Burning Question, Can Science Confirm Marijuana’s Medical Benefits?

After all the usual and proper medical approaches did nothing for her pain, Cheryl Campbell, a nurse and mother, says she finally built up the courage to ask her doctor, “How do you feel about prescribing me marijuana?” The 30-year-old Ottawa woman suffers from fibromyalgia and chronic fatigue syndrome. Her pain is body-wide – a constant, sometimes stabbing ache in her back, hips, knees, shoulders and virtually every joint. Doctors once put her on morphine. It cut the pain, but she couldn’t function. She says her mind felt so heavy with fog she couldn’t carry on a conversation. She’s been using marijuana for pain for two years; she has a federal licence to possess it. She says it helps her sleep at night. In the morning, it helps ease the stiffness in her hips and back enough that she can make it into the shower. Campbell says she owes her ability to get through each day to a drug that critics condemn, especially when it’s smoked – which is how most of the thousands of Canadians who self-medicate with pot prefer to take it. The U.S. Drug Enforcement Agency was unequivocal earlier this year: Smoked marijuana is not medicine, and it’s not safe. “No matter what medical condition has been studied,” the agency ruled, “other drugs already approved by the (U.S. Food and Drug Administration) have been proven to be safer than smoked marijuana.” But research into medicinal marijuana is undergoing a surge of interest, with more evidence emerging not only of its ability to ease human suffering, but also of its apparent safety.

Some say cannabis may be less toxic to humans than over-the-counter pain relievers. Four small but scientifically controlled experiments in recent years have concluded that smoked cannabis can provide moderate relief from chronic, severe non-cancer pain – including HIV-related nerve pain and posttraumatic neuropathy, a dreaded condition that can follow an injury or medical procedure. Both are notoriously resistant to conventional treatments. Scientists are only beginning to tease out the possible anti-cancer properties of pot. Early experiments in animals suggest that purified forms of THC and cannabidiol – two major constituents of marijuana – can induce certain cancer cells, including breast cancer cells, to essentially kill themselves off, a process known as apoptosis. The cells self-destruct; they stop dividing and spreading. Cannabinoids also seem to shut down a tumour’s lifegiving blood supply. Meanwhile, researchers across Canada are testing cannabinoids against arthritis, glaucoma and gastrointestinal inflammatory diseases, such as Crohn’s. “Science is just scratching the surface,” says Dr. Mark Ware, head of the Canadian Consortium for the Investigation of Cannabinoids and director of clinical research at the Alan Edwards Pain Management Unit at Montreal’s McGill University Health Centre. In Canada, synthetic versions of THC and other pure cannabinoids are already available by prescription – pills and sprays approved for cancer pain, for nausea associated with chemotherapy, to stimulate appetite and for the relief of the pain and spasticity of multiple sclerosis. Medical marijuana, Ware argues, is essentially just a different delivery system for cannabinoids.
It’s crude, he acknowledges. It’s also associated with potential harms through the sheer act of burning the plant and smoking it. But even then, he says the evidence is uncertain. “It’s not a done deal that smoking cannabis alone is as potent a cancer-causing agent as tobacco,” Ware says. According to U.S. drug enforcement officials, while smoked marijuana can cause changes in lung tissue that may very well unleash cancer, “it’s not possible to directly link pot use to lung cancer based on existing evidence.” But does it have any legitimate role in medicine? Cannabis sativa preparations have been used as medicine for thousands of years. In The Science of Marijuana, retired Oxford University professor Les Iversen – now chair of the U.K. government’s Advisory Council on the Misuse of Drugs – says Chinese herbal medicine texts dating to 2800 BC recommended cannabis for constipation, gout, malaria, rheumatism and menstrual complaints. Modern interest in cannabis exploded in the 1980s when researchers discovered all mammals – notably humans – have an endogenous, or built-in, cannabinoid system. Essentially, we make our own marijuana. Two types of receptors for cannabinoids – CB1 and CB2 – are found in the brain and spinal cord, nerve cells and immune tissues. The body produces a natural, THC-like chemical called anandamide – the so-called “bliss chemical” – that binds to these receptors. Anandamide has been found to play a part in pain, anxiety and depression. The reason we don’t walk around high all the time is that anandamide is released only in response to some kind of noxious or painful stimuli, such as an injury or inflammation. The neurotransmitter latches onto the receptors and, in the case of pain, helps settle down the firing of nerves in the pain pathway. But it’s broken down quickly, chewed up by enzymes so rapidly that it never reaches a level sufficient to cause a high. When someone smokes marijuana, those exogenous cannabinoids “are obviously going to hit all the cannabinoid receptors in the body,” explains Dr. Jason McDougall, associate professor in the departments of pharmacology and anesthesia at Dalhousie University in Halifax. And since one of those receptors, CB1, is most prominent in the brain, “That’s why we get a lot of those psychoactive effects of the drug.”

But the cannabinoids in pot also occupy receptors in the peripheral nerves involved in the body’s pain system, as well as nerves controlling movement and other functions. Studies of patients with MS have found that cannabis can help with muscle pain, tremors and depression; patients have reported feeling better able to move. Laboratories around the world are examining ways to harness this potential in a way that minimizes psychotropic side-effects. Some are trying to develop a drug that acts peripherally; others are looking for drugs that block the rapid breakdown of our own endogenous cannabinoids – “the same way we treat depression by giving antidepressants that can inhibit or interfere with the breakdown of certain chemicals in our brain like serotonin,” says Dr. Mary Lynch, director of the pain management unit at Queen Elizabeth II Health Sciences Centre in Halifax and past president of the Canadian Pain Society. Studies suggest about 15 per cent of patients reporting to pain or MS clinics are using marijuana. In his book, Iversen says that rats, mice and other lab animals can tolerate doses of cannabis up to 1,000 milligrams per kilogram – the equivalent, he writes, “to a 70 kg person swallowing 70 grams of the drug, about 5,000 times more than is required to produce a high.” Despite its widespread illegal use, there are few, “if any,” reports of fatal overdoses from cannabis, Iversen said. By contrast, thousands die each year from “catastrophic” bleeding in the gut caused by non-steroidal anti-inflammatory drugs, or NSAIDS, he said.

Doctors say that what makes cannabinoids safer than opioid pain medications is that cannabinoid receptors, unlike receptors for opioids, aren’t present in high numbers in the brain stem regions that control breathing and heart rate. “This is one of the reasons cannabinoids are generally safer than many of the other drugs used to treat human disease and pain,” Lynch says. The most common side-effects are sedation and foggy thinking. “You can also get high,” Lynch says. “But many of our patients adjust the dose so they can avoid the side-effects and aim for the therapeutic effects, similar to the way we use any drug.” Ware of McGill said that for cases of severe intractable pain, the prescription oral cannabinoids often don’t work. Some patients prefer the inhaled mode because it’s the fastest way of experiencing its effects. McDougall of Dalhousie has found that when synthetic cannabinoids are injected into the joints of arthritic rats, “we can control the pain in the joint itself” while avoiding the psychoactive effects of the compounds. “We don’t have great agents now,” he says. Many drugs used for arthritis have “multiple negative sideeffects,” he says – including a potential increased risk for cardiovascular disease, kidney disease and gastro-intestinal bleeding associated with long-term use of NSAIDS. “There are still a lot of arthritis patients out there who are not getting adequate pain relief for their disease,” he said. Many are turning to pot. “A lot of patients who are on medical marijuana are taking it to control their arthritic pain,” he says.

That makes Dr. Meldon Kahan nervous. He and others worry that smoked marijuana’s promotion among users as a legitimate medicine, especially for pain, is driving a rise in illicit use at a time when Canadians are already among the highest per capita users of pot in the western world. “A lot of people – particularly young people – are harmed by the notion that cannabis is this harmless herb,” says Kahan, a physician and associate professor in the department of family medicine at the University of Toronto. Kahan says cannabis may trigger psychosis in people with a genetic vulnerability. He says more users – young and old – are becoming addicted. “It’s harming their social relationships, their work.” For select conditions such as HIV-related neuropathy, cannabis “may very well have benefit,” says Kahan, formerly of the Centre for Addiction and Mental Health in Toronto. But others might be confusing its “very mild” analgesic effects with its mood-altering ones, he said. “Cannabis, especially daily use, makes people feel relaxed. It reduces anxiety and stress. People feel mellow and so they may perceive their pain as being blunted, or milder.” Ware says that none of the scientists working seriously in the field today want to be misconstrued as saying, “This is a safe drug for kids to use.” “That is absolutely not the case. We are talking here of using this class of drugs – smoked, oral, spray or otherwise – for patients with severe medical illnesses.” Despite the polarizing nature of pot, “We have to take the middle ground and say, ‘Where are the potential benefits?” Ware says. Campbell, a registered practical nurse who can no longer work because of her pain, says that, if it were not for marijuana, “I don’t know if I’d ever get out of bed and get moving.” After 10 years of pain, “it’s the only thing that helps.”

via : EdmontonJournal.com

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