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Completed

NCT Number: NCT00403117

Effects of a Range of Naltrexone Doses in Combination With Smoked Marijuana

The purpose of this study is to determine if the subjective effects of marijuana will be decreased by low-doses (< 25 mg) of naltrexone and increased by high-doses (> 50 mg) of naltrexone.

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Key information

Conditions

Marijuana Use Behavior Mental Disorders Substance-Related Disorders

Age range

21 year–45 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

About this study

Laboratory animal studies demonstrate that endogenous cannabinoids and opioids are closely inter-related. We have completed a series of studies in marijuana smokers showing that a clinically-utilized dose of naltrexone (50 mg) enhanced the reinforcing and subjective effects of orally-administered tetrahydrocannabinol (THC), while a low naltrexone dose (12 mg) blunted the effects of THC. A better understanding of the effects of a range of naltrexone doses in combination with smoked marijuana has important implications for the following reasons: (1) Alcohol- and opioid-dependent patients receive high doses of naltrexone (50-150 mg), which may increase the abuse liability of marijuana, (2) Low-dose naltrexone blunts THC's intoxicating effects, suggesting potential utility as a treatment medication for marijuana dependence. This study will determine if naltrexone (0, 12, 25, 50, 100 mg) administration 45 min prior to marijuana administration (0, 3.27% THC) alters marijuana's subjective, cognitive or physiological effects. Marijuana smokers will spend approximately 5h/day for a total of 10 days in the outpatient laboratory. Participants will visit the outpatient laboratory 2-3 times per week, with a minimum 48-hr interval between sessions to allow for naltrexone clearance. These data will provide important information regarding the clinical use of naltrexone.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Current marijuana use
  • Able to perform study procedures
  • 21-45 years of age
  • Women practicing an effective form of birth control

Exclusion criteria

  • Current, repeated illicit drug use (other than marijuana)
  • Presence of significant medical illness (e.g., diabetes, cardiovascular disease, hypertension, examination, laboratory hepatitis, clinically significant laboratory abnormalities, tests, 12-lead ECG, Mantoux test LFTs > 3x upper limit of normal)
  • History of heart disease
  • Request for drug treatment
  • Current parole or probation
  • Pregnancy or current lactation
  • Recent history of significant violent behavior
  • Previous adverse reaction to naltrexone
  • Major current Axis I psychopathology Psychiatric interview (e.g., major depressive disorder, bipolar disorder, suicide risk, schizophrenia)
  • Current use of any prescription or over-the-counter medication

Treatment and study plan

Placebo + Inactive Marijuana (0% THC)

Drug

One capsule containing placebo was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before marijuana administration.

Other names: treatment type 1

Placebo + Active Marijuana (3.27% THC)

Drug

One capsule containing placebo was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before administration of a marijuana cigarette containing 3.27% THC (ca. 800 mg) provided by the National Institute on Drug Abuse.

Other names: treatment type 2

Naltrexone 12 Mg+ Active Marijuana (3.27% THC)

Drug

One capsule containing 12mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before active marijuana administration.

Other names: Treatment type 3

Naltrexone 25 Mg + Active Marijuana (3.27% THC)

Drug

One capsule containing 12mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before active marijuana administration.

Other names: treatment type 4

Naltrexone 50 Mg+ Active Marijuana (3.27% THC)

Drug

One capsule containing 25mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before marijuana administration.

Other names: treatment type 5

Naltrexone 100 Mg+ Active Marijuana (3.27% THC)

Drug

One capsule containing 50mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before marijuana administration.

Other names: treatment type 6

Naltrexone 12 Mg + Inactive Marijuana (0% THC)

Drug

One capsule containing 12mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before inactive marijuana administration.

Other names: treatment type 7

Naltrexone 25 Mg + Inactive Marijuana (0% THC)

Drug

One capsule containing 25mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before inactive marijuana administration.

Other names: treatment type 8

Naltrexone 50 Mg + Inactive Marijuana (0% THC)

Drug

One capsule containing 50mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before inactive marijuana administration.

Other names: treatment type 9

Naltrexone 100 Mg + Inactive Marijuana (0% THC)

Drug

One capsule containing 100mg Naltrexone was administered to the participant in a size 00 opaque capsules with lactose filler 45 minutes before inactive marijuana administration.

Other names: treatment type 10

Primary outcomes

  1. Change in Mean Subjective Mood Scores as a Function of Marijuana Strength and Naltrexone Dose.

    Time frame: Baseline compared to 6 week timepoint

    All subjective effects were measured using visual analog scales (VAS), a series of 100 mm long lines labeled 'not at all' at one end (0 mm) and 'extremely' at the other end (100 mm). Participants were instructed to rate their subjective experiences on the line according to how they felt at that particular moment. Subjective assessments included measures of perceived marijuana strength, marijuana "high", "good effects" of marijuana, and how much marijuana was "liked".

    Marijuana's effects were determined by comparing the active and inactive marijuana conditions when paired with the placebo naltrexone condition (one comparison). Naltrexone's intrinsic effects were assessed by comparing placebo and each active dose of naltrexone (12, 25, 50, and 100 mg) under the inactive marijuana condition (four comparisons). Finally, the active marijuana- placebo naltrexone condition was compared to the active marijuana-active naltrexone conditions (four comparisons)

  2. Change in Mean Psychomotor Task Performance as a Function of Marijuana Strength and Naltrexone Dose

    Time frame: Baseline compared to 6 week timepoint

    Change in Digit Symbol Substitution Test (DSST) scores. Increasing scores indicate improvement, on a scale of 0-90.

    The task batteries included total correct attempts on a 3-min DSST.

  3. Change in Mean Heart Rate as a Function of Marijuana Strength and Naltrexone Dose.

    Time frame: Baseline compared to 6 week timepoint

    Change in mean heart rate as a function of marijuana and naltrexone dose

Sponsors and collaborators

Lead sponsor

New York State Psychiatric Institute

Other

Collaborators

  • National Institute on Drug Abuse (NIDA)
  • Research Foundation for Mental Hygiene, Inc.

Registry information

Official study title

Opioid Antagonism Enhances Marijuana's Effects in Heavy Marijuana Smokers

Important dates

Study start
2006
Primary completion
2008
Study completion
2010
First posted
Nov 23, 2006
Registry last updated
Mar 15, 2018

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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