Medical Marijuana: The Continuing Story

• Cannabis
• Drug and Narcotics Control
• Legislation
• jurisprudence

Marijuana—the common name for the variable combination of substances in the leaves, flower tops, and even small branches of the hemp plant Cannabis sativa L.—has been used as a medicinal herb for centuries. According to historical studies of medical practices in numerous ancient cultures, marijuana was believed to have curative properties, delivered through teas, oils, and ointments made from the hemp plant and from smoking dried parts of the plant in pipes or as cigarettes.

Modern scientific investigation into the potential therapeutic uses of marijuana essentially began in the 1960s with the isolation and chemical characterization of the cannabinoids, a family of compounds in the hemp plant that is responsible for the psychoactive properties of marijuana. The cannabinoids, primarily delta-9-tetrahydrocannabinol, more commonly called tetrahydrocannabinol (or THC), are also responsible for the antiemetic, analgesic, appetite-stimulating, and antianxiety or sedative effects of marijuana. In the 1980s, basic science research provided key evidence that explains the reported therapeutic effects of marijuana: The identification of two types of cannabinoid receptors in humans—in the brain and throughout the body on cells of the immune system—and the identification of natural cannabinoid molecules in the body that bind to and activate these receptors. These discoveries have opened the door to understanding the mechanisms of action of endogenous cannabinoids, as well as plant-derived or synthetic cannabinoids, in humans. “Certainly not all the kinks in the pathways are worked out, and probably not all of the involved molecules have been identified yet,” commented Billy Martin, PhD, of the pharmacology and toxicology department of the Commonwealth University in Richmond, Virginia, “But we're on the right track, characterizing the normal physiological pathways used by the cannabinoids to effect pain modulation, control of movement, control of visceral sensation, and other processes.“