The Properties and Effects of Marijuana

The chemical compounds primarily responsible for the psychoactive and medicinal properties of the hemp plant are concentrated in an aromatic, tar-like resin in the flowering tops of the Indian hemp plant (Cannabis sativa). This resin tends to be most potent in the female plants, especially when they are cultivated before the seeds form. (They are also known as sinsemilla, a Spanish word meaning without seed ) It is said that the hemp plant produces the resin as protection from heat in order to preserve moisture during reproduction. The plants highest in resin therefore tend to grow in hot regions such as Mexico, the Middle East, and India. 

It is the flowers, buds, or leaves of the hemp plant that are known as marijuana. The resin itself can be collected and pressed into cakes or lumps called hashish. In addition, the resin can be extracted into a thick, oily liquid known as hashish oil. Any of these preparations can be eaten or smoked. 

The three most prevalent varieties of the Indian hemp plant are Cannabis sativa (C. sativa), the most common of the three varieties, which is tall, loosely branched, and grows as high as 20 feet Cannabis indica, which is three or four feet in height, pyramidal in shape, and densely branched and Cannabis ruderalis, which grows to a height of about two feet with few or no branches. There is disagreement over whether these three cannabis types are different species or whether C. sativa is the main species of Indian hemp, with the other plants 

There are differences among these plants in the leaves, stems, and, most important, the resin. The resin content determines the the effective strength of a hemp preparation yet the resin amount can vary greatly from plant to plant. Hashish, a more concentrated form of resin, is about eight times stronger than marijuana. Cannabis bred specifically for industrial use with little or no 

The psychoactive and medicinal chemical compounds found in the resin of the marijuana plant are known as cannabinoids. The cannabis plant contains more than 460 known compounds over 60 of these have a cannabinoid structure. The only cannabinoid that is highly psychoactive and present in large amounts in the resin of the cannabis plant is tetrahydrocannabinol, or THC. The other two major cannabinoids are the cannabidiols and the cannabinols. It appears that the cannabis plant first produces the mildly active cannabidiols, which are converted to the more psychoactive THCs and then broken down to relatively inactive 

---

The concept of tolerance is important in understanding the properties and effects of marijuana. Tolerance can be defined as the need for increasing doses of a drug over time to maintain the same effect achieved at previous lower doses. Receptors in the brain develop a tolerance to THC. Since the body becomes tolerant to the effects of marijuana, heavy users often feel a decreasing effect from the drug and thus may need to smoke ever-increasing quantities to achieve the earlier high. Because of this, we can see why tolerance is an important characteristic of dependence on marijuana. 

Cannabis sativa, one of the oldest plants farmed by man, has been known for its medicinal properties for at least four millennia (Peters, 1999). The psychoactive-euphoric effects of this plant, as well as its facile and wide climatic range of cultivation, have rendered it a very popular recreational drug. Today, cannabis, or marijuana, is still the focus of strong social, legal, and medical controversy over its therapeutic utility. 

Cannabinoids appear to have a very complex interaction with seizure activity, exerting both anticonvulsant and proconvulsant effects. Anecdotal testimonies abound (Grinspoon and Bakalar, 1993), but there has been very little controlled human research. In single-case studies both use and withdrawal of marijuana have been linked to the resumption of seizures (Keeler and Reifler, 1967 Consroe et al., 1975). In a randomised placebo-controlled blind study, patients who responded poorly to standard treatments experienced improved seizure control in response to cannabidiol administration. Cannabidiol does not interact with cannabinoid receptors, and animal studies indicate that it has different anticonvulsant effects to other cannabinoids (Cunha et al., 1980). As such it may prove to have useful therapeutic properties. 

The cannabis plant has been cultivated for centuries both for the production of hemp flber and for its presumed medicinal and psychoactive properties. The smoke from burning cannabis contains many chemicals, including 61 different cannabinoids that have been identified. One of these, A-9-tetrahydrocannabinol (A-9-THC), produces most of the characteristic pharmacological effects of smoked marijuana. 

In the past, evidence has been obtained that cell-mediated immunity in moderate marijuana smokers may be impaired, as judged by the response of their T-lymphocytes to transformation with phytohaemagglutinin (SED VIII, p. 54). Cushman and Khurana (18 ) have since then studied the effects of marijuana smoking on sheep cell rosetting properties of both early (active) and total T-lymphocytes in vitro. Significantly fewer active rosettes were formed by T-ceUs from a population of 35 individuals who appeared to be chronic marijuana smokers than from 34 control subjects. On the other hand, the late (cold-enhanced) rosettes formed by smokers and non-smokers were similar. 

The body s systems respond more slowly after marijuana is eaten. People who ingest marijuana, which may be cooked and incorporated into a meal, experience a slower onset of effects because the drug has to first go through the digestive process before it reaches the bloodstream and is carried to the central nervous system. The stomach absorbs marijuana unevenly after it is eaten owing to the fat-soluble properties of THC. Regardless of whether THC is inhaled or ingested, heat is required to convert marijuana to its psychoactive properties... 

A South American group has shown that CBD (27) has anxiolytic and antipsychotic properties [181,182] and decreases the anxiety effects of THC [183], Thus, it is quite possible that CBD (and other constituents ) in marijuana mellow the THC effect. Most of the clinical trials published so far are with THC or nabilone. Is it possible that marijuana is a better drug than THC, as is often claimed, because of the presence in it of both CBD and THC If this is correct, is it also possible that other inactive constituents... 

Nabilone is a synthetic cannabinoid and has properties similar to tetrahydrocannabinol (the active constituent of marijuana) which has an antiemetic action. It is used to relieve nausea or vomiting caused by cytotoxic drugs. Adverse effects include somnolence, dry mouth, decreased appetite, dizziness, euphoria, dysphoria, postural hypotension, confusion and psychosis. These may be reduced if prochlorperazine is given concomitantly. 

The most abundant member of this group is the cannabinoid Al-THC-7-oic-acid. When tested in humans as well as in the rhesus monkey, this cannabinoid did not show the behavioral activity or the cardiovascular effects characteristic of the parent substance, THC. (Perez-Reyes, M. In Pharmacokinetics and Pharmacodynamics of Psychoactive Drugs, Barnett, G. and Chiang, N. (eds), Biomedical Press, 1985, pages 287-310 Mechoulam, R. and Edery, M. ln Marijuana, Mechoulam, R. (ed.), Academic Press, New York, 1973). Thus, little attention has been given to the possible pharmacodynamic properties of this metabolite or any of the other acid metabolites of THC. 

In 1839, Or. W. B. O Shaughnessy stimulated the interest of Western medicine with his studies of marijuana in the treatment of various diseases. He found tincture of hemp to be an effective analgesic and to have anti-convulsant and muscle relaxant properties. Between 1839 and 1900 more than 100 articles appeared in scientific journals describing the medicinal qualities of the piant. In 1845 J. J. Moreau de Tours wrote of... 

---