Human beings are fundamentally narcissistic, and this narcissism can be antithetical to good science and good medicine. We place far too much confidence in our individual abilities to understand what happens to us, and we place far too much importance on our own experiences, inappropriately generalizing them. That's why science is so important in medicine---to avoid basing life-or-death decisions on something some guy thinks he might have heard once.
In my recent piece on medical marijuana in Forbes, commenters took me to task for what they perceived to be a host of errors in my reasoning. Some of these deserve to be specifically addressed, but not before a summary of the topic.
Marijuana's legal status is a political issue, not a scientific one. I will leave the politics to those cursed with such things. But I'm responsible for medical decisions, and as much as is possible, I have to look at data dispassionately. I have no doubt the individuals find marijuana beneficial for a wide range of problems---this may be a basis for study, but is not adequate data to prescribe a powerful pharmacologic agent.
In 2000, the University of California established the Center for Medicinal Cannabis Research. This month, they released a summary of results to date.
The federal government has historically made it very difficult to study marijuana. The state of California, though specific legislation, was able to encourage a significant amount of research into the clinical use of marijuana, and this month's report is a summary of their work to date. So far CMCR has produced four published clinical studies and one poster/abstract.
The first study, by Abrams, et al, deals with painful HIV-associated sensory neuropathy (HIV-SN). This is a painful condition that can be caused by HIV infection or by certain treatments for HIV. This is a good place to start, as current treatments are disappointing. The study enrolled 55 patients with HIV-SN, and randomly assigned some to smoke real joints, and other to smoke joints with the cannabanoids extracted. Fifty patients completed the five-day study, with some encouraging results, but there are a few problems. First, it's unlikely that patients remained truly blinded to their assignment (unless they though the treatment group was given Grade F ditch weed). The authors recognized that unblinding might have been a problem. The authors also made an attempt to compare their data to studies of other drugs for this condition, but they did not compare cannabis directly to any other drug, including opioids.
This is a small study, and since the number needed to treat (NNT) found in this study and studies of other drugs was not dramatically different, head-to-head studies of marijuana, opioids, and standard drugs for this condition would be very useful. Given the benefits of opioids in a variety of pain conditions, including neuropathic pain, it would be important to compare the benefits and negative effects of opioids vs. marijuana. Finally, the authors concluded that the drug was generally safe during the five day study, as there were no major adverse events requiring subjects to drop out. I'm not certain this is a fair interpretation:
No patient withdrew from the study because of adverse events. One episode
of grade 3 dizziness related to study medication occurred in the cannabis group. One case of transient grade 3 anxiety possibly related to study medication was reported in each group. Both patients received a one-time dose of lorazepam.
These patients required a second medication to treat the symptoms of the drug. This may or may not be significant when compared to the level of pain relief or when compared to other drugs, but it cannot be concluded that the drug was entirely safe and well-tolerated, especially given what may be observed when there is more than 125 person-days of exposure.
A second study by Ellis, et al, also looked at painful HIV-related neuropathy, and addressed some of the issues with the Abrams study. This was also a small pilot study, but used a crossover design. The authors actually surveyed the subjects to see if they remained blinded, and by the end of the study, many subjects "knew" which toke was placebo and which was the good stuff. They also explicitly addressed one of the interesting questions that comes up in relation to marijuana research.
Because of funding mandates, these studies used smoked marijuana. Given the likely harm of long term smoking of anything, Ellis brought up the need to study non-smoked cannabis. Boosters often promote smoked cannabis as having "special" properties not available in extracts and derivatives, something these two studies, which each contained de-THC'd fatties, argue against.
More important is that while these results are encouraging, they are not enough to make a clear medical recommendation. Two small pilot studies are not sufficient to make significant clinical recommendations. They may give us good reason to study the use of marijuana or its derivatives for the treatment of HIV-related painful sensory neuropathy. Hopefully future studies will include comparisons to standard therapy, and clearer evaluation of long-term effects of marijuana ingestion in these patients.
Abrams DI, Jay CA, Shade SB, Vizoso H, Reda H, Press S, Kelly ME, Rowbotham MC, & Petersen KL (2007). Cannabis in painful HIV-associated sensory neuropathy: a randomized placebo-controlled trial. Neurology, 68 (7), 515-21 PMID: 17296917</span
Ellis, R., Toperoff, W., Vaida, F., van den Brande, G., Gonzales, J., Gouaux, B., Bentley, H., & Atkinson, J. (2008). Smoked Medicinal Cannabis for Neuropathic Pain in HIV: A Randomized, Crossover Clinical Trial Neuropsychopharmacology, 34 (3), 672-680 DOI: 10.1038/npp.2008.120