Years ago, when he was co-host of the humorous medical radio show Wise Quacks, Dr. Rob Sealey decided to look for an expert to interview about the medical uses of marijuana. The only person he and co-host Dr. Dave Hepburn could find was Tommy Chong, the comedian and cannabis rights activist.

 

“My patients were asking the questions and I had no idea how to answer them,” Dr. Sealey told delegates at the two recent FNHA Nursing Education Forums. That experience prompted a quest for knowledge that has led to Dr. Sealey being considered one of Canada’s foremost specialists on the medical uses of cannabis. As he himself acknowledges, there isn’t a lot of competition.

 

“Our college [The Canadian College of Physicians and Surgeons] still doesn’t offer education on the topic,” he said. “Five years ago I was such an anomaly that the college did an audit of my practice and some colleagues were saying I should have my license revoked. Now they’re referring patients to me.”

 

Attitudes have changed – are still changing – however there is still much to learn about cannabis. The plant has been used for therapeutic purposes in many cultures for thousands of years and as recently as the early 19th century it was included in 20 per cent of all prescriptions (Dr. Sealey showed a slide of a cough medicine label listing the ingredients as alcohol, cannabis, chloroform and morphine!)​

 

Where is the Evidence?

 

Cannabis for medical purposes has not been well studied because of its previous illegal status, the complexity of the plant (it has about 500 parts) and the fact that it can’t be patented to make it profitable to research. There is clinical evidence that indicates cannabis is effective in treating chronic neuropathic pain (pain originating from nerve signals and not an injury), chemotherapy-induced nausea and vomiting, spasticity (tight or stiff muscles) in multiple sclerosis, and a form of childhood epilepsy called Dravet syndrome that is almost impossible to control with conventional treatment. As more clinical research is conducted, the evidence for medical cannabis as indicated for other disorders may be forthcoming.

 

Understanding Cannabis

The key to the medicinal versus the recreational use of cannabis is the difference in the plant’s key components.  CBD (Cannabidiol) offers therapeutic benefits and has little, if any, intoxicating properties. THC (tetrahydrocannabinol) is the chemical that causes the euphoria or “high” that goes along with marijuana consumption. While a minor amount of THC is necessary to activate the CBD, therapeutic doses can be taken that result in little if any alteration to the state of mind.

Since the body produces cannabis-like substances as part of the endocannabinoid system (an abundant “messenger” network that is present in both the central and peripheral nervous systems as well as the peripheral organs), medical cannabis can work by fitting into these same receptors. The endocannabinoid system and its role in many medical conditions is not yet fully understood but it is the subject of a growing body of research.

 

How Safe is Cannabis?

The THC forms of cannabis are not recommended for young people, whose brains are more vulnerable to injury while they are still developing until approximately age 25. As delegates heard in the panel discussion on mental health and substance use, cannabis-induced psychosis (from THC) can last up to 30 days in some people and also trigger the onset of psychotic illness.  THC is also addictive, though less so than other substances such as cocaine, alcohol or nicotine. Furthermore, no overdose deaths have been reported with either form of cannabis.

Dr. Sealey noted that edible forms of cannabis can result in excessive ingestion because this form doesn’t produce an immediate effect, which can prompt people to ingest more. Inhalation through a vaporizer is good for a quick response that lasts about three hours. Oils or edibles have a delayed onset of about 60 to 90 minutes and their response, while not as intense as with inhalation, lasts 10 to 12 hours.

“Oil is the only way to dose precisely,” said Dr. Sealey. “It is metabolized by the liver and takes up to two hours to have a noticeable effect, with a peak response at about four hours.”

As for dosages, Dr. Sealey’s mantra is “start low, go slow.”

“I leave it up to the patients to adjust [their dosage],” he said “It’s safe and I’ve never been able to predict what their dosage will be. Some people are very sensitive, some need a large amount.”

Cannabis is safer than opiates. For example, the state of Colorado saw a 24 per cent reduction in mean annual opioid deaths since the legalization of medical cannabis, a rate that continues to decline.  In specific cases, cannabis may be used in place of NSAIDs (non-steroidal anti-inflammatory drugs) such as Advil or Aleve (overdose of some of these drugs is the leading cause of acute liver failure). It is still not widely recognized in the medical community, however. For example, the Canadian Pain Society lists cannabis as third-line therapy, with opioids as second-line.

“We hold cannabis to a different level of evidence than other medications,” said Dr. Sealey. 

Acceptance of existing evidence is one matter. Knowledge among medical practitioners is another. For example, the Arthritis Society is now recommending patients consult their doctors about the use of cannabis but the challenge is finding doctors who know about it.