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

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).

- ELIGI. BILITY CRITERIA:

Participants will be healthy 21-60 year-old male and female heavy drinkers. An equal number
of participants with OPRM 118 AA genotype and those with 1 or 2 copies of the G allele (AG
or GG) will be enrolled. Inclusion and exclusion criteria will be evaluated following
screening conducted under the NIAAA screening protocol as described below

INCLUSION:

- Male and female participants between 21-60 years of age.

- Male participants must have consumed an average of greater than 20 standard drinks per
week, and females must have consumed an average of greater than 15 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:

- Current or prior history of major medical illness, including CNS, cardiovascular,
respiratory, gastrointestinal, hepatic, renal, endocrine, or reproductive disorders
[assessment: clinically significant findings on medical history and physical exam,
ECG, laboratory tests].

- Participation in any other pharmacological intervention study within 4 months prior to
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
questionnaire].

- History of delirium tremens, hallucinations or seizures related to alcohol
withdrawal [assessment: medical history, CIWA-Ar, SCID interview].

- Medication exclusion criteria:

- Any regular or prescribed use of opioid analgesics in the past 3 months.

- 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
4 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].

- Exclusion criteria for MRI:

- 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
fragments).

- Fear of enclosed spaces.

- Inability to lie comfortable on back for up to 2 hours in the MRI scanner
[assessment: NIAAA MRI Safety Screening Questionnaire].

- Exclusion criteria for women:

- 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.

- Breast-feeding [assessment: medical history and physical exam].