Thursday, February 07, 2013
As states across the nation continue to legalize marijuana for medicinal use — and some for recreational use — the conversation about the drug’s benefits begins to heat up. Although marijuana is considered a Schedule I substance — a drug with “no currently accepted medical use” — recent studies have demonstrated empirical evidence that the plant does indeed provide therapeutic relief for chronic pain associated with neurological deficits. But are cannabis’ psychoactive side effects a fair price to pay for relief?
Sativex, an oral spray absorbed by the mucosal lining in the mouth, is a new medicine derived from an isolated cannabinoid found in marijuana developed to help with the management of spasticity related to MS. The drug is currently approved in the United Kingdom, Canada, Spain and New Zealand for treating MS-related spasticity but is not currently approved by the U.S. Food and Drug Administration (FDA).
Spasticity, painful contractions of muscles in the arms and legs, has not been well controlled up to this point, and a study from the Center for Medical Cannabis Research indicates cannabis helps patients with MS control their cramping and ease the pain associated with it. The problem, according to the study’s authors, is patients may not like the fatigue and dizziness caused by smoking cannabis. Additionally, cognitive effects from smoking cannabis make the drug problematic for those suffering from MS, which already causes cognitive deterioration.
Opponents of medicinal marijuana also raise objections to the drug because it has not undergone extensive safety and dosing measures that other drugs must pass under the purview of the FDA. Proponents feel that because marijuana overdose is all but impossible, stringent guidelines do not necessarily matter. Instead, they say, physicians need to wisely recommend the drug to only patients who may benefit from it.
The Question of DosingBecause trials have not been extensive and no uniform dosing measures have been established, opponents of medical marijuana feel as though patients are being presented with a drug that represents more of a variable than an established curative. Eric Voth, M.D., internal medicine, pain medicine and addiction medicine specialist, and Chair of the Institute on Global Drug Policy, notes that all other medications must go through a rigorous process of safety and efficacy testing before becoming accepted for use. Through this process, dosages may be specified.
“On one hand, maybe patients will benefit, but not clearly. On the other, there are negative cognitive effects,” notes Dr. Voth. “As a pain specialist, I’m wondering, ‘Why would I have a patient smoke a substance that I can’t control, can’t dose correctly, have no clear picture as to where it falls on the spectrum, and give patients cannabis with the hope that it makes them feel better?’ I think that’s irresponsible.”
While physicians on both sides of the debate agree that more work needs to be done to establish precise dosing measures, studies have been conducted to measure the efficacy and safety of specific amounts of the most identified cannabinoid (an active component of cannabis plants), delta-9-tetrahydrocannabinol (9-THC), used by patients suffering from chronic pain.
Through his work on medicinal marijuana, Barth Wilsey, M.D., associate physician, Department of Physical Medicine & Rehabilitation, University of California Davis Medical Center, has shown that patients who do not respond to or cannot tolerate other medications can ameliorate neuropathic pain by smoking cannabis cigarettes or inhaling vaporized cannabis with low percentages of THC.
“My work has shown that low doses of cannabis alleviate pain,” says Dr. Wilsey. “Why take higher doses? Why not tell people to take lower doses to see if it alleviates pain? The medical profession needs to teach [medical] students how to handle questions about marijuana dosing.”
In his 2008 study published in the Journal of Pain, Dr. Wilsey wrote that patients with central and peripheral neuropathic pain were divided into groups that were provided cigarettes containing different levels of 9-THC — 7% 9-THC and 3% 9-THC — and both groups achieved analgesia.
“One of the fundamental flaws of the voting issue, whether it’s by ballot initiatives or legislative vote, is that it bypasses the FDA. This creates a consumer protection nightmare: medicine by popular vote.”While the study successfully demonstrated that there may likely be a therapeutic window physicians can use for clinical purposes, objections may be made that smoking a medicine can lead to adverse side effects. Alan Shackelford, M.D., principal physician of Amarimed of Colorado, Intermedical Consulting and Harvard Park Health, recommends cannabis for patients who have reached the end of their treatment options for pain without relief. When smoked, cannabis is absorbed by mucosal linings in the mouth, which allows effects to present quickly in a stronger manner than if absorbed by the stomach via candies or food, which Dr. Wilsey notes is problematic because the liver removes most of cannabis’ active compounds, weakening its effect. Alternative delivery methods, such as vaporization, may eliminate the need for smoking, thus negating the need to light up and inhale harmful carcinogens such as tar.
— Eric Voth, M.D., internal medicine, pain medicine and addiction medicine specialist, Chair of the Institute on Global Drug Policy
“I strongly encourage patients for whom I recommend the use of medical cannabis not to smoke it,” says Dr. Shackelford. “In addition to the fact that you’re inhaling carbon monoxide and tar and a number of other problematic substances, the temperature of burning marijuana destroys many of the 108 compounds that have been shown to have significant physiological benefit.”
Addressing that concern, Dr. Wilsey and his colleagues conducted a second study, which has been accepted for publication by the Journal of Pain, examining the effects of cannabis heated to the point of forming active cannabinoid vapors, but not enough to combust, thus avoiding respiratory toxin. Importantly, for this study, Dr. Wilsey requested cannabis that contained less concentration of 9-THC, this time examining analgesic efficacy of cannabis engineered to contain different levels of 9-THC — 3.53% 9-THC and 1.29% 9-THC. The study’s results further showed evidence for a potentially useful therapeutic window. Patients achieved analgesia with both dose levels of cannabis, and in both studies, psychoactive side effects — the “high” feeling — dissipated in fewer than four hours, suggesting that physicians might easily recommend patients use the drug before going to bed, just as instructions read for other medications that affect motor skills.
Pain Relief or Just Getting High?One question any researcher must answer when studying cannabis use for pain relief is whether patients truly achieve pain relief or are simply too intoxicated to care about the pain. This concern is addressed in Dr. Wilsey’s second Journal of Pain study, regarding the efficacy of vaporized cannabis. Upon examination, the analgesic effects of cannabis “maintained significance above and beyond any influence of the 15 side effects and, therefore, an independent effect on study medication was evident.”
Dangerous MedicineAlthough cannabis has demonstrated benefits in alleviating neuropathic pain resulting from various conditions — among them cancer, human immunodeficiency virus (HIV) and spasticity caused by MS — it has been shown to cause negative side effects as well.
“I don’t want young people to think that cannabis is harmless,” says Dr. Wilsey. “European studies have shown that cannabis may induce schizophrenia in those susceptible to it. I want all the safeguards that have been brought to bear to keep young people off cannabis.”
Additionally, Dr. Wilsey notes that cannabis may also induce paranoia, respiratory depression and loss of motivation. For this reason, Dr. Wilsey recommends that physicians use caution and conduct thorough patient histories before recommending cannabis to patients.
An Alternative to OpioidsAll but lost in the debate over cannabis’ medical benefits is how its use compares with the danger of opioid pain relievers and the epidemic in the United States of prescription pill abuse. Centers for Disease Control and Prevention (CDC) statistics from 2012 show that sales of prescription pain killers have risen 300% since 1999, and in 2008, these drugs contributed to 14,800 overdose deaths — more than cocaine and heroin combined. Dr. Voth notes that, as a pain medicine specialist, he deals with opioids a lot, and physicians must be very careful when prescribing these narcotics.
“You can’t overdose from cannabis unless you take extraordinary amounts, unlike opioids,” explains Dr. Wilsey. “That’s why people are allowed to take cannabis without a prescription where it is legal. They can take enough to alleviate the pain immediately — another benefit of smoked or vaporized cannabis. You don’t have to take it repeatedly if pain goes away.”
In his practice, Dr. Shackelford has seen patients benefit from cannabis regimens, including a 103-year-old woman who uses cannabis as an adjuvant treatment to lower the dose of narcotic pain medicine because cannabis increases the analgesic effect of her medicine.
“The more I researched, the more information I uncovered, and the more reasonable it seemed to consider cannabis as a medical option for patients with those conditions for which marijuana can be recommended based on Colorado law,” explains Dr. Shackelford. “Ultimately, it’s based on outcomes and safety. I found that not to consider it when appropriate was to ignore a treatment option that could have significant benefits for a great many people.”