Cannabis Extract Is Relatively Ineffective for Multiple Sclerosis Patients
Clinical trials do not appear to have proven the effectiveness of Sativex for treating MS-related muscle spasticity.
--by Michael Harkin
One of the worst symptoms associated with multiple sclerosis (MS) is muscle spasticity, or an increase in muscle tone. The symptom affects approximately 60 percent of patients with MS. Negative effects of this spasticity include immobility, pain, difficulty sleeping, and involuntary muscle spasms.
In order to treat this spasticity, drugs must be combined in complex ways. These combinations sometimes not only lack effectiveness, but also bring about undesirable side effects for patients.
One secondary medication licensed for use in the United Kingdom as a treatment for this symptom is nabiximols, which is available under the brand name Sativex. It contains two cannabis extracts, dronabinol and cannabidiol, and is used as a mouth spray. It is currently licensed for use by MS patients who have not responded to other antispasticity medication. The FDA has not yet approved Sativex for use in the United States.
A review of the current available evidence surrounding the effectiveness of Sativex was conducted for the December issue of Drug and Therapeutics Bulletin. The conclusion of the review is that, although Sativex appears to be of minor benefit in treating spasticity, the clinical trials that have occurred to date do not make clear the actual effectiveness of the drug.
The Expert Take
As for why Sativex made it to market without what would seem to be a sufficient level of testing: “You would need to ask the regulators,” says Dr. James Cave, Editor-in-Chief of Drug and Therapeutics Bulletin.
“Sativex has certainly been well-tested (with more trials on the way),” explains Cave. “I suspect they may have considered it an area where we currently have few treatment options… A only modest improvement in a few patients may be better than no drug at all.”
Source and Method
The review found several major issues with the clinical trials that have taken place to date regarding the effectiveness of Sativex as a treatment for MS-related muscle spasms. For instance, one of the trials did not have a sufficient number of participants to render the results valid. Additionally, two of the trials allowed patients to use a higher dose of Sativex than is permitted under clinical guidelines. One further area in which the studies fell short was the amount of time over which the testing took place: the time for which Sativex was used by study respondents ranged from just six weeks to four months.
One of the other major marks against Sativex is its expensive price, compared to other drugs licensed as add-on therapies for MS-related muscle spasms. It costs up to 10 times as much as other drugs used for the same purpose. According to the review, other drugs currently used as add-on treatments for spasticity include tizanidine, diazepam, clonazepam, and dantrolene. The findings suggest that the high price of Sativex might not be justified by its therapeutic potential.
There has been minor improvement in patients taking Sativex compared to those treated with a placebo. However, the trials conducted on the drug appear to have been quite limited in scope, especially considering that the longest lasted only four months.
“Sativex has only moderate evidence to support its use in muscle spasms in multiple sclerosis,” says Cave. Although its illustrated effects may make it a worthwhile addition to currently available licensed medications, it is difficult to definitively say how useful it is as a treatment.
An official statement regarding the use of cannabis extract for treating spasticity is forthcoming from the National Institute for Health and Clinical Excellence (NICE), the group responsible for advising the UK’s National Health Service on such matters.
According to the Multiple Sclerosis Trust in the UK, 48 percent of participants in a phase III clinical trial of Sativex showed improvements in spasticity. Additionally, three quarters of those who responded to the drug reported improvements of greater than 30 percent.
There are currently several clinical trials being performed on Sativex and other cannabis-based products. More information about those trials is available here.