Intermittent Oral Naltrexone Enhanced With an Ecological Momentary Intervention for Methamphetamine-using MSM

October 10, 2025 updated by: Glenn-Milo Santos

The ION+EMI Study: Intermittent Oral Naltrexone Enhanced With an Ecological Momentary Intervention for Methamphetamine-using MSM

This is a double-blind, placebo-controlled phase 2b trial in which 54 MSM who use meth will be randomly assigned (2:1) to receive 12 weeks of as-needed intermittent oral naltrexone 50 mg enhanced with an EMA-informed EMI platform, or receive as-needed placebo with EMA-informed EMI. The 12-week treatment period is consistent with other pharmacotherapy trials for substance use disorders. The proposed sample size is also consistent with other phase 2b trials for substance use treatment. Upon enrollment, participants will complete daily EMA assessments and weekly visits for behavioral surveys and urine testing for meth metabolites, study drug dispensing and computer-based counseling for substance use. Safety laboratory assessments and vital signs will be completed monthly. Efficacy (Specific Aims 1-3) will be assessed upon trial completion as measured by proportion meth-positive urine samples; PrEP and ART adherence by drug levels and viral load testing; and sexual risk behavior data accounting for PrEP use and viral suppression.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Methamphetamine (meth) use is very common among men who have sex with men (MSM), particularly MSM living with HIV. Meth use among HIV-negative and HIV-positive MSM is up to 13 and 34 times more prevalent than in the general U.S. adult population, respectively. Meth use is independently associated with HIV-related sexual risk behaviors among MSM and can function as a barrier to antiretroviral therapy (ART) and pre-exposure prophylaxis (PrEP) adherence. Thus, effective interventions to reduce meth use may also function as an important HIV prevention and care intervention by reducing meth-related HIV risk behavior, and optimizing ART and PrEP adherence. MSM comprise two-thirds of the new infections in the United States. Despite this continued domestic HIV epidemic and the high prevalence of meth use among MSM, few interventions have proven efficacious for MSM who use meth. The investigators seek to address this gap by evaluating the efficacy of intermittent oral naltrexone enhanced with an ecological momentary intervention (ION+EMI) for meth use treatment. Naltrexone, a µ-opioid receptor antagonist, is a promising agent for MSM who use meth. Meth is rapidly metabolized to amphetamine in the bloodstream and daily naltrexone has shown efficacy in reducing amphetamine urine-positivity and relapse. Oral naltrexone is inexpensive and has few toxicities, but the standard daily regimen for naltrexone hampers compliance as patients frequently neglect to take the medication. Alternate regimen schedules have been proposed to increase efficacy and expand the population that may benefit from this pharmacologic agent. One alternative approach is the targeted administration of intermittent oral naltrexone (ION), whereby individuals are instructed to take the medication as needed in anticipation of substance use, after exposure to triggers of substance use, or during periods of craving. Administration of naltrexone prior to exposure to amphetamines significantly attenuated amphetamine craving in 4 trials. Additionally, emerging evidence suggests that ecological momentary interventions (EMI) that respond to in-the-moment contexts can lead to positive health behaviors, such as increasing medication dosing. EMI are particularly well-suited to enhancing as-needed dosing of naltrexone because anticipation of meth use and meth craving in a natural setting changes within a person from moment to moment, and the detection of these momentary fluctuations can support the delivery of just-in-time messages to encourage medication use to prevent participants from proceeding from craving to meth use. A pilot study led by our research team on ION found that meth-using MSM who use at least 1 day per week had significantly greater reductions in meth-using days when treated with as-needed naltrexone, compared to placebo. Moreover, naltrexone participants had greater reductions in serodiscordant receptive anal intercourse and serodiscordant condomless receptive anal intercourse, compared to placebo. In the pilot, participants reported taking study drug 64% of the days that they craved or anticipated meth use. Participants also completed ecological momentary assessments (EMA) with a 74% response rate, indicating that real-time assessments are feasible and acceptable. To build on the results of this study and 4 other naltrexone trials, the investigators propose to evaluate intermittent naltrexone to treat meth in a phase 2b efficacy trial supplemented by an EMA-informed EMI that responds to a participant's real-time craving levels or anticipated meth use to provide in-the-moment medication reminders when participants would most benefit from naltrexone. The investigators hypothesize that pairing ION with EMI will further amplify reductions in meth use by providing just-in-time reminders for naltrexone to optimize adherence, thereby interrupting the progression from craving to meth use.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

  • Name: Janet M Ikeda, MA
  • Phone Number: 628-217-6204

Study Locations

  • United States
    • California
      • San Francisco, California, United States, 94102
        • San Francisco Department of Public Health

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 70 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • cisgender male (male gender and sex assigned at birth)
  • age 18-70 years* (naltrexone's tolerability and safety has been demonstrated among older adults up to age 70)
  • self-reported condomless anal sex with men or missing Pre-Exposure Prophylaxis or antiretroviral therapy doses due to meth use in the prior three months while under the influence of meth
  • self-reported meth use at least weekly
  • mild, moderate or severe meth use disorder
  • positive meth sample via sweat patch or urine testing during screening
  • interested in reducing meth use
  • no current acute illness requiring prolonged medical care
  • no chronic illness that is likely to progress clinically during trial
  • able and willing to provide informed consent and adhere to visit schedule
  • current CD4 count ≥ 200 cells/mm3; or CD4 count of 100-199 cells/mm3 and HIV viral load < 200 copies/mL (if living with HIV)
  • baseline complete blood count, total protein, albumin, glucose, alkaline phosphatase, creatinine, blood urea nitrogen test, and electrolytes without clinically significant abnormalities as determined by study clinician in conjunction with symptoms, physical exam, and medical history

Exclusion Criteria:

  • any psychiatric (e.g., depression with suicidal ideation) or medical condition that would preclude safe participation
  • known allergy or prior adverse reaction to naltrexone
  • current use of any opioids or a known medical condition which currently requires or may likely require opioid analgesics
  • opioid-positive urine test at screen/enrollment visits (naltrexone can induce opioid withdrawal)
  • moderate or severe liver disease (aspartate aminotransferase test, alanine aminotransferase test, or total bilirubin > 3 times upper limit of normal)
  • impaired renal function (creatinine clearance < 60 ml/min)
  • currently participating in another intervention research study with potential overlap
  • severe alcohol use disorder as determined by structured clinical interview for DSM-5 criteria
  • any condition that, in the PI and/or study clinician's judgment interferes with safe participation or adherence to study procedures

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Naltrexone with ecological momentary intervention
Naltrexone Hydrochloride, 50 mg., intermittent with ecological momentary assessment (EMA)
Drug: Naltrexone Hydrochloride
Intermittent Oral Naltrexone, 50 mg
Other Names:
  • ReVia
Behavioral: Ecological Momentary Intervention
Receive ecological momentary intervention if ecological momentary assessment reports meth craving, stress, not taking study drug, or antecedents detected for "high risk" meth use.
Other Names:
  • EMI
Placebo Comparator: Placebo with ecological momentary intervention
Placebo, intermittent with ecological momentary assessment (EMA)
Behavioral: Ecological Momentary Intervention
Receive ecological momentary intervention if ecological momentary assessment reports meth craving, stress, not taking study drug, or antecedents detected for "high risk" meth use.
Other Names:
  • EMI
Drug: Placebo
Intermittent Oral Placebo

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of People With Meth-positive Urine Tests at Weekly Visits
Time Frame: Every week from week 1 to the end of treatment at 12 weeks
As measured by the count of participants with meth-positive urine tests.
Every week from week 1 to the end of treatment at 12 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Mean in Sexual Risk Behaviors at Week 12
Time Frame: Past month behavior, measured at the end of treatment at 12 weeks
As measured by the mean number of sexual partners with whom they used meth, in the prior month, at week 12
Past month behavior, measured at the end of treatment at 12 weeks

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Adherent to PrEP or to Antiretroviral Medication
Time Frame: At the end of treatment at the 12-week visit
As measured by PrEP drug levels being detected in HIV negative participants (PrEP Adherent and viral suppression rates in HIV positive participants (Antiretroviral treatment adherent)
At the end of treatment at the 12-week visit

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Glenn-Milo Santos

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute on Drug Abuse (NIDA)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Glenn-Milo Santos, PhD, MPH, University of California, San Francisco

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 14, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2024

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 1, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 19, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 8, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 10, 2021

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 27, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 10, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
October 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 20-32912
  • R01DA053171 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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