Marijuana is the dried aerial tops of the plant Cannabis sativa L. The compound leaf of five to seven leaflets with serrated edges has been reproduced on so many posters, books, papers and T-shirts as to be recognizable by almost everyone.
Other features of the plant, such as the fact that the male and female plants are separate, and that it produces a “high”, are also common knowledge. However, not so well-known, is the fact that the plant produces small glandular hairs which secrete a greenish-brown sticky fluid.
This resin, which contains a number of substances, produces a group of chemicals, known as cannabinoids, which includes tetrahydrocannabinol (THC), which is the euphoric, hallucinatory agent. The resin, which oozes out naturally or if the cells are broken, hardens on exposure to air and forms stone-like masses which are known as “hashish”.
Tetrahydrocannabinol is a greenish-yellow liquid which is very unstable. The A9 isomer is the most active hallucinatory constituent. Other constituents exert some hallucinatory effect, and cannabinol, although inactive in itself, has a synergistic or reinforcing effect with THC.
As marijuana and hashish have the same active constituents, they have the same effect, only the latter is the more potent. Apart from marijuana and hashish, there is an alcoholic extract known as “red oil“, or more recently as “white oil” which is also used. This is a potent preparation, but not as potent as the resin.
Before cannabis became popular as a social or street drug in Western society, it was used in Western medicine. The medicinal use of the drug was first promoted by William Brooke O’Shaughnessy, a physician practicing in India around 1840.
He had carefully researched the use of cannabis in Indian medicine and had also conducted animal experiments as to toxicity and dosage. He found that cannabis relieved pain, acted as a muscle relaxant and as an anticonvulsant.
Physicians in Britain and Europe thought his findings useful, and reports appeared in medical journals of the application of cannabis to a number of conditions.
In America, the Ohio State Medical Society convened a committee in 1860 to examine the use of cannabis in medicine and claimed the successful treatment of neuralgic pain, dysmenorrhea, delirium tremens, whooping-cough, asthma, nervous rheumatism, chronic bronchitis, muscular spasm, epilepsy and lack of appetite. Some of these conditions are being investigated at present to see if they respond to treatment with cannabis.
Preparations of cannabis were included in the Pharmacopoeias of Britain and the United States. The last official American compendium of drugs to include cannabis was the United States Pharmacopeia of 1938. Cannabis was included in the Indian Pharmacopoeia of 1955 and in the British Pharmaceutical Codex until 1954. The extracts of cannabis were used in mixtures and pills as mild analgesics, to soothe spasm and induce sleep.
Although falling out of favor, as did most other plant extracts because of the difficulty in standardizing the preparations, cannabis continued to be used, and appeared in the 1958 Martindale: The Extra Pharmacopoeia, a reference book used by all pharmacists in English-speaking countries. Tincture of Cannabis was kept in pharmacies in Australia until the 1966 Poisons Act made cannabis a prohibited substance.
The revival of marijuana as a social drug in the 1960’s triggered off an enormous amount of research into the actions of cannabis in the body and on the mind. As part of this interest in the actions of cannabis came a renewed interest in its therapeutic uses. The uses to which it was put in earlier medicine gave the lead to new research into its therapeutic possibilities.
Cannabis was tested on five epileptic children in Britain in 1949. These children had not responded to other therapy. Three of the children showed improvement, one was completely cured, while the fifth showed no convulsions.
In 1974, it was reported that a 24-year-old male needed cannabis with phenobarbitone and diphenylhydantoin to control his seizures.
In Sydney, a 31-year-old male, who had started having seizures several years ago, reported that the use of marijuana had controlled his seizures when conventional therapy had not. He had only had one convulsion in five years and this was when he was unable to get supplies of marijuana.
Of course, in Australia it is illegal to use cannabis and he is legally at risk. It was reported at the 1978 conference on cannabis in Rheims that research is suggesting that cannabidiol, not THC, is better in epilepsy.
Cannabis preparations have been used in patients with terminal cancer to alleviate pain and reduce vomiting induced by chemotherapeutic agents. THC was administered orally to patients with cancer pain.
At a dose of 20 mg, side effects were too adverse to continue use but at 10 mg, the THC was well tolerated and mildly sedative. Probably more valuable in cancer treatment is the fact that THC has been found to reduce vomiting, that it has an anti-depressant action, and that it stimulates the appetite.
Nabilone, a cannabinol derivative developed by a large pharmaceutical manufacturer in the United States, has been shown to be an effective anti-emetic and useful analgesic in cancer patients.
Earlier medical use was mainly as an analgesic/tranquilizer but recent research has not found any particular advantages in this area. As an anti-anxiety drug, THC does not appear to be any better than diazepam (Valium) but could be used. THC does act as an analgesic but the action is variable.
Several synthetic derivatives are being tested an analgesic-sedative relaxants. THC has been tried as premedication in oral surgery but the side effects in terms of time distortion, visual effects and paranoid thought, precludes its use in this field.
One report emphasizes the importance of environment in determining the quality of response to cannabis. It also recognizes the widespread use of the drug and persons practicing in any medical field should be aware of its actions.
In Australia, there is a report of a patient who used cannabis and had no postoperative pain after open heart surgery. This is only one case but bears consideration.
Probably most of the new research has been concentrated on the use of THC in asthma. THC is a bronchodilator and as such has been tested with asthmatic patients. THC is not water-soluble and is therefore difficult to formulate in pharmaceutical preparations.
However, an aerosol has been developed and tested. Aerosol THC was better than isoprenaline after 1 to 2 hours and better than placebo after 2 to 3 hours. Side effects were dose related and the only one of note in the lower therapeutic dose range was some local irritation.
THC aerosol was equally effective when compared with salbutamol (Ventolin) after one hour. However, when given orally, THC was found to be of little use.
The other major area of modern research has been the use of marijuana to relieve intraocular pressure. This action was not known in earlier medicine and was only discovered in 1971. The first report was from a patient who found that smoking marijuana relieved his glaucoma, a condition where the pressure in the eye is increased.
THC administered intravenously in clinical trials reduces intraocular pressure but also produces a “high”. At present this “side effect” precludes its general acceptance as a treatment for glaucoma. In Australia one physician in South Australia applied to the Health Commission to use marijuana with a patient whose glaucoma was not responding to other treatment.
Cannabis was found to have an effect on the heart many years ago, so that some research has been conducted into cannabis and the cardiovascular system. The effects are not only dose related but also dependent on the length of time over which the drug is given.
Single doses produce a rapid heart beat. However, taken over a long period of time, cannabis preparations produced a slowing of the heart and a lowering of the blood pressure. Different derivatives so far tested have produced different effects, and none are without side effects so that it does not appear that cannabis will provide a new drug for high blood pressure.
Cannabis has also been used for the treatment of alcoholism and addiction to the narcotics. There appeared to be more beneficial effects with alcoholics than with narcotics addicts.
In considering the usefulness of any of the cannabinoids as therapeutic agents, it is necessary to avoid the emotionalism that surrounds the social use of marijuana and think of THC and its derivatives as with any other drug.
- Firstly, the action of all drugs in dose related. There is a dose at which no action occurs; there is a dose at which increasing action will occur until a level is reached at which the drug is toxic.
- Secondly, different individuals react differently to drugs depending on age, sex and weight, and on whether other drugs are being taken at the same time, as well as ingestion of food and a number of genetic factors.
- Thirdly, all drugs have some side effects. Antihistamines, taken to dry up nasal secretions cause drowsiness. This is probably an advantage when going to bed with a cold but dangerous when driving a car. Streptomycin can cause deafness and it is, therefore, not given over a long period of time and given only under medical supervision.
The derivatives of cannabis if they are being considered as therapeutic agents, must be given in doses to suit a particular patient and the use should be monitored. As with any other drug the side effects that may occur in a particular patient must be weighed against the benefits to that particular patient.
It would appear that cannabis derivatives could be of use to some patients for epilepsy, glaucoma, asthma and to alleviate the symptoms of cancer. Only continued research will find out the exact, if any, therapeutic uses of cannabis, but ignoring it will find out nothing.