Sativex - factsheet
Date of issue: July 2010
Contents
- Introduction
- What is Sativex?
- How does Sativex work?
- Who can be prescribed Sativex?
- How effective is Sativex in treating MS spasticity?
- How often is Sativex taken?
- What are the side effects of Sativex?
- Does Sativex interact with other medicines?
- Who should not be prescribed Sativex?
- Can I travel abroad with Sativex?
- Clinical trials of Sativex
- References
Introduction
Sativex is the first cannabis-based medicine to be licensed in the UK. In June 2010 the UK Medicines and Healthcare products Regulatory Agency (MHRA) licensed Sativex for use as an add-on treatment for MS-related spasticity when people have shown inadequate response to other symptomatic treatments or found their side effects intolerable.
What is Sativex?
Sativex is formulated as a mouth (oromucosal) spray containing two chemical extracts derived from the cannabis plant: delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). Cannabis plants are thought to contain more than 60 such chemicals - known as cannabinoids - but these two specific cannabinoids have been studied for their effects in MS.
How does Sativex work?
The way cannabinoids work is not fully understood as yet, but discovery of the endocannabinoid system - a natural system found in the human body through which cannabinoids are able to exert their effects - has provided some insight.
The endocannabinoid system is thought to work in a similar way to the opioid system - the system that controls pain. Some pain-killing medicines exert their effects on opioid receptors to provide relief from pain. In a similar way, cannabinoids exert their effects on cannabinoid receptors that are part of the endocannabinoid system.
Receptors are protein molecules in or on the surface of cells to which a substance (such as a drug) can bind, causing a change in cell behaviour or activity. The specific receptors that the active ingredients of Sativex (THC and CBD) exert their effects upon are the CB1 receptor and the CB2 receptor. CB1 receptors are thought to exert their effects in the brain while CB2 receptors are thought to exert their effects on immune cells.
Who can be prescribed Sativex?
The existing oral medications that are used for the treatment of MS spasticity - including baclofen and gabapentin - will continue to be used as first line treatments for MS spasticity. It is only when these treatments offer inadequate relief, or have intolerable side effects, that Sativex may be considered. Sativex is licensed as an add-on therapy - meaning that it will routinely be prescribed in combination with other anti-spasticity medications.
Two clinical trials investigating the effects of Sativex on MS spasticity demonstrated that people who experienced improvements did so within four weeks of receiving the medicine [1,2]. A further trial validated the use of a preliminary four week trial of Sativex as an effective way of identifying people who do respond positively to the treatment and those who do not [3].
Based on these results, Sativex is now licensed as an add-on treatment for moderate to severe spasticity in people who:
- have not gained adequate relief of symptoms from one or more oral medicines, or have experienced unbearable side effects whilst taking these medicines;
- demonstrate significant improvements in spasticity during an initial trial of Sativex.
AND
Sativex is classed as a specialist medicine and treatment with Sativex must be started and supervised by a specialist doctor with experience of treating people with MS spasticity; such as: neurologists, consultant rehabilitation specialists and consultant pain specialists. GPs, nurses and other non-specialist healthcare professionals will have to make appropriate referrals, and GPs should only prescribe Sativex when instructed to do so by the specialist.
A specialist doctor will conduct a full assessment of the severity of spasticity related symptoms and an evaluation of the response to standard spasticity treatments for individuals who might benefit from the use of Sativex. If people who are prescribed Sativex do not show clear improvement in their spasticity related symptoms during an initial trial of the treatment, then it will be stopped.
How effective is Sativex in treating MS spasticity?
In 2009, a phase III trial investigating the effects of Sativex on MS spasticity was conducted in two stages. In the first stage, 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 placebo for 12 weeks. About three quarters of those receiving Sativex reported an improvement of greater than 30% in their spasticity score at least once during the first four weeks of treatment [3].
How often is Sativex taken?
The severity of spasticity symptoms varies from one person to another so the number and timing of sprays will also vary. At the start of treatment the prescribing doctor will advise on frequency and timing of sprays and may suggest a gradual increase until the most effective dose is found. The maximum dose of Sativex is 12 sprays per day. A gap of at least 15 minutes should be left between sprays.
What are the side effects?
The most common side effects reported by people taking Sativex are dizziness and fatigue. Other common side effects include drowsiness, vertigo and nausea. These side effects tend to occur in the first four weeks of treatment, and become less frequent over time. Most common side effects can also be reduced by decreasing the dose of Sativex (taking fewer sprays or waiting longer between sprays). Other common side effects include pharyngitis, loss of concentration, dry mouth, and blurred vision. Rare but more serious side effects of Sativex include hallucinations and stomatitis (inflammation of the mouth). People who experience any significant side effects should not drive, operate machinery or take part in any activity that could prove hazardous.
Studies into long-term use of Sativex in people with MS showed that sudden discontinuation of treatment did not result in any significant withdrawal-like symptoms. Some people reported temporary changes in their sleeping patterns, emotional status and appetite following discontinuation. The lack of withdrawal symptoms suggest that dependence on the treatment is highly unlikely.
Does Sativex interact with other medicines?
The prescribing doctor should be made aware of all other medications you are taking. Particular care should be taken if you are taking any sleeping pills, sedatives or other drugs with sedative effects as combining these medicines with Sativex may cause you to feel more sleepy.
Although there has been no increase in adverse events in patients already taking anti-spasticity agents with Sativex, care should be taken when combining Sativex with muscle-relaxing agents such as baclofen and benzodiazepines as a reduction in muscle tone and power can occur and may put people at greater risk of falls. This risk has not been demonstrated in clinical trials, but people should be aware of this possibility.
Sativex may interact with alcohol and can affect coordination, concentration and the ability to respond quickly.
Who should not be prescribed Sativex?
No studies of Sativex were conducted in people under the age of 18 so it is not recommended for use in children and young people under 18. Though elderly people did take part in the Sativex trials, the effects of Sativex on an elderly MS population were not specifically investigated. Consideration of personal safety, such as the risk of falls, is therefore necessary when prescribing Sativex to elderly individuals.
People with known allergies to cannabinoids or the inactive ingredients of Sativex - propylene glycol, ethanol and peppermint oil should not be prescribed Sativex.
People with known or suspected history or family history of schizophrenia, or other psychotic illness; history of severe personality disorder or other significant psychiatric disorders other than depression associated with their underlying condition should not be prescribed Sativex.
There is too little experience of the use of Sativex in human reproduction to be sure of what its effects might be. Pregnant women should not use Sativex unless their doctor believes the benefits of treatment outweigh the potential risks posed to the baby. For the same reason, both men and women receiving Sativex should use effective contraception during treatment and for three months after stopping. Breastfeeding women should not use Sativex due to the potential risk of exposure to cannabinoids on the development of infants.
.Can I travel abroad with Sativex?
All people leaving the UK with a supply of Sativex will need a letter from their prescribing doctor including:
- name;
- date of birth;
- address;
- outward and return dates of travel; and
- the name, amount and strength of the medicine you are carrying.
Sativex is a controlled drug and its legal status will vary between countries. People receiving Sativex should check its legal status in the countries to which they are travelling. People intending to travel abroad with Sativex should contact the Embassy, Consulate, or High Commission of the country they are travelling to for information relating to the rules of carrying controlled drugs.
People leaving the UK with Sativex will not need a Home Office licence if they are carrying no more than three months supply of Sativex.
Clinical trials of Sativex
Prior to gaining a licence for use in MS-related spasticity, Sativex had been studied for its effects on a number of MS related symptoms including: spasticity and spasms, pain, bladder symptoms, tremor, and sleep disturbance.
Multiple symptom relief
160 people with MS took part in this trial which compared the effects of Sativex versus placebo on spasticity, spasms, pain, bladder and tremor [4]. No significant improvements were seen in overall symptom relief but those who reported spasticity as their main symptom showed a statistically significant improvement on Sativex.
137 people who took part in this study participated in an open-label follow-up trial using Sativex to control spasticity and a number of other symptoms [5]. The trial investigated planned sudden interruption of Sativex and found no consistent withdrawal syndrome. Researchers concluded that Sativex remained effective in people who perceive initial benefit.
Spasticity
189 people with MS and spasticity symptoms took part in a study which compared the effects of Sativex versus placebo [2]. Changes in spasticity during the six-week study were recorded using a patient-reported scale and a clinical measure of spasticity. Improvements were seen on the patient-reported scale but improvements seen on the clinical scale did not reach statistical significance.
Pain relief
66 people with MS took part in this trial which compared the effects of Sativex versus placebo on pain or painful spasms [6]. Sativex was more effective than placebo in reducing the intensity of pain.
Urge incontinence
135 people with MS took part in this study which compared the effects of Sativex versus placebo on bladder symptoms [7]. There was no significant improvement in the number of daily urge incontinence episodes, but the number of night-time episodes were reduced in those taking Sativex. People receiving the drug also reported an improvement in overall bladder symptom severity.
References
-
Collin C, Ambler Z, Kent R, et al.
A randomised controlled study of Sativex in patients with symptoms of spasticity due to multiple sclerosis.
In 22nd Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS 2006), Spain. -
Collin C, Davies P, Mutiboko IK, et al.
Randomised controlled trial of cannabis-based medicine in spasticity caused by multiple sclerosis.
European Journal of Neurology 2007; 14: 290-296. -
Collin C, Ehler E, Waberzinek G, et al.
A double-blind randomized placebo-controlled parallel-group study of Sativex in subjects with symptoms of spasticity due to multiple sclerosis.
Neurology Research 2010; 32 (5): 451-459. -
Wade DT, Makea P, Robson P, et al.
Do cannabis-based medicinal extracts have general or specific effects on symptoms of multiple sclerosis? A double-blind randomised, placebo-controlled study on 160 participants.
Multiple Sclerosis 2004; 10(4): 434-441. -
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. -
Rog DJ, Nurmikko TJ, Friede T, et al.
Randomised controlled trial of cannabis-based medicine in central pain in multiple sclerosis.
Neurology 2005; 65(6): 812-819. -
de Ridder D, Constantinescu C.
Randomised controlled study of cannabis based medicine in patients suffering from multiple sclerosis associated detrusor overactivity.
Poster 411 presented at the 22nd Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS 2006), Spain.
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MS Trust Information Service
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