Tetrahydrocannabinol, also known as THC, Δ⁹-THC, Δ⁹-tetrahydrocannabinol, Δ¹-tetrahydrocannabinol (using an older numbering scheme), or dronabinol, is the main psychoactive substance found in the hemp plant Cannabis sativa. In pure form it is glassy solid in the cold and becomes viscous and sticky if warmed. THC has a very low solubility in water, but a good solubility in most organic solvents like ethanol or hexane.

Its pharmacological actions are the result of its binding to specific cannabinoid receptors located in the brain and throughout the body. Since cannabinoids are not naturally produced in the human body, the search began for the endogenous substance that normally binds to this receptors, the so-called natural ligand, leading to the eventual discovery of anandamide and some related compounds. It has a LD₅₀ value of 1270 mg/kg (male rats), 730 mg/kg (female rats) orally (administered dissolved in sesame oil). Studies of the distribution of the receptors in the brain explain why toxicity of THC is so low (i.e., the LD₅₀ of the compound is so large): parts of the brain that control vital functions such as respiration do not have many receptors, so are relatively unaffected even by doses larger than could ever be ingested under any normal conditions.

Effects include relaxation, euphoria, altered space-time perception, enhancement of visual, auditory, and olfactory senses, disorientation, and appetite stimulation.

A number of studies indicate medical benefits for cancer and AIDS patients by increasing appetite and decreasing nausea, blocking the spread of some cancer-causing Herpes simplex viruses. It has been shown to assist some glaucoma patients by reducing pressure within the eye, and is used, in the form of cannabis by a number of multiple sclerosis patients for relieving spasm. Other studies indicate a variety of negative effects associated with constant, long-term use, including memory loss, depression and loss of motivation. The long-term effects of THC on humans is highly disputed, and the issue is politicized because of its status in the United States as a schedule I drug, according to the Controlled Substances Act (other tetrahydrocannibinol analogues such as Δ⁶-tetrahydrocannabinol are also listed in the Controlled Substances Act.)

Synthetic THC, also known under the substance name dronabinol, is available as a prescription drug (e.g. under the trade name Marinol) in several countries including the USA, The Netherlands, and Germany.

See also

• Cannabinoids
  • HU-210
• Medical marijuana
• War on Drugs
• Cannabis
• THC Ministry

External links

• Scientific American Marijuana research
• THC-pharm, a German producer of THC for pharmacies.
• Erowid Compounds found in Cannabis sativa.