Medical Marijuana

Marijuana

Marijuana is derived from the hemp plant (Cannabis sativa). It's most important psychoactive chemical, delta-9-tetrahydrocannabinol, is contained in a resin that covers the flower clusters and top leaves of the plant; the resin also contains many chemically related substances with lesser effects. Its preparations vary widely in quality and potency depending on the type of plant, climate, soil, and methods of cultivation and manufacture (http://149.101.225.20/dea). The resin can be ingested in the form of a drink or in foods, but usually the leaves and flowering tops are smoked, either in a pipe or in a cigarette called a joint.

The Pharmacology of Natural Products

It is important to keep in mind that marijuana is not a single drug. Marijuana is a mixture of the dried flowering tops and leaves from the plant cannabis sativa (Agurell et al. 1984; Graham 1976; Jones 1987; Mechoulam 1973). Like most plants, marijuana is a variable and complex mixture of biologically active compounds (Agurell et al. 1986; Graham 1976; Mechoulam 1973). Characterizing the clinical pharmacology of the constituents in any pharmacologically active plant is often complicated, particularly when the plant is smoked or eaten more or less in its natural form. Marijuana is not unusual in this respect. Cannabis sativa is a very adaptive plant, so its characteristics are even more variable than most plants (Agurell Dewey and Willett 54-192). Some of the seeming inconsistency or uncertainty in scientific reports describing the clinical pharmacology of marijuana results from the inherently variable potency of the plant material used in research studies.

The Plant

Marijuana contains more than 400 chemicals. Approximately 60 are called cannabinoids; i.e., C21 terpenes found in the plant and their carboxylic acids, analogs, and transformation products (www.oregon.gov). Most of the naturally occurring cannabinoids have been identified. Cannabinoids appear in no other plant. Cannabinoids have been the subject of much research, particularly since the mid 1960s when Mechoulam and his colleagues first isolated delta-9-tetrahydrocannabinol (Delta9-THC) (Mechoulam 1973; Mechoulam et al. 1991). THC in the scientific literature is termed Delta9-THC or Delta1-THC depending on whether the pyran or monoterpinoid numbering system is used.

Cannabinoids of Importance

THC, the main psychoactive cannabinoid in marijuana, is an optically active resinous substance. THC is not soluble in water but is extremely lipid soluble (Graham 23-44). Varying proportions of other cannabinoids, mainly cannabidiol (CBD) and cannabinol (CBN), are also present in marijuana, sometimes in quantities that might modify the pharmacology of THC or cause effects of their own. CBD is not psychoactive but has significant anticonvulsant, sedative, and other pharmacologic activity likely to interact with THC (www.nih.gov).

Potency of Tetrahydrocannabinol

THC is quite potent when compared to most other psychoactive drugs. An intravenous (IV) dose of only a milligram or two can produce profound mental and physiologic effects (Agurell 21-43). Large doses of THC delivered by marijuana or administered in the pure form can produce mental and perceptual effects similar to drugs usually termed hallucinogens or psychomimetics. However, the way marijuana is used in the United States does not commonly lead to such profound mental ...