Marijuana has been used medically, recreationally, agriculturally, and industrially for millennia. As a drug, marijuana was widely used by patients, under the direction and care of physicians and pharmacists, until the early part of the twentieth century, when the Marijuana Tax of 1937 essentially outlawed its use. As a therapeutic mainstay, marijuana then underwent a draconian ban for almost 60 years until California passed Proposition 215 in 1996. Since then, marijuana has undergone an important resurrection and has increasingly gained popularity, acceptance, and momentum.
What started in the West eventually sprouted to the East and is now encroaching on the Midwest. Moreover, Canada has a national program for medical marijuana, and Mexico has recently passed a personal use law, permitting individuals to possess small amounts of marijuana among other drugs.
Marijuana is used for a multitude of ailments; however, its primary utility is restricted to 5 general categories: pain, nausea and vomiting, weight loss associated with debilitating disease, neurologically induced spasticities, and other uses such as glaucoma.
Marijuana is a natural product derived from the Cannabis sativa plant. It has about 450 active constituents, including 60-plus compounds classified as cannabinoids. The compound most often identified as the primary active constituent of marijuana is tetrahydrocannabinol (delta-9-THC, THC), although to a lesser extent, cannabidiol and cannabinol are also highly psychoactive and contribute significantly to marijuana's medicinal effects.[1,2] Nevertheless, marijuana is best understood not as a single uniform plant but as a sophisticated weed with hundreds of variants and a wide range of compositions and effects.
The potency of THC varies from insignificant in hemp, the industrial fiber of the plant, to 3%-6% typically found in smoked marijuana, to > 6% widely found in hashish, a resinous and compressed paste obtained from the dried flowers of the plant. However, recent bioengineering of the plant has greatly impacted this yield for more potent and active products.
There are 2 cannabinoid subtype receptors, CB1 and CB2.[1,2,3] The CB1 receptor exists primarily in the brain and spinal cord and is involved with pleasure, memory, sensory and time perception, and coordinated movement, among other effects. The CB2 receptor is found mainly in the periphery and immune tissue and is involved with immunomodulation, inflammation, nociception, and gastrointestinal motility. In the United States there are 2 commercially available synthetic cannabinoids approved for marketing: Marinol® (delta-9-THC; Solvay Pharmaceuticals, Inc., Marietta, Georgia) and Cesamet® (nabilone; Valeant Pharmaceuticals International, Aliso Viejo, California). Sativex® (delta-9-THC/cannabidiol; GW Pharmaceuticals, Wiltshire, United Kingdom) is a phytocannabinoid-based buccal product approved in Canada and in late-phase clinical testing in the United States.
Medscape Pharmacists © 2010 WebMD, LLC
Cite this: Matthew J. Seamon. Medical Marijuana: An Evolving Landscape - Medscape - Feb 22, 2010.