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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
The CANBACK trial, to determine the efficacy of oral cannabidiol, when compared to placebo, as an adjunct for the treatment of acute non-traumatic low back pain.
Scientific title
A randomized, double-blinded, placebo-controlled, clinical trial assessing the efficacy of CANnabidiol for reducing BACK pain in the emergency department (CANBACK)
Secondary ID [1] 294314 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Back pain 307025 0
Condition category
Condition code
Musculoskeletal 306129 306129 0 0
Other muscular and skeletal disorders

Study type
Description of intervention(s) / exposure
Single dose oral syrup cannabidiol, 400mg, administered by nurse at the bedside.
Intervention code [1] 300618 0
Treatment: Drugs
Comparator / control treatment
Single dose oral caprylic/capric triglyceride syrup, administered by nurse at the bedside.
Control group

Primary outcome [1] 305148 0
The primary outcome measure will be the patients' pain score, determined using a verbal numerical pain scale, range 0-10.
Timepoint [1] 305148 0
2 hours after study medication administration.
Secondary outcome [1] 344317 0
ED length of stay as assessed by hospital electronic medical records.
Timepoint [1] 344317 0
Up to 24 hours post admission to ED..
Secondary outcome [2] 344318 0
Need for rescue analgesia as documented in hospital electronic medical records.
Timepoint [2] 344318 0
Up to 24 hours post admission to ED.
Secondary outcome [3] 344319 0
Adverse events as documented on case sheet or reported by patient during 48 hour follow up phone call. Possible side effects include allergy, tiredness or lethargy (20-30%), diarrhea (10%), nausea or vomiting (10%), headache (10%).
Timepoint [3] 344319 0
48 hours post admission to ED.

Key inclusion criteria
Presentation with acute non-traumatic low back pain, defined as pain and discomfort localized below the costal margin and above the inferior gluteal folds for a period of less than 30 days as assessed by the treating physician. This definition will include those with a past history of low back pain.
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
- cannabis or cannabidiol use in previous 7 days, as reported by participant
- abnormal neurological examination
- fever (>37.6oC)
- a history of malignancy, non-musculoskeletal cause of back pain
- pregnancy - all female participants age < 60 will require a urine Beta hCG to exclude pregnancy.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Numbered containers.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Phase 2
Type of endpoint(s)
Statistical methods / analysis
We believe that a clinically significant difference between the pain scores of the two groups at 2 hours after study medication administration would be 2 out of 10. In order to demonstrate a statistically significant difference between the groups at 2 hours, at least 47 patients are required in each group (mean pain scores in the placebo and CBD groups of 4 and 2, respectively, SD 3, alpha 0.05, 2-sided, power 0.9). As CBD has not previously been examined in the ED setting, a number of assumptions have been made in this calculation. Accordingly, we will enroll 50 patients in each study group.

The primary endpoint will be the difference in pain verbal numerical pain scores between the groups. The analysis will be conducted based on "intention to treat". Continuous variables will be summarized as median and interquartile ranges. The Mann Whitney U test will be used to analyse continuous unpaired continuous data. The Chi square test will be used to analyse unpaired categorical data.
SPSS for Windows statistical software (version 24.0, SPSS Inc., Chicago, Illinois, USA) will be employed for all analyses. Statistical significance will be recognized at 0.05.

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 10372 0
Austin Health - Austin Hospital - Heidelberg
Recruitment postcode(s) [1] 22047 0
3084 - Heidelberg

Funding & Sponsors
Funding source category [1] 298959 0
Name [1] 298959 0
Austin Medical Research Foundation
Address [1] 298959 0
145 Studley Rd, Heidelberg VIC 3084
Country [1] 298959 0
Funding source category [2] 298960 0
Name [2] 298960 0
Austin Emergency Department, Austin Hospital
Address [2] 298960 0
145 Studley Rd, Heidelberg VIC 3084
Country [2] 298960 0
Primary sponsor type
Dr Bronwyn Bebee
Austin Hospital, 145 Studley Rd, Heidelberg VIC 3084
Secondary sponsor category [1] 298176 0
Name [1] 298176 0
Austin Hospital
Address [1] 298176 0
145 Studley Rd, Heidelberg VIC 3084
Country [1] 298176 0

Ethics approval
Ethics application status
Ethics committee name [1] 299894 0
Austin Health Human Research Ethics Committee (HREC)14
Ethics committee address [1] 299894 0
145 Studley Road, Heidelberge VIC 3084
Ethics committee country [1] 299894 0
Date submitted for ethics approval [1] 299894 0
Approval date [1] 299894 0
Ethics approval number [1] 299894 0

Brief summary
Acute, non-traumatic, low back pain is one of the most common musculoskeletal complaints worldwide and affects people of all ages. Although the majority of these individuals present to a primary care provider for assessment and management of their pain, a large proportion present to the emergency department (ED), especially when conventional analgesia is not working. Research suggests that low back pain is one of the leading causes of ED visits worldwide. While simple analgesics, opioids and muscle relaxants are commonly used to provide relief, there is little evidence to support the efficacy of these treatments. Accordingly, the management of acute low back pain in the ED represents a real challenge to clinicians.
Cannabidiol (CBD), a major non-psychotropic constituent of Cannabis, has pharmacological actions as an anxiolytic, antipsychotic, antiemetic and anti-inflammatory. There are data indicating that CBD and its analogues may be beneficial for pain resulting from inflammation. In addition, CBD has considerable efficacy in managing the pain and spasm of patients with multiple sclerosis. Despite these data, no randomized, placebo-controlled trials have been undertaken to assess the utility of CBD for the treatment of acute back pain.
In this study, patients presenting to the Austin ED with a diagnosis of acute (or acute-on-chronic), non-traumatic, low back pain will be randomized to either a single dose of CBD or placebo. This will be as an adjunct to the standard ED medication regimen for this condition. A verbal numerical pain scale (range 0-10) will be used to record pain scores at triage and at 0, 30, 60 and 120 minutes post study drug administration and at ED discharge. Patients may be admitted to the short stay unit during their stay.
We hypothesize that, among patients presenting to the ED with acute, non-traumatic, low back pain, a single dose of oral CBD will result in lower pain scores on the VAS at 2 hours, with minimal adverse effects, as compared to placebo.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 81898 0
Dr Bronwyn Bebee
Address 81898 0
Austin Hospital, 145 Studley Rd, Heidelberg VIC 3084
Country 81898 0
Phone 81898 0
+61 3 9496 5000
Fax 81898 0
Email 81898 0
Contact person for public queries
Name 81899 0
Dr Bronwyn Bebee
Address 81899 0
Austin Hospital, 145 Studley Rd, Heidelberg VIC 3084
Country 81899 0
Phone 81899 0
+61 3 9496 5000
Fax 81899 0
Email 81899 0
Contact person for scientific queries
Name 81900 0
Dr Bronwyn Bebee
Address 81900 0
Austin Hospital, 145 Studley Rd, Heidelberg VIC 3084
Country 81900 0
Phone 81900 0
+61 3 9496 5000
Fax 81900 0
Email 81900 0

No information has been provided regarding IPD availability
Summary results
No Results