This year marked yet another milestone in the quest for pharmaceutical legitimacy when Health Canada approved a Phase II clinical trial involving medical cannabis.

The CAPRI Trial (Cannabinoid Profile Investigation of Vaporized Cannabis in Patients with Osteoarthritis of the Knee), which begins in the next few weeks, is overseen by one of the country’s most established medical cannabis producers, as well as researchers at McGill University Health Centre and Dalhousie University.

The randomized, double-blind, placebo-controlled study will examine the safety and analgesic dosage responses to vaporized cannabis of adults over 50 with osteoarthritis of the knee. The research will consist of several varieties of medical marijuana, with different concentrations of the two major active compounds, delta-9-tetrahydrocannabinol (THC; a mood-altering ingredient) and cannabidiol (CBD; a possible anti-inflammatory).

“The hope is to find a happy medium, a dose patients can safely use that minimizes side effects but helps them live with less pain.”

Arthritis of the knee

“Though it’s a preliminary study, this clinical trial is significant because we’re looking at two important things,” explains Dr. Mark Ware, one of the trial’s primary investigators and associate professor in Family Medicine and Anesthesia at McGill University. “We’re studying how patients respond to the delivery system of vaporized cannabis and we’ll see if there’s a particular ratio of the two major compounds most likely to give an analgesic response. It’s groundbreaking in many ways. The study and people involved will help build our knowledge base. We’re acutely aware of how little information there is out there to help physician make decisions with respect to medical cannabis.”

The trial decided to target those who suffer from arthritis of the knee  for a variety of reasons, including substantial research from animal models that cannabinoids could positively affect the symptoms of osteoarthritis. Another compelling reason to focus on osteoarthritis was that “…arthritic pain is one of the most sinister ones, and it doesn’t seem to go away easily,” says Brent Zettl, president and CEO of Prairie Plant Systems and CanniMed.

He notes that in the company’s tenure as a sanctioned medical marijuana supplier for Health Canada, they found that about 37 percent of the patients under the original program were using medical cannabis to treat some kind of arthritis.

Though there are medications for arthritis patients, Zettl points out that they are not without their issues: “There’s such a strong demand from people who need to manage pain and the options they have aren’t so great. There are a lot of challenges with the negative side effects of opiates like oxycodone.” Dr. Ware also highlights the limitations of current medications, “the standard analgesics currently available can be very effective but can also have significant side effects which can actually limit a patient’s ability to use them.”

The CAPRI trial is an important step in educating people and doctors about the possible benefits of marijuana and allaying deeply rooted fears. “One of the major barriers to the widespread usage and acceptance of medical marijuana is a fear of patient abuse,” says Dr. Ware.

Education is key

“Many physicians are worried that patients who ask for medical cannabis want to use it for recreational purposes. Yet we hear repeatedly from patients that they’re trying to control severe symptoms and cannabis appears to be helping them. They want to achieve a quality of life they can’t have with other medication. By studying medical cannabis we’re trying to strike a balance between what patients tell us and address physicians’ concerns. The hope is to find a happy medium, a dose patients can safely use that minimizes side effects but helps them live with less pain.”