The relationship of pain intensity and opioid craving with delayed methadone dose: A preliminary study of individuals with opioid use disorder.

AIMS: Despite a strong theoretical link between opioid craving and pain, little is known about the temporal relationship between pain and craving and the acute experience of pain in the context of methadone treatment. Using a cross-over design, the current study evaluated the time course of pain and craving and objective experience of pain as a function of the last methadone dose. METHODS: Participants (n = 20) presented for the study in the morning and either received methadone dose as scheduled or delayed dose until the afternoon. During the 4-h study visit, participants completed a series of tasks, including repeated assessment of pain and craving at 0, +40, +70, +130, +160 and +240 min and a cold pressor test (CPT) at +15 and +220 min. RESULTS: Separate mixed model results demonstrated no effect of dosing condition on craving; however, there was a significant dosing condition by time interaction (F(5,209) = 3.38, P = .006) such that pain increased over time in the delayed methadone condition but decreased in time in the scheduled methadone condition. A mixed model predicting self-reported pain revealed a three-way interaction between dosing condition, craving and time (F(5,197) = 2.39, P = .039) explained by a positive association between craving and pain at each time point (except 240 min) in delayed condition (P-range = .004-.0001). A separate mixed model on CPT data indicated a significant condition by time interaction such that pain threshold decreased in the delayed, but not scheduled, condition (F(1,57) = 4.01, P = .050). CONCLUSIONS: These preliminary findings highlight the potential for increased risks after even a short delay in receiving a methadone dose.

Delta-9-tetrahydrocannabinol modulates pain sensitivity among persons receiving opioid agonist therapy for opioid use disorder: A within-subject, randomized, placebo-controlled laboratory study.

The opioid and cannabinoid receptor systems are inextricably linked-overlapping at the anatomical, functional and behavioural levels. Preclinical studies have reported that cannabinoid and opioid agonists produce synergistic antinociceptive effects. Still, there are no experimental data on the effects of cannabinoid agonists among humans who receive opioid agonist therapies for opioid use disorder (OUD). We conducted an experimental study to investigate the acute effects of the delta-9-tetrahydrocannabinol (THC) among persons receiving methadone therapy for OUD. Using a within-subject, crossover, human laboratory design, 25 persons on methadone therapy for OUD (24% women) were randomly assigned to receive single oral doses of THC (10 or 20 mg, administered as dronabinol) or placebo, during three separate 5-h test sessions. Measures of experimental and self-reported pain sensitivity, abuse potential, cognitive performance and physiological effects were collected. Mixed-effects models examined the main effects of THC dose and interactions between THC (10 and 20 mg) and methadone doses (low-dose methadone defined as <90 mg/day; high dose defined as >90 mg/day). Results demonstrated that, for self-reported rather than experimental pain sensitivity measures, 10 mg THC provided greater relief than 20 mg THC, with no substantial evidence of abuse potential, and inconsistent dose-dependent cognitive adverse effects. There was no indication of any interaction between THC and methadone doses. Collectively, these results provide valuable insights for future studies aiming to evaluate the risk-benefit profile of cannabinoids to relieve pain among individuals receiving opioid agonist therapy for OUD, a timely endeavour amidst the opioid crisis.

Integrating cognitive bias modification for pain and opioid cues into medication for opioid use disorder clinical care: Feasibility, acceptability, and preliminary results.

BACKGROUND: Despite high co-occurrence, chronic pain is often unaddressed in treatment for opioid use disorder (OUD) and little is known about mechanisms that may underlie associations between pain and opioid use. Using an attentional bias (AB) task with both pain and opioid cues, we evaluated a cognitive bias modification (CBM) task administered during regularly scheduled medications for OUD (mOUD) dosing visits. The current study evaluated the feasibility, acceptability, and preliminary efficacy of the CBM task. Outcomes for AB tasks used traditional mean-based score and trial-level bias scores (TLBS). METHODS: In a double-blind, randomized controlled trial, 28 individuals with OUD and chronic pain engaged in mOUD were randomized to either CBM or an AB control condition and completed up to three tasks per week for four weeks. Standard AB task was completed at baseline and post-treatment. Participants completed feasibility and acceptability measures, and preliminary efficacy (i.e., change in AB) was assessed using ANOVA models. RESULTS: Participants attended 83.3% of scheduled sessions and generally reported the task was enjoyable, credible, and easy to complete. Preliminary results demonstrated a condition by time interaction highlighting a reduction in AB in the CBM group but not the control group in opioid TLBS variability (F[1,26]=5.01, p = .034) and pain TLBS towards (F[1,26]=6.42, p = .018) and pain TLBS variability (F[1,26]=5.24, p = .03). CONCLUSIONS: The current study supports integrating brief, computer-based tasks designed to reduce AB into mOUD clinical care. The preliminary results suggest that TLBS outcomes may be more sensitive to capture changes in AB; however, larger studies are required.

Development of pulsed intravenous nicotine infusions as a model for inhaled nicotine in humans.

RATIONALE: Although nicotine from cigarettes is delivered in puff-sized amounts, most preclinical and human intravenous (IV) nicotine studies have used bolus or continuous infusions. OBJECTIVES: To determine the feasibility of a pulsed-nicotine infusion model in smokers. METHODS: Following overnight abstinence, 12 adult smokers underwent 5 laboratory sessions. Using a crossover design, in each session, participants were assigned to 1 of 5 conditions: (1) high/fast: 1.0 mg nicotine delivered over 5 pulsed-infusions, then 15 saline infusions; (2) high/slow: 1.0 mg nicotine delivered over 20 pulsed-infusions; (3) low/fast: 0.2 mg nicotine delivered over 5 pulsed-infusions, then 15 saline infusions; (4) low/slow: 0.2 mg nicotine delivered over 20 pulsed-infusions; and (5) placebo: Saline delivered over 20 pulsed-infusions. Subjective drug effects, urges to smoke, nicotine withdrawal, and cognitive performance were measured in each session. RESULTS: Both the high/fast and high/slow conditions were associated with greater "head rush" and "high" (p < 0.05). The high/fast condition also provided greater suppression of urges to smoke and nicotine withdrawal (p < 0.05), indexed by the Questionnaire of Urges to Smoke-Brief, and the Minnesota Nicotine Withdrawal Scale, respectively. The high/fast and high/slow conditions produced greater increases in heart rate (p < 0.01) than saline. Finally, there were no main effects of dosing conditions on cognitive performance, indexed by the continuous performance test. CONCLUSIONS: These findings demonstrate the feasibility of pulsed-nicotine infusions to model nicotine delivery by smoking. This model could inform future studies testing novel smoking cessation therapies and tobacco regulatory studies testing the impact of nicotine reduction approaches.