Effect of Opioid Receptor Modulation on Alcohol Self-Administration and Neural Response to Alcohol Cues in Heavy Drinkers: Role of OPRM1 Gene Variation

  • End date
    Dec 31, 2023
  • participants needed
  • sponsor
    National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Updated on 20 October 2022
Accepts healthy volunteers



Drugs like nalmefene interfere with opioid receptors. This might reduce drinking. The gene OPRM1 determines opioid receptor functions. Researchers want to see if nalmefene affects people s responses to alcohol cues. They also want to compare how nalmefene affects people with different forms of OPRM1.


To test nalmefene s effects on alcohol self-infusion and responses to alcohol cues. To test the role of different forms of OPRM1 on these effects.


Healthy heavy drinkers ages 21 60:

Women: over 15 drinks weekly

Men: over 20 drinks weekly


Participants will be screened with:

Medical history

Physical exam

Heart, blood, and urine tests


Participants will have three 10-hour visits and one 2-hour follow-up visit. They will take a taxi. Visits are about 1 week apart.

Before visits, participants cannot drink alcohol for 1 day or take medicine for 3 days.

All study visits:


Heart monitor

Two-hour alcohol session: A needle guides a thin plastic tube into a vein in each arm. One tube receives alcohol. The other draws blood. Participants give themselves alcohol by pressing a button on a computer.

Relaxing at the center until breath alcohol falls below 0.02 percent, or for 3 hours.

Visits 2 and 3:

Swallowing nalmefene or placebo.

One-hour brain MRI: Participants lie on a table with a coil on their head. They press buttons in response to computer cues.

Follow-up visit: participants will discuss their drinking habits.


Previous studies have shown that the opioid receptor modulator nalmefene can reduce heavy drinking among alcoholics. Genetic variation at the micro-opioid receptor gene locus, OPRM1, specifically the A118G polymorphism, is associated with differential subjective responses to alcohol. Further, the A118G polymorphism has been shown to moderate the effect of opioid receptor modulators on alcohol consumption. However, the role of A118G on nalmefene s effectivenes, and the neural substrates underlying nalmefene s therapeutic effect remain to be explored in humans.

Objective: To evaluate the effect of nalmefene on alcohol self-infusion and neural response to alcohol cues in healthy male and female heavy drinkers, and to examine the role of the OPRM1 A118G polymorphism on this effect.

Study population: Participants will be 21-60 year-old male and female heavy drinkers in good health, as determined by medical history, physical exam, and ECG and lab tests. Participants with current Axis-I mood, anxiety or substance use diagnoses, except alcohol dependence, will be excluded. Participants will be divided into 2 genotypic groups: Group 1 (AA) will include participants homozygous for the major 118A allele (118AA genotype), and group 2 (GX) will include participants carrying 1 or 2 copies of the variant 118G allele (118AG or 118GG genotype).

Design: Participants will undergo 3 study sessions. In the first session, participants will complete an intravenous alcohol self-administration (IV-ASA) where they will have an open bar phase to determine their baseline level of alcohol consumption in the laboratory, as well as to obtain data on tolerability and subjective measures of alcohol effects. In the second and third sessions, participants will receive a single dose of either nalmefene or placebo, in counter-balanced order, before completing functional magnetic resonance imaging (fMRI) scans and IV-ASA procedures. The fMRI scans will include a task where participants will see cues that indicate the possibility of earning alcohol rewards to examine the neural substrates involved in processing alcohol cues, and a task designed to measure neural responses during anticipation and processing of aversive events. The difference in alcohol self-infusions between the two sessions will be compared between the two genotypic groups.

Outcome measures: The primary outcome measures are: (1) nalmefene-induced changes in IV alcohol self-administration; (2) nalmefene-induced BOLD signal changes in neural regions associated with alcohol reward processing, including ventral striatum, amygdala, and insula.;Secondary outcome measures include: (1) Nalmefene-induced BOLD signal changes in neural processing of aversive stimuli during fMRI; (2) Genotypic modulation (at the OPRM1 118 location) of nalmefene s effects on primary outcome measures (BOLD signal change during alcohol reward processing and IV alcohol self-administration).

Condition AUD
Treatment Placebo, Nalmefene
Clinical Study IdentifierNCT02639273
SponsorNational Institute on Alcohol Abuse and Alcoholism (NIAAA)
Last Modified on20 October 2022


Yes No Not Sure

Inclusion Criteria

Male and female participants between 21-60 years of age
Male participants must have consumed an average of greater than 14 standard drinks per
week, and females must have consumed an average of greater than 7 standard drinks per
week during the past 3 months [assessment: 90-day timeline followback (TLFB)completed
at screening visit]
In addition, participants must have on average at least 1 binge drinking day per week
during the last 90 days, defined as a day in which 4 or more standard drinks were
consumed for females and 5 or more standard drinks were consumed for males. Average
number of binge drinking days will be calculated based on total number of binge
drinking days from the TLFB (e.g., for 90 days worth of data, participants with a
total of 13 or more binge drinking days will be eligible)
Participants must be willing and able to refrain from using alcohol one day prior to
each study, and non-prescription medication for 3 days prior to each visit
[assessment: medical history]
Inclusion criteria for women
Use of adequate method of birth control during the study, if female is sexually
active and is not surgically sterilized. Adequate methods of contraception
include: use of oral contraceptives; use of barrier method of contraceptive; use
of an approved IUD or other long-acting reversible contraceptive (LARC); have a
male sexual partner who is surgically sterilized; or have exclusively female
sexual partner(s) [assessment: medical history]

Exclusion Criteria

Any regular or prescribed use of opioid analgesics in the past 3 months
Exclusion criteria for MRI
Current or prior history of major medical illness, including CNS, cardiovascular
Fear of enclosed spaces
respiratory, gastrointestinal, hepatic, renal, endocrine, or reproductive disorders
[assessment: clinically significant findings on medical history and physical exam
Exclusion criteria for women
ECG, laboratory tests]
Participation in any other pharmacological intervention study within 4 months prior to
Breast-feeding [assessment: medical history and physical exam]
the start of this study [assessment: medical history]
Positive hepatitis A, B Antigen, or C, or HIV test [assessment: laboratory test]
An aspartate transaminase (AST) / alanine transaminase (ALT) ratio 3 times greater
than the normal limit [assessment: laboratory test]
Diagnosis of Axis-I anxiety disorders or major depressive disorders in the past 12
months [assessment: SCID interview]
Lifetime diagnosis of Axis-I bipolar disorders or psychotic disorders [assessment
SCID interview]
Suicidal ideation in the past 6 months or suicidal behavior in the past 12 months
[assessment: Columbia Suicide Severity Rating Scale]
Current diagnosis of substance use disorder (SUD), other than alcohol use disorder
mild cannabis use disorder (less than 4 criteria), or current SUD in remission
Current smoking or nicotine dependence is not exclusionary [assessment: SCID-IV/SCID-5
interview, FTND]
Positive result on urine drug screen or breathalyzer test during screening. Positive
urine drug screen or breathalyzer reading during more than 1 study visit will result
in participant withdrawal from the study [assessment: laboratory tests and
breathalyzer test performed at screening or update visit under 14-AA-0181 most
proximal to enrollment]
Currently (i.e., at the time of screening) seeking treatment for alcohol problems or
have undergone inpatient or outpatient detoxification or treatment for alcohol
problems in the past 6 months. [assessment: medical history and physical exam]
Lactose intolerance or rare hereditary problems of galactose intolerance, Lapp lactase
deficiency, or glucose-galactose malabsorption [assessment: medical history and
physical exam]
Alcohol use
Current or prior history of alcohol-induced flushing reaction, including rapid
reddening of the face, rapid heart rate and breathing, and nausea after 1 or 2
drinks [assessment: medical history and physical exam, alcohol flushing
History of delirium tremens, hallucinations or seizures related to alcohol
withdrawal [assessment: medical history, CIWA-Ar, SCID interview]
Medication exclusion criteria
Use of prescription or OTC medications known to interact with alcohol within 2
weeks of the study. These include, but may not be limited to: isosorbide
nitroglycerine, benzodiazepines, warfarin, anti-depressants such as
amitriptyline, clomipramine and nefazodone, anti-diabetes medications such as
glyburide, metformin and tolbutamide, H2-antagonists for heartburn such as
cimetidine and ranitidine, muscle relaxants, anti-epileptics including phenytoin
and phenobarbital codeine, opioid analgesics including darvocet, percocet and
hydrocodone, cough-and-cold preparations which contain anti-histamines, pain
medicines and anti-inflammatories such as aspirin, ibuprofen, acetaminophen
celecoxib and naproxen
Use of medications known to inhibit or induce enzymes that metabolize alcohol for
weeks prior to the study. These include chlorzoxazone, isoniazid, metronidazole
and disulfiram
Use of drugs known to affect hemodynamic response. These include
antihypertensives, insulin and thyroid medications. [assessment: medical history
and physical exam]
Presence of ferromagnetic objects in the body that are contraindicated for MRI of
the head (including but not limited to pacemakers or other implanted electrical
devices, brain stimulators, some types of dental implants, aneurysm clips
metallic prostheses, permanent eyeliner, implanted delivery pump, or shrapnel
Inability to lie comfortable on back for up to 2 hours in the MRI scanner
[assessment: NIAAA MRI Safety Screening Questionnaire]
Pregnant [assessment: urine beta-hCG test at screening]. Women must also test
negative on urine beta-hCG test at the start of every study visit
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