The results of a 2010 study are hopeful.⁵ Bestard and Toth performed an open label comparison of nabilone to gabapentin as either adjuvant therapy or monotherapy for neuropathic pain. Their primary outcome was improvement in pain quality and quantity. This was not a randomized controlled trial, but they did use a control group of patients with neuropathy who declined any medication. Their groups turned out as follows:

Patients treated with either nabilone or gabapentin as monotherapy noted a significant improvement in visual analogue pain scales at three and six months (18.8% at three months and 38.9% at six months for nabilone and 17.3% at three months and 32.7% at six months for gabapentin).

Those treated with either medication as an adjuvant to another drug also noted a significant improvement in VAS scale results (17.9% at three months and 37.7% at six months for nabilone and 17.2% at three months and 33.9% at six months for gabapentin).

There are three things I find important to note here.

Clearly, more high quality experimental large-scale research needs to be done to determine with more certainty the role various cannabinoid drugs may play in patients with pain conditions.

As a podiatrist, I would make two primary comments about the use of these medications for my patients. First, my DEA license doesn’t include Schedule 1 drugs, so I won’t be prescribing them. If these drugs are changed to Schedule 2 in the future, I may consider it. Second, as it stands now, most recommendations are that cannabis is reserved either for very specific conditions (pain reduction and weight gain in cancer patients, for example) or after trials of other medications (essentially a last – or at least later – resort). My own personal treatment algorithm for patients with neuropathic pain is to try one or two commonly used medications, and if those don’t work, I refer the patient to a pain management specialist. My patients, then, would have long ago been referred to pain management by the time they got to the cannabis level of treatment.

It’s becoming imminently clear that cannabinoid medications are going to become increasingly common in both prescribed and non-prescribed versions, and it behooves caregivers to remain cognizant of this. What the future will bring in this arena is anyone’s guess, but it certainly won’t be going away.