Sativex (nabiximols)

Sativex (nabiximols) is a cannabinoid (a product made from compounds including cannabinol taken from the marijuana plant) formulated as an oromucosal spray that has been developed by GW Pharmaceuticals for the treatment of spasticity in people with MS. It is also being tested for the treatment of neuropathic pain (pain due to nerve damage) in people with MS, as well as for use in overactive bladder and cancer pain. Sativex has been approved in Canada, the UK, and several European countries for use in the treatment of spasticity in people with MS who have not adequately responded to other anti-spastic medications, such as Lioresal (baclofen), dantrolene, and Zanaflex (tizanidine). Sativex is currently being tested in the US, but has not been approved for this use by the FDA.

How does Sativex work?

Sativex combines two active components of cannabinoids, tetrahydrocannabinol (THC) and cannabidiol (CBD). THC and CBD act on cannabinoid receptors found on nerves to inhibit synaptic function by reducing the effects of neurotransmitters. In animal studies, THC and CBD have been shown to improve limb stiffness and motor function.

How is Sativex taken?

Sativex is formulated as a spray for oromucosal administration (to be sprayed in the oral cavity and/or throat). It is intended to be taken with another anti-spastic medication and treatment should be started under the supervision of a doctor with expertise treating people with MS. The number and frequency of dosing (sprays) with Sativex will vary from individual to individual and it may take a number of weeks to find the correct dose of Sativex for the individual patient.

During the initial Sativex titration period, you should gradually increase the number of sprays you take per day. You should leave at least 15 minutes between sprays and should not exceed 15 sprays per day. See the manufacturer instructions for more specific information on how to take Sativex. If Sativex does not result in improvement of symptoms during the early stages of treatment, the drug should be discontinued.

Are there people who should not take Sativex?

Sativex should not be taken by persons who have a hypersensitivity to cannabinoids or any other component in the product. It should not be taken by a person with a personal history or family history of schizophrenia or psychotic illness, a history of severe personality disorder, or other significant mental illness, excluding depression related to MS. Nursing mothers should not take Sativex, as its active component can be passed into breast milk and may have harmful developmental effects in a nursing child. Sativex is not recommended for children below the age of 18 years due to a lack of safety and efficacy information in this age group.

What evidence do we have that Sativex works to help control spasticity?

The effectiveness of Sativex has been tested in studies including more than 1,500 people with MS with moderate to severe spasticity who failed to gain adequate control of spasticity with other medications.

In one randomized, placebo-controlled study, a higher percentage of people who received Sativex (45%) compared with placebo (22%) had more than a 30% reduction in a numeric rating scale (NRS) for scoring spasticity severity. Another study, however, failed to find a significant difference between Sativex and placebo in NRS score.

A third study was conducted in an enriched population of patients who demonstrated the capacity to respond to Sativex. The study started with a 4-week, single-blind Sativex treatment period to eliminate people who were not responders, or who did not experience a 20% or greater reduction in NRS score. After this 4-week period, the study randomized 241 patients, who responded during the initial phase, to receive Sativex  (n=124) or placebo (n=117) for an additional 12 weeks. Among the participants in the 12-week phase of the study, a significantly greater percentage of those who received Sativex (74%) compared with those who received placebo (51%) had at least a 30% reduction in NRS. Secondary efficacy endpoints in the study, including patient global impression of change, carer global impression of change, and doctor global impression of change, showed a similar significant benefit for people who received Sativex compared with those who received placebo.

Written by: Jonathan Simmons | Last reviewed: May 2015.
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