Monday, February 25, 2008

Cannabis (drug)

From Wikipedia, the free encyclopedia

Cannabis, also known as marijuana[1] or ganja (from Hindi: गांजा gānjā),[2] is a psychoactive product of the plant Cannabis sativa. The herbal form of the drug consists of dried mature flowers and subtending leaves of pistillate ("female") plants. The resinous form, known as hashish,[3] consists primarily of glandular trichomes collected from the same plant material.

Humans have been consuming cannabis since prehistory,[4] although in the 20th century there was a rise in its use for recreational, religious or spiritual, and medicinal purposes. It is estimated that about four percent of the world's adult population use cannabis annually and 0.6 percent daily.[5] The possession, use, or sale of psychoactive cannabis products became illegal in most parts of the world in the early 20th century. Since then, some countries have intensified the enforcement of cannabis prohibition while others have reduced the priority of enforcement.

History
Evidence of the inhalation of cannabis smoke can be found as far back as the Neolithic age, as indicated by charred cannabis seeds found in a ritual brazier at an ancient burial site in present day Romania.[4] The most famous users of cannabis were the ancient Hindus of India and Nepal, and the Hashshashins (hashish eaters) of present day Syria. The herb was called ganjika in Sanskrit (गांजा/গাঁজা ganja in modern Indic languages).[6][7] The ancient drug soma, mentioned in the Vedas as a sacred intoxicating hallucinogen, was sometimes associated with cannabis.[8]

Cannabis was also known to the Assyrians, who discovered its psychoactive properties through the Aryans.[9] Using it in some religious ceremonies, they called it qunubu (meaning "way to produce smoke"), a probable origin of the modern word 'Cannabis'.[10] Cannabis was also introduced by the Aryans to the Scythians and Thracians/Dacians, whose shamans (the kapnobatai—“those who walk on smoke/clouds”) burned cannabis flowers to induce a state of trance.[11] Members of the cult of Dionysus, believed to have originated in Thrace, are also thought to have inhaled cannabis smoke. In 2003, a leather basket filled with cannabis leaf fragments and seeds was found next to a 2,500- to 2,800-year-old mummified shaman in the northwestern Xinjiang Uygur Autonomous Region of China.[12][13]

Cannabis has an ancient history of ritual use and is found in pharmacological cults around the world. Hemp seeds discovered by archaeologists at Pazyryk suggest early ceremonial practices like eating by the Scythians occurred during the 5th to 2nd century BCE, confirming previous historical reports by Herodotus.[14] Some historians and etymologists have claimed that cannabis was used as a religious sacrament by ancient Jews and early Christians.[15] It was also used by Muslims in various Sufi orders as early as the Mamluk period, for example by the Qalandars.[16] In India and Nepal, it has been used by some of the wandering spiritual sadhus for centuries, and in modern times the Rastafari movement has embraced it as a sacrament.[17] Elders of the modern religious movement known as the Ethiopian Zion Coptic Church consider cannabis to be the Eucharist, claiming it as an oral tradition from Ethiopia dating back to the time of Christ, even though the movement was founded in the United States in 1975 and has no ties to either Ethiopia or the Coptic Church.[18] Like the Rastafari, some modern Gnostic Christian sects have asserted that cannabis is the Tree of Life.[19][20] Other organized religions founded in the past century that treat cannabis as a sacrament are the THC Ministry,[21] the Way of Infinite Harmony, Cantheism,[22] the Cannabis Assembly[23] and the Church of Cognizance.

The production of cannabis for drug use remains illegal throughout most of the world through for ex. International Opium Convention of 1925, the Marijuana Tax Act of 1937, the 1961 Single Convention on Narcotic Drugs, the 1971 Convention on Psychotropic Substances, and the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, while simple possession of small quantities is either legal, or treated as an addiction rather than a criminal offense in a few countries.


Medical use
Main article: Medical cannabis
A synthetic form of one chemical in marijuana, Delta-9 Tetrahydrocannabinol (THC), is a controversial treatment for medical use. The American Marijuana Policy Project, a pro-cannabis organization, claims that cannabis is an ideal therapeutic drug for cancer and AIDS patients, who often suffer from clinical depression, and from nausea and resulting weight loss due to chemotherapy and other aggressive treatments.

A recent study by scientists in Italy has also shown that cannabidiol (CBD), a chemical found in marijuana, inhibits growth of cancer cells in animals.[24]

FDA and comparable authorities in Western Europe, including the Netherlands, have not approved smoked marijuana for any condition or disease. The current view of the United States Food and Drug Administration is that if there is any future of marijuana as a medicine, it lies in its isolated components, the cannabinoids and their synthetic derivatives.[25]

A synthetic version of the cannabinoid THC named Dronabinol has been shown to relieve symptoms of anorexia and reduce agitation in elderly Alzheimer's patients.[26] Dronabinol has been approved for use with anorexia in patients with HIV/AIDS and chemotherapy-related nausea.

Glaucoma, a condition of increased pressure within the eyeball causing gradual loss of sight, can be treated with medical marijuana to decrease this intraocular pressure. There has been debate for 25 years on the subject. Some data exist, showing a reduction of IOP in glaucoma patients who smoke marijuana,[27] but the effects are short-lived, and the frequency of doses needed to sustain a decreased IOP can cause systemic toxicity. There is also some concern over its use since it can also decrease blood flow to the optic nerve. Marijuana lowers IOP by acting on a cannabinoid receptor on the ciliary body called the CB receptor.[28] Although marijuana is not a good therapeutic choice for glaucoma patients, it may lead researchers to more effective, safer treatments. A promising study shows that agents targeted to ocular CB receptors can reduce IOP in glaucoma patients who have failed other therapies.[29]

Medical marijuana is used for analgesia, or pain relief. “Marijuana is used for analgesia only in the context of a handful of illnesses (e.g., headache, dysentery, menstrual cramps, and depression) that are often cited by marijuana advocates as medical reasons to justify the drug being available as a prescription medication.”[30] It is also reported to be beneficial for treating certain neurological illnesses such as epilepsy, and bipolar disorder.[31] Case reports have found that cannabis can relieve tics in people with obsessive compulsive disorder and Tourette syndrome. Patients treated with tetrahydrocannabinol, the main psychoactive chemical found in cannabis, reported a significant decrease in both motor and vocal tics, some of 50% or more.[32][33][34] Some decrease in obsessive-compulsive behavior was also found.[32] A recent study has also concluded that cannabinoids found in cannabis might have the ability to prevent Alzheimer's disease.[35] THC has been shown to reduce arterial blockages.[36]

Another use for medical marijuana is movement disorders. Marijuana is frequently reported to reduce the muscle spasms associated with multiple sclerosis; this has been acknowledged by the Institute Of Medicine, but it noted that these abundant anecdotal reports are not well-supported by clinical data. Evidence from animal studies suggests that there is a possible role for cannabinoids in the treatment of certain types of epileptic seizures.[37] Marijuana "numbs" the nervous system slightly, possibly preventing shock. A synthetic version of the major active compound in cannabis, THC, is available in capsule form as the prescription drug dronabinol (Marinol) in many countries. The prescription drug Sativex, an extract of cannabis administered as a sublingual spray, has been approved in Canada for the treatment of multiple sclerosis.[38] Dr. William Notcutt states that the use of MS as the disease to study “had everything to do with politics”.[39]


New breeding and cultivation techniques
Main article: Cannabis (drug) cultivation
It is often claimed by growers and breeders of herbal cannabis that advances in breeding and cultivation techniques have increased the potency of cannabis since the late 1960s and early '70s, when delta-9-tetrahydrocannabinol was discovered and understood. However, potent seedless marijuana such as "Thai sticks" were already available at that time. In fact, the sinsemilla technique of producing high-potency marijuana has been practiced in India for centuries. Sinsemilla (Spanish for "without seed") is the dried, seedless inflorescences of female cannabis plants. Because THC production drops off once pollination occurs, the male plants (which produce little THC themselves) are eliminated before they shed pollen to prevent pollination. Advanced cultivation techniques such as hydroponics, cloning, high-intensity artificial lighting, and the sea of green method are frequently employed as a response (in part) to prohibition enforcement efforts that make outdoor cultivation more risky. These intensive horticultural techniques have led to fewer seeds being present in cannabis and a general increase in potency over the past 20 years. The average levels of THC in marijuana sold in United States rose from 3.5% in 1988 to 7% in 2003 and 8.5% in 2006.[40]

"Skunk" cannabis is a potent strain of cannabis, grown through selective breeding and usually hydroponics, that is a cross-breed of Cannabis sativa and C. indica. Skunk cannabis potency ranges usually from 6% to 15% and rarely as high as 20%. The average THC level in coffeehouses in the Netherlands is about 18–19%.[41]

The average THC content of Skunk #1 is 8.2%; it is a 4-way combination of the cannabis strains Afghani indica, Mexican Gold, Colombian Gold, and Thai: 75% sativa, 25% indica. This was done via extensive breeding by cultivators in California in the 1970s using the traditional outdoor cropping methods used for centuries.

In proposed revisions to cannabis rescheduling in the UK, the government is considering scheduling the more potent cannabis material as a separate, more restricted substance.

A Dutch double-blind, randomized, placebo-controlled, cross-over study of male volunteers with a self-reported history of regular cannabis use aged 18–45 years concluded that smoking of cannabis, with higher THC reflecting the content levels of netherweed (marijuana with 9–23% THC) as currently sold in coffee shops in the Netherlands, may lead to higher THC concentrations in serum (the internal dose). Smoking of cannabis with higher THC concentrations leads to an increase of the occurrence of effects, particularly among younger or inexperienced cannabis smokers, who do not adapt their smoking to the higher THC.[42] Smoking of cannabis with higher THC concentrations was associated with a dose-related increase of physical effects (such as increase of heart rate, and decrease of blood pressure) and psychomotor effects (such as reacting more slowly, being less concentrated, making more mistakes during performance testing, having less motor control, and experiencing drowsiness).

What was well observed in the Dutch study was that the effects based from a single dose—the smoking of one piece of a joint for 20–25 minutes—lasted for more than eight hours. The reaction time was still significantly slower about five hours after smoking. At that time, the THC serum concentration was low, but still present. This means that even when individuals have the impression that their state has returned to baseline and that they can smoke another piece of joint, the effect of the first joint may be still present. When subjects smoke on several occasions per day, accumulation of THC may occur.

Another study showed that 15 mg THC result in no learning whatsoever occurring over a three-trial selective reminding task at two hours. In several tasks, delta(9)-THC increased both speed and error rates, reflecting “riskier” speed–accuracy trade-offs.[43]

Criminalization and legalization

Since the beginning of the 20th century, most countries have enacted laws against the cultivation, possession, or transfer of cannabis for recreational use. These laws have impacted adversely on the cannabis plant's cultivation for non-recreational purposes, but there are many regions where, under certain circumstances, handling of cannabis is legal or licensed. Many jurisdictions have lessened the penalties for possession of small quantities of cannabis, so that it is punished by confiscation or a fine, rather than imprisonment, focusing more on those who traffic the drug on the black market. There are also changes in a more restrictive direction such as the closing of coffee shops in the Netherlands, the closing of the open drug market in Christiania, Copenhagen, the Gonzales v. Raich rule in 2005 that the Commerce Clause of the United States Constitution allow the federal government to ban the use of marijuana, including medical use anywhere in the United States and the proposal for higher minimum penalties as in Canada. Although recently in Canada the use of marijuana has been decriminalized and laws in certain provinces (such as British Columbia) have been un-enforced.

Some jurisdictions use mandatory treatment programs for frequent known users with freedom from narcotic drugs as goal. Simple possession can carry long prison terms in some countries, particularly in East Asia, where the sale of cannabis may lead to a sentence of life in prison or even execution.

Effects
Main article: Health issues and effects of cannabis
Cannabis has psychoactive and physiological effects when consumed, usually by smoking or ingestion. The minimum amount of THC required to have a perceptible psychoactive effect is about 10 micrograms per kilogram of body weight[44] (which, in practical terms, is a varying amount, dependent upon potency). A related compound, Δ9-tetrahydrocannabivarin, also known as THCV, is produced in appreciable amounts by certain drug strains. This cannabinoid has been described in the popular literature as having shorter-acting, flashier effects than THC, but recent studies suggest that it may actually inhibit the effects of THC. Relatively high levels of THCV are common in African dagga (marijuana), and in hashish from the northwest Himalayas.


Health issues
Main article: Health issues and the effects of cannabis
Whilst some studies and tests have proven inconclusive,[45]a recent study by the Canadian government found cannabis contained more toxic substances than tobacco smoke. It contained 20 times more ammonia, (a carcinogen) and five times more of hydrogen cyanide (which can cause heart disease) and of nitrogen oxides, (which can cause lung damage) than tobacco smoke.[46] Cannabis use has been linked to psychosis by several peer-reviewed studies. A 1987 Swedish study claiming a link between cannabis use and schizophrenia was criticized for not differentiating between cannabis use and the use of other narcotics, and its results have not been verified by other studies. More recently, the Dunedin Multidisciplinary Health and Development Study published research showing an increased risk of psychosis for cannabis users with a certain genetic predisposition, held by 25% of the population.[47]

In July 2007, British medical journal The Lancet published a study that indicates that cannabis users have, on average, a 41% greater risk of developing psychosis than non-users. The risk was most pronounced in cases with an existing risk of psychotic disorder, and was said to grow up to 200% for the most-frequent users.[48][49][50]

Although long terms effects of cannabis use is polarised in the scientific community preventing any firm consensus of its effects, short term effects are well documented. Effects such as short-term memory and attention loss, loss of motor skills and dexterity, reduced reaction time, and lower abilities to perform skilled activities can be hazardous to human life if combined with potentially hazardous activities such as driving. Cannabis use can also lead to anxiety and panic reactions. There is also evidence that some of the above effect can become permanent with heavy usage [51]

Multiple studies have shown that chronic heavy cannabis smoking is associated with increased symptoms of chronic bronchitis, such as coughing, production of sputum, and wheezing. Lung function is also significantly poorer and there is a significantly greater amount of abnormalities in the large airways of marijuana smokers than in non-smokers.[52] [53][54].

All of these health issues can potentially be exacerbated by a cannabis dependence syndrome [55].

1 comment:

Andrew said...

Here's another interesting article on dronabinol in people with bipolar disorder.

Successful treatment of sexual dysfunction with dronabinol: a case report