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U.S. Department of Health and Human Services,
Investigating Possible Medical Uses of Marijuana
Overview: The Department of Health and Human Services (HHS) supports scientifically valid research to determine whether marijuana offers medical benefits. While some individuals report that marijuana has helped them with the effects of certain diseases, approval of marijuana for medical purposes would require the same level of scientific evidence required for other pharmaceutical products. So far, there has been little scientific evidence that smoked marijuana can serve as a therapeutically useful drug. Meanwhile, the hazards to health posed by smoked marijuana are well-established.
HHS' National Institutes of Health (NIH) and the independent Institute of Medicine (IOM) have both conducted reviews of existing research on the possible medical effectiveness of smoked marijuana. Both reviews concluded that research so far has not demonstrated a therapeutic benefit. But the reviews also concluded that further research was justified, especially for certain diseases. The IOM review in particular found that some chemical components of marijuana show promise for therapeutic use. The IOM report called for study of alternative means for delivering any components found to be beneficial, given the health hazards associated with smoking marijuana.
Several factors make it difficult to carry out scientifically valid research on smoked marijuana. While NIH has supported research projects involving marijuana, few qualifying applications for such research are submitted. In order to support additional research, HHS created a special process that enables the department to provide research grade marijuana for non-NIH funded projects found to have scientific merit. A multi-agency HHS committee reviews research applications, and those with scientific merit are allowed to purchase research-grade marijuana from HHS after they have obtained permission from the Drug Enforcement Agency (DEA) and an Investigational New Drug (IND) license from the Food and Drug Administration (FDA). Seven research proposals approved by the committee were scheduled to begin this spring. Five other proposals are awaiting action by DEA. Four more proposals were submitted this year.
One product, Marinol (the synthetic oral form of the major active ingredient in marijuana) has been approved for many years for patients undergoing chemotherapy and for patients with AIDS. In 1999, the DEA reclassified Marinol, making the drug more easily available for patients.
REVIEWS OF EXISTING RESEARCH
The NIH held a workshop in 1997 to discuss research in the field of possible therapeutic uses for smoked marijuana. Nonfederal experts in fields such as cancer treatment, infectious diseases, neurology and ophthalmology reviewed existing research. The invited experts assessed what is known about marijuana's possible therapeutic potential, and discussed the major scientific questions that remain unanswered; the indications that might hold promise for future research; and factors to be taken into account in undertaking clinical research on this subject.
The workshop concluded that there are too few scientific studies to determine marijuana's therapeutic utility, but that research is justified into marijuana's use for certain conditions or diseases: pain; neurological and movement disorders; the nausea of patients who are undergoing chemotherapy for cancer; loss of appetite and weight (cachexia) related to AIDS; and glaucoma. The experts also called for peer-reviewed research to provide clear answers about marijuana's effects in the most promising applications. They also stressed that clinical trials to determine any therapeutic effects of marijuana must be well-designed and carefully conducted to produce reliable results. The written summary of the panel's conclusions was provided to the NIH director in August 1997.
The full text of the report of the NIH workshop is available on the Internet at http://www.nih.gov/news/medmarijuana/MedicalMarijuana.htm.
In addition to the NIH workshop, the IOM, part of the National Academy of Sciences, carried out a separate assessment of the scientific knowledge of health effects and possible medical uses of marijuana. The IOM project was funded by the White House Office of National Drug Control Policy. The IOM report was issued March 17, 1999. Some of its conclusions were similar to those of NIH. The IOM report is available at http://pompeii.nap.edu/books/0309071550/html/index.html.
PAST NIH-SPONSORED RESEARCH
NIH's research on the therapeutic aspects of marijuana has focused primarily on a synthetic form of the major active ingredient in marijuana, delta-9-tetrahydrocannabinol (THC). In the late 1970s, two National Cancer Institute (NCI) pilot studies were performed with smoked marijuana as well as oral THC. These small studies suggested that the utility of smoked and oral THC varied in part by the type of cancer chemotherapy being administered. As information developed regarding the potential benefit of THC as an antiemetic for patients undergoing chemotherapy, the NCI supported the development of the drug dronabinol--synthetic THC--as an oral antinausea drug for such patients.
In 1985, the FDA approved dronabinol (Marinol), for treatment of nausea and vomiting associated with cancer chemotherapy in patients who have not responded to conventional antinausea (antiemetic) therapy. FDA also approved dronabinol in 1992 for use in loss of appetite and weight loss related to AIDS. Since 1986, Marinol had been classified by the DEA as a Schedule II drug, which placed certain restrictions on the prescribing of it. In July 1999, in accord with the scientific and medical evaluation and recommendations of HHS, DEA lowered Marinol to a Schedule III drug. One of the results of this change is that physicians will be allowed to write prescriptions with as many as five refills in six months. The change also reduces record-keeping requirements and distribution restrictions.
Other NIH institutes have conducted or supported some research--beginning over 20 years ago and into the present--aimed at evaluating the potential of synthetic THC in the management of conditions that include pain, muscle spasms and HIV-associated cachexia. In particular, the National Eye Institute (NEI) supported research studies from 1978 to 1984 in an effort to determine whether marijuana, or drugs derived from marijuana, might be effective as a treatment for glaucoma (elevated intraocular pressure). These studies demonstrated that some derivatives of marijuana lowered intraocular pressure when administered orally, intravenously or by smoking, but not when topically applied to the eye.
However, none of these studies demonstrated that marijuana--or any of its components--could safely and effectively lower intraocular pressure any more than a variety of drugs on the market. As research with other potential glaucoma drugs has shown, simply lowering intraocular pressure does not necessarily control the disease. In addition, some potentially serious side effects were noted, including an increased heart rate and a decrease in blood pressure in studies using smoked marijuana.
In assessing possibilities for future research, the experts attending the NIH workshop weighed the potential of smoked marijuana as a medicine as compared with existing approved therapies for conditions where smoked marijuana has been suggested. In glaucoma and nausea associated with cancer chemotherapy, for example, safe and effective treatments other than marijuana now exist for these conditions. Glaucoma can usually be effectively controlled with several existing medical and surgical treatments. These include a variety of prescription eye drops and pills used for glaucoma treatment that either enhance the drainage of fluid from the eye or decrease its production. Treatment with an argon laser has proved beneficial in NEI-sponsored clinical trials and is usually used in conjunction with drops or pills. Finally, several procedures that employ incisional surgery may be performed to improve drainage flow. Although these procedures have a fairly high success rate, they are generally reserved until medical therapy is no longer effective.
According to the NCI, other antiemetic drugs or combinations of antiemetic drugs have been shown to be more useful than smoked marijuana or synthetic THC as "first-line therapy" for nausea and vomiting caused by anticancer drugs. Examples include drugs called serotonin antagonists, including ondansetron (Zofran) and granisetron (Kytril), used alone or combined with dexamethasone (a steroid hormone); metoclopramide (Reglan) with diphenhydramine and dexamethasone; high doses of methylprednisolone (a steroid hormone) combined with droperidol (Inapsine); and prochlorperazine (Compazine). Research with other agents and combinations is under way to determine their usefulness in controlling chemotherapy-induced nausea and vomiting.
A number of medications have been shown to be effective for pain control and for HIV-associated wasting, which are among the most frequently cited conditions for which marijuana has been proposed as potentially helpful. These medications include opiates and anti-inflammatory drugs for pain, while for HIV wasting, the synthetic hormone megestrol acetate, dronabinol and somatropin are FDA-approved. Researchers in government and the private sector are continuing to develop improved methods of treatment for each of these conditions.
As in other research areas, NIH reviews grant applications on the medical utility of marijuana and is prepared to fund those applications that meet the accepted standards of scientific design and that, on the basis of peer review, are competitive with other applications that qualify for funding. However, research involving smoked marijuana poses several challenges. For example, studies on smoked marijuana would have to take into account how to objectively measure a positive therapeutic effect, given the fact that a blind study, in which neither the doctor or patient knows which drug is being used, would be difficult. In addition, the psychoactive effects of marijuana limit its use in people who experience depression instead of euphoria from the drug and in those who find the intoxicating sensation disorienting and unpleasant.
NIH has focused its marijuana-related research on dronabinol because the orally-administered drug eliminates some of the known difficulties of using smoked marijuana as a drug-delivery system. These difficulties include the respiratory effects of smoking, exposure to a large mix of chemicals present in the marijuana plant (including about 60 cannabinoids) and to potential contamination with organisms that may be hazardous to someone whose immune system is impaired, and the variability of the dose that patients absorb when they smoke. Like smoked marijuana, dronabinol has psychoactive as well as therapeutic effects.
The immediate effects of marijuana include rapid heart beat, some loss of coordination, and impaired short-term memory. In addition, the drug adversely affects critical skills, including those necessary to drive a car safely, such as judgment of distance and reaction time.
The group of experts noted in their report from the workshop that the risks associated with marijuana, especially smoked marijuana, must be considered not only in terms of immediate adverse effects on the lung, but also the long-term effects in patients with chronic diseases. They also felt the possibility that frequent and prolonged marijuana use might lead to clinically significant impairments of immune function is great enough that studies on immune function should be part of any research project on the medical uses of marijuana. This is especially true in studies involving patients with compromised immune systems. Members of the group also were concerned about the effects of the dangerous combustion byproducts of smoked marijuana on patients with chronic diseases. Therefore, they favored the development of a smoke-free inhaled delivery system that could deliver purer forms of marijuana's most active ingredient, THC, or its related compounds known as cannabinoids.
PROVIDING FOR BROADER RESEARCH
In May 1999, HHS announced it would create a new mechanism to provide research-grade marijuana not only for NIH-funded research but also for scientifically valid research that is funded by other sources. A special multi-agency Public Health Service (PHS) committee now reviews non-NIH funded clinical studies and assesses them both for scientific quality and the likelihood that they will yield data on possible benefits.
After a study is approved by the PHS committee, the researcher applies for an IND license from the FDA and must also obtain a DEA registration for Schedule I substances. When these are obtained, NIH provides research-grade marijuana for the project on a reimbursable basis (researchers reimburse the contractor of the National Institute on Drug Abuse for the costs of growing and producing the research-grade marijuana.) In this way, NIH is able to produce and supply research-grade marijuana for a variety of clinical studies that would not otherwise be possible.
Most of the research approved by the PHS committee so far is sponsored by the Center for Medicinal Cannabis Research at the University of California. Seven research proposals approved by the committee were scheduled to begin this spring. Five other proposals are currently awaiting action by DEA. Four more new proposals were submitted this year. This represents a substantial increase in scientifically valid research involving marijuana.
This new procedure does not signal a change in HHS' view on the therapeutic efficacy of marijuana, but it represents a way to enable more research to be done to evaluate the possible merits of marijuana for medical uses. Details of this new HHS procedure can be found in the NIH Guide for Grants and Contracts, May 21, 1999 at http://www.nih.gov/grants/guide/notice-files/not99-091.html.
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