Safety and Efficacy of Medical Cannabis Oil in the Treatment of Patients with Chronic Pain

Seeking for effective therapeutic strategies, the investigators are proposing to test the effectiveness of different formulations of medical cannabis oil to alleviate chronic pain, which was partially relieved with conventional prescriptions. Furthermore, the investigators would like to assess the effect of different formulations of medical cannabis oil on other symptoms associated to chronic pain like anxiety and depression, as well as insomnia and appetite. Finally, as recently recommended for clinical studies on medical cannabis, the investigators will examine the safety profile of different cannabis formulations focusing on the following elements: a real chronic administration with more than two weeks of treatment, a larger number of patients, and the clinical relevance of medical cannabis oil to change the amount and type of concomitant medications used to control chronic non-cancer and cancer pain.

This is a 6-week randomized, double-blind, placebo-controlled, parallel group design trial followed by an open-label extension phase of 12 weeks, to evaluate the safety and efficacy of different formulations of medical cannabis oil to reduce chronic pain intensity.

The study will be conducted at Santé Cannabis Clinic, the only medical cannabinoid therapy clinic, located in Montreal, Quebec. One hundred and sixty consecutive adult patients, male and female, with chronic non-cancer and cancer pain (at least 3 months in duration), with an average weekly pain intensity score greater than 4 on the 11 points NRS, will be prospectively recruited and invited to participate in this trial.

Informed consent will be obtained by a Research Assistant.

After baseline documentation with standardized scales, patients will be randomized to one of 4 parallel groups:

* Group A: THC/CBD ratio 1:1 capsule
* Group B: THC/CBD ratio 1:2 capsule
* Group C: THC/CBD ratio 0.1:2 capsule
* Group D: Placebo capsule Patients will have a dose titration phase during the first week. The dose escalation will allow patients to adapt to the potential adverse effects (AEs) of the medical cannabis.

Follow-up visits will be done after 1 week and 6 weeks of treatment. At the end of the first phase of the study, patients who wish to participate in the open-label extension phase will have the option to continue in the same treatment regimen. For the placebo group, the investigator may propose one of the cannabis oils to the subject if they feel it may potentially provide benefits.

They will take this new treatment for other 12 weeks. For this open-label extension phase the follow-up visits will be done after 4 weeks and 12 weeks of treatment.

Eligibility Criteria:
Inclusion Criteria:

1. Written informed consent
2. Adult patients (older than 18 years of age), male and female, with chronic non-cancer and cancer pain (at least 3 months in duration)
3. Patients experiencing an average weekly pain intensity score greater than 4 on a 11 points NRS
4. Subject agreed to follow the protocol
5. Naïve cannabis patients with chronic non-cancer and cancer pain (not used cannabis in any presentation in the last 12 weeks)
6. Patients receiving opioids and other concomitant pain medications should have a stable dose for the last 15 days.
7. Normal cognitive status according to MiniCog
8. Normal liver function (defined as aspartate aminotransferase 10-40 U/L and alanine aminotransferase 7-56 U/L)
9. Normal renal function (defined as serum creatinine level \<133 µmol/L and Estimated Glomerular Filtration Rate (eGFR) greater than or equal to 60)
10. Negative result on βhuman chorionic gonadotropin pregnancy test (if applicable)
11. Ability to read and respond to questions in French or English.
12. A female volunteer must meet one of the following criteria:

    If of childbearing potential - agrees to use one of the accepted contraceptive regimens from at least 28 days prior to the first drug administration, during the study and for at least 60 days after the last dose.

    If of non-childbearing potential - should be surgically sterile or in a menopausal state
13. A male volunteer with sexual partners who are pregnant, possibly pregnant, or who could become pregnant must be surgically sterile or agrees to use one of the accepted contraceptive regimens from first drug administration until 3 months after the last drug administration.

Exclusion Criteria:

1. Acute pain (less than 3 months in duration)
2. Previous serious adverse event or hypersensitivity to cannabis or cannabinoids
3. Inability to understand and comply with the instructions of the study
4. Presence of significant cardiac disease (history of unstable ischemic heart disease, heart failure, severe and uncontrolled hypertension) that, in the opinion of the investigator, would put the patient at risk of a clinically significant arrhythmia or myocardial infarction
5. Current substance use disorder according to the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM 5)
6. Life-time history of dependence on cannabis or diagnosis of cannabis use disorder (CUD) according to the DSM 5
7. Life-time history of DSM 5 schizophrenia, bipolar disorder, or previous psychosis with or intolerance to cannabinoids
8. Current or history of suicidal ideation
9. Pregnant, breast-feeding or female patients of child-bearing potential and male patients whose partner is of child-bearing potential, unless willing to ensure that they or their partner use effective contraception
10. Hepatic impairment (aspartate aminotransferase more than three times normal) or renal function impairment (serum creatinine level \>133 µmol/L, Estimated Glomerular Filtration Rate (eGFR) \<60)
11. Cognitive impairment according to MiniCog
12. The patient is currently using or has used cannabinoid based medications within 90 days of study entry and is unwilling to abstain for the duration of the study
13. Positive urine drug screen for cannabinoids and other potential abuse substances (e.g. alcohol, cocaine, amphetamines and methamphetamines, unprescribed opioids)
14. Participation in another clinical trial within 30 days of enrolment in our trial