GW Pharmaceuticals

Who are they?

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"My professional view of cannabis as a substance is that it appears to be a remarkably safe substance in comparison to most medicines prescribed today. The more I learn about this plant the more fascinated I become. It has through its various constituents multiple effects of therapeutic interest, many of which are now being validated by the enormous growth in basic cannabinoid research." - Dr Geoffrey Guy, Chairman of GW Pharmaceuticals.

On the 11th of June 1998, the campaign for the availability of medical marijuana received a boost, as a UK-based company, GW Pharmaceuticals received a license from the Home Office in order to conduct research into the medicinal uses of cannabis. The company had noted the large amounts of evidence that cannabis has beneficial effects on a number of medical symptoms. They then set out to conduct controlled clinical trials to evaluate these with a view to producing a final product to bring relief to thousands of sufferers to whom existing pharmacological treatments do not suffice. GW Pharmaceuticals thus became the only company in the UK licensed to provide raw cannabis materials for trials.

Is this legal?

Research on medicinal cannabis is generally forbidden under the Misuse of Drugs Act 1971. GW Pharmaceuticals applied to the Home Office in order to receive permission to conduct these vital trials. They receieved two licences:
A Cultivation Licence, allowing GW Pharmaceuticals to grow cannabis plants from seed or by cloning, subject to strict conditions.
A Possession and Supply for Medical Research licence allowing GW Pharmaceuticals to store cannabis in specified secure conditions, and supply the stored cannabis solely for research purposes.

GW Pharmaceuticals then collaborated with the Dutch plant-breeding company Hortapharm which allows GW Pharmaceuticals to use any of Hortapharm's cannabis plant varieties, and provide assistance in the cultivation of their own, in return for the development of devices to safely administer the cannabis medication into patients.

The first cannabis seeds were sown in July 1998, and by November 1998, GW Pharmaceuticals had a healthy crop of 5000 cannabis plants growing in the agreed secure storage structure in the South of England. It was thought that during the research about 20000 plants would be needed, most of which would be cloned off the 5000 grown from seed.

In January 1999 the first harvest was taken. Plants were cut off above the stem, dried, and then transferred to a laboratory.

In June, an application was made for GW Pharmaceuticals to establish a partner company in Canada to continue its investigations in more detail.

By November, the clinical trials were well underway. According to the company, humans were monitored whilst ingesting different extracts of cannabis through varied delivery devices for the first time. This formed part of the Phase 1 trial which was completed without problems. The results of this study allowed the selection of the best cannabis extracts for further testing. Significant differences may be expected in the effectiveness of plants which differed in the ratios of the cannabinoids.

The trial procedure

As with any other medication, for cannabis to be 'officially' proved an effective and safe medicine, it needs to go through several medical trials. These typically occur in 3 phases.
Phase 1 establishes the 'safety' of the drug. Healthy subjects ingest variable amounts of the drug and their physical functions are monitored to ensure no harm occurs to them. As a result of this, a safe dose-range can be established.
Phase 2 establishes the 'efficacy' (effectiveness) of the medication in potential patients. A small group of people suffering from the relevant affliction are medicated and studied to see whether the drug is in any way effective. This allows sensible tests to be developed and provides a mechanism for interpreting results.
Phase 3 involves much larger scale trials involving hundreds of potential patients. Typically comparisons between the active compounds, placebos and different medicines are taken. Special issues are considered such as special target patient groups (e.g. children) and interactions with other drugs.

By April 2000, GW Pharmaceuticals had received a clinical trial exemption certificate from the Medicines Control Agency. This was permission from the UK medical authorities to start a Phase 2 trial, involving patients who had multiple sclerosis, severe pain, spasticity and related conditions. The trials took place in several locations but commenced in Great Yarmouth's James Paget Hospital, initially under supervision by Dr Willy Notcutt. In this case, the trial was to establish the effectiveness of pain relief using a cannabis-based sublingual spray. Trials soon expanded into other areas of the country, including their first 'off-shore' research location in Guernsy.

Overall, the Phase 2 trials went well, and by May 2001 started its Phase 3 trials, involving many more patients living in more diverse locations. Hundreds of patients were involved, in a cross-country coordinated study based in Oxford. At this stage, £12 million had been spent on the trials, and the company hoped to be able to produce its first authorised prescription medicine in 2003, which would be targeted at patients who suffered from Multiple Sclerosis, arthritis, cancer pain and spinal cord injuries amongst others. This medicine would as far as possible attempt to try and let the patients gain medical benefits without psychoactive 'side effects' and without the health dangers related to smoking. The method of delivery was such that the patients could adjust their doses individually to provide the best level of benefit without side effects. In addition the company received an Investigational New Drug approval from Health Canada, allowing them to commence further Phase 2 trials in Canada - the first step in the 'international roll-out of GW's product activity'.


Many self-medicating patients smoke cannabis in order to relieve their symptoms, as this allows quick action and an easy method of dose titration. However, smoking does produce unwanted side-products such as tars. To avoid these, GW Pharmaceuticals have looked into other methods of ingestion. These include:
Sub-lingual spray - allows patients to spray their medication under their tongue using a conventional medical spray.
Sub-lingual tablet - a pill patients let dissolve under their tongue.
Inhaler - an electrical inhalation device allowing patients to 'smoke' their medication without the associated tars etc, in a similar vein to a vapouriser.

At the same time, GW Pharmaceuticals were seeking admission into the Alternative Investment Market of the London Stock Exchange. They wished to raise £16 million from investors, in order to fund the expansion of the already-large trials, their cultivation and production facilities and to allow research to take place in other places in Europe and America. They gained entry to the Stock Exchange and floated with unprecedented success - raising £25 million from investors, showing perhaps the interest, excitement and practical success of the trials so far.

The general success of the trials gives hope of a change of law allowing thousands of sufferers to relieve their illness via a relatively safe medication.

The current Phase 3 trials some of GW Pharmaceutical's products are going through are in effect the final stage in preparing an application to the Medicines Control Agency for a Product Licence Approval

This Product Licence is an endorsement by the medical authorities of the UK that a medicine is safe and effective. The Government still has the final say - even when cannabis has been proven to be an unusually safe and effective medicine, it still won't be able to be used under the current law. However, the UK Government has indicated that if GW Pharmaceuticals are granted a licence, it would be willing to change the Misuse Of Drugs Act 1971 to allow the prescribing of a cannabis-based medicine.

This has lead GW Pharmaceuticals to suggest in 2001 that the day you can walk into your Doctor's office with a severe medical complaint and receive a prescription for legal, pure, safe and affordable cannabis-based medication may only be 2 or 3 years away.

2010 update

Sativex still hasn't been properly licenced as a medicine, but was made avaiable in 2006. It can now be prescribed, but is very hard to get.

2019 update

Sativex is finally approved for the NHS

For more information, see GW Pharmaceuticals official website.