The cannabis conundrum


By Roxanne Tang and Susan C. Jenkins

Meet Jim, a 70-year-old resident of an assisted living home. He is in generally good health, but he has been plagued by chronic pain for over five years. Jim’s physician has been prescribing opioid medication for the pain, but Jim is not managing well, and his quality of life is suffering. His doctor is considering whether medical cannabis (also known as medical marihuana or marijuana) might be an appropriate addition to Jim’s therapy. There are many factors he will have to assess before he makes that decision.


The basics

Medical cannabis is not the same as the drug that can be bought on the street. It is subject to strict quality control, testing, and analysis to ensure a safe product, free of contamination from mold, bacteria, or pesticides.

Medical cannabis should not be thought of as a single agent. Over 100 cannabinoids (chemical compounds that act on specific receptors in the brain and body) have been identified in cannabis. Two key cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD).

THC is the principle psychoactive component of cannabis and is responsible for the euphoria or “high” from using cannabis and psychotropic effects. It is effective in relieving pain, muscle spasms, and controlling nausea.

CBD is mainly non-psychoactive. It is thought to have anti-inflammatory, analgesic, anti-nausea, anti-emetic, and antipsychotic effects. The relative concentrations of THC and CBD vary widely among cannabis strains and significantly impact the pharmacological and therapeutic effects of the final cannabis product.

In addition, plant chemicals called terpenes, terpenoids, and flavonoids play a key role in modulating the effects of cannabinoids.

Cannabis is different from any other pharmacologic agent. At present, there is insufficient scientific evidence to establish the safety and efficacy of cannabis to the level required by Health Canada. There are no approved indications, no standardized format, no drug identification number (DIN), and no dosing guidelines. Cannabis is generally not a first-line agent. It is more commonly used after other treatments have proven unsuccessful.

Possible benefits, potential risks

There is strong evidence that cannabis can have therapeutic benefit as an antiemetic in chemotherapy-induced nausea or vomiting, as an analgesic in chronic pain patients, and to reduce spasticity in adults with multiple sclerosis. Cannabis is also commonly used for stress, anxiety, and certain sleep disorders, although efficacy is difficult to quantify and tends to be highly subjective. More clinical research is needed for the use of cannabis in these and other conditions.

Cannabis can cause some significant adverse effects that must be taken into account when determining its appropriateness for an individual patient. Drowsiness and dizziness, two well-known side effects, can increase the risk of falls, posing particular problems for elderly patients. Other potential adverse effects include fatigue, impairment of short-term memory and information processing, altered judgment, and decreased attention, which can be a concern in patients already suffering from cognitive decline.

Care must be taken to minimize the risk of drug interactions. Residents taking other psychoactive drugs, antidepressants, or anti-anxiety medications must be carefully monitored, as cannabis can enhance the actions or side effects of these medications.

How does all of this impact Jim, our chronic pain patient? Because he is in generally good physical and mental health aside from his chronic pain and he takes no medications other than analgesics, Jim’s doctor decides he’s a suitable candidate for medical cannabis.


Access to Medical Cannabis

The Access to Cannabis for Medical Purposes Regulation (ACMPR) provides the framework for patients to legally acquire medical cannabis in Canada today. The channel of distribution differs from that of any other medication. The “prescription” must be written by a physician or nurse practitioner, ordered from a licensed producer, and delivered directly to the patient by mail order. At this time, it is not legal for the licensed producer to provide cannabis in any other format except seed (for patients to grow their own plants), dried or fresh cannabis, or as cannabis oil. Furthermore, the ACMPR does not allow pharmacists to play a role in the safe distribution of medical cannabis as they would do with other medications.


Implications for the healthcare team

Current legislation doesn’t address the use of medical cannabis in the retirement home or long-term care environment. For example, it is the responsibility of the client for ordering, registering with the licensed producer, receiving, storing, dosing, handling, and disposing properly of unused cannabis. Residents are often cognitively or physically challenged and incapable of taking on these responsibilities.

Security is an important issue when dealing with cannabis. Steps must be taken to ensure that it is stored securely (under lock and key), so that unauthorized individuals do not have access to it. Excess cannabis must be destroyed safely prior to disposal.

Nurses and other health professionals are struggling to develop protocols to deal with medical cannabis that are in keeping with the ACMPR, the Nursing Home Act, and other required regulations.

Dosing and administration

Because there is no standard dosing guidelines for cannabis, dosing is highly individualized. It relies to a great extent on experimentation to find the dose that provides maximum therapeutic value with a minimum of adverse effects. The general rule of thumb is to “start low and go slow.”

Health professionals do not condone smoking cannabis, as this releases the same toxins and carcinogens as smoking tobacco. Additionally, secondhand smoke and the distinctive aroma released by combusting cannabis are significant issues.

The most common and accepted routes of administration for medical cannabis are inhalation by vaporization and oral consumption of the oil. Vaporization, or “vaping,” involves heating the dried cannabis to a lower temperature than smoking and inhaling the resultant vapour thru a special device.

Cannabis in an oil format permits more precise dosing and standardization of strength. This is a highly concentrated product, so only a few drops need to be taken. The oil is typically swallowed or placed under the tongue.

For medical purposes, baking or cooking with cannabis or making a tea out of cannabis leaves is not recommended. It is extremely difficult to control the potency and dosing of cannabis once the physical properties have been modified in this fashion.

With inhalation (smoking or vaporizing), the effects are typically felt within a few minutes and peak within a half hour. Acute effects usually last between two and four hours.

With oral ingestion of cannabis oil, the effects are much slower. Onset of action is generally 30 to 45 minutes but may be more than two hours, depending on the individual. It typically peaks three to four hours after dosing and lasts much longer than inhaled cannabis.  Because of its longer duration of action, oral cannabis is more difficult to titrate, and patients should wait a minimum of four hours before taking more to avoid overdosing.


Revisiting Jim

It has now been six months since Jim began his cannabis therapy. His pain is better controlled, he has been able to reduce his use of other pain medications, and he has been able to participate in more activities. He is happier and feels that the quality of his life has improved substantially.

Susan C. Jenkins is a freelance writer and editor specializing in medicine, pharmacy, and healthcare. She can be reached at Roxanne Tang, RPh, BSP is a pharmacist and Director of Pharmacy Practice with Medical Pharmacies Group Limited. She advocates for regulatory amendments to allow pharmacists to distribute cannabis for medical purposes.   



Please enter your comment!
Please enter your name here