marijuana or marihuana, drug obtained from the flowering tops, stems, and leaves of the hemp plant, Cannabis sativa (see hemp ) or C. indica; the latter species can withstand colder climates. It is one of the most commonly used drugs in the world, following only caffeine , nicotine , and alcoholic beverages in popularity. In the United States, where it is usually smoked, it also has been called weed, grass, pot, or reefer.

The Plant

C. sativa grows as a common weed in many parts of the world, and drug preparations vary widely in potency according to climate, cultivation, and method of preparation. C. indica is a shorter, hardier variety with rounded blue-green leaves, grown in Afghanistan for hashish. Most marijuanas grown in the United States since the late 1980s are hybrids of the two and yield a much more potent product than the marijuana of the past. The resin found on flower clusters and top leaves of the female plant is the most potent drug source and is used to prepare hashish , the highest grade of cannabis. The bud of the female plant, called sinsemilla, is the part most often smoked as marijuana.

The Drug

The effects of marijuana vary with its strength and dosage and with the state of mind of the user. Typically, small doses result in a feeling of well-being. The intoxication lasts two to three hours, but accompanying effects on motor control last much longer. High doses can cause tachycardia, paranoia, and delusions. Although it produces some of the same effects as hallucinogens like LSD and mescaline (heightened sensitivity to colors, shapes, music, and other stimuli and distortion of the sense of time), marijuana differs chemically and pharmacologically.

The primary active component of marijuana is delta-9-tetrahydrocannabinol (THC), although other cannabinol derivatives are also thought to be intoxicating. In 1988 scientists discovered receptors that bind THC on the membranes of nerve cells. They reasoned that the body must make its own THC-like substance. The substance, named anandamide, was isolated from pig brains in 1992 by an American pharmacologist, William A. Devane.

Marijuana lowers testosterone levels and sperm counts in men and raises testosterone levels in women. In pregnant women it affects the fetus and results in developmental difficulties in the child. There is evidence that marijuana affects normal maturation of preadolescent and adolescent users and that it affects short-term memory and comprehension. Heavy smokers often sustain lung damage from the smoke and contaminants. Regular use can result in dependence.

The Legalization Question

With the increase in the number of middle-class users in the 1960s and 1970s, there came a somewhat greater acceptance of the view that marijuana should not be considered in the same class as narcotics and that U.S. marijuana laws should be relaxed. The Drug Abuse Prevention Act of 1970 eased federal penalties somewhat, and 11 states decriminalized possession. However, in the late 1980s most states rewrote their drug laws and imposed stricter penalties. Opponents of easing marijuana laws have asserted that it is an intoxicant less controllable than alcohol, that our drug-using society does not need another widely used intoxicant, and that the United States should not act to weaken UN policies, which are opposed to the use of marijuana for other than possible medical purposes.

Medical Uses

Controversy surrounds the medical use of marijuana, with proponents saying it is useful for treating pain and the nausea and vomiting that are side effects of cancer chemotherapy and for restoring the appetite in people with AIDS. Although its active ingredient, THC (synthesized in 1966 and approved by the U.S. Food and Drug Administration in 1985) is available by prescription in pill form, proponents say it is not as effective as the herb and is more expensive. A 1999 U.S.-government-sponsored study by the Institute of Medicine found that marijuana appeared beneficial for certain medical conditions, such as nausea caused by chemotherapy and wasting caused by AIDS. Because of the toxicity of marijuana smoke, however, it was hoped that further research might lead to development of new delivery systems, such as bronchial inhalers.

The Office of National Drug Control Policy has opposed legalization of the medical use of marijuana, citing law enforcement issues and the possibility that some would use it as a pretext to sell marijuana for nonmedical use, and the FDA said in 2006 that, despite the 1999 report, that marijuana "has no accepted or proven use in the United States." Proponents, disregarding the law, have set up networks for the distribution of the drug to people who they judge will be helped by it and continue to lobby for its legalization for medical use. Voters in several U.S. states have approved initiatives intended to legalize marijuana for medical uses, but, as a result of a Supreme Court ruling in 2005, such initiatives do not protect medical users with a prescription from federal prosecution. Another, lower court ruling permits doctors to discuss medical use of marijuana with their patients but forbids them to help patients obtain the drug. A number of countries, including Canada, permit the medicinal use of the drug.

History of Marijuana Use

Marijuana has been used as an agent for achieving euphoria since ancient times; it was described in a Chinese medical compendium traditionally considered to date from 2737 BC Its use spread from China to India and then to N Africa and reached Europe at least as early as AD 500. A major crop in colonial North America, marijuana (hemp) was grown as a source of fiber. It was extensively cultivated during World War II, when Asian sources of hemp were cut off.

Marijuana was listed in the United States Pharmacopeia from 1850 until 1942 and was prescribed for various conditions including labor pains, nausea, and rheumatism. Its use as an intoxicant was also commonplace from the 1850s to the 1930s. A campaign conducted in the 1930s by the U.S. Federal Bureau of Narcotics (now the Bureau of Narcotics and Dangerous Drugs) sought to portray marijuana as a powerful, addicting substance that would lead users into narcotics addiction. It is still considered a "gateway" drug by some authorities. In the 1950s it was an accessory of the beat generation ; in the 1960s it was used by college students and "hippies" and became a symbol of rebellion against authority.

The Controlled Substances Act of 1970 classified marijuana along with heroin and LSD as a Schedule I drug, i.e., having the relatively highest abuse potential and no accepted medical use. Most marijuana at that time came from Mexico, but in 1975 the Mexican government agreed to eradicate the crop by spraying it with the herbicide paraquat, raising fears of toxic side effects. Colombia then became the main supplier. The "zero tolerance" climate of the Reagan and Bush administrations (1981-93) resulted in passage of strict laws and mandatory sentences for possession of marijuana and in heightened vigilance against smuggling at the southern borders. The "war on drugs" thus brought with it a shift from reliance on imported supplies to domestic cultivation (particularly in Hawaii and California). Beginning in 1982 the Drug Enforcement Administration turned increased attention to marijuana farms in the United States, and there was a shift to the indoor growing of plants specially developed for small size and high yield. After over a decade of decreasing use, marijuana smoking began an upward trend once more in the early 1990s, especially among teenagers, but by the end of the decade this upswing had leveled off well below former peaks of use.

Bibliography

See J. S. Hochman, Marijuana and Social Evolution (1972); E. Marshal, Legalization (1988); M. S. Gold, Marijuana (1989); L. Grinspoon and B. J. Bakalar, Marijuana: The Forbidden Medicine (1995); publications of the Drugs & Crime Data Center and Clearinghouse, the Bureau of Justice Statistics Clearinghouse, and the National Clearinghouse for Alcohol and Drug Information.

marijuana Narcotic drug prepared from the dried leaves of the Indian hemp plant (Cannabis sativa); it is different from hashish, which is prepared from resin obtained from the flowering tops of the plant. Possession of the drug is illegal in many countries. See also addiction

Marijuana

Definition

Marijuana and its medically active components, called cannabinoids, are used in cancer therapy to reduce nausea and vomiting caused by chemotherapeutic medications. This drug, however, is considered an illegal substance in the United States.

Purpose

Marijuana can be used with a variety of cancer chemotherapeutic agents that cause nausea and vomiting. Marijuana seems to work best at preventing nausea and vomiting with mild to moderately active chemotherapeutic agents. There are limited studies showing it does help reduce nausea and vomiting caused by the most powerful cancer chemotheraupeutic drugs. Marijuana may also be used by cancer patients to stimulate appetite.

Description

Marijuana, a plant with known psychoactive properties, has been used by human beings for thousands of years as a medicine. Ancient Chinese writings tell of its use for headaches, menstrual pains, and abdominal distress. It was used in the United States as a medicine for a variety of aliments until 1937, when its use was discouraged by the Marijuana Tax Act, which imposed high taxes on its use. In 1970, it was classified by the U.S. Government as a drug having no known medical use and a high potential for abuse. However, people who use marijuana recreationally have long reported that the drug helped ease nausea and vomiting, leading to its use by cancer patients to help ease the nausea and vomiting brought about by many anti-cancer medications. Because of its illegal status, there are very few well-researched studies examining the effectiveness of marijuana.

When the drug is smoked, it is immediately absorbed into the bloodstream through the rich network of blood vessels in the lungs. Within five to ten minutes the most active chemical part of marijuana, delta-9-THC, reaches the brain, where it produces its anti-nausea and anti-vomiting effects. These effects peak in about one hour, and last for about three hours.

Recommended dosage

Since marijuana is still an illegal drug under federal law, there are no uniform recommended dosages. The amount of delta-9-THC in marijuana determines the strength of the drug, which in turn will affect the amount needed for therapeutic effects.

When marijuana is smoked, the patient can alter the dosage of delta-9-THC simply by altering how much smoke is inhaled, the amount of time taken between inhalations, how deeply the smoke is inhaled, and how long the smoke is held in the lungs. Since the anti-nausea and anti-vomiting effects of marijuana are so rapid in onset, most patients quickly learn how much marijuana they need to smoke to achieve the desired results.

Marijuana can also be taken orally, most commonly either in a tea or baked in cookies. When used this way, the dosage a patient receives is more variable than smoking due to a slower absorption rate in the stomach versus the lungs. A pill containing THC known as dronabinol, is taken as an initial dose of five mg one to two hours before chemotherapy treatment. It can be then taken as five mg every two to four hours after treatment for up to six times a day.

Precautions

The few studies that have examined the safety of marijuana all seem to agree that it is a relatively safe drug. The chances of an overdose appear quite small. However, high doses can lead to tachycardia, or rapid heart rate, in a small percentage of users. Because of this, people with a history of heart problems should only use marijuana under the supervision of a trained health care provider. Since marijuana is also known to cause drowsiness, it should not be used in situations in which people need to remain alert, such as driving. In addition, smoking marijuana increases the risk of lung cancer.

Side effects

The side effects of marijuana use may or may not occur, depending on such variables as the dosage used, the method used to take the drug, and the frame of mind of the patient when using the drug. Typical side effects include euphoria, which is a feeling of well being, along with talkativeness and spontaneous laughter. These side effects are usually seen within a half hour of inhaling or ingesting the drug.

Drowsiness, or feeling sleepy, is another common side effect of using marijuana. The drowsiness appears to be dose related. Other side effects commonly seen are "red eye." This effect is caused by the dilation, or widening of the blood vessels in the eye. A rapid heart rate, or tachycardia, is seen in marijuana users. This side effect also appears to be dose related, and usually occurs within 20 minutes of drug use and stops after about 45 minutes. Marijuana users also usually experience an increased appetite. It generally occurs within one hour of using the drug.

Rarely, more troublesome side effects can be seen after marijuana use. These side effects more often occur in people using large does of the drug, or smoking marijuana that is particularly potent. Side effects seen in these instances can include depression , anxiety, paranoia, confusion, and hallucinations. These side effects generally last only as long as one is using the drug, and do not generally reappear unless marijuana is used again.

Interactions

Marijuana appears to alter the absorption and elimination of certain other drugs, although studies are limited on this subject. Due to its tendency to make people sleepy or tired, marijuana should not be used with alcohol, sedatives, or sleeping pills. It has also been reported that marijuana increases the elimination of theophylline, which is a medication used in the treatment of asthma.

Resources

BOOKS

Grinspoon, Lester and James B. Balalar. Marijuana, the Forbid den Medicine. New Haven:Yale University Press, 1997.

Joy, E. Janet, Stanley J. Watson Jr., and John A. Benson Jr. ed. Marijuana and Medicine. Washington D.C.: National Academy Press, 1999.

Mathre, L. Mary, ed. Cannabis in Medical Practice. Jefferson, N.C.:McFarland & Company, 1997.

OTHER

Women's Alliance for Medical Marijuana. <http://www.wamm.org>.

Canadian Medical Marijuana Association. <http://communities.msn.ca/CanadianMedicialMarijuanaAssociation>.

Edward R. Rosick, DO, MPH, MS