Prescription Medication Interactions

Phase 1

Completed

• Conditions: Opioid Use; Sedative Use
• Interventions: Drug: Opioid Agonist; Drug: Sedatives

• Registration Number: NCT04315181
• Lead Sponsor: Sharon Walsh

Brief Summary

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.

Detailed Description

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.

Study Timeline

• Study Start: 2019-03-25
• Study First Submitted: 2020-03-17
• Study First Submitted QC: 2020-03-17
• Study First Posted: 2020-03-19
• Primary Completion: 2023-05-06
• Study Completion: 2023-05-06
• Results First Submitted: 2024-05-03
• Status Verified: 2024-06
• Results First Submitted QC: 2024-06-25
• Last Update Submitted: 2024-06-25
• Results First Posted: 2024-06-27
• Last Update Posted: 2024-06-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 11

Inclusion Criteria

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

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Exclusion Criteria

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

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Placebo / Placebo	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Placebo / Oxycodone 20mg	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Placebo / Oxycodone 20mg	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Placebo / Placebo	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Placebo / Oxycodone 40mg	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Placebo / Oxycodone 40mg	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 600mg / Placebo	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 600mg / Placebo	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 1200mg / Placebo	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 1200mg / Placebo	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 600mg / Oxycodone 20mg	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 1200mg / Oxycodone 20mg	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 1200mg / Oxycodone 20mg	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 600mg / Oxycodone 40mg	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 600mg / Oxycodone 40mg	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 1200mg / Oxycodone 40mg	Opioid Agonist	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 1200mg / Oxycodone 40mg	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.
Gabapentin 600mg / Oxycodone 20mg	Sedatives	Participants will receive non-therapeutic experimental doses of gabapentin (600 and 1200 mg, p.o.), alone and in combination with oxycodone (20 and 40 mg, p.o.). The experimental sessions are designed to capture the time-action curves for the test drugs (Tmax for gabapentin ≈ 2.5 hr; oxycodone ≈ 1.5 hr). Therefore, oxycodone will be administered 1 hr after gabapentin to align peak responses.

Primary Outcome Measures

Name	Time	Method
Change in Subject-Rated Outcome: Visual Analog Scale (VAS) Drug Liking	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 Outcome Measures

Name	Time	Method
Change in Subject-Rated Outcome: Visual Analog Scale (VAS) Drug Effect	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.
Change in Respiration Rate	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.
Change in End-tidal Carbon Dioxide (EtCO2)	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.
Change in Oxygen Saturation	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.

Trial Locations

Locations (1)

Center on Drug and Alcohol Research; 🇺🇸 Lexington, Kentucky, United States