Neurologists are facing increasing pressure from their patients to prescribe medicinal cannabis, despite little or no evidence to support its use in conditions such as MS.
Newcastle neurologist Professor Jeannette Lechner-Scott says she is frequently asked about cannabis as an-add on therapy by patients with multiple sclerosis, Parkinson’s disease and epilepsy.
“It would be something I have been discussing with probably 80% of my patients, says Professor Lechner-Scott, who runs a multidisciplinary Multiple Sclerosis Clinic at the John Hunter Hospital in Newcastle and conjoint professor at the University of Newcastle.
“I think one misunderstanding is that cannabis is curing MS,” she told the limbic. “The benefit of cannabis on disease cause or activity is questionable. It can help with symptoms, but it doesn’t improve MS, it’s not going to cure someone who is in a wheelchair.”
Under recent changes to the law, doctors can apply to the TGA to become “authorised prescribers” of medicinal cannabis and then apply to access a range of cannabis products not approved by the TGA, via the Special Access Scheme (SAS).
Latest TGA figures show that to date, 33 doctors have become authorised prescribers, including at least one paediatric neurologist.
Professor Lechner-Scott says she does not prescribe medical cannabis through the SAS due to concerns about known side effects, such as ability to operate machinery, as well as potential interactions with prescribed medication.
“The major issue with medicinal cannabis is that it isn’t one drug, there is a variety of products on the market that claim different concentrations, but they have not really been tested so I don’t really consider them a drug because they are not regulated.”
“The process (TGA approval process for medicines) is in place for a reason and when the studies are showing me compelling evidence of benefit over side effect then I will prescribe it.”
Professor Lechner-Scott says she may prescribe the pharmaceutical form of cannabis, Sativex, for muscle spasticity in MS, when other treatments have failed.
Sativex was approved several years ago by the TGA, and Professor Lechner-Scott was a member of the advisory board for the sponsor.
But it “hasn’t actually taken off that much in Australia” which she speculates is due to its cost of about $1700 per month as it is not listed on the PBS.
Many patients who have taken Sativex will add, or substitute, with other cannabis products sourced without medical oversight, says Professor Lechner-Scott .
This is a problem, given the risk of side effects, which the TGA lists as including sedation, nausea and vomiting, psychosis, convulsions and paranoid delusions.
“It is unlikely that cannabis is a solution for everything. There is even a push in Parkinson’s to use cannabis. [But] the more indications are for whatever substance the less likely that it’s true.”
The TGA has recently published resources on the current evidence base for medicinal cannabis for doctors.
According to the TGA website, there is no scientific data to support use of medicinal cannabis for chronic nociceptive pain, and the data to support its use for chronic neuropathic pain conditions is still limited.
Professor Lechner-Scott says a potential positive aspect to the public pressure to access medical cannabis is that it may translate into research funding, including for her own research into the effects of medicinal cannabis on adults with MS.
“It’s certainly a pressure that makes us aware we need to be well informed, it’s a pressure that I hope will result in more and better studies with cannabis”.
In the debate over medicinal cannabis, the RACP has repeatedly urged caution on the lack of evidence for neurological indications and voicing concern that in Australia its introduction has not followed the usual research-based safety and effectiveness processes.
In a 2015 submission to the Victorian Law Review Commission on Medicinal Cannabis, the college said there was insufficient evidence to justify usage in paediatric epilepsy outside clinical trials, except in cases of drug-resistant disease where the threat of seizures is so high to outweigh any harms from cannabis.
The college noted that many MS-treating specialists believed there was sufficient evidence for Sativex to treat muscle spasticity, although adding “the RACP acknowledges that in 2013 the Pharmaceutical Benefits Advisory Committee rejected a submission to subsidise Sativex, on the basis that trials did not demonstrate better efficacy than existing options”.