Cannabidiol in Opioid Use Disorder and Chronic Pain

The SAFTEE is a multi-symptom checklist that has been used successfully in the investigators previous studies to assess and monitor any adverse events and possible side effects of study medications. It includes information regarding the severity of any presenting symptoms (0= none, 1= mild, 2= moderate, and 3= severe), as well as the course of action taken by the study staff in response. The SAFTEE is administered before the administration of CBD at baseline, (timepoint -30 minutes) and 4 hours after the administration of CBD (timepoint +240 minutes) during each test session. Data will be presented as the number of participants that reported symptoms on the SAFTEE.

The DEQ will be administered to assess the abuse potential of CBD. The DEQ is a 10-item questionnaire used to assess the subjective effects of psychoactive drugs. Each item is a visual analogue scale (VAS) ranging from 0-100. The questionnaire is used to measure whether a subject feels the drug "feels high", likes or dislikes the effects, and whether they want more of the drug. The primary DEQ outcome will be the Stimulatory Effects subscale, obtained by averaging participants responses to the items: "Feel High"; "Feel Stimulated"; and "Feel the Drug Strength".

The HVLT will be used to assess the cognitive effects of CBD. The primary outcomes will be immediate and delayed recall, which index verbal memory. The HVLT consists of a 12-item word list, composed of four words from each of the three semantic categories. The participant is instructed to listen carefully as the examiner reads the word list and attempt to memorize the words. The participants' free recall of the list is recorded. The same procedure is repeated for two more trials (immediate recall). After approximately 15 minutes the participant will be asked to recall as many words from the list as they can without the list being re-read to them (delayed recall).

The cognitive/psychomotor effects of CBD will be assessed using the Continuous Performance Test (CPT). CPT is a computerized neuropsychological assessment that measures participants sustained and selective attention. For the CPT, the primary outcome will be the throughput score, which indexes attention/working memory accuracy (i.e. percent of correct responses) and speed (i.e. reaction time).

Pain threshold and tolerance will be assessed using a comprehensive QST battery. This is a reliable, dynamic, and computerized method of quantifying distinct mechanisms of the pain experience. QST measures are sensitive to the effects of cannabinoids, important biomarkers of chronic pain, and predictors of the pain treatment response. Threshold: the temperature the participant first begins to feel pain (average pain threshold). Tolerance: the temperature when the participant can no longer tolerate the stimuli. The temperature ranges from 37° Celsius to 50° Celsius. A lower temperature represents a lower pain threshold/tolerance and a higher temperature represents a higher pain threshold/tolerance.

CPM indexes top-down pain inhibition, by leveraging the "pain inhibits pain phenomena". In CPM, a test stimulus is rated on a -100 to +100 Numeric Rating Scale (NRS) for pain both alone and during a concurrent conditioning stimulus applied elsewhere on the body. The CPM Score is the difference between these two ratings. CPM score is a Difference (Delta): Pain rating (test stimulus alone) - Pain rating (test stimulus with conditioning stimulus) Interpretation: Higher (more positive) values indicate greater pain inhibition.

TSP involves the repeated administration of noxious stimuli, indexing bottom-up pain facilitation. Therefore, TSP measures the increase in pain perception with repeated noxious stimuli, calculated as the area under the curve (AUC) of pain ratings over time during repeated stimulation. Higher TSP scores indicate worse outcomes (greater pain facilitation/central sensitization), while lower TSP scores indicate better outcomes (less pain facilitation/central sensitization). The TSP AUC values represent the cumulative pain experience during repeated stimulation (VAS units*seconds), where larger values reflect greater temporal summation of pain, which is associated with central nervous system sensitization and chronic pain conditions.

The pain VAS will be used by participants as a secondary rating scale for pain severity pain testing. This scale ranges from 0 to 100 and contains of a horizontal line, anchored by verbal descriptors of "no pain" and "pain as bad as it could be". Participants will place a vertical line at the point that best indicates their present pain.

The PCS is a 13-item self-report scale designed to measure negative thoughts and feelings associated with pain. Each item is rated on a 5-point scale: 0 (Not at all) to 4 (all the time). Total scores range from 0 to 52, with higher scores indicating greater catastrophizing. The PCS contains three subscales: magnification (scores ranging from 0-12), rumination (scores ranging from 0-16), and helplessness (scores ranging from 0-24).

The HCQ-SF-14 consists of 14 statements about the respondent's feelings and thoughts about using heroin as he or she is completing the questionnaire (i.e., right now). Each of the 14 items is scored on a scale from 1 (Strongly Disagree) to 7 (Strongly Agree). The HCQ-SF-14 score is obtained by adding the scores of all 14 statements and dividing the total by 14. Higher scores on the HCQ-SF-14 indicate a stronger craving for heroin. The HCQ-14 was administered before (+150 minutes) and after (+155 minutes) participants watched a cue-induced craving video. The difference of the two HCQ-14 scores (post - pre) will be used to index cue-elicited craving.

The SOWS is a 16-item, participant-administered questionnaire designed to rate the intensity of opioid withdrawal symptoms. It assesses symptoms on a 0-4 scale ("not at all" to "extremely"), with total scores of 1-10 indicating mild, 11-20 moderate, and 21-30 severe withdrawal.

The PANAS is a 20-item self-report questionnaire listing adjectives relating to Positive Affect (PA) (e.g., excited, inspired) and Negative Affect (NA) (e.g., distressed, afraid). Items are rated on a Likert scale ranging from 1 "Very slightly or not at all" to 5 "extremely". The PANAS yields separate PA and NA scores, each ranging from 10 to 50. Higher PA scores indicate more positive feelings, while higher NA scores indicate more negative feelings. These scores are used to track emotional states over time. The PANAS will be used to measure the effects of CBD on mood.

The investigator will explore if sex moderates the relationships hypothesized in the primary and secondary objectives.