14 October 2011

The pros and cons of medicinal marijuana - Smoking away the pain

For years, Audra, 50, has suffered severe pain from sciatica, a condition caused by damage to the sciatic nerve that runs from the lower spine to the leg and foot. The pain was so debilitating that she could barely walk and had to take sick leave from her job as a lab technician in Montreal. “My leg was burning so badly at one point that I wanted to have it amputated,” she says.

Audra tried just about every prescription pain reliever available, including opiates such as morphine and oxycodone. Her condition has improved with the addition of the anticonvulsant drug pregabalin and the antidepressant bupropion, but both these agents have miserable side effects. The only thing that significantly eased her pain was marijuana. “If I smoked a little pot, it would instantly, I mean instantly, decrease the pain enough that I could actually go out for the occasional walk and maintain contact with society,” she says.

She resorted to buying marijuana on the street — something she found distasteful. “I was dealing with criminals, basically,” she says. Every month, she was spending $300 and smoking 1.5 ounces (42.5 grams).

Now Audra has a permit under Health Canada’s Marihuana Medical Access Division. This allows her to possess the drug without being prosecuted. Canada is one of only two countries (the Netherlands is the other) to operate such a program. Our version includes a marijuana-cultivation facility in Saskatchewan (the exact location of which is secret for security reasons), where a single strain is grown, prepared and shipped to patients across the country. That strain is cannabis sativa, which contains about 12% tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana. Almost 5,000 Canadians now have physicianapproved licences to possess the drug for medicinal purposes, and about 3,500 have licences to grow the plant.

Audra is among the many patients with illnesses ranging from epilepsy and multiple sclerosis, to fibromyalgia and cancer whose pain or mobility is substantially eased by smoking marijuana. That may be because receptors on the surface of nerve cells in the brain and spinal cord are able bind to THC. It appears that THC prevents these neurons from becoming overactive, which is the root cause of the nerve pain experienced by patients like Audra.

Three prescription drugs also contain THC: nabilone and dronabinol — both oral agents — and a sublingual spray marketed as Sativex and containing THC and another cannabinoid called cannabidiol. But many patients maintain that smoking the drug works faster and better and gives them more control over their doses.

Smoking the drug can exert pharmacological effects within seconds, while oral agents can take a couple of hours, says Dr. Mark Ware, director of clinical research at the Alan Edwards Pain Management Unit of the McGill University Health Centre in Montreal. “Some people with migraines or epileptic seizures want a rapid onset of symptom relief. As well, you can carefully control the dosage, so if one puff doesn’t work after five minutes, you can have another, whereas with a pill or a spray, patients have to wait one to two hours to see a clinical effect.” No commercially available cannabinoid agent has as rapid an onset of action as medical marijuana.

Barbara Titsch, 69, finds that smoking hemp works better than any other pain reliever she’s tried. She has a permit from Health Canada to buy seeds from the federal government and to grow two plants outdoors at her home on the outskirts of Montreal. She dries and bags the plants and smokes them to relieve her intense pain from fibromyalgia, osteoarthritis and osteoporosis.

In the past, her pain was so severe that five years ago, she had to give up her clothing-manufacturing business. Today, she’s still in pain, but after smoking marijuana, she can at least walk up and down stairs, go shopping and do laundry.

Aside from pain, cannabis relieves other symptoms of illness, including nausea and vomiting in patients with cancer, anorexia and weight loss in patients with HIV/AIDS, and spasticity in those with multiple sclerosis. Unlike the case with some painkillers, constipation is not a common adverse effect of THC. There is some suggestion that cannabis and cannabinoid drugs can also act as an anti-anxiety agent for patients with post-traumatic stress disorder, although this has not been proven, says Ware.

Smoking marijuana may also give patients in excruciating pain a much-needed emotional boost. “That feeling of well-being may actually be a not-unwanted effect for someone suffering terribly with, for example, cancer pain,” says Ware.

Opponents of medical marijuana say that it can cause respiratory disease. It’s true that it’s associated with upper airway irritation and bronchitis, but there’s no clear evidence that it causes lung cancer or emphysema, says Ware. He adds that potential toxins are reduced by the use of vaporizers, which heat the drug to temperatures that release cannabinoids without burning the cannabis.

Other critics point out that the quality of the smoked products may vary widely and contain impurities. But according to Ware, Health Canada’s cannabis is certified to be free of contaminants, including heavy metals and microbes.

Another argument against medical marijuana is that it may lead to dependence or outright addiction. Ware counters that there is no clear evidence of this. “We have to be careful about interpreting such data from recreational-use studies since the two populations are very different. Careful monitoring of patients who use any such medication is required to detect behaviours that suggest inappropriate medication use.”

The “mild drowsiness factor the next day” is another downside of smoking medical marijuana, says Audra. But she’s quick to stress that “it’s all relative. If you’re in a lot of pain, you can’t concentrate, either.” She finds that smoking the drug actually “pushes the pain to the recesses of my mind so I can watch a TV program or talk to someone and not be totally overwhelmed by the pain.”

Naysayers maintain that patients who smoke marijuana will be unable to function normally, but that’s not typically the case since analgesic agents work differently in people in pain. “When you’re in severe pain and you take a drug that lowers the pain, you don’t get the same high as someone not in pain who takes it just to get high,” says Audra. Ware agrees that pain patients don’t experience the same euphoric effects from pain drugs as healthy people “because they have a different body chemistry and different receptor profile, and they carefully titrate [control the concentration of ] the dose to achieve clinical effects rather than intoxication.”

Yet another argument against smoking cannabis is that it could lead to abuse, but again, that doesn’t appear to be the case, says Ware. “Some people assume that patients are going to smoke volumes of the stuff and are just getting wasted. In fact, patients who are using cannabis responsibly report that using one or two puffs just to control their symptoms allows them to function normally.”

Barbara, for example, smokes only on an as-needed basis. The intensity of her pain increases as the day progresses. “I wait as long as I can — maybe until one or two in the afternoon — and take as little as possible,” she says. And she doesn’t so much get high from smoking as become more normally functional. “It doesn’t interfere with my brain; it just goes straight to my body, and I can feel my muscles become more relaxed and my anxiety about the pain lessen.”

Audra, too, insists she’s not abusing the drug. “It’s not abuse if it’s helping you to be more productive, and if your untreated pain is keeping you from mixing with society,” she says. “Without the relief that marijuana provided, I may have become suicidal.”

But there’s still the stigma of smoking an illicit drug — of being considered a “pothead.” Both Audra and Barbara initially hid their smoking from judgmental members of their families, and Audra is still reluctant to smoke in front of her adult son and daughter, saying she feels “awkward.” Barbara’s family is okay with it now.

In addition, many doctors are not keen to authorize the use of medical marijuana, possibly because they’re unfamiliar with how the body’s cannabinoid receptor system works and because clear evidence of the risks and benefits is lacking. Says Ware, who leads educational sessions on the topic for medical professionals, “We’re seeing an increase in knowledge and comfort levels, but there’s still a long way to go. Some groups of professionals are very resistant to the idea because of the lack of clear evidence of safety and efficacy.”

The Canadian Medical Association (CMA), for one, opposes the medical use of herbal marijuana precisely in the absence of supporting evidence and recommends that doctors not dispense medical marijuana under the existing regulations. It believes that the federal program unfairly places physicians in a gatekeeper role for access to herbal marijuana medication “without full knowledge of its effectiveness, proper dosage or short- and long-term side effects,” according to a CMA position statement.

In contrast, says the CMA, prescription oral agents that contain THC avoid the toxic by-products of smoked marijuana, have undergone clinical trials that demonstrate their safety and effectiveness and have been approved by Health Canada.

Ware acknowledges that there’s not as much information on herbal cannabis as there is on prescription medications, and since no organization — including the federal government — is sponsoring large clinical trials, this information is not going to be readily available any time soon.

“So the question is: How can physicians manage medical cannabis in the absence of such data?” says Ware. “And the answer is through balanced and open discussions — based on the best available evidence — between doctor and patient and an agreement to mutually monitor safety and effectiveness.”

He points out that the CMA accepts that physicians who feel qualified to support a patient’s application to possess medical cannabis do so in accordance with regulations and calls for government to carry out clinical research and undertake physician-education projects.

Thanks to a new pain-relief regimen that includes puffing cannabis, but on a reduced level, Audra has been able to go crosscountry skiing (her “favourite thing in the world”) and to return to work. She’s thrilled to be a productive member of society again — something she feels is essential to her well-being. “I smoke marijuana when the alterative would be living in excruciating pain and not sleeping all night and then not being able to work the next day,” she says. A few puffs in the middle of the night when the pain spikes gives her the kind of fast relief she can’t get from popping a pill.

Pauline Anderson
Canadian Health Magazine
© Canadian Medical Association

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