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By: William Bennett, M.D.
Co-chair, Drug Watch International Drug Strategy Institute

In the past 35 years, through hybridization and sophisticated growing techniques, the potency of marijuana has escalated from the .5 percent THC found in 1960s ditch weed* to varieties with a THC potency (marijuana's main psychoactive compound) in excess of 30 percent.  This is manifested in a tremendous increase in episodes of psychiatric emergency associated with marijuana use.  Further, ingesting marijuana, in the form of brownies or space cakes, is associated with increased heart rate, nausea, vomiting, loss of consciousness, and anxiety, and it can be life-threatening.  Marijuana is now one of the leading causes of drug-related emergency room episodes.

Marijuana, whether smoked or eaten, is whole plant material and contains 483 compounds, including some that are carcinogenic or toxic. These compounds will affect each individual in a different way and will be magnified by any other drugs, legal or illegal, that the individual may have taken, as well as other factors such as fatigue and stress.  Without testing each batch of marijuana, which varies not only from hybrid to hybrid but from grower to grower and plant to plant, there is no way of knowing the exact potency of THC or any of the other 482 compounds found in marijuana.  Even if this could be done, it would still be impossible to determine an appropriate dose for medical use, because the combustion associated with smoking transforms the marijuana into over 2,000 compounds, each impacting the patient differently.  And, if eaten, depending on the metabolism of the individual and other drugs the person might be taking, it would be absorbed at different rates, or perhaps not absorbed at all.  And finally, because THC is fat soluble, it is retained in the body for a much longer period of time than compounds that are water soluble.  That being the case, after one or two days of self-dosing, there is no way to tell how much marijuana remains in the body with potential to interact adversely with other drugs.

Even though there are anecdotal accounts of marijuana having medicinal properties, conscientious researchers and physicians consider it extremely unwise and dangerous to suggest that an individual smoke or ingest crude marijuana to obtain possible medical benefit.

GW Pharmaceuticals, the British company doing research on cannabis with the aim of developing prescribable cannabis-based medications, is using hybrid, high-grade marijuana as a starting point, not crude marijuana, extracting the THC and other cannabinoids, and then recombining them in various measurable strengths to test in human trials.  In these trials the patients are given a specific dose of a specific replicable compound.  They are not given marijuana plant material.  In fact, the cannabinoid compounds GW Pharmaceuticals is developing could just as easily be synthesized, bypassing the use of crude plant material as a cannabinoid source.

Just as taxol is not yew tree bark, and digoxin is not foxglove, cannabinoids are not marijuana although Dronabinol (THC), marketed under the brand name Marinol, is often referred to as marijuana or cannabis, fueling the public's misperception.  Marinol is a refined drug, produced in pill form of varying strengths that can be prescribed by physicians for medical use.  Its interaction with other drugs is known, and the physician can warn the patient of side effects.

The public needs to understand the dangers in blindly accepting the rhetoric that crude plant material, particularly one with as many known unpleasant and dangerous side effects as marijuana, can be taken safely.  Even drugs that have been arduously tested for safety and efficacy can be dangerous when used in combination with other drugs, or when an inappropriate dose is given, or when other factors affect the patient.  Physicians prescribing such medications should be well aware of these potentials and advise the patient.  Because of its multiple compounds, there is no way a physician can safely prescribe marijuana plant material, even were the U.S. Government to capitulate to legalization of this dangerous and unpredictable substance.


NOTE: Cannabis-based medicines are made of cannabinoids that have been extracted from the raw plant material as opposed to being synthesized, much the same as vitamin C is typically synthesized but may be extracted from plant material such as rose hips.  The end product contains only the purified ingredient.  Research is currently underway by GW Pharmaceuticals plc, the company licensed by the [British] Home Office to develop cannabis extracts into non-smoked prescription medicines.  Additional information can be found at