Sativex® available by
prescription for treatment of MS-related pain
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Medical Update Memo
June 20, 2005 (Updated)
Summary On June 20, Sativex®, a cannabis-based
drug for the treatment of MS-related pain, became available
for prescription. The drug consists of various extracts from
the cannabis plant. It is administered via a spray into the
mouth. Canada is the first country to approve Sativex. According
to Bayer Canada, the cost of Sativex per vial is $124.95 (base
price). Each vial contains approximately 51 sprays. The average
dose per day is five sprays at an average cost of $12.25 per
day. Based on this dosage, the base cost would be approximately
$4,475 (the retail cost will be more depending upon pharmacy
dispensing fees and other factors). Since the dosage is variable,
to a maximum of 14 sprays per day, costs would increase or
decrease accordingly. The Multiple Sclerosis Society of Canada
welcomes the availability of Sativex, which will provide people
with MS and their physicians another choice in treating pain,
which is a common symptom of the disease.
Details
Health Canada approval of Sativex on April 19 made Canada the
first county in the world in which the cannabis-based spray
is available as a prescribed treatment for MS-related pain.
On June 20, Bayer Canada announced that Sativex had become
available for prescription. Sativex is sprayed under the
tongue or on the inside of the cheek from a dispenser that
is programmed to deliver a pre-selected dosage. It is described
as a whole marijuana plant extract. It includes two components
of marijuana tetrahydrocannabinol (THC) and cannabidiol.
According to Bayer Canada, the cost of Sativex per vial is
$124.95 (base price). Each vial contains approximately 51 sprays.
The average dose per day is five sprays at an average cost
of $12.25 per day. Based on this dosage, the base cost would
be approximately $4,475 (the retail cost will be more depending
upon pharmacy dispensing fees and other factors). Since the
dosage is variable, to a maximum of 14 sprays per day, costs
would increase or decrease accordingly. Private or group drug
insurance plans may cover all or some of the cost. Sativex
has yet to be approved for reimbursement by any federal, provincial
or territorial drug program.
According to Bayer Canada, people who are prescribed Sativex
should be aware that current regulations do not allow it to
be taken out of Canada since it is a cannabis-based product
and, therefore, a controlled substance.
Health Canada has approved Sativex with conditions, under the
Notice of Compliance with Conditions (NOC/c) policy. This authorization
reflects the promising nature of the clinical evidence to be
confirmed with further studies. Products approved under Health
Canada's NOC/c policy have demonstrated promising benefit,
are of high quality and possess an acceptable safety profile
based on a benefit/risk assessment for the approved use.
Health Canada approval was based on the results from a small,
four-week clinical trial carried out in Great Britain by GW
Pharmaceuticals, the company that developed Sativex. The study
involved 66 people with MS at a research centre in Britain.
Participants had central neuropathic pain because of MS. Half
of the group received Sativex in a spray dispenser and the
other half received a sham (placebo) spray in a similar dispenser.
The primary outcome measure was to measure the effectiveness
of Sativex in relieving central neuropathic pain compared to
placebo. Secondary measures included sleep disturbance, participants'
perception of their condition at the end of treatment and other
quality of life assessments.
Study results and possible mechanism of action Participants
in the Sativex group used fewer sprays per day than did the
placebo group. In addition, individuals in the treated group
reported they experienced pain relief, had less sleep disturbance
and felt their condition had improved.
There were more side effects in the Sativex-treated group versus
the placebo group. When combining data from this and several
other phase three clinical trials (total of 166 participants),
the most common side effect of Sativex was dizziness which
occurred in 41.6% of treated participants versus 13% of participants
in the placebo group. There was also more nausea in the treated
group (10.2%) than in the placebo group (7.4%) and more fatigue
in the treated group (11.4%) versus the placebo group (5.6%).
Side effects tended to diminish overtime.
Cannabinoids is the name given to more than 60 related chemicals
in the marijuana plant. Cannabinoids appear to bind to receptor
molecules on the surface of neurons in the brain and spinal
cord. Through a complex process, cannabinoids appear to prevent
neurons from becoming overactive, which leads to the neuropathic
pain sometimes experienced in MS. Neuropathic pain results
directly from damage to the nerves.
A number of clinical trials have been carried out in the past
five years to test the effectiveness and safety of marijuana
as a treatment for MS pain and spasticity. Some studies used
the smoked variety of marijuana, while others used extracts
of the plant delivered in various ways. The outcome of the
largest study, which looked at spasticity, was mixed in that
while those on active treatment did not have an objective improvement
as measured by a standardized scale, treated participants reported
improvements in walking speed, another measure of spasticity,
and symptoms of spasticity, muscle spasms, sleep and pain.
Pain as a symptom of MS
Up to 80 percent of people with MS report some type of pain.
A recent study of pain at Dalhousie University involving 85
people with MS found that 53 percent of people with MS experienced
pain during the study period and that 17 percent reported continuous
pain. Of those reporting pain, 65 percent took medication to
control pain, with 90 percent reporting that their pain could
be controlled about half of the time. Study participants who
reported pain had poorer overall mental health than people
who were pain free or who had well-controlled pain. There is
a wide variety of pain associated with MS from a range of causes:
generalized pain, muscle spasms, trigeminal neuralgia (shooting
pain in the face), painful sensations in the legs, feet and
hands.
Background and status of marijuana as a therapy in Canada Marijuana's
role as a medication is complex and controversial. It was used
as a medication in the nineteen century but was outlawed in
most western countries in the early to mid twentieth century.
Recently in Canada, the federal government developed a medicinal
marijuana program, which allows people who meet certain criteria
to have permits to possess and grow marijuana. MS is among
the conditions for which a permit can be applied. In some cases,
Health Canada will provide marijuana to people who hold permits.
Details about how to apply for permits are available at the
Health Canada website: www.hc-sc.gc.ca;
then click on Drugs and Health Products and then Medical Use
of Marihuana. Information is also available by calling the
Health Canada Cannabis Medical Access Office toll-free: 1-866-337-7705
or (613) 954-6540.
It is not known if the approval of Sativex will result in any
changes to the Health Canada Marijuana Medical Access Program.
One issue that has arisen from the Health Canada medical marijuana
is that some physician organizations have advised their members
not to prescribe marijuana because of the lack of information
about optimum prescribing and potential legal issues.
Other cannabis-based drugs are Marinol® (dronabinol)
and Cesamet® (nabilone). Both are synthetic versions
of THC in tablet form. They are used primarily by people with
cancer and AIDS to treat nausea related to certain treatments
and to stimulate the appetite.
Multiple Sclerosis Society of Canada comment
The Multiple Sclerosis Society of Canada welcomes the availability
of Sativex, which will provide people with MS and their physicians
another choice in treating pain, which is a common symptom
of the disease. "Having available another way to manage pain
is encouraging news," said Dr. William J. McIlroy, national
medical advisor.
ASK MS Information System Code:
1.4.1.20.d2
Disclaimer
The Multiple Sclerosis Society of Canada is an independent,
voluntary health agency and does not approve, endorse or
recommend any specific product or therapy but provides
information to assist individuals in making their own decisions.
