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The Effects of Cannabis

By Dr. Mohamed Isa Abd. Majid
The Sun, September 7, 1996

THE TERM CANNABIS IS USED TO refer to the cannabis plant and any of it 202s parts or extracts that produce somatic or psychic changes in man. Besides cannabis, other frequently used street terms which refer to the same plant are ganja, Indian Hemp, pot, marihuana, marijuana and stick.

Cannabis (Cannabis sativa L.) is a plant widely distributed, throughout most tropical and temperature regions of the world. Historically, this plant has been cultivated for the tough fibre of the stem, the seed used in feed mixtures, and the oil as an ingredient of paint, as well as for its biologically active substance.

A tobacco-like substance is produced by drying the leaves and flowering tops of the plant. Cannabis varies significantly in its potency depending on the source and selectively of plant materials used.

Among drug abusers, it is believed that only the flowering tops and leaves of the cannabis plant contain significant quantities of the drug. The drug contains potent ingredients which provide "the kick" and is generally considered to be the most sought after by drug addicts.

The plant material has been used as a drug for centuries. In 1839 it entered the annals of western medicine with the publication of an article surveying its therapeutic potential including its possible use as an analgesic and anti-convulsant agent. Even a dictionary of Malayan medicine published in 1939 claimed that cannabis together with Indian hemp and another plant may be used to treat leprosy.

With the introduction of many new synthetic drugs in the later part of the 20th century as well as the variability of the natural product's potency and instability over time, interest in cannabis as a medication waned.

The advent of sophisticated analytical equipment together with complex chemical synthesis enabled many active compounds of the plant to be characterised.

These include cannabinol, cannabinoil, cannabinolidic acids, cannabigerol, cannabicheromene and several isomers of tetrahydrocannabinol - one of which is believed to be responsible for most of cannabis' characteristic psychoactive effects. This active isomer is delta 9-tetra-hydrocannabinol (THC), one of 61 cannabinoids available in cannabis.

Cannabis products are usually smoked in the form of loosely rolled cigarettes ("joints"). They may be used alone or in combination with other substances. They may also be administered orally, but have been reported to be three times more potent when smoked. The effects are felt within minutes, reaching their peak in 10 to 30 minutes and may linger on for two or three hours.

A condensed description of these effects is inadequate or even misleading. Most information depend upon the experience and expectations of the individual as well as the activity of the drug itself. Low doses tend to induce restlessness and an increasing sense of well-being, followed by a dreamy satate of relaxation, and frequently hunger, especially a craving for sweets.

Changes of sensory perception - more vivid sense of sight, smell, touch, taste, and hearing - may be accompanied by subtle alterations in thought formation and expression.

Stronger doses intensify these reactions. The individual may experience shifting sensory images, rapidly fluctuating emotions, and a flight of fragmentary thoughts with disturbed associations; an altered sense of self identity; impaired memory, and a dulling of attention despite an illusion of heightened insight. This state of intoxication may not be noticeable to an observer.

High doses may result in image distortions, a loss of personal identify, fantasies and hallucinations.

For the past 10 years, there has been a resurgence in the scientific study of cannabis.

One goal of the study was to develop therapeutic agents, where if used as directed in medical treatment, will not produce harmful side effects.

While THC can now be synthesised in the laboratory, it is a liquid insoluble in water. It decomposes on exposure to air and light. THC is also difficult to be prepared in stable dosage units.

Some of the more active areas of research include the control of nausea and vomiting caused by chemotherapeutic agents used in the treatment of cancer. Another area of research is its use in decreasing intraocular pressure in the treatment of glaucoma.

How Marijuana Affects The Body

The intake of 5 to 10 mg of THC into the bloodstream is sufficient to "get a high." A cannabis high is a combination of sedation, tranquilisation and mild hallucination. The user experiences mood changes which include mild euphoria, a relaxed dreamy reverie, a feeling of well-being, heightened appreciation of sounds and colors, remembrance of pleasure, imperception of time and space, a lag between thought and reaction, less precise thinking, and a flattened affect.

The individual may also experience hunger, thirst, and uncontrollable laughter, or nausea, dizziness and dryness of the mouth. Not all of these effects are experienced by every user.

Panic reactions are often reported, together with feelings of persecution, confusion and fear. This reaction seems to occur especially in a user who has taken high doses of the drug. In general, high doses of THC can cause illusions, pseudo-hallucinations, and paranoid thinking.

Memory And Perception:

There is now a general agreement that even moderate doses of cannabis can cause short-term memory loss. Moderate doses impair intellectual functioning in several areas, including the ability to read with comprehension, to acquire, store, and recall information, and to communicate clearly. Attention span, tracking and perception may be impaired These reactions are all dose-related and temporary but are important in adolescents who are especially vulnerable to any long-term learning impairments.

Impaired concentration and memory deficits in the classroom not only slow the development of cognitive skills, but also coping skills, such as handling stress and the pressure of social adjustment and peer relationships. This means that young people can turn to the drug as a crutch to cope with the difficult process of growing up.

The Cardiovascular System

Respiratory System:

In moderate doses, THC causes bronchodilation; it might be beneficial to asthmatics. Heavy use has the opposite effect, causing slight obstruction of air passages. Heavy cannabis users will experience inflammation of the bronchi, sore throat, and inflamed sinuses.

Daily smoking of one joint will the volume of air that the lungs can expel after one breath. This is similar to smoking 16 tobacco cigarettes a day. Cannabis smoke appears to be more detrimental too the lungs than cigarette smoke.

Cannabis smoke has more tar than cigarette smoke. The practice of smoking the joint down to the end also ensures that the tars get into the smoker's lungs. Condensed cannabis smoke is said to contain about 50% to 100% more mutagens than tobacco.

Some researchers believe that the carcinogenicity of cannabis is equivalent to that of cigarette smoke. Both vapours contain carcinogenic polycylic hydrocarbons such benzopyrene.

One biopsy of the lungs of a cannabis smokers show extensive microscopic abnormalities associated with the development of bronchitis, emphysema, and lung cancer.

The combined use of cannabis and tobacco is worse than the use of either substance alone. Rodent skins painted with cannabis tars develop tumours just as they do with tobacco tars, However, direct confirmation of the generation of human lung tumour by cannabis has not yet been made.

Motor Coordination:

Cannabis will impair a person's driving ability, even after normal social use. It has been identified to cause marked deterioration in the performance of motor drivers under test conditions as well as impaired ability to handle emergency situations.

Drug interactions between cannabis and alcohol is especially effective in impairing motor coordination and steadiness of the feet Three drinks together with cannabis can cause intense nausea and vomiting.

Reproductive Functions:

Research reports on the effects of cannabis on reproduction are incomplete and sometimes contradictory.

Because of this, their significance is not clear. Cannabis appears to produce a brief fall in sperm production and alters the sperms' shape and mobility. In animals and probably in humans, THC reduces testosterone levels. However, the significance of this finding remains in doubt.

Pubescent boys appear to be especially at risk from a lowered testosterone level. Long-term administration of THC to mice cause an increase in abnormal ova. Studies of women who used cannabis regularly during pregnancy has shown that stillbirths and neonatal deaths increased. Studies have implicated cannabis in a syndrome indentical to the foetal alcohol syndrome. However, poly-drug use in the women studied made it difficult to pinpoint teratogenicity.

Amotivational Syndrome:

In the amotivational syndrome, it is suspected that regular use of cannabis dulls the mind of the smoker, blunts enthusiasm, takes away drive and makes the person content to sit around all day, red-eyed, but happy and hungry.


Although tolerance to most of the effects of THC can develop, it does not necessarily lead to increased drug taking. Regular heavy use leads to a mild physical and psychological dependence. The cannabis abstinence syndrome is characterized by irritability, restlessness, sleep disturbances, tremors, weight loss, GI upset, sweating and anorexia.

Other Actions

Burnout is a term used by cannabis smokers to describe the effects of long-term use. Young people who smoke cannabis heavily over long periods of time can become dull, slow moving and inattentive. Bourned-out users can be so unaware of their surroundings that they do not respond when friends speak to them and they do not realise they have a problem.

The most common adverse reaction to cannabis is a state of anxiety or panic, sometimes accompanied by paranoid thoughts. These can range from general suspicion to a fear of losing control and going crazy. Acute anxiety reactions are usually experienced by novice users, especially those who have ingested one of the more potent cannabis samples. Panic symptoms usually dissapear in a few hours as the drugs' effects wear off; most of the time, they can be handled by simple reassurance.

What are the risks?

The short-term risks to physical health in normal adults from occasional social smoking of cannabis appear to be minimal. Long-term smoking, especially in heavier amounts, can cause bronchitis and general irritation to the respiratory tract.

While there is no proof, very long-term inhalation of the mutagen and carcinogens in cannabis smoke very likely predisposes a person to cancer of the lung. People suffering from chronic diseases, psychosis or epilepsy are at risk if they smoke cannabis. Similarly, pregnant and nursing women should not smoke cannabis, nor should people taking medicines for diabetes or epilepsy.

In addition, those who drive vehicles or operate machinery while under the influence of THC or its metabolites are at increased risk of accidents. Cannabis smokers run a slight risk of poisoning from contaminations in their cannabis samples.

In 1982, the United States Centre for Disease Control reported that dozens of cases of salmonella intestinal infections were caused by the handling of cannabis that had been adulterated with animal manure. Cannabis will decrease the production of stomach acid, which is an important defence against infectious organisms swallowed. Regular cannabis smokers will become susceptible to infections.

How Long Does Marijuana Last in the Body?

THC reaches the brain quickly and produces a euphoric high in 20 to 30 minutes. Its obvious effects disappear in two to three hours. However, residual effects are demonstrable up to 10 hours after smoking a joint. THC is fat soluble and it and its breakdown products are stored in the brain, lungs, testes, ovaries, and body fat. Its slow release from these tissues permits its detection in the urine for up to 10 days following the last dose.

THC ingested by smoking or eating cannabis is transformed in the liver to 11-hydroxy-THC, and then to 9-carboxy-THC. Also formed are 8-hydroxy-THC. Its detection in the body or urine is taken as definitive proof of cannabis use.

The primary urinary ,metabolite of THC in humans is the 9-carboxy compound. Unlike THC and the hydroxylated derivatives which are psychoactive, 9-carboxy-THC is inactive. Chemistry laboratories are now equipped to detect THC and its metabolites in nanogram quantities in cannabis smokers' urine.

Studies have shown that because of its fat solubility, THC in active forms may be retained in the body for as long as 45 days after smoking.

In spite of the illegality of cannabis and the ill-effects of the substance, large numbers of people, especially youths, continue to use cannabis regularly. It is still being sought after, perhaps, based on the belief among users that they are harming no one, compared to cigarette smokers or alcohol drinkers.

It should be pointed out that the active ingredient in cannabis can make a user behave irritionally. There is now a growing trend in developed economies to legalise the use of cannabis based on the argument that cannabis is considerably less harmful than tobacco and alcohol, the most commonly used legal drugs.

In addition, there have been attempts to recognise cannabis as a drug for a wide variety of medical problems, based on its historical use as well as several scientific reports.

The above said medical use of cannabis has been evaluated by independent authorities which conclude that the alleged therapeutic properties have not been adequately studied in a scientific context and their general medical potential remains a matter of conjecture.

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