Biased Opioid Agonists for Treatment of Opioid Withdrawal in OUD

Summary

Participation Requirements

Description

Background. Opioid-agonist medications (methadone and buprenorphine) are the most effective treatments available for opioid addiction. However, they are not effective in all cases, and with the vast number of people requiring treatment in the current crisis, even a modest increase in the percentage ...

Background. Opioid-agonist medications (methadone and buprenorphine) are the most effective treatments available for opioid addiction. However, they are not effective in all cases, and with the vast number of people requiring treatment in the current crisis, even a modest increase in the percentage of people who respond to treatment would represent a substantial benefit in public health. Recent advances in neuropsychopharmacology have led to the discovery of a new class of opioid agonists that are functionally selective. That is, they are biased towards specific post-receptor pathways and in theory can produce therapeutic opioid effects (analgesia, withdrawal relief) while minimizing side effects (sedation, respiratory depression) that can lead people to discontinue treatment with methadone or buprenorphine. Objective. Our goal is to assess the efficacy and tolerability of a biased opioid agonist for suppressing or reversing opioid withdrawal. Participant population. Adults who are physically dependent on opioids and already receiving chronic daily methadone treatment (up to 53 enrolled; up to 30 completers, plus three to run in an initial unpowered dose-finding pilot). Target enrollment will include 40% women and 60% minorities (mostly African-American), reflecting the demographics of the relevant local population. Experimental design. A double-blind within-subject randomized placebo-controlled experiment will be used to test whether a biased opioid agonist suppresses withdrawal when given about 52 h after discontinuing methadone. TRV734 (capsule form), a biased opioid agonist with good oral bioavailability, will be compared to placebo and to oxycodone (positive control) in matching capsules. A signal of efficacy and safety in the proposed laboratory study will be our cue to embark on a larger clinical trial. Methods. Participants will stay at the inpatient unit for 13-21 consecutive nights to help ensure that participants use no additional opioids during a 52-hr opioid abstinence period prior to each test session. The first three participants will be enrolled in an unpowered dose-finding five-session pilot study (18-26 consecutive nights) to test placebo, oxycodone, and a range of doses of TRV734, starting on the high side of the analgesic dose range. The highest dose that relieves withdrawal symptoms with no appreciable adverse effects will be used as the higher of two doses for the participants in the main study. To help demonstrate that TRV734 s effects are dose-related, we will also select a lower dose with withdrawal-relief efficacy intermediate between placebo and the higher dose. For participants in the main study, there will be four experimental sessions: one each with placebo, oxycodone, and the two doses of TRV734. Safety and research measures will be collected before (baseline) and for 4 hours after administration of study drugs. The participant s usual methadone dose will be administered after each session. Outcome measures: The primary outcome will be suppression of withdrawal symptoms, to be assessed by the SOWS (Subjective Opioid Withdrawal Scale). Secondary outcomes will include safety, specificity of effects (e.g., absence of psychomotor slowing), tolerability, and suppression of objective signs of withdrawal. Instruments used for these assessments will include the COWS (Clinical Opioid Withdrawal Scale), scales for opioid effects, psychomotor assessments, and differential dropout across sessions. We hypothesize that the higher dose of TRV734 will be superior to placebo in therapeutic effects and have lower adverse effects (including effects on alertness and psychomotor performance) compared to oxycodone.

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