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OpenTrials
Completed

NCT Number: NCT04315181

Prescription Medication Interactions

This study will examine the effects of doses of opioid/placebo and doses of sedative/placebo, alone and in combination. The primary outcomes are related to pharmacodynamic measures (subjective ratings of drug liking and other abuse-related effects; physiological outcomes) to determine the interaction effects of these compounds.

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Key information

Conditions

Opioid Use Sedative Use

Age range

18 year–55 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

Center on Drug and Alcohol Research

Lexington, Kentucky, 40508, United States

About this study

Gabapentin and oxycodone are commonly used in combination for the treatment of chronic pain. Gabapentin is now widely misused/abused with studies indicating that gabapentin abuse is especially common among individuals with opioid misuse. The nature of gabapentin's abuse-related effects have been described in case reports and online as sedative-like and opioid-like, with descriptive reports including sedation, euphoria, talkativeness and increased energy. Despite their widespread co-administration both for licit and illicit purposes, no controlled psychopharmacological studies to our knowledge have directly examined the effects of oxycodone (or another opioid agonist) and gabapentin in combination. This study's objective is to characterize the subjective effect profile of gabapentin, examine the interaction between gabapentin and oxycodone, and assess the acute analgesic response to gabapentin and oxycodone, alone and in combination, across a range of doses for each drug.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Healthy adults, ages 18-55
  • Current non-medical use of opioids and sedatives

Exclusion criteria

  • Physical dependence on opioids, alcohol, or benzodiazepines/sedatives/hypnotics
  • Seeking treatment for drug use
  • Significant medical problems

Treatment and study plan

Opioid Agonist

Drug

Abuse liability evaluation.

Sedatives

Drug

Abuse liability evaluation.

Primary outcomes

  1. Change in Subject-Rated Outcome: Visual Analog Scale (VAS) Drug Liking

    Time frame: This outcome was recorded prior to and in regular intervals after drug administration for the duration of the session (approx. 8 hours per session).

    Participants rated their subjective drug liking on a standardized VAS scale (0 to 100). Raw data transformed to peak scores. Higher scores indicate greater drug effects.

Secondary outcomes

  1. Change in Subject-Rated Outcome: Visual Analog Scale (VAS) Drug Effect

    Time frame: This outcome was recorded prior to and in regular intervals after drug administration for the duration of the session (approx. 8 hours per session).

    Participants rated their subjective drug effect on a standardized VAS scale (0 to 100). Raw data transformed to peak scores. Higher scores indicate greater drug effects.

  2. Change in Respiration Rate

    Time frame: Respiration rate was recorded prior to and in regular intervals after drug administration for the duration of the session (approx. 8 hours per session).

    Respiration rate (number of breaths per minute). Raw data transformed to trough scores. Lower scores indicate greater impairment.

  3. Change in End-tidal Carbon Dioxide (EtCO2)

    Time frame: EtCO2 recorded prior to and in regular intervals after drug administration for the duration of the session (approx. 8 hours per session).

    EtCO2 collected via capnograph monitored throughout each session. Raw data transformed to peak scores. Higher scores indicate greater impairment.

  4. Change in Oxygen Saturation

    Time frame: Oxygen saturation recorded prior to and in regular intervals after drug administration for the duration of the session (approx. 8 hours per session).

    Oxygen saturation (measured as a percentage through pulse ox) monitored throughout each session. Raw data transformed to trough scores. Lower scores indicate greater impairment.

Sponsors and collaborators

Lead sponsor

Sharon Walsh

Other

Collaborators

  • National Institute on Drug Abuse (NIDA)

Registry information

Official study title

Prescription Medications: Pharmacodynamics and Interaction Effects

Important dates

Study start
2019
Primary completion
2023
Study completion
2023
First posted
Mar 19, 2020
Registry last updated
Oct 20, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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