Tetrahydrocannabinol

The chemical compound tetrahydrocannabinol (THC) is the psychoactive substance in cannabis.

Its molecular formula is C₂₁H₃₀O₂, with a molecular weight of 314.45. Its chemical name is tetrahydro-6,6,9-trimethyl-3-pentyl-6H-dibenzo[b,d]pyran-1-ol, and it may also be known as (L)-delta-1-tetrahydrocannibinol, or trans-delta-1-tetrahydrocannibinol. It has a boiling point of 200°C (392°F). It has a LD₅₀ of 1270 mg/kg (male rats), 730 mg/kg (female rats) orally (administered dissolved in sesame oil).

Its actions on the body are the result of its binding to a cellular receptor, which was known as the cannabinoid receptor. Since cannabinoids are not naturally produced in the human body, the search began for this receptors' endogenous ligand (the substance that normally binds to it), leading to the eventual discovery of anandamide. 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. It has been shown to assist some glaucoma patients by reducing pressure within the eye, and is used, illegally, 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 due cannabis' status as a narcotic.

Since Sep 1, 2003, the medicine Dronabinol (which contains THC) is available in Dutch pharmacies, for cancer and AIDS patients. An American analogue called Marinol is also available.

See also: medical marijuana, cannabis, War on Drugs