Much to learn about medical marijuana
A recent front-page headline in the Guardian was sure to get the attention of the many Islanders suffering from acute and chronic pain.
It reported on a conference on medical marijuana held in Charlottetown. The keynote speaker delivered a sincere endorsement of cannabis in helping him manage his chronic back pain and symptoms of multiple sclerosis. He recommended that physicians use cannabis as a first line drug to treat pain.
He implied that many physicians are ignorant of the benefits of cannabis and need to be encouraged to “get with the program.”
As a specialist in pain medicine, I have had considerable experience working with patients using medical marijuana, and, with due respect, would caution that marijuana is not “safer than water,” nor is it as essential to life.
Physicians are hesitant to embrace not yet proven therapies, particularly when the preponderance of support comes from testimonials and political activism, and not through carefully designed clinical testing.
Opinions to the contrary, we do indeed know quite a bit about cannabis, its botany, its effects on humans, its clinical utility and many of its risks and benefits.
Unfortunately, much of our knowledge comes from animal research and not a whole lot from clinical testing on humans.
According to our experts, here's some of what we know.
Clinical studies supporting the safety and efficacy of smoked cannabis for therapeutic purposes are limited, but slowly increasing in number. There are no clinical studies on the use of cannabis edibles (e.g. cookies, baked goods) or topicals for therapeutic purposes. It has been repeatedly observed that the psychotropic side effects of cannabinoids limit their utility.
Cannabis smoke contains many compounds not found in either extracts or vapour, including a number which are known or suspected carcinogens or mutagens. Moreover, comparisons between cannabis smoke and tobacco smoke have shown that the former contains many of the same carcinogenic chemicals found in tobacco smoke.
The body’s endocannabinoid system plays an important role in the modulation of pain states. Research involving patients suffering from pain suggests that cannabinoids may be most effective for chronic, primarily neuropathic pain.
There is evidence that cannabis dependence (physical and psychological) occurs, especially with chronic heavy use. The addiction potential for cannabis has been estimated at about nine per cent, compared to nicotine at 32 per cent or heroin at 23 per cent.
Cannabis should not be used by any person under the age of 18. The adverse effects of cannabis on mental health are greater during adolescence than in adulthood. The risk of an acute psychotic break by age 26 is 4.5 times higher in regular cannabis smokers who start at age 15. It is 1.6 times higher if cannabis smoking doesn’t start until age 18. The risk of developing schizophrenia doubles in regular cannabis users, particularly those using high-potency sinsemilla [skunk] who start in their early teens. Chronic cannabis use may have negative effects on memory.
The routine use of cannabinoids to treat primary anxiety or depression should be viewed with caution, and especially discouraged in patients with a history of psychotic disorders.
Cannabis should be used cautiously in patients with a history of substance abuse because such individuals may be more prone to abusing cannabis.
Cannabis should be used with caution in patients receiving concomitant therapy with sedative-hypnotics or other psychoactive drugs because of the increased risk of overdose or addiction due to additive or synergistic CNS depressant or psychoactive effects.
Cannabis is not recommended for women of childbearing age not on a reliable contraceptive, as well as those planning pregnancy, who are pregnant or women who are breastfeeding. Men, especially those on the borderline of infertility and intending to start a family, are cautioned against using cannabis since exposure could potentially reduce the success rates of intended pregnancies.
Patients using cannabis should be warned not to drive or to perform hazardous tasks because impairment of mental alertness and physical coordination may decrease their ability to perform such tasks.
The estimated human lethal dose of intravenous tetrahydrocannabinol [THC] is 30 mg/kg, although there have been no documented deaths exclusively attributable to cannabis overdose.
In my experience, the therapeutic value of cannabis in managing chronic pain is limited by its adverse effects.
We still have a lot to learn about the appropriate clinical use of ' medical marijuana' and should not be in a hurry to jump on this bandwagon.