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Sativex - factsheet

Date of issue: revised March 2009

About Sativex

Sativex is a cannabis based medicine that is taken as a mouth spray.

Trials of Sativex have shown some effect in some people as a treatment for spasticity, pain, bladder symptoms and problems with sleeping. The drug gives relief from symptoms, rather than preventing the symptom from occurring.

Sativex is not licensed in the UK. The Medicines and Healthcare Regulatory Authority (MHRA), the licensing body for drugs in the UK, has indicated that whilst it is satisfied of the quality and safety of Sativex, the clinical evidence for its effect on symptoms is not sufficiently robust.

In December 2007 the MHRA published its Public Information Report for Sativex on its website. The report provides potential prescribers with information on the assessment of quality, safety and efficacy of Sativex. It is based on the information submitted by the manufacturer, GW Pharmaceuticals, in support of its licence application.[1]


Research

GW Pharmaceuticals, the manufacturer of Sativex, have conducted a number of trials of the drug. In these, Sativex was used as an add-on drug rather than as a replacement for any existing medicines.

Bladder dysfunction in advanced MS

An early Sativex trial was undertaken at the National Hospital for Neurology and Neurosurgery in London with a small number of people with MS with severe bladder problems. 21 people were recruited and results were reported from 15. Urinary urgency, the number of incontinence episodes and volume of urine lost, and the frequency of day-time and night-time urination all improved significantly following treatment. Participants' own assessment of pain, spasticity and sleep also reported improvements.

Multiple symptom relief

This trial involved 160 people from three centres across the UK. It looked at Sativex's effect across five symptoms: spasticity, spasms, bladder problems, tremor and pain. Analysis of the results produced a negative result overall, as everyone in the trial reported an improvement on pain, regardless of whether they were receiving Sativex or a dummy placebo. When evaluation of the effect of pain was removed from the results, people who reported spasticity as their main symptom showed statistically significant improvement on Sativex. Quality of sleep was also shown to improve significantly for people receiving Sativex. Slight but not statistically significant improvements were reached on a number of other measures.[2]

Long-term follow up study

137 people who had participated in the Multiple symptom relief study entered this open-label trial, using Sativex to control spasticity and a number of other symptoms. Participants were assessed every eight weeks and follow up continued for an average of 14 months. In total, 58 patients (42%) withdrew from the trial. 24 of these were due to lack of efficacy; 17 due to adverse events, 6 withdrew consent and 11 for other reasons. The majority of adverse events were mild, including oral pain, dizziness, diarrhoea, nausea and alterations to the mucus membrane in the mouth (oromucosal disorder). Serious adverse events included first-ever seizures (epilepsy) in four people. The trial investigated planned sudden interruption of cannabis-based medicine and found no consistent withdrawal syndrome. Researchers concluded that long-term use of Sativex remained effective in people who perceived initial benefit. The precise nature and rate of risks with longer-term use, especially epilepsy, require larger and longer-term studies.[3]

Pain relief

A trial in Liverpool found that Sativex was effective for people with MS experiencing dysaesthetic pain (uncomfortable, abnormal sensations, such as pins and needles, burning or crawling feelings, numbness or tightness) or painful spasms. 66 people received either Sativex or placebo, and pain and sleep disturbance were recorded daily on an 11-point rating scale. The treatment group reported an average reduction in the intensity of pain of 2.7 points as opposed to 1.4 in the placebo group. The effect on sleep disturbance was also marked, with a reduction of 2.5 points in the treatment group and 0.8 in the placebo group. Although the spray was well tolerated, some people reported dizziness, dry mouth, drowsiness and some effect on long-term memory.[4]

Spasticity

189 people with MS who experience spasticity received either Sativex (124 people) or placebo (65 people), over six weeks. Changes in spasticity were measured against a patient-reported scale and the Ashworth measure of spasticity. Statistically significant improvements were seen on the patient-reported scale. Measurement on the Ashworth Scale showed a trend to improvement but did not reach statistical significance. Eight people withdrew from the trial due to adverse events; six were receiving Sativex and two were receiving placebo.[5]

Analysis of previous studies has shown that after four weeks of treatment it is possible to identify reliably those people who respond to Sativex and those for whom it has little or no effect. The lack of clarity on this was a significant reason why the MHRA indicated in July 2007 that it would not be able to grant a licence for the drug, based on the data then available.

As a result, another trial was undertaken involving two stages. In the first, 573 people received Sativex for four weeks. The 241 people who responded to the drug went into the second stage where they received either Sativex or a dummy placebo for 12 weeks.

The study results were announced by GW Pharmaceuticals in March 2009. They indicated a significant improvement on spasticity scores for the treatment group. 74% of participants receiving Sativex reported an improvement of greater than 30% in their spasticity score. 51% of people on placebo reported the same improvement.[6]

Based on these results, GW Pharmaceuticals have announced their intention to submit Sativex for regulatory approval in the second quarter of 2009.[6]


Taking Sativex

Sativex spray is administered under the tongue or in the cheeks. The drug is supplied in packs of four vials. Based on average usage by a typical patient, these should last for six weeks of treatment. However, as with any drug, some people may require a higher dose and some a lower one. Usage suggests that some people find Sativex beneficial whilst others do not.

Side effects reported in the trials have included dizziness, drowsiness and a dry mouth. Sativex is not recommended for pregnant women and people under 18 years old. People with a history of psychotic problems should not take the drug.

Sativex may impair the mental and/or physical abilities required for certain potentially hazardous activities such as driving a car. People should not drive or engage in activities requiring unimpaired judgement and coordination after they have taken the drug.


Being prescribed Sativex

Sativex is not licensed in the UK, however the Canadian regulatory authority granted a licence in 2005. Doctors in the UK can only prescribe the drug on a 'named patient basis' if they feel that it is the appropriate treatment for the individual with MS. Drugs prescribed on a 'named patient basis' are on the direct responsibility of the prescribing doctor.

As Sativex is not licensed, some primary care trusts or health boards may be unwilling to fund treatment on the NHS.

Further information about Sativex for people with MS and their doctors can be obtained from Bayer Medical Information on 01635 563116.

Sativex is manufactured by GW Pharmaceuticals. Once it is licensed, Bayer will market Sativex in the UK.

For more information on cannabis and MS, see our Cannabis factsheet.


References

  1. Medicines and Healthcare products Regulatory Agency.
    Sativex Oromucosal Spray (Tetranabinex and Nabidiolex, as extract of Cannabis sativa L.) - UK/H/961/01/DC.
    London; Medicines and Healthcare products Regulatory Agency: 2007.

    Available from MHRA website - checked 17 March 2009

  2. Wade DT, Makela P, Robson P, et al.
    Do cannabis-based medicinal extracts have general or specific effects on symptoms in multiple sclerosis? A double-blind, randomised, placebo-controlled study on 160 participants.
    Multiple Sclerosis 2004;10(4):434-441.
  3. Wade DT, Makela P, House H, et al.
    Long-term use of a cannabis-based medicine in the treatment of spasticity and other symptoms in multiple sclerosis.
    Multiple Sclerosis 2006;12(5):639-645.
  4. Rog DJ, Nurmikko TJ, Friede T, Young CA.
    Randomized, controlled trial of cannabis-based medicine in central pain in multiple sclerosis.
    Neurology 2005;65(6):812-819.
  5. Collin C, Davies P, Mutiboko IK, et al.
    Randomized controlled trial of cannabis-based medicine in spasticity caused by multiple sclerosis.
    European Journal of Neurology 2007; 14(3): 290-296.
  6. GW Pharmaceuticals website - checked 17 March 2009