Cancer Health Center

Cannabis use for medicinal purposes dates back at least 3,000 years.[1,2,3,4,5] It was introduced into Western medicine in the 1840s by W.B. O'Shaughnessy, a surgeon who learned of its medicinal properties while working in India for the British East Indies Company. Its use was promoted for reported analgesic, sedative, anti-inflammatory, antispasmodic, and anticonvulsant effects.

In 1937, the U.S. Treasury Department introduced the Marihuana Tax Act. This Act imposed a levy of one dollar an ounce for medicinal use of Cannabis and one hundred dollars an ounce for recreational use. Physicians in the United States were the principal opponents of the Act. The American Medical Association (AMA) opposed the Act because physicians were required to pay a special tax for prescribingCannabis, use special order forms to procure it, and keep special records concerning its professional use. In addition, the AMA believed that objective evidence that Cannabis was harmful was lacking and that passage of the Act would impede further research into its medicinal worth.[6] In 1942, Cannabis was removed from the U.S. Pharmacopoeia because of persistent concerns about its potential to cause harm.[2,3]

In 1951, Congress passed the Boggs Act, which for the first time, included Cannabis with narcoticdrugs. In 1970, with the passage of the Controlled Substances Act, marijuana was classified as a Schedule I drug. Drugs in this category are distinguished as having no accepted medicinal use. Other Schedule I substances include heroin, LSD, mescaline, methaqualone, and gamma-hydroxybutyrate.

Despite its designation as having no medicinal use, Cannabis was distributed to patients by the U.S. government on a case-by-case basis under the Compassionate UseInvestigational New Drug program established in 1978. Distribution of Cannabis through this program was discontinued in 1992.[1,2,3,4] Although federal law prohibits the use of Cannabis, 16 states and the District of Columbia permit its use for certain medical conditions.

The main psychoactive constituent of Cannabis was identified as delta-9-tetrahydrocannabinol (THC). In 1986, synthetic delta-9-THC in sesame oil was licensed and approved for the treatment of chemotherapy-associated nausea and vomiting under the generic name dronabinol. Clinical trials determined that dronabinol was as effective as or better than other antiemetic agents available at the time.[7] Dronabinol was also studied for its ability to stimulate weight gain in patients with AIDS in the late 1980s. Thus, the indications were expanded to include treatment of anorexia associated with human immunodeficiency virus infection in 1992. Clinical trial results showed no statistically significant weight gain, although patients reported an improvement in appetite.[8,9]

Within the past 20 years, the neurobiology of cannabinoids has been analyzed.[10,11,12,13] The first cannabinoid receptor, CB1, was pharmacologically identified in the brain in 1988. A second cannabinoid receptor, CB2, was identified in 1993. The highest concentration of CB2 receptors is located on B lymphocytes and natural killer cells, suggesting a possible role in immunity. Endogenous cannabinoids (endocannabinoids) have been identified and appear to have a role in pain modulation, control of movement, feeding behavior, and memory.[11]

References:

1. Abel EL: Marihuana, The First Twelve Thousand Years. New York: Plenum Press, 1980. Also available online. Last accessed October 21, 2011.
2. Joy JE, Watson SJ, Benson JA, eds.: Marijuana and Medicine: Assessing the Science Base. Washington, DC: National Academy Press, 1999. Also available online. Last accessed October 21, 2011.
3. Mack A, Joy J: Marijuana As Medicine? The Science Beyond the Controversy. Washington, DC: National Academy Press, 2001. Also available online. Last accessed October 21, 2011.
4. Booth M: Cannabis: A History. New York, NY: St Martin's Press, 2003.
5. Russo EB, Jiang HE, Li X, et al.: Phytochemical and genetic analyses of ancient cannabis from Central Asia. J Exp Bot 59 (15): 4171-82, 2008.
6. Schaffer Library of Drug Policy.: The Marihuana Tax Act of 1937: Taxation of Marihuana. Washington, DC: House of Representatives, Committee on Ways and Means, 1937. Available online. Last accessed October 21, 2011.
7. Sallan SE, Zinberg NE, Frei E 3rd: Antiemetic effect of delta-9-tetrahydrocannabinol in patients receiving cancer chemotherapy. N Engl J Med 293 (16): 795-7, 1975.
8. Gorter R, Seefried M, Volberding P: Dronabinol effects on weight in patients with HIV infection. AIDS 6 (1): 127, 1992.
9. Beal JE, Olson R, Laubenstein L, et al.: Dronabinol as a treatment for anorexia associated with weight loss in patients with AIDS. J Pain Symptom Manage 10 (2): 89-97, 1995.
10. Devane WA, Dysarz FA 3rd, Johnson MR, et al.: Determination and characterization of a cannabinoid receptor in rat brain. Mol Pharmacol 34 (5): 605-13, 1988.
11. Devane WA, Hanus L, Breuer A, et al.: Isolation and structure of a brain constituent that binds to the cannabinoid receptor. Science 258 (5090): 1946-9, 1992.
12. Pertwee RG: Pharmacology of cannabinoid CB1 and CB2 receptors. Pharmacol Ther 74 (2): 129-80, 1997.
13. Felder CC, Glass M: Cannabinoid receptors and their endogenous agonists. Annu Rev Pharmacol Toxicol 38: 179-200, 1998.