Wednesday, October 28, 2015

Medical Marijuana and RLS

Medical Marijuana and RLS
By Jacquelyn Bainbridge, PharmD, and Mark Buchfuhrer, MD, FRCP(C), FCCP, FAASM

The medical and recreational use of marijuana is increasing in the
U.S. The drug remains illegal under federal law (even though it is
legal in 23 states and the District of Columbia), but a federal
spending bill passed in December 2014 prohibits the Justice
Department from using federal funds to enforce this ban in states
with medical marijuana laws.

Medical marijuana is recognized as a legitimate medical application
for many disease states. Restless legs syndrome (RLS) is one disease 
for which patients are
looking to experiment with medical marijuana to relieve symptoms
when more conventional treatments are unsuccessful, too expensive
or cause unwanted side effects.

Current treatment for RLS
Current treatment for RLS includes dopaminergic agents, an
alpha-2-delta ligand subunit drug, and other medications that are not
approved by the U.S. Food and Drug Administration (FDA) for
treating RLS. The FDA-approved drugs demonstrate
effectiveness by enhancing dopamine activity in the brain (Requip,
Mirapex, Neupro Patch) or by modifying calcium channels on nerves
(Horizant), which changes the excitability of nerves that carry
RLS sensations or pain.

Medical marijuana in RLS
There are no current studies or clinical trials on the use of medical
marijuana in RLS. Though marijuana is not FDA approved
for medical indications in the disease, anecdotal evidence from some
patients’ experiences with the drug have shown improvement in
some of the symptoms commonly associated with RLS.

Marijuana works mainly by acting on multiple cannabinoid receptors
in the brain to provide variable psychoactive effects (that is, affecting
mental processes) on areas including motor activity, coordination and
pain relief by inhibiting prostaglandin biosynthesis and thus blocking
pain receptor pathways.

Although there are no studies examining the use of marijuana for
treating RLS, there is some clinical experience available based
on its anecdotal use by many patients. Typically, ingested marijuana
(through brownies or cookies, for example) does not seem to benefit
RLS very much, while inhaled marijuana (through a
marijuana cigarette or vaporizer) works very quickly and effectively.
Most RLS sufferers report that after only a few puffs of a
marijuana cigarette or a few inhalations of vaporized medical
marijuana, even very severe symptoms are relieved within minutes.
The relief does not last very long, wearing off after one or two hours.
Therefore, inhaled marijuana works best for RLS symptoms
that occur mainly at bedtime. Patients have reported that a one month
supply of medical marijuana may last three to four months
when used to treat bedtime RLS symptoms.

Marijuana is a structurally diverse chemical. Very little is known
about the 489 constituents of the marijuana plant, Cannabis sativa.
It is known that 70 of these constituents are cannabinoids, and the
remainder are potentially unwanted neuroactive substances that cross
the blood-brain barrier. An important distinction regarding cannabis
products is that tetrahydrocannabinol (THC) is the major
psychoactive ingredient (that is, it affects mental processes), and
cannabidiol (CBD) is the major non-psychoactive component. It is
believed that products that are high in CBD and low in THC will
produce wanted effects in the brain with little or no side effects on
mental processes.

Some of the cannabinoids widely consumed are:
  • Cannabinoid-rich preparations of cannabis in the herb (marijuana)
    or resin form
  • Cannabinoid-containing pharmaceutical products containing natural
    cannabis extracts (Sativex, a GW Pharmaceuticals drug in clinical trials
    in the U.S. and approved for use in Canada and other countries)
  • Synthetic cannabinoid (dronabinol (Marinal)), tetrahydrocannabinol (THC)
    or nabilone (Cesamet)

Studies on medical marijuana for treating pain and muscle spasticity
have shown a significant reduction in symptoms compared to
placebo. In addition, these studies found no significant adverse
effects, and patient tolerability to marijuana was good. The most
common side effects of marijuana reported included dizziness,
fatigue, dry mouth and nausea.

Many factors limit the use of medical marijuana in RLS. First,
no clinical trials have documented its benefits for treating
RLS. Second, studies of medical marijuana in pain and
muscle spasticity involved small study populations over a short period
of time, and therefore do not provide information on how a patient
would respond to long-term use. We also do not know the side
effects or complications of using medical marijuana over the long
term. Finally, the use of marijuana is very limited in the U.S. as it is
still considered illegal under federal law.

In summary, in addition to federal acceptance of the legality of
marijuana, more clinical trials are needed to validate whether the
use of medical marijuana would be beneficial in patients with
RLS.

Article from NightWalkers, Winter 2015, p. 8