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IACM 3rd Conference on Cannabinoids in Medicine
Leiden, 9-10 September 2005
The International Association for Cannabis as Medicine (IACM) held its third international scientific conference on cannabinoids in medicine at Leiden University, the Netherlands, 9-10 September 2005 in cooperation with the Office for Medicinal Cannabis of the Dutch Ministry of Health and the Institute of Biology, Leiden University.

The International Association for Cannabis as Medicine (IACM) was founded in March 2000 (www.cannabis-med.org : text in 6 languages). It is a scientific society advocating improvement of the legal situation concerning the use of the hemp plant (Cannabis sativa L.) and its pharmacologically most important active compounds, the cannabinoids, for therapeutic applications by promoting research and dissemination of information.

Conference abstract book

The abstract book with the programme, lecture and poster abstracts for the international conference can be downloaded from the website (www.cannabis-med.org/english/nav/home-leiden.htm).

It was evident from the conference that scientists and the pharmaceutical industry in a number of countries are actively researching different aspects of cannabis and cannabinoids. These countries include the USA, Canada, United Kingdom, Netherlands, Germany, Italy, Belgium, Israel, Spain, Switzerland, Australia, Argentina and Japan. The Netherlands is the only country where the ministry of health has an office for medicinal cannabis (OMC). The OMC is designated as the national agency for the controlled cultivation of cannabis under standardised conditions and its distribution to pharmacies.

What is cannabis ?

Cannabis, also widely known as marijuana, is commonly used to describe the product made from the female flowers of the plant Cannabis sativa L, also known as hemp. Many varieties of this plant occur. There are varieties specifically used for fibres (paper, rope, textile), varieties for hempseed from which an edible vegetable oil is produced and varieties for medicinal purposes. The term hemp refers to the use of the stalk and seed, while cannabis refers to the use of the flowers and leaves. The term hashish refers to cannabis resin from the female flowers in which the pharmacologically active compounds are found. The fibre type of cannabis contains very low levels of the pharmacologically active compounds and is still widely cultivated in Europe.

Hemp is a hardy plant which has been cultivated since ancient times when primitive man first started growing crops. Down the centuries hemp fibre was extensively used for making rope, cord, thread, cloth and paper and was consequently an important agricultural product. The earliest printed paper in existence, a Chinese text dating back to 770 AD, is made of pure hemp. Use of hemp for paper continued until the beginning of the 20th century when chemical were invented that allowed paper to be made from wood pulp. The ships of Christopher Columbus were fully rigged with hemp ropes and sails. Even today, the interior panels in some modern cars are based on hemp fibre. Hemp seeds, rich in lanolin and linolenic acids, are extremely nutritious and would probably have been gathered by early man as food, while hemp seed oil has been used for many purposes including industrial, cosmetic and food.

Medicinal cannabis

Cannabis has a long history of use for medicinal purposes that goes back many thousands of years. The first written record of its medicinal use was in the pharmacopoeia of the Chinese Emperor Shen-Nung in 2700 BC. It was also used in ancient India both for medicinal purposes and for its intensification of sensory perception in relation to religion and mysticism.

In modern times, Canada became the first country to adopt a system allowing the medicinal use of marijuana in July 2001. In 2003 the Netherlands became the first country in the world to offer cannabis as a medicine. In most countries of the world, cannabis is still listed as an illegal drug.


There are currently three main groups of cannabinoids: herbal cannabinoids that occur only in the cannabis plant; endogenous cannabinoids produced in the bodies of humans and animals; synthetic cannabinoids that are similar compounds produced in the laboratory.

The cannabis plant produces at least 60 different herbal cannabinoids as well as some 200-250 non-cannabinoid constituents. The cannabinoids are the active ingredients of cannabis and include the psychotropic dronabinol (tetrahydrocannabinol - THC) and the non-psychoactive cannabidiol (CBD). Herbal cannabinoids activate the body’s cannabinoid receptors.

There is growing evidence that cannabis may be effective in alleviating symptoms of intractable (chronic) pain, muscular convulsions and spasms, tremor, inflammation, anorexia/appetite stimulation, acute migraine, neurological diseases, severe asthma, depression, nausea caused by chemotherapy and glaucoma in patients with a variety of diseases and conditions including MS, AIDS, spinal cord injury, and cancer.

Synthetic cannabinoids are a hot topic in industrial drug development since compounds with a similar activity (agonists) to THC are useful for treating appetite problems, while in the future compounds with the opposite effect (antagonists) may be available to treat obesity.


Methods of use currently include inhalation by smoking (pipes), vaporization or water-pipes, oral such as tea, sublingual tablets or spray, capsules, cannabis chocolate bars; topical use in the form of ointment or crème. The advantage of smoking or inhalation is that the effect starts within minutes, whereas oral use may take more than an hour before an effect is felt.


Conference presentations and posters


Philip Robson et al.
An interesting presentation in the first session (clinical studies) concerned the results of a double-blind placebo-controlled trial, presented by British researchers, into the long-term effects in multiple Sclerosis (MS) of a cannabis-based medicinal extract (CBME - Sativex) in the form of an oral spray. 137 patients took part in this study and all of them suffered significantly from at least one of the following symptoms: spasticity, spasms, bladder problems, tremor or pain. The study demonstrated that the beneficial effects of CBME on spasticity and other symptoms in MS seem to be maintained over long-term treatment, with no evidence of tolerance. The most common adverse effects were oral irritation from the spray, dizziness, diarrhoea and nausea.

Donald I. Abrams et al
A clinical study using smoked cannabis in 50 patients with HIV-related painful peripheral neuropathy came from the University of California San Francisco. The researchers concluded that smoked marijuana is effective in reducing chronic ongoing neuropathic pain as well as acute pain in the experimental pain model. The magnitude of the response of the neuropathic pain is similar to what is seen with gabapentin, a widely used treatment for HIV neuropathy.

Jeffrey Y. Hergenrather et al.
Californian physicians involved in the practice of cannabis consultations regularly encounter patients with autoimmune and idiopathic inflammatory conditions. A substantial number of these patients have Crohn’s disease. This pilot study concerned a retrospective chart review of 20 patients with Crohn’s disease who were approved to use cannabis for relief of symptoms, including abdominal pain, diarrhoea, fatigue, anorexia and weight loss as main complaints. Preliminary results indicate that the majority of patients experienced a substantial improvement of their clinical course and a marked reduction or discontinuation of conventional medication following the regular use of cannabis.

Two studies concerned the clinical use of the vaporisation technique, one study from the Netherlands and one from California USA:


Arna Hazekamp et al.
These researchers from the Netherlands believe that what is needed for optimal use of medicinal cannabinoids is a feasible, non-smoked, rapid-onset delivery system. The aim of this study was to evaluate the use of the Volcano® vaporizer in terms of reproducible administration of pure THC without the formation of degradation products. Vaporization is a technique that reduces the intake of toxic components. The Dutch researchers concluded that by using the Volcano for pulmonal administration of THC, delivery was achieved comparable to smoking but without degradation products or harmful by-products in significant amounts. The Volcano seems to be a safe and effective cannabinoid delivery system for patients and is currently being used in clinical studies as a standard method for testing new synthetic cannabinoids.

Donald I. Abrams et al.
This Californian study also concluded that vaporization is a safe mode of delivery and said that participants had a clear preference for vaporization over smoking.

A poster from the Trimbos Institute in the Netherlands gave food for thought:


Matthijs G. Bossong and Raymond J.M. Niesink
This poster concerned the hypothesis that the abuse of cannabis during adolescence increases the risk of developing psychoses and psychotic symptoms in adulthood. The aim of this study was to find a biological explanation for this increased risk.
The conclusion of the researchers was:

  • abuse of cannabis during adolescence disrupts the function of the endogenous cannabinoid system
  • developmental processes will be disturbed, resulting in improper brain circuitry and synaptic connectivity
  • incorrect adult circuitry of the PFC will cause erroneous integration, interpretation and controlling of impulses
  • thus use of cannabis during adolescence may induce psychoses and schizophrenia.

All abstracts can be found in the abstract book on the IACM website www.cannabis-med.org.


My general conclusion from this conference is that, although much research is being done worldwide, there is nevertheless still a long way to go before all the active ingredients of this very complex plant are known and understood. Much more research is needed to a) produce a form of treatment that eliminates unwanted side-effects while retaining the beneficial medicinal effects and b) to further investigate both the tolerance aspect and the addiction aspect.

There indeed appear to be beneficial palliative and anaesthetic effects for those with muscular spasms and intractable pain, MS, AIDS, cancer and possibly other medical conditions.

However, it is clear that medicinal cannabis in all forms still has the risk of uncontrollable and unpredictable side-effects which may be severe or frightening in some patients. The mood changes induced by cannabis may result in nightmares or confusion in certain people while use may precipitate neuroses or psychoses in those who are at risk or predisposed to psychotic disorders. Smoking cannabis particularly produces unwanted side-effects and there is a suspicion that it may give a greater risk of cancer than normal tobacco. On the other hand, inhalation produces faster effects than an oral drug.

A problem exists for patients being treated with medicinal cannabis with regard to driving under the influence of medicinal cannabis. This aspect is currently being looked into.

A problem for researchers is that is difficult to carry out placebo-controlled trials with smoked/inhaled cannabis since it is instantly obvious to most participants if they are receiving placebo and not cannabis.

Bearing in mind the current problems with side effects, treatment is at present most appropriate in patients with intractable severe symptoms when no other treatment provides relief. On the other hand, however, the side-effects currently being experienced with cannabis by some patients should be balanced against the sometimes equally severe side-effects caused by other regular drugs.

Further research and development will undoubtedly bring useful treatment options in future years. Maybe this will include a pain treatment option for patients with painful bladder syndrome/interstitial cystitis.

Jane Meijlink

updated 14.02.2006 16:02 © 2006-2018 International Painful Bladder Foundation (IPBF). All rights reserved.