Medical Marijuana for Neuropathic Pain

BY DAVID J. GOLDSTEIN, PHD, FCP* PROFESSOR OF CLINICAL PHARMACOLOGY PHILADELPHIA COLLEGE OF OSTEOPATHIC MEDICINE

Marijuana for pain? Who does that? Actually, many Americans do across all ages even into the geriatric range.

Opioids have been among the most widely used drugs to relieve acute and chronic pain but there are issues with long-term use. In 2022, the Departments of Veterans Affairs and of Defense issued their Clinical Practice Guideline for pain management. As stated therein, “The guideline development group does not recommend use of opioid analgesics in the daily management of chronic pain. The benefits that opioids can provide are small and are outweighed by the risks to the patient.”

Is marijuana a good substitute? In my opinion, it is. However, what is missing are well-designed clinical studies to provide greater understanding of this beneficial effect.

As a medical scientist, I have been conducting clinical research for decades to improve analgesia in patients with cancer and/or neuropathic pain as well as in the immediate post-op period of those recovering from surgery. Currently, I have two preliminary (pilot) studies in progress.

One of my current investigations is at the Philadelphia College of Osteopathic Medicine (PCOM). Along with my clinical colleague, Katherine Galluzzi, DO, I administer THC to those presenting with chronic neuropathic pain. Our patients have diverse etiologies, e.g., multiple sclerosis, diabetic peripheral neuropathy, temporomandibular joint disorder, but all have suffered from nerve pain for at least two months. The insurance classification for chronic pain coverage is three months but as a medical scientist I can start treating patients earlier. Funding is from the PCOM Division of Research, and there is no cost to any patient.

THC is the main psychoactive ingredient in marijuana but also provides analgesia. We use Marinol-CIII, an FDA-approved drug officially sanctioned only for treating nausea and vomiting from cancer chemotherapy, and as an appetite stimulant in those suffering from a lack of appetite such that their lives are in danger, e.g., AIDS patients.

The use of THC for analgesia is not banned in the USA but is considered an ‘Off’-Label’ use, that is, one that does not have FDA authorization. To receive approval, I – as the Principal Investigator – submitted our study for evaluation by the PCOM Institutional Review Committee (IRB). Permission was granted, and the project began.

We carefully evaluate all patients who wish to participate since entrance is not automatic. Some of the criteria for admission are age 18 to 75 years old, and having neuropathic pain for at least two months. Participation is not permitted for several reasons including patients with cardiovascular or liver problems, epilepsy, depression or substance use disorders.

This is a seven-week study. Patients are seen every week. For the first two, patients complete a pain diary three times a day, using an 11-point scale from ‘0’ [ “I have no pain”] to ‘10’ [ “This is the worst pain I ever had”]. They also list how many of their usual pain medications they take each day. If there are no problems in this important record-keeping aspect, they are given, in Week 3, capsules containing 5 mg of THC; one is to be taken at night at lights-out time. Patients continue to be seen each week, and decide at that time if they wish to go up to the next doses, i.e., increasing by 5 mg up to 20 mg in Week 6, the last week.

I need to emphasize that this is a ‘pilot’ study; in clinical research; this means it is a starter project. This investigation involves a limited number of patients who will be given THC in gradually increasing doses to observe if there are any reductions in pain, and

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215-848-6880 what, if any, side effects occur. If the early results are promising from a pilot study, then researchers run a larger study that has at least two groups, one of which is a placebo. It is always important to do this in larger studies because sometimes patients experience true benefit from placebo that is actually from their own internal desires. They have a strong expectation that the product will work – and, for them, it does. Therefore, the placebo effect is real, and is important to study along with the active drug at some later point with larger numbers of patients.

Okay, so what have Dr. Galluzzi and I found in the seven patients that we treated? The average pain score in the first two weeks with no THC was 4.9 but after the four weeks of taking THC (going from 5 mg to 20 mg at ‘lights-out’ time), the score dropped to 2.7. It is a real clinical effect whenever the average score drops by at least 2 points. However, subjects have reported not only less pain – which is the most important – but other benefits as well. My patients always ask about weight gain having heard that marijuana increases appetite (a/k/a/ the ‘munchies’). Good news! While two did have a slight increase, the other five lost weight! Why? Well, they reported being able to sleep better so they had less stress and did not seek comfort food (e.g., ice cream) as often. With less pain they were able to be more active, e.g., greater distances in walking their dogs.

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There were some side effects. We had to remove two patients from the study because they were experiencing dizziness; at night, when going to the bathroom, this serious side effect could cause a fall with a severe outcome like a bone fracture.

As mentioned, this is a limited investigation but recruitment is still occurring. If any person with chronic neuropathic pain for a duration of at least two months is interested in more information, please contact me: fredg@pcom.edu.

I am also starting another pilot study on the pain-relieving benefit of a combination of THC plus cannabidiol (CBD) for chronic pain which will described in a subsequent article.

* Fellow in Clinical Pharmacology

1. Sandbrink F et al. The Use of Opioids in the Management of Chronic Pain: Synopsis of the 2022 Updated U.S. Department of Veterans Affairs and U.S. Department of Defense Clinical Practice Guideline Ann Intern Med. doi:10.7326/M22-2917