GWP.L Regulatory News (GWP)

Sativex® Approved in the Czech Republic

Porton Down, UK; 15 April 2011: GW Pharmaceuticals plc (AIM:GWP) today announces that Sativex® oromucosal spray has been approved in the Czech Republic as a treatment for spasticity due to Multiple Sclerosis (MS).

This approval follows GW's announcement on 22nd March 2011 that the European Mutual Recognition Procedure had successfully completed with all six countries involved recommending approval. The countries involved in the MRP were Germany, Italy, Denmark, Sweden, Austria and the Czech Republic. The Czech Republic is the first of these countries to approve Sativex. The remaining countries involved in the MRP are expected to approve Sativex in the coming months.

Launch timing in each country will be dependent on national regulations concerning pricing and reimbursement. In accordance with previous guidance, GW's marketing partner, Almirall S.A., anticipates launch in Germany, Denmark and Sweden before the end of 2011 with the remaining countries, including the Czech Republic, expected in 2012.

Sativex® is also in phase III clinical development for the treatment of cancer pain, Almirall holds the marketing rights to this medicine in Europe (except the United Kingdom).

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Notes to Editors

Sativex®

Sativex® is an endocannabinoid modulator made of two actives - THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol)-, which was developed and is manufactured by GW Pharmaceuticals plc, UK., Almirall holds marketing rights in Europe (except United Kingdom).

Sativex® is indicated as an add-on treatment for patients with moderate to severe spasticity due to multiple sclerosis (MS) who have not adequately responded to other anti-spasticity medications and who have demonstrated a clinically significant improvement in symptoms related to spasticity during an initial treatment testing periodI.

Sativex® contains active ingredients known as 'cannabinoids' which are extracted from the plant Cannabis Sativa grown and processed under strictly controlled conditions. Cannabinoids react with cannabinoid receptors that exist naturally throughout our body, including the brain.II A receptor is a site located in a brain cell in which certain substances can stick or "bind" for a while. If this happens, this binding has an effect on the cell and the nerve impulses it produces, causing a 'dimming-down' of the spasticity symptom. In patients who respond to Sativex®, this is the effect that improves their spasticity symptoms and helps them cope with their daily activities.III

Spasticity

In the five main EU markets there are around 500,000 people suffering from MS IV and in Spain around 40,000 cases of the disease have been reported. Spasticity is a symptom defined by patients and carers as muscle spasms, seizing-up, stiffness and/or difficulty in moving muscles and it is one of the most common symptoms of MS, occurring in up to 75% of MS sufferers in the course of the disease. Spasticity can affect many aspects of the daily lives of patients with MS and is one of the main factors contributing to their distress and disability.V

About GW Pharmaceuticals

GW Pharmaceuticals plc (AIM:GWP) was founded in 1998 and is listed on the AiM, a market of the London Stock Exchange. Operating under licence from the UK Home Office, the company researches and develops cannabinoid pharmaceutical products for patients who suffer from a range of serious ailments, in particular MS and cancer pain. GW has assembled a large in-house scientific team with expertise in cannabinoid science as well as experience in the development of both plant based prescription pharmaceutical products and medicines containing controlled substances. GW occupies a world leading position in cannabinoids and has developed an extensive international network of the most prominent scientists in the field.

For further information, please visit www.gwpharm.com

This news release may contain forward-looking statements that reflect GWs current expectations regarding future events, including development and regulatory clearance of the GW's products. Forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors, including (inter alia), the success of the GW's research strategies, the applicability of the discoveries made therein, the successful and timely completion of uncertainties related to the regulatory process, and the acceptance of Sativex® and other products by consumer and medical professionals.

GW Pharmaceuticals: Cannabinoid Science: Mechanism of action. Available at. http://www.gwpharm.com/mechanism-of-action.aspx (latest access: 11/08/2010).

I Patient leaflet

II GW Pharmaceuticals: Cannabinoid Science: Mechanism of action. Available at. http://www.gwpharm.com/mechanism-of-action.aspx (latest access: 11/08/2010).

III GW Pharmaceuticals: Cannabinoid Science: Cannabinoid Compounds. Available at http://www.gwpharm.com/types-compounds.aspx (Last accessed: 01/07/10).

IV Multiple Sclerosis International Federation: European map of ms database. ©2010 EMSP, MSIF. Available at: www.europeanmapofms.org (latest access: 11/08/2010). Top five EU countries include: France, Germany, Italy, Spain and UK.

V Rizzo MA et al. Prevalence and treatment of spasticity reported by multiple sclerosis patients. Mult Scler 2004;10:589-595.