Although research cannot resolve all the legal and ethical issues related to medicinal use of marijuana, it can address the drug’s efficacy in treat- ment. Ideally, data on the utility of cannabis may inform these ethical and legal debates. Several key issues are important in evaluating research on medical marijuana. These concern the advantages and disadvantages of case studies and randomized clinical trials, as well as the relative costs and benefits of alternative medications. Case studies and randomized clinical trials each provide important information. Almost all medical uses of marijuana started with successful treatments of individual cases. One person found the drug helped alleviate a symptom and simply spread the news. Physicians published some of these reports, which oc- casionally inspired formal research projects. These case studies are superb for generating ideas for further work. Nevertheless, opinions vary on whether or not they provide enough information to encourage prescrib- ing marijuana or cannabinoids. Fans of case studies emphasize that med- ical problems have unique features. Essentially, every use of every ther- apy is its own case study. Individual responses to drugs vary. As a result, physicians alter dosages and treatments based on ideographic reactions.
Proponents of case studies also mention that many medications gained widespread use based on only a few positive results, including aspirin, insulin, and penicillin. They emphasize that large studies require consid- erable time and expense, potentially preventing people from using a help- ful drug. These arguments in support of case studies can be particularly compelling when previous research has already established a medication’s safety. For example, a few studies in the mid-1970s showed that a daily aspirin might help prevent a second heart attack. Yet a large study of the treatment did not appear until 1988. Without a large clinical trial, phy- sicians did not recommend a daily aspirin to prevent a second heart at-
tack. This bias against smaller studies cost thousands of lives. Many peo- ple died during the lag between the initial evidence and the completion of a large clinical trial (Grinspoon & Bakalar, 1997).
In contrast, single cases also have many drawbacks. People tend to publish and remember the successful treatments but forget the failures. Without a placebo control, we do not know if improvements arose sim- ply from expectation. Many symptoms ebb and flow with time. Perhaps some individual cases would have spontaneously recovered without any treatment. To minimize these potential problems, researchers perform randomized clinical trials. They randomly assign large samples of partic- ipants to receive cannabinoids or a placebo. If the treatment group im- proves more, the healing effects clearly do not stem from some natural ebb and flow in the symptoms or from a patient’s expectations that the drug will work. These studies are expensive and time consuming, but they can provide the best data possible. Clinical trials of many drugs receive funding from drug companies. Yet given the limited potential for smoked marijuana to generate a profit for these companies, funding ran- domized control trials to establish its medical efficacy remains difficult.
Another issue important to the evaluation of medical marijuana con- cerns relative costs and benefits. Many evaluators suggest that cannabis must outperform all other available drugs in order to receive approval for treatment (IOM, 1999). Most supporters of this idea prefer estab- lished drugs based on the belief that they have lower potential for abuse. Physicians and patients must consider this cost relative to the drug’s ad- vantages. Critics of this idea accuse drug companies of interfering with marijuana research because of its low potential for increasing their profits (Herer, 1999). These critics highlight that the approval of other medi- cations usually requires simple evidence of safety and efficacy, not su- periority to other drugs. For example, the Food and Drug Administration (FDA) approved fluoxetine (Prozac) based on its ability to relieve de- pression better than a placebo. The FDA did not require data comparing it to other standard antidepressants. Thus, marijuana should only need evidence of efficacy and safety to receive approval for medical use.
In addition to established efficacy, the price of the drug and its side effects also contribute to its costs and benefits. Price and side effects play an important role in comparisons between oral THC, smoked marijuana, and other medications. Dronabinol (Marinol), the synthetic version of THC, costs as much as $13 for a 10 mg pill (Rosenthal & Kleber, 1999). (Typical treatments can require two of these pills per day.) The price of
dronabinol can drop to approximately $8 for pills purchased in bulk. (A special program provides the drug to low-income patients at a reduced rate.) The same 10 mg of THC appears in half of a typical marijuana cigarette. This amount of cannabis costs less than $5 if purchased in bulk on the underground market. The price could fall markedly if the National Institute on Drug Abuse (NIDA) provided the marijuana or if the gov- ernment lifted legal sanctions. Thus, smoked marijuana is cheaper, pro- viding a clear advantage over oral THC and many other drugs.
Smoked marijuana also may have fewer side effects than oral THC and many other drugs. Patients can smoke a small amount, notice effects in a few minutes, and alter their dosages to keep adverse reactions to a minimum. Long-term health effects appear in chapter 7, but smoked marijuana for brief interventions or as a treatment for the terminally ill has no more negative side effects than many other popular drugs.
Controlled studies reveal that cannabinoids can decrease pressure in- side the eye for glaucoma patients, alleviate pain, reduce vomiting, en- hance appetite, promote weight gain, and minimize spasticity and invol- untary movement. Other work suggests additional therapeutic effects for asthma, insomnia, and anxiety. Yet only a few studies have compared cannabinoids to established treatments for these problems. Case studies and animal research suggest that the drug may also help a host of other medical and psychological conditions. These include seizures, tumors, insomnia, menstrual cramps, premenstrual syndrome, Crohn’s disease, tinnitus, schizophrenia, adult attention deficit disorder, uncontrollable violent episodes, post-traumatic stress disorder, and, surprisingly, drug addiction. The cases may provide enough evidence to stimulate research- ers to conduct randomized clinical trials examining the impact of can- nabinoids on these problems. The evidence of marijuana’s effectiveness for treating each of these medical conditions appears below.