Cannabis sativa is an erect herb commonly known as hemp or marijuana, or by vernacular names such as grass, weed, refer, and pot. C. sativa is a member of the Cannabinaceae or hemp family. Marijuana can be cultivated illegally in eastern and central North America. Marijuana was legal in the United States for industrial, recreational and medicinal uses until 1937 (Anon., 1996a).
C. sativa contains about sixty various psychoactive chemicals called cannabinoids. The most active component in C. sativa is tetrahydrocannabinol or THC which is found in greatest concentrations in the flowering tops and leaves of the hemp plants. The word marijuana refers to the whole plant and the resin from hemp or also called hashish (Anon., 1996b).
Presently, C. sativa has four medicinal values. First, it is used to relieve nausea and increase appetite. Second, it brings about the reduction of intraocular pressure in glaucoma. Third, it causes a reduction of muscle spasms. Fourth, it provides relief from mild to moderate chronic pain (Anon., 1996a).
In 1975, a study was conducted testing the effects of marijuana on the cardiovascular system. People between the ages of 30-40 years, whom had never smoked marijuana were used for this experiment. Results showed that there is no direct cardiac effect of tetrahydrocannabinol (THC) unless the THC dose is 50 fold. There were no changes in stimulation of ephedrine production (which stimulates the sympathetic nervous system), levels of blood glucose, lactate or pyruvates and fatty acid fractions. Changes to these effects were observed when the THC dose was 50 fold (Beacansfield, 1975).
In a study in 1982, researchers analyzed the biological effects of chronic use of marijuana in human subjects. Pathological and biochemical tests were in a normal range. Chronic use did not produce serious, harmful effects in humans and a general medical examination showed no abnormalities. The researchers also concluded that marijuana can act as a hypotensive and reduce blood sugar, which is useful for treating hypertension, especially diabetic hypertension (Singh et al., 1981).
Marijuana alleviates nausea, vomiting, and the loss of appetite which results from the chemotherapy treatment (Anon., 1996a). A study conducted on cancer patients found that 14 out 20 patients exposed to THC showed an antiemetic effect. In comparison, patients exposed to the placebo or a "marijuana-like drug" showed no antiemetic effect (Sallan et al., 1975). The study concluded that THC is an effective antiemetic for cancer patients receiving chemotherapy in a dosage of 10 mg per square meter per dose every four hours for at least three doses (Sallan et al., 1975). Also smoking the marijuana shows a stimulation of increase in appetite and it is starting to be used to treat anorexia and other eating disorders (Anon. 1996b).
A survey of oncologists found that 48% would prescribe marijuana to some patients if it was legal. Also, of these oncologists, 44% have recommended the illegal use of marijuana to patients to alleviate nausea and vomiting (Doblin and Kleiman, 1991). Another study found that smoking marijuana rather than ingesting marijuana orally resulted in 72% reduction in nausea and vomiting (Chang, et al, 1979).
In the 19th century, Cannabis was used to treat migraine headaches, which acted by blocking the pain and preventing attacks. Migraines are caused by the release of the neurotransmitter serotonin and smoking marijuana or the THC inhibited the release of serotonin. Now people with migraines smoke a small amount of marijuana when an early sign of attack appears. Researchers are not sure if the effect of cannabis on migraine is an analgesic or antiemetic (Volfe, et al., 1985).
Cannabis can be used to treat bronchial asthma. A study conducted on patients with bronchial asthma compared the effects of 500 mg of smoked marijuana (2% delta-9-THC) with 500 mg of smoked placebo marijuana (0% delta-9-THC). The marijuana immediately treated the bronchospasm but the placebo marijuana showed a gradual recovery of 30-60 minutes. It was concluded that cannabis is an effective treatment for bronchial asthma (Tashkin, et al., 1975).
There are some side effects of smoking marijuana. Most people experience a "high" which is characterized by mood changes, easy laughing, elation, heightened awareness, mild aberrations of fine motor co-ordination, and minimal distortion of their activities and interactions with others (Sallan, et al., 1975). Another common side effect is somnolence which means an inducement of sleep. When marijuana is smoked at a high dose people can undergo a paranoid ideation, apprehension, fear, panic and frightening visual hallucinations (Sallan, et al., 1975). The manifestation of the side effects are dependent upon the dose of marijuana smoked.
Anon. 1996a. Don't Jail Medicinal Marijuana Patients. NORML. http://www.norml.org/medical/medmj.shtml
Anon. 1996b. Tetrahydrocannabinol - THC. http://www.ch.ic.ac.wk1/vchenlib/mim/bristol/thc.htm
Beacanfield, P.C.R. 1975. Some cardiovascular effects on cannabis, experiment in 30-40 year olds. Amhearst 87:143-146.
Chang, et al. 1979. Delta-9-Tetrahydrocannabinol as an antiemetic in cancer patients receiving high dose methotrexate. Annals of Internal Medicine 91:819-824.
Doblin, R. and M. Kleiman. 1991. Marijuana as antiemetic medicine: A survey of oncologists' experiences and attitudes. F. Cline Oncology 9:1314-1319.
Sallan, S.E., N.E. Ainberg, and E. Frex. 1975. Antiemetic effects of delta-9-tetrahydrocannabinol in patients receiving cancer chemotherapy. The New England Journal of Medicine 293:795-797.
Singh, N., S. Vrat, B. Ali, and K.P. Bhargava. 1981. An assessment of biological effects of chronic use of cannabis in human subjects. Quarterly Journal of Crude Drug Research 19: 81-91.
Tashkin, D.P., B.J. Shapiro, Y.E. Lee, and C.E. Harper. 1975. Effects of smoked marijuana in experimentally induced asthma. American Review of Respiratory Disease 112.
Volfe Z., A. Dvilansky. and I. Nathan. 1985. Cannabinoids block
release of serotonin from platelets induced by plasma from migraine
patients. International Journal of Clinical and Pharmacological
Research 5:243-246.
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