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Intermittent Naltrexone Among Polysubstance Users (Project iN)

This study has been completed.
National Institute on Drug Abuse (NIDA)
Information provided by (Responsible Party):
Glenn-Milo Santos, University of California, San Francisco Identifier:
First received: November 2, 2012
Last updated: December 12, 2014
Last verified: December 2014
Naltrexone, a µ-opioid receptor antagonist, is a promising agent for methamphetamine-using and binge-drinking men who have sex with men (MSM). Naltrexone has shown efficacy in reducing relapse to amphetamines and is FDA-approved for alcohol dependence. Oral naltrexone is inexpensive and has few toxicities but the standard daily regimen for naltrexone is problematic as patients forget to take the medication. Given the challenges in daily dosing, alternate regimen schedules have been proposed to increase efficacy and expand the population that may benefit from this pharmacologic agent. One approach is intermittent targeted administration of naltrexone, whereby individuals take the medication as-needed in anticipation of substance use or during periods of craving. Administration of naltrexone prior to exposure to amphetamines significantly attenuates craving and targeted naltrexone has shown efficacy in reducing heavy alcohol use. However, there have been no studies assessing intermittent targeted dosing of naltrexone among methamphetamine-using and binge-drinking MSM. Polysubstance use patterns are common among MSM, and studies among those who abuse more than one substance are urgently needed. The aims of this study are to determine whether targeted dosing of naltrexone is feasible, tolerable and acceptable among non-dependent methamphetamine-using and binge-drinking MSM.

Condition Intervention Phase
Drug: Intermittent Oral Naltrexone
Drug: Placebo
Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention

Resource links provided by NLM:

Further study details as provided by University of California, San Francisco:

Primary Outcome Measures:
  • Feasibility [ Time Frame: proportions eligible and enrolled assessed on ongoing basis throughout the study, proportion of visits completed assessed bi-weekly for each participant; overall retention assessed over 2 month follow-up for each participant ]
    Proportion of persons screened who are eligible and enrolled; proportion of scheduled study visits completed; final retention by study arm.

  • Tolerability [ Time Frame: at each bi-weekly visit throughout the 2 month follow-up for each participant ]
    Comparison of adverse events in the naltrexone and placebo arms.

  • Acceptability [ Time Frame: adherence assessed daily through electronic monitoring, pill count and self-report assessed at bi-weekly visits over the course of 2 month follow-up ]
    Adherence to naltrexone and placebo, as determined via electronic monitoring device (WisePill) data, pill count, and self-report.

Secondary Outcome Measures:
  • Methamphetamine use and drinking outcomes [ Time Frame: assess at baseline, month 1 and month 2 visits ]
  • Sexual Behaviors [ Time Frame: assessed at baseline, month 1 and 2 visits ]

Enrollment: 30
Study Start Date: May 2013
Study Completion Date: November 2014
Primary Completion Date: October 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Naltrexone
Intermittent oral naltrexone to be taken on an as-needed basis for 8 weeks.
Drug: Intermittent Oral Naltrexone
Placebo Comparator: Placebo
Intermittent oral placebo to be taken on an as-needed basis for 8 weeks
Drug: Placebo


Ages Eligible for Study:   18 Years to 70 Years   (Adult, Senior)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  1. male gender or transgender male-to-female
  2. self-reported anal sex with men in the prior six months while under the influence of meth and/or alcohol
  3. self-reported meth use at least bi-weekly in the prior three months
  4. at least weekly binge drinking (five or more drinks on a single drinking session) in the prior three months

4) interested in reducing meth use and/or binge drinking 5) HIV-negative by rapid test or medical record of HIV infection 6) no current acute illnesses requiring prolonged medical care 7) no chronic illnesses that are likely to progress clinically during trial participation 8) able and willing to provide informed consent and adhere to visit schedule 9) age 18-70 years 10) baseline complete blood count (CBC), total protein, albumin, glucose, alkaline phosphatase, creatinine, blood urea nitrogen (BUN), and electrolytes without clinically significant abnormalities as determined by study clinician in conjunction with symptoms, physical exam, and medical history

Exclusion Criteria:

  1. any psychiatric (e.g., depression with suicidal ideation) or medical condition that would preclude safe participation in the protocol
  2. known allergy or previous adverse reaction to naltrexone
  3. current use of or dependence on any opioids or a known medical condition which currently requires or may likely require opioid analgesics
  4. opioid-positive urine test at enrollment
  5. current cluster of differentiation 4 (CD4) count < 200 cells/mm3
  6. moderate or severe liver disease (aspartate aminotransferase, alanine aminotransferase, or total bilirubin > 3 times upper limit of normal)
  7. impaired renal function (creatinine clearance < 60 ml/min)
  8. currently participating in another research study
  9. meth or alcohol dependence as determined by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (SCID) criteria
  10. any condition that, in the principal investigator and/or study clinician's judgment interferes with safe participation or adherence to study procedures.
  11. unwillingness to provide minimum locator for information
  12. not having a cellular phone that can send or receive a text message
  13. plans to leave the Bay Area during study follow-up
  14. not comfortable speaking and reading English, enough to participate in a program in English
  Contacts and Locations
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Please refer to this study by its identifier: NCT01723384

United States, California
San Francisco Department of Public Health, Substance Use Research Unit
San Francisco, California, United States, 94102
Sponsors and Collaborators
University of California, San Francisco
National Institute on Drug Abuse (NIDA)
Principal Investigator: Glenn-Milo Santos, PhD University of California, San Francisco
Study Director: Jason Euren, MA San Francisco Department of Public Health
  More Information

Responsible Party: Glenn-Milo Santos, Assistant Professor, University of California, San Francisco Identifier: NCT01723384     History of Changes
Other Study ID Numbers: 12-09809
R36DA035109-01 ( US NIH Grant/Contract Award Number )
Study First Received: November 2, 2012
Last Updated: December 12, 2014

Keywords provided by University of California, San Francisco:
sexual behavior

Additional relevant MeSH terms:
Narcotic Antagonists
Physiological Effects of Drugs
Sensory System Agents
Peripheral Nervous System Agents processed this record on April 28, 2017