Home Page of the DPNA Website Learn about the Drug Prevention Network of the Americas, its history, principles, members, supporters, and board Looking for information about drug prevention?  Check out our web page links, books, presentations, position papers, and brochures Want to connect with national, regional or international drug prevention sites?  Visit our extensive Links section. Keep up with the latest drug prevention news and events. Ready to become a part of the Drug Prevention Network of the Americas?  Sign up on line.



WWW DPNA News and Updates
Drug Research
Opinions
Drug Effects
Drug Information
Drug Trends
Best Practices
Drug Legalization
Drug Policy
Books and Guides
Brochures
Courses
Presentations
Funding Sources

 


Is cannabis a medicine

Dr. Hans Koeppel, M.D.

Cannabis has been promoted in the United States over the last 20 years as a means of relieving a wide range of conditions. It is said to provide relief for chronic states of pain, loss of appetite in the case of aids patients and cancer sufferers, nausea and vomiting (as a result of chemotherapy), asthma, glaucoma (increased internal pressure on the eye) and for sufferers of multiple sclerosis. Many marijuana users report that their symptoms are relieved, and that smoking this substance confers a feeling of well-being. As a result of referendum decisions, doctors in ten US states can now prescribe marijuana as a medicine.

But various questions remain unanswered:

  • Is cannabis really effective?

  • Do we really take into account the cancer risk produced by smoking parts of a dried plant that contains hundreds of chemical substances, some of which are classed as carcinogenic?

  • Should we not wait until the active ingredient becomes available in a pure form, for administration by tablet or as drops?

  • What about the side-effects?

  • The main question is: Does cannabis fulfil the strict official guidelines on what constitutes an approved medical drug?
     

Cannabinoids

The terms “cannabis” and “marijuana” refer to the dried, unfertilized female flowers and leaves of the Indian hemp plant. The narcotic effect of the hemp plant is obtained from the 60 cannabinoids that it contains, particularly delta-9-tetrahydrocannabinol (THC), its biological precursor cannabidiol (CBD) and the THC decomposition product cannabinol (CBN). These substances stimulate the cannabinoid receptors in the central nervous system of the organism. The body’s on-board (endogenous) triggers for these receptors are called endocannabinoids, which play an important role in the modulation of many neuronal processes.
 

Endogenous cannabinoids

Human cannabis receptors CB1 and CB2 were discovered only 15 years ago. The human body possesses more CB1 receptors than dopamine, serotonin and noradrenaline. The endogenous substance that docks with these receptors to make them effective is anandamide. The role of anandamide receptor systems in the human body continues to be unclear.

The largest number of CB1 receptors, to which anandamide and THC attach themselves, are found in the brain. CB1 receptors are located above all in the frontal lobes (responsible for motivation, planning) and in the basal ganglia and cerebellum (responsible for movement, coordination). In the limbic system, these receptors are present above all in the hypothalamus (regulation of food intake and body weight). Many of these receptors are also present in the hippocampus (memory). Their relatively low presence in the brain stem, from where the respiratory system is controlled, explains why it is not possible to die from an overdose of cannabinoids.

CB2 receptors are distributed around most of the body’s organs, with high concentrations in the spleen, the testicles and the immune cells.


How the body absorbs cannabis

Marijuana, or THC, can be taken in various ways:

- Smoking leads to fast absorption by the body, with an immediately high plasma concentration. A particular disadvantage in this respect is the inhalation into the lungs of three times more tar than the equivalent in cigarettes.

The results of smoking cannabis are somewhat comparable to those of heavy cigarette smoking. It can lead to lung diseases such as chronic bronchitis, phlegm, shortness of breath and whooping cough, apart from colds, inflammation of the lungs and lung cancer.

- Synthetic THC in pill form, from an inhaler or as an oral spray: In order to avoid absorption of medicine by smoking, synthetic THC has been tested in pill form, and from an inhaler or oral spray.

Marinol, a synthetic THC, has been approved in the USA as a prescription drug since 1985, as have Nabilone in the UK and Dronabinol in Germany. The drug can be used to combat the nausea suffered by cancer patients undergoing chemotherapy, and for stimulating the appetite of people suffering from aids. Studies show however that swallowed THC results in widely fluctuating levels of bioavailability, i.e. the amount of substance absorbed by the body cannot be predicted, and varies from person to person.

A plant extract of cannabis has recently become available in the UK as an oral spray sold under the Sativex brand name. The bioavailability of Sativex is more constant than when the drug is delivered in tablet form.

Compared to THC in tablet form, THC in suppository form delivers good bioavailability, constant plasma levels and thus greater effectiveness. Suppositories provide an ideal method of delivery for patients suffering from nausea and vomiting as a result of chemotherapy. However, no such preparation is yet available on the market.

As soon as fat-soluble THC enters the body, it is taken up by fatty tissue for temporary storage. Its half-life period in the body (i.e. the time taken for half of the THC to be eliminated) is approximately one week. A long half-life period of this type makes dosage difficult, and brings with it a danger of accumulations of the substance in the body, resulting in symptoms of toxicity.

Development of new medicines

The standards applied worldwide are, for good reason, very high when it comes to the approval of new substances designed for medical use. These norms are largely based on quality, safety and effectiveness.

1. Quality

Requirements: development of constant forms of dosification covering the latest known compound. Clinical trials cannot be carried out without a constant form of dosification. All active ingredients must be identified, and their chemical properties must be known. The active ingredients must be tested for purity. There are maximum permitted levels with respect to impurities such as pesticides, bacteria and fungi, fertilizers and their products of decomposition. These tests must be recognized, and it must be possible to replicate them in any laboratory.

Cannabis contains over 400 chemical substances, in quantities that vary with the type of plant and method of cultivation. Many of these 400 substances are still unidentified. The concentrations of THC and other cannabinoids can also vary. For these reasons, it has to date not been possible to standardise the active ingredients. Cannabis is often contaminated with microbes, fungi, fertilizers and pesticides.

All scientific articles on cannabis or THC criticize the fact that testing is carried out on substances of varying composition. Some studies have been carried out with cannabis, others with synthetic THC such as Marinol or Nabilone, with cannabinol or with intramuscular injections of levonantradol.

2. Safety

The health consequences of smoking cannabis are serious, as is the danger of developing mental problems and addiction.

- Physical health: The main risk is of damage to the lungs, as hundreds of carcinogenic substances are inhaled. This results in an increased risk of cancer of the respiratory organs and chronic lung damage.

Cannabis in the form of synthetic THC also has undesired effects on the brain. This has resulted in such conditions as attention deficit and loss of memory and perception, with a negative effect on movement coordination. These side-effects also exert a harmful influence on driver behaviour and safety in the workplace. The long half-life period supposes heightened risk for persons who work, for example, with industrial or construction machinery, or in chemical plants or power stations.

Further consequences of cannabis consumption include harm to the hormone and immune systems.

- Mental health: The smoking of cannabis can lead to general feeling of anxiety, loss of motivation, panic attacks, ideas of persecution, psychotic symptoms and the onset of schizophrenia. Cannabis use can lead both to the onset of schizophrenia in persons so predisposed, or to a worsening of the symptoms in persons already suffering from this condition.

- Dependency: Withdrawal symptoms can include restlessness, excitability, irritability, insomnia, nausea and muscular cramps.

- Pregnancy/parenthood: The children of mothers who smoke cannabis during pregnancy suffer from stunted growth and have learning difficulties and behavioural problems, along with a ten-fold increased risk of contracting leukaemia. This is in addition to the problems that arise if parents are unable, as a result of their drug consumption, to act as effective guardians and educators.

3. Effectiveness

The effectiveness of a substance is investigated accordingly in various clinical-test phases. These clinical tests are a vital prerequisite if a substance is to be approved for medicinal use.

Clinical test phase I involves trials of the substance on healthy test subjects in order to study bodily absorption rates, bioavailability, half-life period and the speed at which the substance is eliminated from the body.

Clinical test phase II is used to investigate the effect on patients with different symptoms and medical conditions in order to determine the most effective dose.

In phase III, large groups of subjects are tested in order to reveal any statistically relevant factors. Control groups, which are given only a placebo or generic standard medicine, are also included in the testing process. The study must be randomized and double-blind.

If all studies are successful, i.e. if the substance’s therapeutic properties are proven and there are no major problems with toxicity or serious undesired side-effects, the active ingredient is then recognised as a medicine and approved as such by the corresponding health authorities.

Cannabis has not undergone these clinical-test phases, and has not been recognised as a medicine by any public health authority. Therefore, its use is not harmless, it is possibly of no benefit and it can be a health risk.