As recently as a decade ago a review of the world literature on the status of the efficacy and safety of cannabinoids for pain and spasticity revealed that only nine randomized studies of acceptable quality had been conducted [1]. All of these were single dose studies comparing oral synthetic THC (or cannabinoid analogs or congeners) to codeine or placebo...In the past decade, the scope and rigor of research has increased dramatically. This research has employed cannabis, cannabis-based extracts, and synthetic cannabinoids delivered by smoking, vaporization, oral, and sublingual or mucosal routes.

Smoking cannabis provides rapid and efficient delivery of THC to brain. THC can be detected immediately in plasma after the first puff of a cigarette; peak concentrations occur within 10 minutes, then decrease to approximately 60% of peak by 15 minutes and 20% of peak by 30 minutes, but there can be wide inter-individual variation in concentrations achieved [3]. Rapid onset and predictable decay means that self-titration of dosing is attainable.

Evidence is accumulating that cannabinoids may be useful medicine for certain indications. Control of nausea and vomiting and the promotion of weight gain in chronic inanition are already licensed uses of oral THC (dronabinol capsules). Recent research indicates that cannabis may also be effective in the treatment of painful peripheral neuropathy and muscle spasticity from conditions such as multiple sclerosis [58]. Other indications have been proposed, but adequate clinical trials have not been conducted. As these therapeutic potentials are confirmed, it will be useful if marijuana and its constituents can be prescribed, dispensed, and regulated in a manner similar to other medications that have psychotropic effects and some abuse potential. Given that we do not know precisely which cannabinoids or in which combinations achieve the best results, larger and more representative clinical trials of the plant product are warranted. Because cannabinoids are variably and sometimes incompletely absorbed from the gut, and bioavailability is reduced by extensive first pass metabolism, such trials should include delivery systems that include smoking, vaporization, and oral mucosal spray in order to achieve predictable blood levels and appropriate titration. Advances in understanding the medical indications and limitations of cannabis in its various forms should facilitate the regulatory and legislative processes.

The classification of marijuana as a Schedule I drug as well as the continuing controversy as to whether or not cannabis is of medical value [59] are obstacles to medical progress in this area. Based on evidence currently available the Schedule I classification is not tenable; it is not accurate that cannabis has no medical value, or that information on safety is lacking. It is true cannabis has some abuse potential, but its profile more closely resembles drugs in Schedule III (where codeine and dronabinol are listed). The continuing conflict between scientific evidence and political ideology will hopefully be reconciled in a judicious manner [60, 61]. In the meantime, the decision to recommend this treatment in jurisdictions where use of medical marijuana is already permitted needs to be based on a careful assessment that includes proper diagnosis of a condition for which there is evidence that cannabis may be effective, along with consideration as to response to more standard treatments. Prior substance abuse history, psychiatric comorbidity, and other factors need to be weighed in a risk benefit analysis. Part of this analysis should consider that the potential longer-term harms of the cannabinoids are not fully understood: these include abuse and a dependence syndrome, adverse psychiatric and medical effects in vulnerable populations, and documented risk to traffic safety when combined with alcohol, and perhaps singly [62]. In the long term, as further studies demonstrate whether cannabis is effective for various indications, this should lead to development of novel modulators of the endocannabinoid system which may be prescribed and used as more traditional medicines.

The federal government, in its attempt to keep marijuana illegal and misunderstood, recently sponsored a study which was conducted by the University of California Center for Medical Cannabis. The goal of the study was to disprove the many other studies that show cannabis to be safe and effective in treating symptoms, side-effects and diseases. Guess what? The CMCR came to the same conclusion as those other studies: marijuana is medically useful and effective. Oops. That’s rather inconvenient, isn’t it?

As published in the Open Neurology Journal, this new study showed that cannabis treats many conditions including chronic pain, peripheral neuropathy and the side-effects of chemo therapy, among other things. The study also showed that other delivery systems besides smoking – vaporizing, tincture, ingestion – work almost as well as lighting up. But smoking is the best way to take cannabis. Good thing another recent study showed that marijuana does not cause lung cancer.