The Chinese Emperor Shen Nung, in 2737 B.C., described the therapeutic use of marijuana for joint pain, constipation, malaria, and childbirth. Therapeutic and religious use achieved great popularity in India around 1000 B.C. Medicinal use of marijuana continued, and spread to Africa, the Middle East, and the Arabian Peninsula into the 18th century.
Marijuana was introduced into western medicine by a physician, W.B. O'shaughnessy who, in 1839, described its use for pain control, muscle relaxation, appetite stimulation, and as a treatment for nausea, and for seizures. The psychiatrist Moreau, in 1845, published an article describing the use of marijuana in his patients. In 1850, marijuana was added to the U.S. Pharmacopoeia. Information regarding medical uses of marijuana disseminated throughout North America and Europe. By 1900, more than 100 scientific articles had been published on medical marijuana. Marijuana extracts were being marketed by prominent pharmaceutical companies.
Use of marijuana declined in the U.S. from 1900 through the 1930s due to difficulty in standardizing preparations, development of alternative "mainstream" pharmaceuticals, and taxation by the Federal Marijuana Tax Act of 1937. By the 1930s, there were at least 2000 medicines, with over 280 manufacturers. Marijuana was removed from the U.S. Pharmacopoeia in 1942. In 1970, The Controlled Substances Act classified marijuana as a "Schedule 1" drug, in the same category as heroin.1
Marijuana is a synonym (slang) for cannabis, which is derived from the marijuana plant, Cannabis sativa. The primary active constituents in the marijuana plant are Delta9- tetrahydrocannabinol (THC) and Cannabidiol (CBD).2 The human body has a receptor-signaling system for marijuana known as the Endogenous Cannabinoid System (ECS). The ECS has two types of receptors that activate very different bodily functions: CB1 receptors are very abundant in the brain, and solely mediate the behavioral, analgesic, and euphoric effects of marijuana (THC) (e.g., memory, cognition, perception, and pain). CB2 receptors are not very abundant in the brain, but are highly expressed in the gut and immune cells where they regulate inflammation and immune function. Cannabidiol (CBD) activates these receptors (e.g., anti-inflammatory, antiseizure, anti-nausea, and anti-anxiety).