The overarching hypotheses of this protocol are that (1) persistent brain glutamate changes induced by chronic opioid use will exacerbate use of cocaine during opioid physical dependence and withdrawal and (2) n-acetylcysteine (NAC) will ameliorate glutamatergic dysregulation, and thus will reduce both opioid and cocaine demand. These hypotheses will be tested with two specific aims. Specific Aim 1. Determine the reinforcing effects of cocaine in individuals with comorbid opioid and cocaine use disorder with physiological dependence on opioids during NAC maintenance. All subjects will be maintained on oral hydromorphone. They will also be randomly assigned to receive placebo or oral NAC (2.4 g/day), stratified by sex. After dose stabilization, experimental sessions will be conducted in which subjects complete hypothetical cocaine purchase tasks during opioid maintenance and opioid withdrawal. The hypotheses are: 1) cocaine purchasing will be greater during opioid withdrawal and 2) NAC maintenance will attenuate cocaine purchasing across opioid maintenance and withdrawal periods. Specific Aim 2. Evaluate glutamate functionality during periods of opioid maintenance and withdrawal in individuals with comorbid opioid and cocaine use disorder and physiological dependence on opioids during NAC maintenance. Subjects will undergo magnetic resonance spectroscopy to evaluate brain glutamate changes as a function of opioid maintenance/withdrawal state and NAC maintenance. The hypotheses are: 1) glutamate levels will be elevated during opioid withdrawal and 2) NAC maintenance will ameliorate elevated glutamate levels.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
24
Subjects will be randomized to receive 2.4 oral n-acetylcysteine daily.
Subjects will receive up to 192 mg oral hydromorphone daily.
Subjects will be randomized to receive placebo n-acetylcysteine daily.
Prior to some experimental sessions, subjects will receive placebo hydromorphone
University of Kentucky Laboratory of Human Behavioral Pharmacology
Lexington, Kentucky, United States
RECRUITINGUniversity of Kentucky Department of Behavioral Science
Lexington, Kentucky, United States
RECRUITINGHypothetical opioid purchasing
Amount of opioids purchased on a hypothetical purchase task
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
Hypothetical cocaine purchasing
Amount of cocaine purchased on a hypothetical purchase task
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
Glutamate function
Magnetic resonance spectroscopy of brain glutamate levels
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
Gamma Aminobutyric Acid (GABA) function
Magnetic resonance spectroscopy of brain GABA levels
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
Craving
Scores on a locally developed craving scale from 1-10, with higher scores indicating more craving
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
Subjective opioid withdrawal
Self-reported scores on the Subjective Opioid Withdrawal Scale with scores from 0-64, with higher scores indicating more withdrawal
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
Clinical opioid withdrawal
Self-reported scores on the Clinical Opioid Withdrawal Scale with scores from 0-48, with higher scores indicating more withdrawal
Time frame: After at least seven days of maintenance on n-acetylcysteine or placebo
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