Sativex
SATIVEX INVESTIGATIONAL CANNABIS-BASED TREATMENT FOR PAIN AND MULTIPLE SCLEROSIS
Developed by GW Pharmaceuticals, Sativex is a whole plant medicinal cannabis extract indicated for the relief of symptoms of multiple sclerosis as well as treatment of severe neuropathic pain.
In March 2003, GW Pharmaceuticals submitted a product licence application for Sativex to the UK Medicines and Healthcare Products Regulatory Agency (MHRA). The company has also entered a licensing agreement with German drugs group Bayer. This gives Bayer exclusive rights to market Sativex in the UK with the option to extend this to other countries in Europe and the Commonwealth. For multiple sclerosis sufferers in the UK, an approved cannabis medicine may be available on prescription in 2003. Once approved in the UK, GW Pharmaceuticals and Bayer will seek wider European approval. It is expected that US approval will take two or three years.
Sativex and a related tetrahydrocannabinol (THC) medicine are also undergoing phase III trials for the relief of cancer pain. If this indication is approved, Bayer has an option to market these drugs for neuropathic-related cancer pain.
CANNABIS-BASED MEDICINES
Estimates suggest that between 10% and 30% of multiple sclerosis patients in Europe smoke cannabis to ease the pain and disabling symptoms of the disease. This activity is illegal and patients run the risk of prosecution. In the UK, cannabis-based medicines were in fact outlawed in 1968 after legislation banned doctors from prescribing tincture of cannabis. This preparation contained high concentrations of the active THC psychotropic ingredient and was popular among recreational cannabis users.
The UK Government gave GW Pharmaceuticals special permission to investigate medicines derived from cannabis and has indicated that the law will be changed to allow doctors to prescribe them if approved by the MHRA. This would represent a major step forward for multiple sclerosis patients as for the first time they would have access to safe and effective cannabis-derived drugs on prescription.
Sativex is a cannabis extract containing tetranabinex (THC) and nabidiolex (cannabidiol - CBD) as its principal component. It does not contain the active substance found in recreational cannabis and so patients taking Sativex will not become intoxicated. Sativex is administered by means of a spray into the mouth rather than smoked.
To meet demands for this innovative drug, GW Pharmaceuticals has increased production of cannabis at its fortified greenhouses to 60t/y.
CLINICAL TRIALS ON SATIVEX POINT TO GOOD EFFICACY AND SAFETY
Phase III placebo-controlled trials in about 350 patients with multiple sclerosis have shown that administration of Sativex as an under-the-tongue spray is a safe and effective treatment for symptom relief in multiple sclerosis. Compared with placebo, significantly more patients in the Sativex treatment arm experienced reduced neuropathic pain, spasticity, and sleep disturbances. These final trial results, which form the basis of regulatory submission, were apparently much better than the company had expected.
Additional trials are under way to assess the effectiveness of Sativex in treating cancer pain and spinal cord injury. Anecdotal evidence suggests that Sativex and related compounds can dull severe pain while allowing patients to perform daily activities.
TREATMENT OF SEVERE NEUROPATHIC PAIN
Neuropathic pain, which is frequently chronic, arises when neurones in the brain or peripheral nervous system become hyper-sensitised and generate abnormal or prolonged impulses. There are many causes of neuropathic pain including diabetic neuropathy, post-herpetic neuralgia, fibromyalgia, multiple sclerosis and cancer. Around 40% of cancer patients suffer some degree of neuropathic pain.
Severe neuropathic pain has proved difficult to treat and evidence suggests that none of the available drugs, mainly opiods, is effective in more than 50% of patients. Thus, it represents an area of unmet clinical need. The encouraging data from the Sativex phase III registration trials in multiple sclerosis patients suggest cannabis-derived medicines may have a valuable place in this sector of the pain market.
MARKETING COMMENTARY
In Europe alone there are some 500,000 multiple sclerosis patients on top of the 4 million experiencing neuropathic pain. This fact, together with a market poorly served by currently available drugs, presents an excellent opportunity for Sativex if the encouraging results seen in multiple sclerosis are reproduced in other patient groups. Regulatory approval of Sativex, which is expected in 2003, will set an important precedent for the use of cannabis-derived drugs.
From http://www.drugdevelopment-technology.com/projects/sativex
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